EA016839B1 - Compressible objects having a predetermined internal pressure combined with a drilling to form a variable density drilling mud - Google Patents

Abstract

A compressible object is described that may be utilized in drilling mud and with a drilling system to manage the density of the drilling mud. The compressible object includes a shell that encloses an interior region. Also, the compressible object has an internal pressure (i) greater than about 200 pounds per square inch at atmospheric pressure and (ii) selected for a predetermined external pressure, wherein external pressures that exceed the internal pressure reduce the volume of the compressible object and wherein the shell being designed to reduce localized strains of the compressible object during expansion and compression of the compressible object.

Description

FIELD OF THE INVENTION

The present invention generally relates to a method for intensifying drilling and production operations from underground formations. More specifically, the present invention relates to a method for selecting, manufacturing and using compressible objects with drilling fluid to form a variable density drilling fluid that minimizes or eliminates the number of different sized casing pipes used inside the borehole.

State of the art

This section is intended to familiarize the reader with various aspects of the technology that may be associated with exemplary embodiments of the present invention described and / or stated below. It seems that this discussion will be useful for communicating to the reader information in order to facilitate understanding of specific methods according to the present invention. Accordingly, it should be understood that these statements should be read in this perspective and not necessarily as a consideration of the prototype.

Hydrocarbons, such as oil and gas, have been produced for many years. To produce these hydrocarbons, a well is typically drilled at intervals with casing of varying diameters to reach the subterranean formation. Casing pipes are lowered into the borehole to prevent collapse of the walls of the borehole, to prevent unwanted flow of drilling fluid into the formation and / or to prevent fluid from entering the borehole. Typically, a casing installation process includes a trip, casing descent, and casing cementing. Because casing pipes at various intervals pass through already installed casing strings, the lower casing strings usually have smaller diameters. In this way, the casing strings form a telescopic configuration that passes with decreasing diameter in each of the subsequent intervals.

In addition to casing, drilling fluid circulates inside the borehole to remove cuttings from the borehole. The weight or density of the drilling fluid is typically maintained between the pore pressure gradient and the hydraulic fracture pressure gradient for drilling operations. However, the pore pressure gradient and hydraulic fracture pressure gradient increase as the actual vertical depth of the well increases, which is a problem for maintaining the weight of the drilling fluid. If the weight of the drilling fluid is less than the pore pressure gradient, an ejection may occur in the well. The discharge is the outflow of formation fluid into the borehole, which must be controlled to continue drilling operations. In addition, if the weight of the drilling fluid exceeds the pressure gradient of the hydraulic fracturing, the drilling fluid may leak into the formation. These losses in drilling fluid circulation result in the loss of large volumes of drilling fluid, which must be replenished to continue drilling operations. Accordingly, casing pipes are used to help maintain the weight of the drilling fluid within the range between the pore pressure gradient and the hydraulic fracture pressure gradient to continue drilling operations to great depths.

When underground formations are located at great depths, the costs and time associated with well formation increase. For example, with a telescopic configuration, the initial casing strings must be large enough to provide a borehole diameter of a predetermined value for the drilling tool and other devices near the subterranean formation. As a result, the diameter of the initial casing is relatively large to provide an applicable final borehole diameter.

A large diameter increases the cost of drilling operations, because the cost is associated with an increased size of casing, increased volume of cuttings that must be removed, and increased volume of cement and drilling fluid used to form the borehole. In essence, the cost of typical drilling operations can lead to the economic impossibility of developing some underground formations.

A variety of methods are used to reduce the diameter of the casing strings. For example, in drilling operations, a variable density drilling fluid may be used to maintain the drilling fluid within the range between the pore pressure gradient and the hydraulic fracture pressure gradient. As noted in International Patent Application Publication No. \ ¥ 0 2006/007347, the authors of 1οϊίζζοΐίί s1 a1., Compressible objects may include compressible or crumpled hollow objects of various shapes or structures. These are compressible objects that are selected to achieve optimal compression in response to changes in pressure and / or temperature. These compressible objects may be involved in recirculation as part of a variable density drilling fluid to provide volume changes that reduce the number of casing spacing in the borehole.

However, the use of compressible objects in a variable density drilling fluid can be promising. For example, compressible objects must be made to provide a certain degree of compression and be resilient. Further compressible objects should be designed for

- 1 016839 compression at certain pressures to provide volume changes at specific intervals within the borehole. In addition, drilling fluid that is combined with compressible objects can be selected to include certain additives to interact with compressible objects to improve a variable density drilling fluid. Essentially, there is a need for a method for selecting and manufacturing compressible objects for use in drilling fluids in the preparation of a variable density drilling fluid.

Other information may be found in at least US Pat. and publication of international patent application No. AO 2006/007347.

SUMMARY OF THE INVENTION

In one embodiment of the invention, a compressible object is provided comprising a shell that encloses an inner region in which the compressible object has an internal pressure of greater than 200 psi at atmospheric pressure and is selected for a given external pressure in which the external pressures that exceed internal pressure reduce the volume of the compressible object, while the shell is designed to compensate for local stresses in the compressible object during expansion and contraction of the compressible object. The internal pressure can also be more than 500 psi (3.445 MPa) at atmospheric pressure, more than 1500 psi (10.335 MPa) at atmospheric pressure or more than about 2000 psi (13.780 MPa) at atmospheric pressure. The internal pressure can vary from 200 psi (1,378 MPa) up to the tensile strength of the sheath material at atmospheric pressure in the range from 2,000 psi (13,780 MPa) up to the tensile strength of the sheath material atmospheric pressure and / or in the range of 1,500 psi (10.335 MPa) to 3500 psi (24.115 MPa) at atmospheric pressure.

In some embodiments, the compressible object may include a shell enclosing the inner region and having internal pressure. The shell may have a structure designed to compensate for local stresses on a compressible object during its expansion and contraction. Additionally or alternatively, compressible objects may include a shell enclosing the inner region and having a shell that experiences less deformation when the external pressure is almost equal to the internal pressure than when the external pressure is above or below a predetermined compression interval. Still further or alternatively, the shell may enclose an interior region that is at least partially filled with foam.

The compressible objects described above may include or be adapted according to any of the following characteristics or features. For example, in some embodiments, the compressible object may have the following: have an internal pressure higher than about 500 psi (3.445 MPa) at atmospheric pressure; a shell that experiences less deformation when the external pressure is almost equal to the internal pressure than when the external pressure is higher or lower than the internal pressure; a shell having one or more structural elements to reduce local stress, which may include a flange; the shell wall thickness, which varies within the surface of the compressible object to reduce local stress; the shell wall thickness, which is greater at the equator of a compressible object to reduce local stress; have an internal pressure higher than about 2000 psi (13.780 MPa) at atmospheric pressure, be an ellipsoid shaped object with a geometric aspect ratio between 2 and 5, when the external pressure is almost equal to the internal pressure; represent an object of the shape of an ellipsoid with a ratio of geometric dimensions in the range between 3 and 4, when the external pressure is almost equal to the internal pressure; have a shell with a ratio of equivalent diameter to wall thickness in the range from 20 to 200; have a shell with a ratio of equivalent diameter to wall thickness in the range of 50 and 100; have a shell comprising a stratified inorganic mineral as a reinforcement or as a gas-tight barrier in a polymer matrix, have a shell comprising a nanofiber reinforcement in a polymer matrix to achieve specific properties of the wall material; have a shell comprising a gas-tight barrier layer and a carrier layer; wherein the gas-tight barrier layer may include a metal or metal alloy layer formed on the inner or outer side of the carrier layer, and the carrier layer may include a polymer layer; have an equivalent diameter of the compressible object in the range between 0.1 and 50 mm when the external pressure is less than the internal pressure; have an equivalent diameter of the compressible object in the range between 0.1 and 5.0 mm when the external pressure is less than the internal pressure; include foam in the inner region, in which the foam includes one of homopolymers, polymer blends, copolymers, interpenetrating net structures, block copolymers, thermosetting polymers, amorphous polymers, crystalline polymers, chemically crosslinked copolymers, thermoplastic elastomers, rubbers, liquid crystal polymers and any combination thereof and / or have a structure with open or closed

- 2 016839 pores.

In a first alternative embodiment, a drilling fluid is described comprising compressible objects, wherein at least a portion of the compressible objects has an internal pressure of more than 200 psi at atmospheric pressure and is selected for a predetermined pressure in which the external pressures that exceed internal pressure reduce the volume of the compressible object and in which the shell is designed to compensate for local stresses in the compressible object during expansion and contraction of the compressible object . The drilling fluid includes drilling fluid in which the density of the drilling fluid changes due to a change in the volume of compressible objects in response to pressure changes as the drilling fluid and compressible objects circulate to the surface towards the mouth of the borehole.

In some embodiments, the compressible object may include a shell enclosing the inner region and having internal pressure. The shell may have a structure designed to compensate for local stresses on the compressible object during its expansion and contraction. Additionally or alternatively, the compressible objects may include a shell enclosing the inner region and able to experience less deformation when the external pressure is almost equal to the internal pressure than when the external pressure is above or below a predetermined compression interval. Additionally or alternatively, the shell may enclose an inner region that is at least partially filled with foam.

Drilling fluids within the scope of the present description described in the previous paragraph may provide a variety of features and / or characteristics. Exemplary options may include any one or more of these features or characteristics. For example, the present description includes drilling fluids in which gas compression within a compressible object controls the compression of a compressible object when the external pressure exceeds internal pressure, each of at least a portion of the compressible objects has an internal pressure above about 500 psi (3.445 MPa) at atmospheric pressure, compressible objects include the first part of compressible objects having a first internal pressure, and the second part of compressible objects having a second internal pressure different from the first internal pressure, and which may further include a third of compressible objects having a third internal pressure different from the first internal pressure and the second internal pressure, the equivalent diameter of the compressible object varies between 0.1 and 50 mm, such as between 0.1 and 5.0 mm, compressible objects include the first part of compressible objects having a first volume at atmospheric pressure, and the second part of compressible objects having a second volume at atmospheric pressure, different from the first volume, and which can complement flax includes a third part of compressible objects having a third volume at atmospheric pressure different from the second volume and the first volume, compressible objects include a first part of compressible objects having a first shape, and a second part of compressible objects having a second shape different from the first shape; each of the compressible objects has a shell capable of experiencing less deformation when the external pressure is approximately equal to the internal pressure than when the external pressure exceeds or less than the internal pressure, each of the compressible objects is able to compensate for the local stresses and instabilities of the compressible object during expansion and compression of the compressible object; each of the compressible objects has one or more structural elements to reduce local stress, which may include a flange; each compressible object has a shell, the wall thickness of which varies within the surface of the shell to reduce local stress; each compressible object has a shell whose wall thickness is greater at the equator of the compressible object to reduce local stress; each of the compressible objects has an internal pressure above about 2000 psi (13.780 MPa) at atmospheric pressure; each of the compressible objects is an ellipsoid shape object with a geometric aspect ratio in the range between about 2 and about 5 when the external pressure is almost equal to the internal pressure, preferably between about 3 and about 4 when the external pressure is almost equal to the internal pressure; each of the compressible objects has a shell with a ratio of equivalent diameter to wall thickness in the range from 20 to 200, preferably between 50 and 100; each of the compressible objects has a shell comprising a stratified inorganic mineral as a reinforcement or as a gas-tight barrier in a polymer matrix, while the shell may include nanofiber reinforcement in a polymer matrix to achieve specific properties of the wall material; each of the compressible objects has a shell comprising a gas-tight barrier layer and a carrier layer, the gas-tight barrier layer may be formed on the inner or outer side of the carrier layer and may include a metal or metal alloy layer, and the carrier layer may include a polymer layer; the drilling fluid further includes weighting agents for controlling the density of the drilling fluid and a plurality of compressible objects, which weighting agents may include one of barite, hematite, galena, and any combination thereof; the drilling fluid further includes formates for controlling the density of the drilling fluid in drilling fluid systems and reducing the addition of insoluble weighting agents capable of increasing the viscosity of the drilling fluid and compressible objects; compressible

- 3 016839 objects include foam in the inner region, including one of homopolymers, polymer blends, copolymers, interpenetrating network structures, block copolymers, thermosetting polymers, amorphous polymers, crystalline polymers, chemically crosslinked copolymers, thermoplastic elastomers, rubbers, liquid crystal polymers and any combination thereof; compressible objects have an open or closed pore structure.

In a second alternative embodiment, a method of drilling a well is described, comprising selecting compressible objects, each of which at least a portion has an internal pressure of greater than 200 psi (1.378 MPa) at atmospheric pressure, and is selected for a given external pressure in which external pressures that exceed internal pressure reduce the volume of the compressible object; selection of drilling fluid; introducing compressible objects into the drilling fluid to form a variable density drilling fluid, providing a density between the pore pressure gradient and the hydraulic fracturing pressure gradient for at least one well interval as the variable density drilling fluid circulates to the surface toward the wellhead; drilling a well with a variable density drilling fluid at the well site. Further, as soon as the well is formed, hydrocarbons can be extracted from it. In some embodiments, the compressible object may include a shell enclosing the inner region and having internal pressure. The shell may have a structure designed to compensate for local stresses on the compressible object during the expansion and contraction of the object. Additionally or alternatively, the compressible objects may include a shell enclosing the inner region and able to experience less deformation when the external pressure is almost equal to the internal pressure than when the external pressure is above or below a predetermined compression interval. Additionally or alternatively, the shell may enclose an inner region that is at least partially filled with foam.

Methods within the scope of the present description described in the previous paragraph can provide many signs and / or characteristics. Exemplary options may include any one or more of these features or characteristics. For example, the present description includes methods having the following features: compressible objects have an internal pressure above about 500 psi (3.445 MPa) at atmospheric pressure; each of the compressible objects has a shell capable of experiencing less deformation when the external pressure is approximately equal to the internal pressure than when the external pressure exceeds or is less than the internal pressure; each of the compressible objects includes a plurality of states having a first state at atmospheric pressure having a first volume, a second state inside a well having a second volume, and a third state inside a well having a third volume that is smaller than the first volume and larger than the second volume, and the internal pressure exerts less load on the walls of the compressible object in the third state than in the first state and second state; additional mixing of weighting agents in the drilling fluid to control the density of the drilling fluid and compressible objects; the compressible object has an internal pressure above about 1500 psi (10.335 MPa) at atmospheric pressure; each of the compressible objects has one or more structural elements to reduce local stresses, such as a flange; the compressible object is an ellipsoid shape object with a geometric aspect ratio in the range between 2 and 5, when the external pressure is almost equal to the internal pressure; the compressible object is an ellipsoid shape object with a ratio of geometric dimensions between 3 and 4 when the external pressure is almost equal to the internal pressure; each of the compressible objects has a shell with a ratio of equivalent diameter to wall thickness in the range from 20 to 200, preferably from 50 and 100; each of the compressible objects has a shell comprising a gas-tight barrier layer and a carrier layer, the gas-tight barrier layer may include a metal or metal alloy layer, and the carrier layer may include a polymer layer; additional combination of weighting agents with drilling fluid, while weighting agents include one of barite, hematite, galena, and any combination thereof; additional combination of formates with drilling fluid to control the density of drilling fluid and compressible objects in drilling fluid systems and to minimize the addition of insoluble weighting agents that can increase the viscosity of drilling fluid and compressible objects; compressible objects include foamed material in the inner region having one of homopolymers, polymer blends, copolymers, interpenetrating mesh structures, block copolymers, thermosetting polymers, amorphous polymers, crystalline polymers, chemically crosslinked copolymers, thermoplastic elastomers, rubbers, liquid crystal polymers and any combination those; compressible objects have an open or closed pore structure.

In a third alternative embodiment, a method for producing a variable density drilling fluid is described, comprising selecting compressible objects, each of which at least a portion has an internal pressure of greater than 200 psi (1.378 MPa) at atmospheric pressure, and is selected for a predetermined pressure of a well in which external pressures that exceed internal pressure reduce the volume of the compressible object; selection of drilling fluid to be combined with compressible objects; mixing compressible objects with drilling fluid

- 4 016839 for the formation of a variable density drilling fluid that maintains a density between the pore pressure gradient and the hydraulic fracture pressure gradient for at least one well interval as the variable density drilling fluid circulates to the surface towards the wellhead. In some embodiments, the compressible object may include a shell enclosing the inner region and having internal pressure. The shell may have a structure designed to compensate for local stresses on the compressible object during the expansion and contraction of the object. Additionally or alternatively, compressible objects may include a shell enclosing the inner region and having a shell that experiences less deformation when the external pressure is almost equal to the internal pressure than when the external pressure is above or below a predetermined compression interval. Still further or alternatively, the shell may enclose an inner region that is at least partially filled with foam.

Methods within the scope of the present description described in the previous paragraph can provide many features and / or characteristics. Exemplary options may include any one or more of these features or characteristics. For example, the present description includes methods characterized by the following features: compressible objects have an internal pressure above about 500 psi (3.445 MPa) at atmospheric pressure, such as above 1500 psi (10.335 MPa) at atmospheric pressure; the compressible object has a shell capable of experiencing less deformation when the external pressure is approximately equal to the internal pressure than when the external pressure exceeds or is less than the internal pressure; each of the compressible objects includes a plurality of states, including a first state at atmospheric pressure having a first volume, a second state inside a borehole having a second volume, and a third state inside a borehole having a third volume that is smaller than the first volume and large, than the second volume, and the internal pressure exerts less load on the walls of the compressible object in the third state than in the first state and second state; additional mixing of weighting agents in the drilling fluid to control the density of the drilling fluid and compressible objects; each of the compressible objects has one or more structural elements to reduce local stress, which may include a flange; each of the compressible objects is an ellipsoid-shaped object with a ratio of geometric dimensions between 2 and 5, when the external pressure is almost equal to the internal pressure, preferably between 3 and 4; each of the compressible objects has a shell with a ratio of equivalent diameter to wall thickness in the range from 20 to 200, such as in the range from 50 and 100; each of the compressible objects has a shell comprising a gas-tight barrier layer and a carrier layer, the gas-tight barrier layer may include a metal or metal alloy layer, and the carrier layer may include a polymer layer; additional combination of weighting agents with drilling fluid, while weighting agents include one of barite, hematite, galena, and any combination thereof; additional combination of formates with drilling fluid to control the density of drilling fluid and compressible objects in drilling fluid systems and to minimize the addition of insoluble weighting agents that can increase the viscosity of drilling fluid and compressible objects; compressible objects include foam in the inner region, including one of homopolymers, polymer blends, copolymers, interpenetrating mesh structures, block copolymers, thermosetting polymers, amorphous polymers, crystalline polymers, chemically crosslinked copolymers, thermoplastic elastomers, rubbers, liquid crystal polymers and any combination those; compressible objects have an open or closed pore structure.

In a fourth alternative embodiment, a borehole drilling system is described comprising a borehole, a variable density drilling fluid located in a borehole and having compressible objects and drilling fluid, each of at least a portion of the compressible objects having an internal pressure exceeding 200 pounds per square inch (1.378 MPa) at atmospheric pressure and selected for a given pressure in the well, and external pressures that exceed internal pressure reduce the amount of compressible EKTA. The system further includes a drill string located in the well, and bottom hole equipment connected to the drill string and located in the well. In some embodiments, the compressible object may include a shell enclosing the inner region and having internal pressure. The shell may have a structure designed to compensate for local stresses on the compressible object during the expansion and contraction of the object. Additionally or alternatively, the compressible objects may include a shell enclosing the inner region and able to experience less deformation when the external pressure is almost equal to the internal pressure than when the external pressure is above or below a predetermined compression interval. Alternatively, the shell may enclose an interior region that is at least partially filled with foam.

Systems within the scope of the present description described in the previous paragraph can provide many features and / or characteristics. Exemplary options may include any one or more

- 5 016839 such signs or characteristics. For example, the present description includes systems characterized by the following features: each of the plurality of compressible objects has an internal pressure above about 500 psi (3.445 MPa) at atmospheric pressure, such as above 1500 psi (10.335 MPa) or higher 2,000 psi (13,780 MPa); compressible objects include a first part of compressible objects having a first internal pressure and a second part having a second internal pressure different from the first internal pressure, and which may further include a third part having a third internal pressure different from the first internal pressure and the second internal pressure ; compressible objects include a first part of compressible objects having a first volume on the surface of the well and a second part having a second volume on the surface of the well other than the first volume, and which may further include a third part having a third volume on the surface of the well other than the second volume and the first volume; compressible objects include a first part of compressible objects having a first shape and a second part having a second shape different from the first shape; each of the compressible objects has a shell capable of experiencing less deformation when the external pressure is approximately equal to the internal pressure than when the external pressure exceeds or is less than the internal pressure; each of the compressible objects is able to compensate for local stresses and instabilities of compressible objects during the expansion and compression of compressible objects; each of the compressible objects has one or more structural elements to reduce local stress, which may include a flange; each of the compressible objects has a shell with a thickness that varies within the shell surface to reduce local stress and is the largest at the equator of the compressible object; each of the compressible objects is an ellipsoid shape object with a geometric aspect ratio in the range between 2 and 5, when the external pressure is almost equal to the internal pressure, preferably between 3 and 4; each of the compressible objects has a shell with a ratio of equivalent diameter to wall thickness in the range from 20 to 200, preferably from 50 and 100; each of the compressible objects has a shell comprising a stratified inorganic mineral as a reinforcing material or as a gas-tight barrier in a polymer matrix; the sheath includes nanofiber reinforcement in a polymer matrix to achieve specific properties of the wall material; each compressible object has a shell comprising a gas-tight barrier layer and a carrier layer, the gas-tight barrier layer may be formed on the outer or inner side of the carrier layer and may include a metal or metal alloy layer, and the carrier layer may include a polymer layer; the drilling fluid further includes weighting agents to control the density of the drilling fluid and a variety of compressible objects, while the weighting agents may include one of barite, hematite, galena, and any combination thereof; the drilling fluid further includes formates for controlling the density of the drilling fluid in drilling fluid systems and reducing the addition of insoluble weighting agents capable of increasing the viscosity of the drilling fluid and compressible objects; compressible objects include foam in the inner region, including one of homopolymers, polymer blends, copolymers, interpenetrating mesh structures, block copolymers, thermosetting polymers, amorphous polymers, crystalline polymers, chemically crosslinked copolymers, thermoplastic elastomers, rubbers, liquid crystal polymers and any combination those; compressible objects have an open or closed pore structure.

A method for manufacturing compressible objects is further described, including selecting a structure for the compressible object; the choice of the wall material of the compressible object, the manufacture of a compressible object with a shell having an inner region and an internal pressure greater than 200 psi (1.378 MPa) at atmospheric pressure and selected for a given external pressure, while external pressures that exceed internal pressure , reduce the amount of compressible object. Internal pressure can range from 200 psi (1.378 MPa) up to the tensile strength of the sheath material at atmospheric pressure, up to 2000 psi (13.780 MPa) up to the tensile strength of the sheath material at atmospheric pressure, and / or in the range from 1500 psi (10.335 MPa) to 3500 psi (24.115 MPa) at atmospheric pressure.

In some embodiments, the method includes preparing a chamber having a first pipe located inside the second pipe; the formation of a polymer bubble of polymer material in the second pipe and gas in the first pipe; exposing the outer surface of the polymer bubble to a crosslinking liquid to form a compressible object; removing cross-linking liquid after curing the compressible object, in which the compressible object has an internal pressure of more than 200 psi (1.378 MPa) at atmospheric pressure and is selected for a given external pressure, while external pressures that exceed the internal pressure reduce the amount of compressible object.

Additionally or alternatively, the method includes manufacturing a device having a lower chamber with a nozzle for introducing gas, and an upper chamber with a nozzle for introducing liquid and a nozzle for discharging liquid, wherein the plate having perforations separates the nozzle for introducing gas

- 6 016839 from nozzles for fluid inlet and fluid outlet; placement of the polymer sheet on the plate; creating pressure in the lower chamber to achieve a pressure higher than in the upper chamber; the formation of compressible objects from a polymer sheet in which each of the compressible objects has a shell forming an inner region and an internal pressure greater than about 200 psi at atmospheric pressure, and is selected for a given external pressure, with external pressures which exceed internal pressure reduce the volume of the compressible object.

Additionally or alternatively, the method may include preparing foamed matrices; applying a coating of metallic material to the foam matrices; firing metal-coated foam matrices to form compressible objects. The compressible object may have a shell forming an inner region and an internal pressure of greater than about 200 psi (1.378 MPa) at atmospheric pressure and selected for a given external pressure, while external pressures that exceed the internal pressure reduce the amount of compressible object.

In other embodiments, the method may include preparing a foamed matrix; coating the foam matrix with a pigment layer; placing the pigment-coated foam matrix in a gas filled reactor; irradiating the pigment-coated foam matrix in a reactor to form a metal-coated foam matrix; coating firing a metal-coated foam matrix to form compressible objects. In addition, the compressible object may have a shell that encloses the inner region and has an internal pressure greater than about 200 psi (1.378 MPa) at atmospheric pressure and selected for a given external pressure, with external pressures that exceed the internal pressure, reduce the amount of compressible object.

Brief Description of the Drawings

The above and other advantages of the present method may become apparent after reading the following detailed description and with reference to the drawings, in which FIG. 1 is an illustration of an example drilling system in accordance with certain aspects of the present technology;

FIG. 2Ά-2Ό — exemplary diagrams and embodiments of a compressible object in accordance with aspects of the present technology;

FIG. 3A-3C are exemplary embodiments of a compressible object in various states in accordance with aspects of the present technology;

FIG. 4 is an exemplary diagram of variously designed compressible objects in accordance with aspects of the present technology;

FIG. 5 is an exemplary block diagram of the selection and application of a variable density drilling fluid for the drilling system of FIG. 1 in accordance with certain aspects of the present technology;

FIG. 6 is an exemplary block diagram of the selection and manufacture of compressible objects for the block diagram of FIG. 5 in accordance with certain aspects of the present technology;

FIG. 7 is an exemplary graph regarding the shape of compressible objects in accordance with some aspects of the present technology;

FIG. 8Ά-8Β are exemplary embodiments of the manufacturing processes used in the block diagram of FIG. 6, in accordance with certain aspects of the present technology;

FIG. 9 is an exemplary flowchart of the manufacturing process used in the flowchart of FIG. 6, with compressible objects having a foam matrix, in accordance with some aspects of the present technology;

FIG. 10 shows exemplary embodiments of compressible objects made according to the block diagram of FIG. 9, in accordance with certain aspects of the present technology;

FIG. 11Ά-11Β are exemplary embodiments of the manufacturing processes used in the block diagram of FIG. 6, in accordance with certain aspects of the present technology;

FIG. 12Ά-12Ο are embodiments of a compressible object having a flange in accordance with certain aspects of the present technology;

FIG. 13 is an exemplary graph regarding the addition of a flange to a compressible object, in accordance with some aspects of the present technology.

Detailed description

In the following detailed description, the invention will be described in connection with its preferred embodiments. However, to the extent that the following description formulates a specific embodiment or specific application of the invention, this is intended to be illustrative only. Accordingly, the invention is not limited to the specific embodiments described below, but rather, the invention includes all alternatives, modifications, and equivalents falling within the true scope of the appended claims.

The present invention is directed to a method, composition and system for the selection, manufacture and use of compressible objects in a variable density drilling fluid. In particular, compressible objects can be used with drilling fluid to form a variable drilling fluid

- 7 016839 density for drilling operations in the well. Compressible objects and drilling fluid are selected to maintain the weight of the drilling fluid in the range between the pore pressure gradient and the pressure gradient of the hydraulic fracturing within the borehole. More specifically, according to the present methods, compressible objects have an internal pressure greater than about 200 psi (1.378 MPa) at atmospheric pressure, greater than about 500 psi (3.445 MPa) at atmospheric pressure, or more preferably greater than about 1,500 psi (10.335 MPa) at atmospheric pressure. Compressible objects can include compressible or crumpled hollow objects with various shapes, such as spheres, cubes, pyramids, flattened or oblong spheroids, cylinders, pads and / or other shapes or structures that are selected to achieve optimal compression in response to changes in pressure and / or temperature. In addition, as discussed below, compressible objects may include polymers, polymer composites, metals, metal alloys, and / or polymer or polymer-composite multilayer materials with metals or metal alloys, which are obtained in a variety of ways. Accordingly, various methods and systems are described for selecting and obtaining compressible objects. It should further be noted that the following methods and procedures are not limited to drilling operations, but can also be applied to well completion operations or any operations for which the use of variable density fluids is preferred.

In FIG. 1 illustrates an exemplary drilling system 100 in accordance with some aspects of the present technology. In drilling system 100, a drilling rig 102 is used to drill a well 104. Well 104 may extend into surface 106 to reach underground formation 108. Underground formation 108 may include a variety of rock layers, which may or may not include hydrocarbons, such as oil and gas , and may be referred to as zones or intervals. Essentially, well 104 can create fluid channels between the subterranean formation 108 and production equipment (not shown) located on surface 106. Production equipment can process hydrocarbons and transport hydrocarbons to consumers. However, it should be noted that the drilling system 100 is illustrated for illustrative purposes and the present technology may be applicable to circulating fluids in a borehole for any purpose, such as for performing drilling operations or extracting fluids from an underground field.

To reach the subterranean formation 108, the drilling rig 102 may include drilling components, such as a bottom hole assembly 110, drillstrings 112, casing strings 114 and 115, a drilling fluid processing unit 116 for processing a variable density drilling fluid, and other drilling control systems 118 borehole and production operations. Each of these drill components is used to form the borehole 104. The bottom of the drill string assembly 110 may include a drill bit and is used to extract rock from the formation, cement, or other materials from the borehole. The casing 114 and 115 may provide support and stability when deployed in the subterranean formation 108, which may include surface casing 115 and an intermediate or production casing 114. The production casing 114 may extend down to a depth close to the underground formation 108 or extend through it. The drilling fluid installation 116 may include equipment that can be used to prepare a variable density drilling fluid. For example, processing unit 116 may include vibratory mixers, separators, hydrocyclones, and other suitable devices (for example, as described in international patent application No. PCT / ϋδ 2007/003691, filed February 13, 2007).

During drilling operations, the use of variable density drilling fluid 118 as a drilling fluid allows the operator to drill deeper beneath surface 106, maintain sufficient hydrostatic pressure, prevent the influx of reservoir fluid (gas or liquid) and remain below the hydraulic fracture pressure gradient (EC ), which can withstand underground formation 108. As noted in the publication of patent application No. \ ¥ 0 2006/007347, the authors Ροϊίζζοΐίί c1 a1., which is given for information, the compressible objects may preferably have a compression ratio that is precisely adapted to create the weight of the drilling fluid, the value of which is in the range between the pore pressure gradient and the hydraulic fracture pressure gradient over the depth interval specified for drilling production. That is, the compressible objects should have essentially recoverable walls bearing the load and low gas permeability inside the compressible objects. The definition of substantially recoverable means that the accumulation of plastic deformation in the wall of the shell due to repeated cyclic loads on compressible objects between the surface and the bottomhole zone of the borehole does not cause significant damage to the load-bearing wall or a significant loss of internal gas pressure during repeated cycles (i.e., two or more cycles) as the well is drilled to a predetermined depth. In addition, the definition of low permeability means that the internal pressure in the compressible objects during operation remains

- 8 016839 within the allowable limits for a given period of time required to drill a borehole to a given depth.

While the addition of compressible objects to the drilling fluid to control the density of the drilling fluid depending on the depth was described in the publication of patent application No. \ ¥ About 2006/007347 by Ροϊίζζοΐΐί c1 a1., The design of compressible objects and the choice of drilling fluid to provide this functionality are difficult. In particular, repetitive compression cycles typically experienced by a variable density recirculating drilling fluid, within the limits of the mechanical properties of existing materials, may become limiting for compressible objects. As such, the manufacturing process of compressible objects may require consideration of a variety of factors that affect the durability and performance of compressible objects, as discussed further below.

First, it should be noted that large compression ratios are required to achieve the desired change in the density of the drilling fluid with a depth within the limits established by the maximum volume fraction of compressible objects, which are caused by the action of compressible objects on the rheological characteristics of the fluid, as described in publication No. \ ¥ О 2006/007347 . Accordingly, this compressible objects must be given certain properties, designed to provide large compression ratios and the beginning of compression within certain ranges or pressure levels. The compression ratio of a hollow object, which is one embodiment of compressible objects, may be limited by the value of the initial uncompressed volume (i.e., in an uncompressed or expanded state) divided by the volume occupied by the material including the shell wall, plus the volume of compressed gas inside the shell for the differential DR pressures for the discussed borehole interval. Large compression ratios are provided if the walls of the compressible objects are thin and flexible. Accordingly, the compressible objects can preferably be designed so that the compression and re-expansion of the compressible objects can occur without significant permanent deformation of the walls (i.e., permanent deformation leading to early fatigue failure of the walls of the compressible object).

In addition, a predetermined external pressure or compression depth and a predetermined compression interval of compressible objects can be precisely adapted to provide changes in the density of the drilling fluid at specific depths or close to those inside the borehole. Typically, the compression of an object that begins on the surface is of limited value. In these applications, compressible objects are compressed from the surface in a predetermined compression interval or range extending down to a certain depth. As a result, these compressible objects can be used in some specific applications for surface drilling, but may not be suitable for a deep water environment or deeper drilling intervals. To ensure density changes in excess of a specific predetermined pressure range for specific depths or external pressures, the starting depth and depth range for a given pressure range over which compression may occur is preferably controlled by compressible objects. For example, the initial internal pressure in a compressible object can be selected based on the depth at which a stepwise change in compressibility is desired. At depths in the drill string (i.e. drilling fluid inside the borehole), for which the pressure is lower than the initial internal pressure in the compressible objects, the change in the volume of the compressible objects is determined by the Young's modulus of the wall material and the pressure difference across the thickness of the wall material. At depths for which the pressure in the mud column exceeds the initial internal pressure, the change in the volume of compressible objects gradually begins to be controlled by the compressibility of the gas. That is, a predetermined compression interval is a pressure range from external pressure, which is approximately equal to the internal pressure in the compressible object, to external pressure, which essentially compresses the compressible object (i.e. compresses the compressible object to a compressed state, which is discussed further below) . Essentially, compressible objects can be made to begin to compress at a given pressure or close to it, or at a predetermined depth, and / or for a specific predetermined pressure range, so as to provide a change in density in specific parts or intervals of the borehole.

For compression at a certain depth, the walls of compressible objects can be designed to maintain a predetermined internal pressure. The initial internal pressure of compressible objects for a given mud density is determined by the depth at which the transition to gas compression is controlled by a change in the volume of compressible objects. Typically, an internal pressure of greater than about 200 psi (atmospheric pressure) greater than 500 psi may be used. inch (3.445 MPa) at atmospheric pressure greater than 1,500 psi inch (10.335 MPa) at atmospheric pressure or more preferably more than 2000 psi (13.780 MPa) at atmospheric pressure. For a given initial internal pressure, the achievable compression ratio of an object depends on the ratio of the wall thickness to the effective diameter of the compressible object. While the wall thickness is preferably as thin as possible, the lower limit of the wall thickness is determined by the minimum thickness capable of withstanding

- 9 016839 internal gas pressure at an external pressure of about 1 atm (0.101 MPa), which typically occurs on surface 106. Accordingly, a material with a tensile strength greater than 10,000 psi (68,900 MPa) can typically be used. ), as discussed below, to maintain the internal pressure for the compressible object. Essentially, the internal pressure can range from 200 psig (1,378 MPa) up to the tensile strength of the sheath material at atmospheric pressure, range from 2,000 psig (13,780 MPa) up to the tensile strength the rupture of the shell material at atmospheric pressure and / or in the range from 1500 psi (10.335 MPa) to 3500 psi (24.115 MPa) at atmospheric pressure.

Further, for a given internal pressure and the diameter of the compressible object, the minimum wall thickness that can be applied is therefore determined by the tensile strength of the tensile strength of the wall material. It is desirable to minimize wall thickness within these tensile strengths, since the ratio of the volume of the wall material to the total volume of the compressible object is adjusted to the upper limit of the achievable compression ratio, as noted above. Accordingly, while a compressible object may include many shapes, such as cubes, pyramids, flattened or oblong spheroids, cylinders, pads, for example, spherical and elliptical objects with spherical or close to spherical, inflated geometric shapes are applicable for reasons of optimization rheological characteristics of a compressible drilling fluid. Accordingly, the compressible objects may include elliptical and / or spherical objects, such as hollow metal spherical and elliptical objects under pressure, with a ratio of geometric dimensions (i.e., the ratio of large diameter to small diameter) in the range between about 1 and 5, to provide compression ratios up to 5: 1 or more.

The construction of a compressible object can be further complicated by structural instabilities. For example, a spherical object for a given internal pressure and diameter may be limited by structural instabilities characteristic of the architecture of the spherical object itself. Structural instabilities may include local stresses, such as the instability of equatorial protrusion during the swelling phase and the instability of creasing of the apex during the compression phase. Essentially, the design of the compressible object can also be designed to compensate or reduce local stresses and instabilities during the expansion and contraction of compressible objects. Accordingly, the modeling of a spherical object in finite element analysis is also discussed below, which may be one embodiment of a compressible object, as shown in FIG. 2Ά-2Ό.

FIG. 2Ά is an example diagram and embodiments of a compressible object. In diagram 200, a compressible object is an almost spherical object that has a geometric aspect ratio of about 1.0 and a wall thickness of 10 μm. The ratio of the geometric dimensions of an object is defined as the ratio of the major axis to the minor axis, which is discussed below.

In FIG. 2Ά shows a graph 200 of maximum strain 202 relative to the compression coefficient 204 of an elastic spherical object. The maximum strain 202 represents the largest strain at any point in the compressible object in this state. Graph 200, which is compiled using a finite element analysis program such as LBLriZ ™ TEL, includes a characteristic curve 206 of a spherical object in various states. As the characteristic curve 206 shows, in order to provide a compression ratio of at least 5: 1, an excess of linear elastic deformation of about 12% is required. Along the characteristic curve 206, the maximum elastic deformation does not develop evenly on the surface of the object during compression, but is localized due to instability of the protrusion during compression.

Specific examples of localized strain on an object are shown in FIG. 2B illustrating a partial view of an object 210, such as a spherical or elliptical object, subjected to compressive pressure that is external to the object. The elastic deformation of the object 210 during compression of the latter is controlled by the localization of stress associated with the instability of creasing of the tip, which is indicated by the flattened region 214. The instability of creasing of the tip is the indentation of the flattened region 214 due to the inability of the structure to withstand the external pressure applied to this region. In particular, regions 216 represent locations or zones of the most severe local deformation, which are fixed in the characteristic curve 206 in FIG. 2Ά. As shown, the severity of this instability increases with increasing wall thickness.

Based on the above discussion, the compressible object must have a tensile strength sufficient to withstand the internal pressure, and a reversible linear elongation or elastic deformation, large enough to withstand the required deformation. Assuming that the shell of a spherical or nearly spherical compressible object is metallic, the metal or metal alloy must have sufficient tensile strength within its elastic limit to maintain internal pressure and provide at least 12% reversible

- 10 016839 th linear extension. While tensile strength can be easily achieved, few metals or metal alloys have a tensile strength exceeding 1%. If a reversible linear elongation of more than 1% is desired, typical materials may be insufficient. Exceptions to this limitation are some amorphous metal alloys with an elastic strain limit of up to about 2%, and shape memory alloys (for example, the Νίίοΐ family of titanium-nickel (сплав) alloys) that exhibit pseudo-elastic strains of up to 8% with less than about 0.1% permanent deformation. Accordingly, typical metals or metal alloys cannot provide at least 12% reversible linear elongation if a spherical structure is used as the initial shape.

To achieve the desired reversible linear elongation, the compressible object can be designed to subdivide the deformation of the compressible object into different states. For example, compressible objects can have three different states, such as an initial state, an expanded state, and a compressed state. In one embodiment, the initial state may be, for example, a flattened spheroid with a geometric aspect ratio of less than 1.0. FIG. 2C shows a flattened spherical object 220 having a major axis 222 and a minor axis 224. As noted above, the ratio of the geometric dimensions of the object 220 in the initial state is defined as the ratio of the major axis 222 to the minor axis 224. Under these conditions, the required deformation of the compressible object is divided into two phases . The total required deformation can be subdivided into an expanded state and a compressed state. Inflating, or the first phase, involves expanding a compressible object from an initial state to an expanded state, which may be limited by the tensile strength of the wall material and / or structural instabilities of a fully expanded compressible object, characteristic of the initial state of the architecture of the compressible object and the initial internal pressure.

In particular, in FIG. 2Ό a flattened spherical object 230 with an initial ratio of geometric dimensions 4: 1, a wall thickness of 10 μm and an internal pressure in the swollen state of 10.9 MPa is subjected to internal pressure, which inflates the flattened spherical object 230. The maximum elastic deformation of the object 230 during its expansion is controlled by localization stresses associated with the equatorial protrusion of the wall, which is indicated by the flattened regions 232 and 234. The instability of the equatorial protrusion of the wall is a crushing region Astea 232 and 234 due to the narrowing of the equatorial girdle associated with the inflation of a flattened spherical object 230. In general, it has been shown that the sensitivity of a compressible object to equatorial protrusion increases as the initial ratio of the geometric dimensions of the compressible object increases, the internal pressure increases and the wall thickness decreases. In this example, the expanded state may be a state of equilibrium with an external pressure of one atmosphere (0.101 MPa), and where the compressible object has a spherical or almost spherical shape (i.e., the ratio of the geometric dimensions is about 1.0).

The second phase may include compression of the object from the expanded state back to about the initial state at a time when the deformation due to the initial expansion almost completely disappears, and subsequent further compression to a fully compressed state, which may again be limited by the elastic deformation of the wall material of the fully compressed object. The compressed state can be, for example, an equilibrium compressed form due to a hydrostatic compressive load applied to the compressible object at a certain depth of the bottomhole zone of the well. Accordingly, compressible objects can be constructed using these conditions to provide a suitable compression ratio, which is preferred for use inside a borehole.

FIG. 3A-3C are exemplary embodiments of a compressible object in various states in accordance with aspects of the present technology. In the embodiments shown in FIG. 3A-3C, modeling in the framework of finite element analysis is used to demonstrate the various states of a compressible object, which in this example is an ellipsoid. Each of FIG. 3A-3C is a partial image of a compressible object in various states. As shown in FIG. 3A, the elliptical object may be in the initial state 300 and have a major axis 302 and a minor axis 304 with a geometric aspect ratio of 4: 1. In FIG. 3B, the elliptical object may be in the expanded state 306 and have a major axis 308 and a minor axis 310, and a geometric aspect ratio of less than 4: 1. In FIG. 3C, the elliptical object may be in a compressed state 312 and have a major axis 314 and a minor axis 316, and the aspect ratio is much larger than 4: 1. Accordingly, the ratio of geometric dimensions for each of the different states 300, 306 and 312 may vary depending on the expansion and / or compression of the elliptical object. Compressible objects having different initial ratios of geometric dimensions are discussed further in FIG. 4.

FIG. 4 is an exemplary graph of compressible objects with different initial shapes in accordance with aspects of the present technology. To form a graph 400 of the relationship between the maximum deformation 402 and the compression ratio 404 for various compressible objects,

- 11 016839 having a wall thickness of 15 μm, simulation is applied in the framework of finite element analysis. Graph 400 includes a first characteristic curve 406 for a spherical object, a second characteristic curve 407 for an elliptical object having a 2: 1 geometric aspect ratio, a third characteristic curve 408 for an elliptical object having a 3: 1 geometric aspect ratio, and a fourth characteristic curve 409 for an elliptical object having a geometric aspect ratio of 4: 1, which may be an elliptical object in FIG. 3A-3C, and a fifth characteristic curve 410 for an elliptical object having an aspect ratio of 5: 1.

As shown by the characteristic curves 406-410, the maximum strain increases and decreases between different states. For objects with an initial ratio of geometric dimensions 3: 1, the characteristics of the maximum linear elastic deformation are determined by the instability of creasing of the tip described above. For compressible objects with an initial ratio of geometric dimensions much larger than 3: 1, the maximum deformation decreases from the expanded state to the minimum value for the initial or close state, which is the global minimum for deformation on the compressible object. Further, the maximum deformation increases from the initial state until a completely compressed state is reached. Essentially, the maximum strain in the initial state of compressible objects is close to zero, as shown by characteristic curves 406-410. This aspect is clearly demonstrated by the fourth characteristic curve 409. Along the characteristic curve 409, the expanded state is localized at point 416, the initial state is localized at point 414, and the compressed state is localized at point 412. It is obvious that the initial state of the compressible object has the smallest deformation compared to the expanded and compressed states. In addition, this compressible object has a maximum deformation of about 0.085, which approximately represents the value of the maximum reversible deformation for the phase transition from the austenitic to martensitic phases in the Νίΐοϊ family of alloys with their pseudoelastic state. That is, the characteristic curve 409 shows that an elliptical object having an initial geometric ratio of 4: 1 is a suitable structure and wall thickness to provide a specific compression ratio of more than 5: 1, with an internal pressure suitable for the practical implementation of the invention disclosed in publication of international patent application No. XVO 2006/007347. Each of the other characteristic curves 406-408, 410 goes beyond the maximum reversible strain of 0.085. Deformations in excess of deformation at the stage of completion of the phase transition from the austenitic to martensitic phases at a level of approximately 8% can result in permanent deformation leading to a limitation of fatigue life under cyclic loading.

From graph 400, the expansion and subsequent compression of the compressible object is constrained by the instability of equatorial protrusion during expansion and the previously described instability of creasing of the tip during the compression phase. By modeling expansion and subsequent compression, the initial structure of the compressible object can be designed to minimize reversible elongation for a particular compression ratio. In particular, for a compressible object with a constant wall thickness made of a ΝίΤί alloy with shape memory, with an austenitic-martensitic phase transition temperature below about 0 ° C and a target internal expanded pressure of 1500 psi, excessive (10.335 MPa , excess), the initial ratio of the geometric dimensions of the compressible object before expansion can preferably be between about 3 and 4, with a wall thickness of between about 15 and 20 microns, to avoid exceeding about 8% linear elongation anywhere with Enki compressible object for a compression ratio of up to 8: 1. As noted above, in order to be applicable to publication No. νθ 2006/007347, the alloy must be in a pseudo-elastic state. Ordinary shape memory alloys with phase transition temperatures of about 0 ° C are unsuitable for this application. The need for the temperature of the phase transition from the austenitic phase to the martensitic phase below about 0 ° С suggests that the alloy should remain pseudo-elastic over the entire temperature range as a whole, which takes place during the action of compressible objects in the drilling fluid.

Based on the modeling methods discussed above, compressible objects can be constructed from certain materials and have a special structure to provide specified compression ratios that are within the deformation limitations of existing materials. At these compression ratios, compressible objects may be applicable to certain applications, such as the drilling and production operations described above. By way of example, compressible objects may be applicable if they provide a reversible compression coefficient greater than or equal to a five-fold expanded state in the particular discussed depth interval. Compressible objects can be included in a variable density drilling fluid with a volume fraction of up to 40 or 50% to provide a change in the density of the drilling fluid corresponding to typical values of the pore pressure gradient and / or hydraulic fracture pressure gradient. By changing the density of the drilling fluid when adding up to 50 vol.% Small compressible objects with a low density, which may have a diameter of about 1 mm, grad

The pressure inside the borehole can essentially be controlled to reduce the number of casing pipes used inside the borehole. In particular, for deep-sea applications, the number of casing intervals can be reduced significantly below what is achievable with non-conductive drilling systems or multi-gradient systems, without significant modification of existing machinery or equipment. Essentially, well cost can be reduced by between 30 and 50% for certain applications. Accordingly, the selection of compressible objects and the manufacture of compressible objects are discussed below in FIG. 5.

FIG. 5 is an exemplary block diagram of the selection and use of a variable density drilling fluid for the drilling system 100 shown in FIG. 1, in accordance with some aspects of the present invention. This flowchart 500 may be better understood in conjunction with the consideration of FIG. 1, 3A-3C and 4. In block diagram 500, compressible objects and drilling fluid may be selected to formulate a variable density drilling fluid for the well. These compressible objects may include objects, each of which has a shell enclosing the inner region, and in which the compressible object has an internal pressure of more than about 200 psi (1,378 MPa) at atmospheric pressure, 500 psi (3,445 MPa) at atmospheric pressure, 1,500 psi (10.335 MPa) at atmospheric pressure and / or 2,000 psi (13,780 MPa) at atmospheric pressure and is selected for a predetermined external pressure at which external pressures that exceed internal pressure, reduce both a compressible object, while the shell experiences less deformation when the external pressure is approximately equal to the internal pressure than when the external pressure is above or below a predetermined compression interval of the compressible object, or in which the shell is configured to experience less deformation when the external pressure approximately equal to the internal pressure than when the external pressure is greater than the internal pressure or less than the internal pressure, and / or compressible objects have a shell in that encloses an interior region at least partially filled with foamed material. Variable-density drilling mud can be used to intensify well drilling operations. This method can intensify drilling operations by preparing a variable density drilling fluid that expands drilling operations to the next limit or reduces the need for additional casing. Accordingly, drilling operations performed in the described mode can reduce the levels of low productivity using additional casing pipes, excluding them from drilling operations.

The flowchart begins at initial stage 502. At stage 504, the values of the hydraulic fracturing pressure gradient and the pore pressure gradient can be determined. For example, the values of the hydraulic fracturing pressure gradient and the pore pressure gradient can be determined by obtaining information from the well location and / or performing calculations to estimate the hydraulic fracturing pressure gradient and the pore pressure gradient. Compressible objects can then be selected to provide specific volumetric changes at step 506. The choice of compressible objects may include operational considerations, such as removing compressible objects from the drilling fluid for surface recirculation, limiting the potentially harmful effects of the high volume fraction of compressible objects on the rheological characteristics of the drilling fluid and facilitating the flow of compressible objects through pumps and openings in fluid ducts. Essentially, compressible objects can be sized to have an equivalent diameter between 0.1 and 50 mm and / or preferably between 0.1 and 5.0 mm. An equivalent diameter is defined as the diameter of a sphere with a volume equal to that of a fully expanded compressible object at atmospheric pressure. The selection of compressible objects may include the use of compressible objects with different sizes or volumes on the surface of the borehole and / or with various shapes to control the increase in viscosity of the drilling fluid. The selection of compressible objects is further described in FIG. 6.

At 508, drilling fluid may be selected. Drilling fluid, which may include a variety of drilling fluid weighting agents, can be selected to provide a specific density that can interact with compressible objects to maintain the density of the drilling fluid in the range between the hydraulic fracture pressure gradient and pore pressure gradient, which is discussed further below. Compressible objects and drilling fluid may be combined in step 510. The combination of compressible objects and drilling fluid may include mixing or compounding the compressible objects with drilling fluid, as described in international patent application No. PCT / ϋδ 2007/003691, filed February 13, 2007. Further compressible objects and drilling fluid can be combined before delivery to the site of the well or delivered separately with a combination of compressible objects and drilling fluid at the site of the well. It should be noted that compressible objects can be delivered in refrigerated vehicles, such as trucks, and on ships, in order to reduce the risks associated with the release of internal pressure inside compressible objects.

Compressible objects and drilling fluid, which may represent

- 13 016839 - a variable density drilling fluid 118 (FIG. 1), can be used in drilling operations at stage 512. Drilling operations can include any processes where surface fluids are used to achieve and maintain the desired hydrostatic pressure in the borehole, and / or processes for circulating this fluid, among other uses, for removing cuttings from a borehole. Once a well has been drilled, hydrocarbons may be produced in step 514. Hydrocarbon production may include completion of the well, installation of equipment inside the well along the production tubing, production of hydrocarbons from an underground reservoir, processing of hydrocarbons in a surface installation in an oil or gas field and / or others similar operations. The process then ends with step 516.

FIG. 6 is an exemplary block diagram of the selection and fabrication of compressible objects discussed in the block diagram of FIG. 5, in accordance with certain aspects of the present technology. This flowchart 600 may be better understood in conjunction with the consideration of FIG. 1, 3A-3C, 4, and 5. Box 600 describes a process for selecting compressible objects to maintain drilling fluid density within a well between a pore pressure gradient and a hydraulic fracture pressure gradient. Advantageously, the use of compressible objects in a variable density drilling fluid can intensify drilling operations by reducing the size of the borehole and casing and can achieve greater depths.

The flowchart begins at step 602. At step 604, the pressure gradient of the hydraulic fracturing and the gradient of the pore pressure of the well are obtained. The values of the hydraulic fracturing pressure gradient and the pore pressure gradient can be determined by obtaining information from the well location and / or performing calculations to estimate the hydraulic fracturing pressure gradient and the pore pressure gradient. The structure of each of the compressible objects is then selected at step 606. The selection of the structure of the compressible objects may include applying finite element analysis to adapt the structures and geometric shapes of the compressible objects to the characteristics of the materials available, as described above. At 608, wall materials for compressible objects are selected. The choice of wall materials may include thin films of metals and / or a metal alloy formed by mechanical or deposition methods, polymers with or without microfibre reinforcement and / or nanofibers in the polymer matrix to achieve specific properties of the wall material (for example, as determined by analysis by the finite element method for compressing an object). In addition, wall materials may include exfoliating inorganic mineral as a reinforcing agent or as a barrier to reduce gas permeability in the polymer matrix; thin films of metals and / or metal alloy formed by deposition methods on the surfaces of polymer materials, with or without chemical modification of the polymer surface, to form a load-bearing wall or barrier to gas permeability. Thin films of metals and / or a metal alloy can be deposited on a polymer sheet before molding a compressible object or on a preformed compressible polymer object. The metal layer can be formed on the inner or outer surface of the compressible objects or introduced into the polymer wall or the polymer multilayer material consisting of the same or different polymers.

Surface treatments can be selected for the manufacture of compressible objects at step 610. Surface treatments can include physical and / or chemical surface treatments to improve the integrity and adhesion of thin films of metals and / or metal alloys to the surface of polymer objects or to enhance chemical and / or physical compatibility of the polymer or metal outer wall of compressible objects with drilling fluid.

Once selected, compressible objects are manufactured in step 612. The manufacture of compressible objects may include a variety of polymerization, deposition, surface treatment and other manufacturing processes used to form wall structures of the compressible object. For example, the manufacture of wall structures may include coaxial blow molding methods, where the polymer is a load-bearing wall, coaxial blow molding methods, where the polymer is a matrix for deposition of a metal or metal alloy as a load-bearing wall; dispersion polymerization methods, where the polymer is a matrix for deposition of a metal or metal alloy as a supporting wall and / or interfacial polymerization methods, where the polymer is a matrix for deposition of a metal or metal alloy as a supporting wall. Fabrication may include the deposition of a continuous layer of metal or metal alloy on the surface of a compressible polymer object in liquid media at both low and high pressures using electric and non-electrical cladding methods, the deposition of a continuous layer of metal or metal alloy on the surface of a compressible polymer object from gaseous media at high pressure using methods of chemical vapor deposition with activation by ultraviolet radiation and / or deposition with loshn layer of metal or metal alloy on the surface of a compressible hollow object under vacuum using physical methods and / or chemical vapor deposition. Vacuum Methods

- 14 016839 deposition may or may not include lowering the internal pressure inside the compressible object before deposition. This can be done, for example, by first reducing the internal pressure in the compressible hollow object by cooling the pressurized compressible hollow object, preferably to a temperature below which the gas inside the compressible hollow object can be liquefied. Manufacturing processes may include casting or molding a flat metallized polymer sheet or film to form parts of compressible objects and joining components using mechanical, chemical and / or thermal methods, forming a flat polymer sheet or film to form parts of a compressible object before metallization, and joining components with using mechanical, chemical and / or thermal methods, the deposition of metal or metal alloy on a polymer sheet with chemical th and / or physical pre-treatment or without it, to improve adhesion and integrity, and the subsequent removal of the polymer matrix from a flat free separate sheet consisting of metal or metal alloy, physical, chemical and / or thermal methods, leading to the formation of a thin metal sheet suitable for mechanical molding into components of compressible objects, and the subsequent connection of components by mechanical, thermal and / or chemical methods, the deposition of metal or metal alloy on a polymer sheet preformed into a matrix for individual components of metal or a metal alloy for a compressible object, and the subsequent removal of the polymer matrix from the metal component by chemical, mechanical and / or thermal methods, and the subsequent connection of the components by mechanical, thermal and / or chemical ways.

At block 614, compressible objects can be checked or tested. Verification and testing may include cyclic compression tests to verify internal pressure and to quantify the fatigue life of compressible objects with or without microstructural analysis of the bearing wall and joints, if any. Then, the compressible objects may be sent for storage at step 616. Storage of the compressible objects may include placing the compressible objects in a storage bunker. Compressible objects can be stored at ambient temperature or at a pressure equal to or higher than the internal pressure in the compressible objects, to facilitate packaging of compressible objects in a storage bunker. Alternatively, compressible objects may be stored in a refrigerated medium to reduce internal pressure within compressible objects. Cold compressible objects can then be stored in a bunker at ambient pressure or at elevated pressure to facilitate packing of compressible objects in a storage bunker and shipment of compressible objects to other places, such as a well location, for storage or other similar actions. The process ends with step 618.

Accordingly, based on the above description, the selection and application of these compressible objects may include various aspects that determine the design of the compressible objects. For example, the nature of the transition to deformation controlled by gas compression depends on the mechanical properties of the shell or wall material and the process of changing such properties in repeated compression cycles. Essentially, the compression of hollow objects leads to different gradients in the density of the drilling fluid above and below the depth determined by the initial internal pressure in the hollow objects. Since the use of compressible objects having different internal pressure values may be preferable to intensify or expand drilling operations, changing the volume fraction and distribution of internal pressure values in compressible objects can provide the desired result in maintaining the effective weight of the drilling fluid in the range between the pore pressure gradient and the gradient hydraulic fracturing pressure.

The use of various gases can also determine the design of compressible objects. For example, a hollow object may be filled with a mixture of liquefied and non-liquefied gases. The addition of liquefied gas provides an additional degree of freedom in accurately adapting to variations in the density of the drilling fluid as the depth changes. At temperature and pressure at the gas / liquid interface, a condensable gas liquefies with an increase in density and a corresponding decrease in volume. A decrease in the internal volume of a hollow object results in a sequential increase in the effective density of the drilling fluid with increasing depth and temperature in accordance with the conditions of phase transformation. An additional advantage of using a gas mixture containing a liquefied gas is the final internal volume occupied by the liquefied gas at the depths at which it has become liquid, since the compressibility of the condensed liquid is generally lower than that of the non-liquefied gas. As a result, the volume of the condensed liquid can be used to control the upper limit of deformation experienced by the wall of the hollow object. This can be used to control the fatigue life of flexible objects as they circulate between the bottomhole zone of the borehole and the surface.

Moreover, the design of compressible objects may be affected by operating conditions. In particular, limiting the change in the volume of a huge number of compressible objects having a small diameter mixed with the drilling fluid makes it possible to precisely adapt the initial size and / or shape of the compressible objects to achieve stable rheological characteristics of a complex drilling fluid

- 15 016839 bones inside the vertical column of the drilling fluid in the borehole. To create an applicable drilling fluid of variable density, the initial properties of the liquid phase for a given volume fraction of compressible solid objects are selected to suspend both drilled rock fragments and compressible objects in the annulus of the borehole during operations without circulation. In addition, the viscosity of the composite drilling fluid must be adjusted to allow for pumping within the well using slurry and mud pumps within acceptable limits. In addition, the use of compressible objects with various sizes can further improve operational capabilities. These and other aspects are further discussed below.

The structure of compressible objects.

To determine the structure of the compressible objects at step 606 in FIG. 6, finite element digital modeling can be used. Digital finite element modeling may include implicit methods and / or explicit methods. In these methods, walls or shell elements can be represented in the form of mesh structures with dimensions and shapes adapted for higher resolution in the areas under consideration, such as areas of high stress and / or deformation for the construction of a compressible object. The digital model in the finite element method can be used to simulate the entire three-dimensional object or a portion of the object related to the three-dimensional object by virtue of symmetry. Further, the architecture of compressible objects can be determined by various criteria, such as materials and the use of compressible objects, which are discussed in this and other sections of the application.

Regarding the use of compressible objects, it should be noted that the structure of compressible objects can facilitate the periodic removal of compressible objects from the recirculating drilling fluid. This may simplify minimizing the potentially harmful effects of the high volume fraction of compressible objects on the rheological characteristics of the drilling fluid and / or facilitate the flow of compressible objects through equipment such as pumps and openings in fluid ducts. Essentially, compressible objects may include structures having an equivalent diameter in the range of about 0.1 to 5.0 mm. The equivalent diameter is again defined as the diameter of a sphere with a volume equal to that for a fully expanded compressible object with an external pressure of 1 atm (0.101 MPa). In addition, the shape of the compressible objects can be adjusted to increase packing density and reduce the effect on fluidity. For example, a spherical or elliptical object can provide the highest packing density and the least impact on the fluid flow inside the well compared to objects with the shape of a pad or rod.

Another criterion for the structure of the object is the wall thickness. As noted above, the wall thickness should be as small as possible within the limits due to structural instabilities and properties of existing materials in order to maximize the compression limit of the compressible object. However, the lower limit of the wall thickness is determined by the minimum thickness capable of holding the desired internal gas pressure at an external pressure of about 1 atm (0.101 MPa), which typically occurs on the surface of the Earth.

To determine the optimal geometry of compressible objects can be used digital modeling by the finite element method. Finite element digital modeling is well known to those skilled in the art. These methods may include modeling walls in the form of shell elements of compressible objects or in the form of a mesh object with variable mesh sizes and shapes. Certain areas of interest, such as areas of high stress and / or deformation for the construction of a compressible object, can be instantiated with a higher resolution (i.e., a finer mesh) to get more information about these areas. Further, the model can be used to simulate the entire three-dimensional compressible object, a segment of the compressible object, or a part of the compressible object, which may be related to the three-dimensional structure of the compressible object due to symmetry.

As an example, one preferred method for analyzing and optimizing combinations of the geometry of a compressible object, the characteristics of the material of a compressible object, the properties of an internal gas, internal pressure, and the reaction of a compressible object to changes in external temperature and / or pressure is intended to create a model using the finite element method or the entire compressible object in whole, or parts of a compressible object (i.e. hemispheres, due to symmetry). Using a computer program such as AVariK ™. or any other suitable software package for finite element analysis for compressible objects, a digital model of the finite element method can be generated. In this model, an explicit method can be used to track contact between the internal surfaces of compressible objects during compression. To minimize fluctuations in function during the modification of the external pressure, the external pressure can be initially set to a value equal to the internal pressure. Then, the external pressure can slowly decrease to ambient pressure, which can be performed over a period of time (for example, 0.5 s), essentially sufficient to eliminate dynamic artifacts in the simulation. Depending on the flow characteristics of the wall material and any manifestations of protrusion,

- 16 016839 the amplitude and speed of external pressure loading and pressure relief can be adjusted to minimize vibrations. After the digital model is formed by the finite element method, another analysis can be carried out. For example, a compressible object may be subjected to a cyclic pressure test. Then, analysis of the data obtained from the cyclic pressure test can be applied to understand the effect of the geometry of the compressible object, the dimensions of the compressible object and / or the characteristics of the material. In addition, if the digital model is constructed using shell elements, sudden changes in the geometry of the grid should be excluded to reduce potential deviations in the calculation of local stresses.

As a specific example, the digital model of the finite element method in FIG. 3A-3C. In these embodiments, the compressible object has the shape of a flattened ellipsoid. The initial ratio of geometric dimensions can vary from 1 to 10, with a more preferred ratio of geometric sizes ranging from 2 to 5. The use of a hollow compressible object in the form of a flattened ellipsoid with an internal pressure with an initial ratio of geometric sizes greater than 1 has the advantage that at an external surface pressure equal to the ambient pressure, the object in the form of an ellipsoid swells and reaches a ratio of geometric dimensions of about 1, depending on the internal ennego pressure and material characteristics as shown in FIG. 3B. If an ellipsoid-shaped object has an initial aspect ratio of 4: 1, a ΝίΤί-alloy wall with a uniform thickness of 10 μm, and an internal pressure of 1,500 psi (10.335 MPa), the ratio of the geometric dimensions in the expanded state is about 1.22: one. As the external pressure increases, the ellipsoid-shaped object tends to return to the initial state 300. In the initial state 300, the ratio of the geometric dimensions of the ellipsoid-shaped object is such as for the initial design with low elastic deformation, as shown in FIG. 3A and 4. Then, as the pressure builds up, the ellipsoid-shaped object is further compressed to a compressed state 312, as shown in FIG. 3C.

Wall material for compressible objects.

In addition to the structure, various materials can be used for the wall of compressible objects based on the criteria discussed above, as noted at 608 in FIG. 6. In particular, shell or wall materials may be subdivided into two classes of commercially available materials, which are metallic materials and polymeric materials. Metallic materials may include metals, metal alloys, and alloys with pseudo-elastic characteristics (for example, strains associated with reversible stress caused by structural changes due to phase transformation). Further, the superplastic behavior of ultrathin (for example, <500 A (0.05 μm)) films of metal or a metal alloy can also be used to obtain a wide variety of metals and metal alloys (for example, aluminum (A1), copper (Cu), nickel titanium (ΝίΤί), etc.) suitable for use as a thin impenetrable barrier in combination with a non-metallic load bearing wall that corresponds to the mechanical properties of the load bearing wall. More specifically, metallic materials may include, but are not limited to, binary ΝίΤί alloy, close to binary ΝίΤί-alloy, three-component alloys лег with alloying additives of iron and chromium, alloys of 60% magnesium and 40% copper (MD-40Ci), β-Τί alloys -9.8Μο-4ΝΒ-2ν-3Α1), metal glasses and amorphous metals (for example, alloys based on zirconium (Ζγ), iron (Fe) and / or magnesium (MD)), etc. Polymeric materials may include polymers and blends of polymers with or without reinforcing materials (for example, microfibre and nanofibre, nanotubes, exfoliating inorganic fillers with proper orientation inside the polymer wall, etc.). Examples of polymers with suitable properties include, but are not limited to, a commercially available polyimide, such as Liieh-K. and H11ex-8.

Since each of these materials has specific properties, such as tensile strength and reversible elongation, the material used for the walls of compressible objects is a factor determining the wall thickness. The definition can be based on a digital model of the finite element method, as noted above, to evaluate different values of the thickness of the shell or wall of various materials. For example, if the material of the load-bearing wall is a metal or metal alloy, only metals and metal alloys with sufficiently high elastic or pseudoelastic characteristics should be selected, since deformations associated with a reversible stress, which is caused by a structural change due to phase transformation, must be reversible for repeated use of compressible objects. As noted above, even the selection of these materials should be carried out in conjunction with careful design of the geometry of the outer wall of the compressible object to prevent localization of stresses during compression and repeated expansion. In particular, geometry and material can be used to optimize wall thickness relative to particle size, vary the thickness of the bearing wall and / or mechanical properties with localization on the surface of compressible objects and / or vary the ratio of the geometric dimensions and large diameter of the hollow compressible objects in the form of a flattened spheroid and etc. Accordingly, these various factors are considered when choosing a material for compressible objects.

- 17 016839

As an example of varying the wall thickness, the wall material can be used as an influence factor for the ratios of the geometric dimensions of a compressible object, such as the elliptical object discussed above in FIG. 3A-3C. In FIG. 7, finite element calculations give a variety of shapes that have different ratios of geometric dimensions within the limits determined by the properties of existing materials. Finite element calculations can represent compressible objects having a geometric aspect ratio of between 2 and 5, with a ratio of equivalent diameter to wall thickness between 20 and 200, or more preferably between 50 and 100. As shown in FIG. 7, a graph 700 of the wall thickness effect is shown for maximum deformation of 702 compressible objects depending on the ratio of 704 equivalent diameter to wall thickness for various shapes, which are shown by curves 706-711 derived from digital finite element simulation. For compressible objects of a spherical shape, curve 706 corresponds to a compression ratio of 3.5, curve 707 corresponds to a compression ratio of 3, and curve 708 corresponds to a compression ratio of 2. For compressible objects with an elliptical shape, curve 709 corresponds to a compression ratio between 3.5 and 2, curve 710 corresponds to a coefficient compression between 3 and 2, and curve 711 corresponds to a compression ratio of 2. From graph 700 it is clear that compressible objects having a geometric aspect ratio greater than one with a thinner wall (i.e., a higher ratio of ivalentnogo diameter to wall thickness), are preferred, because they provide higher compression ratios with correspondingly lower maximum strain. In addition, it may be preferable to maintain the maximum deformation below a predetermined value, about 0.06, as determined by the maximum allowable deformation, in order to achieve the proper fatigue life of the bearing wall. A minimum fatigue life of at least 2000 to 3000 cycles is typically desirable. Based on these restrictions, an object in the form of an ellipsoid with a ratio of geometric dimensions of 2 or more and a ratio of equivalent diameter to wall thickness greater than 65 gives a compressible object that is below a predetermined value, as shown by curve 711.

In addition to a single material, the walls of compressible objects may include two or more layers. For example, a coated composite shell may include a load-bearing layer or a load-bearing wall and a wall representing a gas-tight barrier. The load bearing wall may be a relatively thick wall having a thickness in the range of 1 to 50 μm, and the gas barrier wall may be a thin wall having a thickness in the range of less than or equal to 5 μm. For example, a polymer wall bearing a load, which may be hollow inside or be deposited on a polymer foam matrix, can be used to create the structure of a compressible object. The gas barrier wall, which may be internal or external relative to the load-bearing wall, may be an impermeable barrier layer of metal or a metal alloy that retains internal pressure and has a thickness of less than 500 A (0.05 μm). Alternatively, the compressible objects may have a thin (i.e. <5 μm) wall of the shell that is either hollow inside or deposited on the foamed polymer material, with a relatively thick (i.e. 1 μm) <wall thickness <50 μm, bearing load, and a barrier a wall of a layer of metal or metal alloy, which provides a supporting support and a gas-tight barrier.

The choice of surface treatments for compressible objects.

As indicated at 610 in FIG. 6, various surface treatments can be used for compressible objects. Surface treatments can be applied to improve the integrity and adhesion of polymer layers or films of metal and / or metal alloy on the surface of compressible objects, such as polymer objects. Accordingly, surface treatments can be applied to improve specific characteristics, such as compatibility with the base fluid and the permeability of the shell layers to maintain internal pressure, which is discussed below.

For compressible objects with internal pressure having a load-bearing wall made of polymer and / or elastomer with or without reinforcement, surface treatment can be used to increase the integrity of the metal and / or non-metal film deposited on the polymer surface to reduce the gas permeability of the load-bearing wall . In general, elastomers, crystalline polymers and / or polymer blends have gas permeability parameters too high to be applicable to the manufacture of compressible objects. Accordingly, in addition to introducing exfoliating inorganic fillers into the polymer wall, the deposition of a continuous, thin (i.e. <500 A (0.05 μm)) coating with low gas permeability can either be applied on the wall surface or embedded in a multilayer wall structure. For example, the coating may be a thin gas-tight barrier made of metal, metal alloy, or inorganic material, which is applied using a variety of physical and / or chemical processing methods to an external region of the wall surface of a compressible object. In particular, the deposited coating may have a thickness of less than 500 A (0.05 μm) and include aluminum (A1), nitinol (ΝίΤί), or any other suitable material. Surface treatments for

- 18 016839 enhancing the uniformity and / or integrity of these permeability reducing layers may include the following:

1) anionic functionalization of the surface, for example sulfonation, carboxylation, that is, the formation of acid fragments, as well as other methodologies and chemical approaches of anionic functionalization used by qualified specialists in this field of technology;

2) chemical methods of cationic functionalization by quaternization, for example, the formation of fragments of sulfonium salts, phosphonium salts, ammonium salts, used by qualified specialists in this field of technology;

3) the introduction of zwitterionic, ionic functional groups and amphoteric functional groups practiced by qualified specialists in this field of technology;

4) the introduction of functional fragments of maleic acid by reaction with maleic anhydride and related reactions known to qualified specialists in this field of technology;

5) controlled oxidation, for example, peroxides, high-temperature plasma etching in an oxygen atmosphere, ozone, etc .;

6) methods of chemical vapor deposition and related chemical approaches;

7) corona treatment methods for surface functionalization used by qualified specialists in this field of technology.

A wide variety of methods are available for the deposition of metal and / or inorganic barrier coatings. One of the factors that can influence the choice of the deposition method is the internal pressure in the compressible object. For example, if there is a small initial gas pressure inside the compressible objects or is absent, the low-permeability coating of metal, metal alloy or inorganic material can be applied by various methods of physical and chemical deposition at low pressure to uniformly coat compressible objects with non-planar geometry. If the internal pressure in the compressible objects and the permeability of the wall are such that a low-pressure medium (i.e. typically <1 x 10 ^-3 mm Hg (133.32 x 10 ^-3 Pa)) is required for physical and chemical deposition methods at low pressure cannot be provided, deposition methods compatible with the internal gas pressure and relatively high gas permeability of the wall can be applied. In this example, compressible objects may be contained in a gas or liquid medium under high pressure to prevent loss of internal pressure through the wall of the compressible object during storage and coating. For a liquid medium under high pressure, the coating on the wall surface can be performed, for example, by electric or non-electric cladding using methods known to those skilled in the art. For a gaseous medium under high pressure, the coating on the wall surface can be performed, for example, by deposition by chemical vapor deposition or by chemical vapor deposition with activation by ultraviolet radiation.

Alternatively, the internal gas pressure inside the compressible objects can be reduced to a level that allows the use of a number of industrial methods of physical and chemical deposition at low pressure, available for the object without pressure or polymer sheet. In this example, a gas that can be condensed by lowering the temperature of the compressible object can be used to create internal pressure in the compressible object. For example, if the gas contained inside the compressible object is oxygen (O) at a pressure of 10 MPa, subsequent cooling of the compressible objects to the temperature of liquid nitrogen (EI ₂ ) at atmospheric pressure can reduce the internal pressure to a level less than or equal to 1x10 ^-3 mmHg. (133.32 x 10 ^-3 Pa).

Similar considerations for a hollow load-bearing polymer wall can be extended to compressible objects with internal pressure having a load-bearing wall made of polymer and / or elastomeric foamed material and a gas barrier made of metallic and / or non-metallic impermeable barrier material, or to a polymer and / or an elastomeric ultrathin hollow shell or a polymer and / or elastomeric foam material used as a matrix for the deposition of a load-bearing wall of metal and / or and a metal alloy, as noted above. In the latter example, an ultra-thin polymer shell or polymer foam can be used as a matrix to deposit a relatively thick load-bearing wall of metal and / or metal alloy. The load bearing wall of metal and / or metal alloy in this example may have a thickness of from about 5 to 50 microns. An ultra-thin polymer shell or polymer foam may include any polymer and / or elastomer with or without reinforcement and surface treatments to improve the uniformity and integrity of the load-bearing wall of a metal and / or metal alloy. In this example, only such a thickness of the ultrathin polymer shell and / or mechanical strength of the foam material is required to be sufficient to maintain the desired particle shape during the process

- 19 016839 deposition.

Production of compressible objects.

As discussed in step 612 of FIG. 6, once the structure and materials of the wall for compressible objects are selected, a variety of manufacturing methods can be applied to create compressible objects. These manufacturing methods may include a variety of processes such as contouring, precipitation, thermomechanical processing, and other similar manufacturing processes. Contour formation processes in which a material is given a different shape, such as compressible objects, may include chemical etching, mechanical etching, and the like. During etching processes, material is removed from the base material. Deposition processes in which the material is coated or transferred onto another material may include physical vapor deposition, chemical vapor deposition, electrochemical and / or non-electric deposition, metallization, sputtering, evaporation, molecular beam epitaxy, and the like. Thermomechanical processes, which are processes in which the shape and microstructure of a material is formed or changed, can include cold rolling, hot rolling, stamping, drawing, trimming, hardening, solid solution heat treatment, etc.

For the manufacture of compressible objects can be used in a variety of ways that are combined to give the desired properties of compressible objects, as described above. The manufacturing path of compressible objects can be determined based on the specific desired properties of the compressible objects. For example, low gas permeability, flexibility of an object, mechanical integrity, low cost, relative ease of production of an object, commercial availability of materials, and / or environmentally acceptable characteristics of materials are some of the properties that can be considered. Other properties may include, among other parameters, the desired range of sizes of compressible objects, particle size distribution and geometric aspect ratios, potential approaches to surface functionalization to increase the adhesion of the metal to the polymer, the possibility of introducing additional blowing agent (s) to produce a hollow object containing gas under high internal pressure (for example, the use of a blowing agent for hollow objects with internal pressure, filling with gas under high pressure and the like).

Accordingly, the manufacturing processes can be arranged to create compressible objects, which are gas-filled polymer objects, including internal structures, which are either hollow or at least partially filled with foam material. For example, FIG. 8Ά-8Β represent exemplary embodiments of manufacturing processes in which compressible objects are created that are hollow inside. Similarly, FIG. 9, 10 and 11Ά-11Β represent embodiments of manufacturing processes in which compressible objects are filled, filled with foam material or based on foam matrices.

Ά. Production of compressible objects in the form of hollow objects.

The manufacturing processes described below relate to the production of compressible objects that are formed as hollow objects, which may or may not be filled with gas. These manufacturing processes can be used to form compressible objects, each of which has a shell enclosing the inner region, each of the compressible objects has an internal pressure of more than about 200 psi at atmospheric pressure, 500 psi. inch (3.445 MPa) at atmospheric pressure, 1500 psi (10.335 MPa) at atmospheric pressure or 2000 psi (13.780 MPa) at atmospheric pressure, and / or has a shell that encloses an inner region and is selected for predefined external pressure, in which external pressures that exceed internal pressure reduce the volume of the compressible object, a shell configured to experience less deformation when the external pressure is approximately equal to the internal pressure than when the external pressure exceeds the internal pressure, or is less than the internal pressure, or a shell that experiences less deformation when the external pressure is approximately equal to the internal pressure than when the external pressure is greater or less than a predetermined range compression of the compressible object and / or shell, which is at least partially filled with foamed material. While many manufacturing processes are described, FIG. 8Ά-8Β are exemplary embodiments of manufacturing processes in which compressible objects having hollow internal regions are created.

FIG. 8Ά-8Β are exemplary embodiments of the processes used in the block diagram of FIG. 6, in accordance with certain aspects of the present technology. In FIG. 8Ά shows an exemplary embodiment of an apparatus for creating compressible objects in accordance with the present technology. With this embodiment 800, compressible objects, such as hollow polymer shells or polymer foam structures, can be fabricated in a pressure medium formed by a pressure chamber 802. Β As an example, compressible objects are shown as hollow polymer shells 804 with a gas-filled inner cavity 806, but may include polymer foam structures and other compressible objects, discussed below.

- 20 016839

In this manufacturing process example, the nozzle 808 of the coaxial blow molding apparatus at the end of the central pipe 810 is located in the coaxial pipe 812 in the pressure chamber 802. Inside the annular annular channel formed between the central pipe 810 and the coaxial pipe 812, and inside the central nozzle pipe 810, a sufficient pressure difference is independently created to form the polymer material 814 to form hollow polymer shells 816 that are filled with gas 818 from the central pipe 810. In this embodiment action gas 818, filling the polymer bubble 820, forms and then separates the latter from the nozzle 808 for coaxial blow molding. The pressure chamber 802 may be filled with gas, or liquid, or a combination thereof, and separation in the event of bubble formation may be due to surface tension, gravity, buoyancy, fluid flow, or a combination thereof. As soon as the polymer bubble 820 is separated, it can fall into the crosslinking bath 822 inside the tank reservoir 824, which contributes to the crosslinking of the polymer wall. The chemical nature of the crosslinking bath may be determined by the particular polymer selected for the wall material, and is well known to those skilled in the art of polymer synthesis technology. After the curing bath, the hollow polymer shells 804 with the gas-filled inner cavity 806 are formed and can then be removed by transferring to a pressure shut-off chamber (not shown) where the crosslinking liquid is separated from the compressible objects under pressure and the compressible objects are transferred to the container for storage.

Further, during or after polymerization and / or separation of the hollow polymer shells 804, the environmental pressure acting on the hollow polymer shells 804 can be reduced to expand the hollow polymer shells 804 to their final size and shape in an expanded state. This expanded state may be predetermined based on wall thickness, mechanical properties of the material, object architecture, and internal pressure before, during, or after cooling of the walls. If the polymer wall is a load-bearing element, the expansion of the diameter after synthesis can be used to change the mechanical properties of the polymer wall. For example, by deformational reorientation of the polymer chains and / or reorientation of the reinforcing material in the polymer wall of the hollow polymer shells 804.

Depending on the material used, special adjustments can be made to the manufacturing process. For example, if the polymer material 814 is a polymer melt with or without reinforcement, the nozzle 808 may be heated to reduce the viscosity of the melt to provide the desired flow characteristics of the polymer melt. Also, if the polymer material 814 is a monomer polymer or a mixture of monomers with or without reinforcement, and with or without an initiator, polymerization of the walls of the polymer bubble 820 after separation from the nozzle 808 can be performed using a variety of methods, such as ultraviolet initiation polymerization radiation, free radical polymerization, thermochemical polymerization, etc., which are known to qualified specialists in this field of polymer synthesis technology.

In FIG. 8B shows yet another exemplary embodiment 830 of an apparatus for creating compressible objects in accordance with the present technology. In Embodiment 830, compressible objects, such as hollow polymer shells or polymer foam structures, can be fabricated in a pressure medium formed in a pressure chamber 832. The pressure chamber 832 is divided into a lower chamber 838 having a gas inlet 840, and an upper chamber 842 having a liquid inlet 844 and a liquid outlet 846. By way of example, compressible objects are shown as hollow polymer shells 834 with a gas-filled inner cavity 836, but may include polymer foam structures and other compressible objects discussed above.

In this example of a manufacturing process, a thin film 848 of a suitable polymer melt or polymer precursor can be formed on a plate 850 perforated with a large number of holes or slots 852. The size and location of the holes 852 can be configured to continuously form gas-filled bubbles 854 that have a hollow polymer the shell 834 and the gas-filled inner cavity 836, which are separated and float from the plate 850 and fall into the liquid under pressure and filling the upper chamber 842, when the plate 850 is under pressure at the desired pressure difference between the upper and lower chambers 838 and 842. It should be noted that many alternative geometrical shapes of the holes can be applied to form hollow compressible objects with internal pressure from a thin film of the polymer precursor and / or polymer melt. Gas-filled bubbles can exit the upper chamber 842 through a fluid outlet 846 and can be separated from the liquid by density difference and then transported to a storage container.

As an alternative to the method of creating compressible objects, tubes of metal, metal alloy and / or polymer can be used to form compressible objects. In this manufacturing process, compressible objects are formed from tube material by cutting

- 21 016839 knowledge of the tube material into segments of the desired length and closing of the ends of the tube material using mechanical, chemical or thermal methods. The internal pressure in the resulting compressible objects, which can be formed in the form of a cushion, sphere, tapered spheroid, rotation ellipsoid, or any other desired shape, can be controlled by closing the ends of the pipe segments and forming the desired contour in a pressure-controlled environment. The pressure medium may be a pressure chamber, which is similar to the pressure chamber discussed above. In addition, compressible objects can be formed either before or after metallization of the polymer wall of the tube material from the polymer and / or elastomeric tube with or without reinforcement.

As another alternative embodiment of the method of creating compressible objects, preformed sheets can be used to form compressible objects. In this method, for the manufacture of compressible objects, mechanical, thermal, or chemical bonding of preformed sheets can be applied. Preformed sheets may include layered composite structures, which may include two versions. One embodiment may be a relatively thick polymer wall bearing a load composed of a relatively thin continuous impenetrable barrier layer of metal, metal alloy and / or non-metallic material. In particular, the load-bearing polymer wall may have a wall thickness between about 5 and 50 μm, while a continuous impermeable barrier layer of metal or metal alloy may have a wall thickness that is less than about 500 A (0.05 μm). The second embodiment is a thin polymer sheet as a matrix for deposition of a relatively thick layer of metal or metal alloy, which serves as both a load-bearing wall and a gas-tight barrier. For example, a thin polymer layer may have a thickness of less than about 5 microns, while a layer of metal or metal alloy may have a wall thickness between about 5 and 50 microns. For other embodiments, any combination of layered or multilayer embodiments with a polymer thickness and a metal or metal alloy thickness within these limits may be used.

To produce these compressible objects, one or more layered preformed sheets can be made flat and then formed into a preformed component of the object using any of a variety of methods for forming a polymer sheet and / or film known to those skilled in the art. Examples include a metallized polymer sheet for food packaging, a metallized Mylar sheet for balloons, decorative metal coatings on polymer films, and a metallized polyimide film for aerospace thermal screens. If the preformed components of the object must be connected to form compressible objects, the connection of the preformed components can be performed in many ways known to those skilled in the art of polymer film bonding technology. Examples include, but are not limited to, thermal bonding, adhesive bonding, mechanical bonding and the like.

In this embodiment of the manufacturing method, a layer of metal or metal alloy can be formed inside or outside the compressible object using the same series of physical and / or chemical methods described above and known in the field of deposition of coatings from metals, metal alloys and / or non-metallic materials. For example, a layer of a metal or metal alloy can be applied to the outer and / or inner surface by methods similar to those described for depositing on coaxial blown bubbles or bubbles formed by the aforementioned dispersion polymerization. The coated polymer wall can then be thermomechanically molded into a preform having a layer of metal or metal alloy on the inner surface, the outer surface, or both. In this embodiment, reinforcing, surface treatment to improve integrity and adhesion, and reorienting the reinforcing material and / or polymer chains using mechanical stresses can also be used to make flat preformed sheets and can be performed in a manner similar to coaxial blow molding or dispersion polymerization.

As an additional manufacturing technology, the method for producing a composite sheet described above can also be used to obtain a separate relatively thick sheet of metal and a metal alloy suitable for mechanical molding with the formation of components of compressible or crumpled objects or particles. This approach to the manufacture of a single sheet of metal or metal alloy is particularly suitable when a thin metal sheet is difficult to manufacture by conventional thermomechanical methods used in the manufacture of a metal sheet. In particular, a sheet of metal and metal alloy may have a thickness between about 5 and 50 microns. To form a separate metal sheet, the polymer matrix can be removed from the thin metal sheet after the deposition of the metal or metal

- 22 016839 alloy, before or after any additional thermomechanical processing necessary to seal the deposited thin sheet. Removal of the polymer matrix can be accomplished by a variety of mechanical, chemical, and / or thermal methods known to those of ordinary skill in the art. Alternatively, the sheet of polymer matrix may be preformed into components of compressible objects before deposition of a thin film of metal or metal alloy to form a separate preform of metal or metal alloy.

As yet another embodiment of a manufacturing method, hollow compressible objects can be formed by physical and / or chemical vapor deposition (as described above) of the chemical components of a thermosetting polymer onto a hollow matrix of a thermally depolymerizable polymer or polymer foam material. Following the deposition, the components of the thermosetting polymer can be involved in a partial interaction with each other by increasing the temperature to form a self-supporting layer of the thermosetting resin blank on the surface of the hollow shell or foam matrix of the depolymerizable polymer. After the self-supporting layer of the thermosetting polymer preform is formed, the temperature can be further increased to depolymerize the hollow and / or foam matrix, and the depolymerization products are removed from the resulting hollow self-supporting object by diffusion through the wall of the thermosetting polymer preform. Finally, partially cured self-supporting hollow billets of thermosetting polymer objects can be placed in the autoclave under high pressure, and the pressure inside the hollow objects by diffusion through the pre-formed wall of the thermosetting polymer comes into equilibrium with the high gas pressure created inside the autoclave. Then, the temperature in the gaseous medium under high pressure can be increased even more to completely cure the thermosetting polymer in order to reduce the gas permeability of the wall and achieve optimal mechanical characteristics of the wall material. As above, metallization of the outer surface of a fully cured and pressurized thermoset polymer shell can be performed by the methods described above for hollow polymer shells under pressure obtained by coaxial blow molding.

Further, as yet another embodiment, compressible objects can be mechanically conditioned during manufacture to strengthen the load-bearing wall of compressible objects by reorienting the microfiber and / or nanofiber reinforcement and / or polymer chains contained in the wall material using mechanical stresses. This mechanical conditioning may include, but is not limited to, expanding the compressible object to its final size and shape.

B. Production of compressible objects using a foam matrix.

In addition to the production of hollow objects in the manufacturing processes, a matrix of foam material can be used to create a specific shape in the production of compressible objects. In these manufacturing processes, compressible objects having a shell that encloses an inner region and an internal pressure of greater than about 200 psi (1.378 MPa) at atmospheric pressure, 500 psi (3.445 MPa) at atmospheric pressure can be formed. , 1,500 psi (10.335 MPa) at atmospheric pressure or 2,000 psi inch (13.780 MPa) at atmospheric pressure and is selected for a predetermined external pressure in which external pressures that exceed the internal pressure reduce the volume of the compressible object, a shell at least partially filled with foam and / or a shell capable of undergoing or experiencing less deformation when the external pressure is approximately equal to the internal pressure than when the external pressure exceeds the internal pressure, or is less than the internal pressure, or in which the shell undergoes It exhibits less strain when the external pressure is approximately equal to the internal pressure than when the external pressure is greater or less than a predetermined compression range of the compressible object. The foam matrix may include homopolymers, polymer blends, copolymers, interpenetrating net structures, block copolymers, thermosetting polymers, thermoplastic polymers, amorphous polymers, crystalline polymers, chemically crosslinked copolymers, thermoplastic elastomers, rubbers, liquid crystal polymers, etc. of foam material can be formed with various predetermined shapes, such, but not limited to, such as a sphere, rod, thin plate, flattened or odolgovatye spheroids, ellipsoids of revolution and / or any combination of these geometric shapes. Further, the foam matrices used in the manufacture of compressible objects, such as rods, thin plates, and the like, can be structured to contain a wide variety of porous structures (e.g., closed and / or open pores), pore wall thicknesses, and pore density. These diverse designs can be useful for producing hollow objects covering a wide range of mechanical characteristics.

Foamed blanks can be obtained by injection molding, cutting and coating methods, which may be similar to those related to the use of foaming

- 23 016839 materials for the manufacture of insulation and / or packaging. Cutting methods may include cutting foam blocks into fragments with various shapes and sizes. Injection molding methods, which may include extrusion, blow molding, injection molding and the like, may include molding a foam material in a desired intricate shape that can reduce or eliminate the laborious cutting and the amount of waste generated by this technology. In addition, foam materials having numerous stiffness zones and containing reinforcing fillers can be produced by injection molding methods. The previously described coating methods can also be used to coat a foam preform, which methods may include electrically cladding, non-electric cladding, physical vapor deposition, chemical vapor deposition, chemical vapor deposition with ultraviolet activation, and the like, and can be used to form a relatively thin layer of metal or a metal alloy on a foam matrix. The application of a coating layer of a metal or metal alloy in this embodiment is used to increase the impermeability of compressible objects, which may include a gas (or mixture of gases) under pressure. Alternatively, a polymer matrix may be used to deposit a relatively thick load-bearing wall of metal and / or metal alloy using injection molded or mechanically formed polymer foam material with or without internal pressure. The metal load bearing wall may have a wall thickness of from about 5 to 50 μm and an internal pressure above about 200 psi (1.378 MPa) at atmospheric pressure or more, depending on the desired application.

As a first embodiment, blowing agents can be used to form a foam matrix for compressible objects. Typically, the use of physical blowing agents results in a closed-cell foam matrix that can be formed from a variety of materials. For example, polyurethane, polystyrene (Ρ8) and polyvinyl chloride are materials used in the manufacture of polymeric foam materials. Typically, foamed polyurethanes are produced as a result of the formation of carbon dioxide (CO ₂ ), while foamed polystyrene and polyvinyl chloride are obtained using physical blowing agents such as nitrogen (Ν2) and CO2. The use of physical blowing agents reduces the amount of any polluting solvents that can interfere with the process. The use of CO ₂ and Ν ₂ has several advantages, such as chemical inertness, incombustibility, natural origin, low cost, easy accessibility, environmental acceptability (no harmful effects on the ozone layer) and low toxicity to humans.

Each of the methods for producing polymer foamed materials in which physical blowing agents are used is based on similar principles. These principles are saturation of the polymer with a gaseous penetrant (blowing agent) at high pressure, quenching of the gas-polymer mixture in a supersaturated state either by depressurization, or by raising the temperature, and nucleation and growth of gas cells dispersed in the bulk of the polymer matrix. When quenching a gas-polymer mixture, the solubility of the gas in the polymer matrix decreases, which leads to the aggregation of gas molecules in the form of nuclei. As the gas diffuses into the formed cells, the free energy of the polymer matrix decreases. The process of nucleation and cell formation determines the morphology of the cells in the polymer material and the properties of the polymer material. In addition, the process can occur uniformly throughout the bulk of the material or heterogeneously in high energy regions, such as phase interfaces. In areas of high energy, the free energy for the nucleation of stable voids is lower than homogeneous nucleation. As a result, predominant nucleation of voids occurs at the interface.

In semi-crystalline polymers, crystalline domains can serve as heterogeneous nucleation points for the formation of gas bubbles. In general, cell growth is controlled by the time it takes for the gas to diffuse into the cells before quenching, the temperature of the manufacturing process, the degree of supersaturation, the rate of gas diffusion into the cells, hydrostatic pressure or load applied to the polymer matrix, interfacial energy, and viscoelastic gas polymer properties mixtures. The stiffness of the polymer matrix is typically controlled by the foaming temperature. It should be noted that reducing the average cell size generally increases stiffness. The work required to expand the gas cell must overcome the additional stress due to increased rigidity. By increasing the saturation pressure, the free energy barrier for the formation of stable nuclei is reduced, and additional nucleation points arise due to swelling of the matrix, changes in the free volume, and / or the formation of crystalline phase interfaces. This results in an increase in cell density and, consequently, a decrease in the average cell diameter. Semicrystalline polymers exhibit significantly higher cell densities than amorphous polymers, which is due to the contribution of heterogeneous nucleation at the interface between the amorphous and crystalline zones. Since the gas does not dissolve in crystallites, nucleation is heterogeneous, which makes control difficult

- 24 016839 cellular structure of foamed semi-crystalline polymers. As a result, low crystallinity polymers produce foams with an almost uniform structure. As polymer crystallinity increases, less desirable heterogeneous foams with irregular cell sizes are observed.

Since the method of foaming using physical blowing agents is universal, this technology can be used to make foamed polymer matrices with closed cells for compressible objects. For example, amorphous as well as semi-crystalline polymers can be processed within a temperature range close to the glass transition temperature (T _d ), up to temperatures almost reaching the melting temperature of the material. As an example, the manufacturing process for producing foam matrices and coating the foam matrices is discussed below in FIG. nine.

FIG. 9 is an exemplary flowchart for manufacturing compressible objects in FIG. 6, in which a foam matrix is used in accordance with some aspects of the present technology. This flowchart 900 may be better understood while referring to FIG. 1 and 6. In block diagram 900, a method for manufacturing compressible objects having a foamed inner region is described.

The flowchart begins at step 902. At step 904, foamed material can be obtained. Foamed material can be formed in a variety of ways, which are discussed above. Foamed material may include polymeric materials, such as moderate to high crosslinked elastomers, with and without reinforcement, such as macro to intermediate and nanoscale fibers, nanotubes, exfoliating inorganic fillers (e.g. clays), and polymer blends with reinforcement and without it, such as fibers from macroscale to intermediate and nanoscale, nanotubes, exfoliating inorganic fillers (e.g. clays) and the like. At 906, foam can be formed into foam matrices. Foamed matrices can include a variety of shapes, such as cubes, rectangles, rods, squares, and other regular or irregular shapes, as discussed above. To form foamed matrices, foamed material or polymeric material can be formed into fragments with different geometric shapes and sizes by cutting or other suitable methods. Then, at step 908, the formed foam matrices may be coated with material. The material may include a thin metal or non-metallic coating to reduce gas permeability, which is applied by any suitable deposition method, as discussed above. Coatings can include a wide variety of compositions, including pure metals, metal alloys and / or layers of various metals or metal alloys, individually or in combination with non-metallic layers, among others. At step 910, the coated foam matrices can be further surface treated to enhance adhesion to the surface of the polymer foam matrix and to promote the integrity of these coatings. These surface treatments may be similar to the surface treatments discussed above. The process ends with step 912.

The coating of these differently formed foam matrices is shown in FIG. 10. In FIG. 10, various foam matrices are shown, such as an object in the form of a pillow 1002, an elliptical object 1003 and a spherical object 1004. These objects 1002-1004 of the foam matrix are formed with various shapes in step 906. Then, the objects 1002-1004 of the foam matrix can be coated with a metal layer 1006 in step 908. In particular, the foam matrix objects 1002-1004 can be coated with a thin metal coating (eg, copper) by a non-electric cladding method. Being coated, the foam matrix objects 1002-1004 can be further coated with a surface treatment layer 1008 in step 910.

As a specific example of a given manufacturing method, a first foam matrix and a second foam matrix are described. The first foam matrix may be an air-filled foam microcapsule having cells with a size of about 1000 to 1500 μm in diameter, while the second foam matrix may be an air-filled foam microcapsule having cells of a size of about 250 to 500 μm in diameter. These foam matrices can be cut into fragments with different geometric shapes and sizes, as noted above. Then, the formed foam matrices can be sequentially coated with a thin metal coating (for example, copper) by a non-electric cladding method. Metal coatings may include, among others, a wide variety of compositions, including metals, metal mixtures, alloys, shape memory alloys.

It should further be noted that surface treatments can be adapted to various foam matrices. For example, if the foam matrix is made of polystyrene, the latter is a non-polar and chemically reactive polymer. The degree of functionalization, i.e. sulfonation, can be controlled by a number of parameters, such as solvent, sulfuric acid concentration, reaction temperature, reaction time, catalyst and catalyst concentration. Essentially, it should be noted that the chemical nature of surface functionalization and the subsequent procedures can be modified to adapt to the chemical nature

- 25 016839 surface and structure of the material, such as nylon, polyesters, polyurethanes, among many other polymeric materials. Surface functionalization and etching may include acid treatment, base treatment, oxidation, nitration, sulfonation, phosphonylation, among many other chemical approaches. See book 1. Magsb, Abuaiseb Ogdashs Sbet1vbu: Weasboiv, Mesbashvt, app 8bis, third edition, беοΙιη Abeu & 8oiv, New York (1985), sections on sulfonation, mild oxidation, esterification, carboxylation, free radical reactions accession, chain free radical reactions and quaternization, etc.

As a first specific example, the foam matrices may be uniformly coated in a manner such as non-electric cladding with copper to form rod-shaped foam objects. The foamed matrix may be an air-filled foamed microcapsule having cells with a diameter of from 1000 to 1500 microns. If this foam matrix is made up of polystyrene, the manufacturing process may include the functionalization of the polystyrene core by the action of a 30% solution of sulfuric acid (H ₂ 8 O ₄ ) over a 21-hour period. The surface of the functionalized polymer can be activated using a sensitization process with tin compounds and activation with palladium (δη-Pb), otherwise known as seeding. This baiting process is familiar to those skilled in the art. The process involves sequential immersion of the polystyrene core in an acidified solution of tin chloride (8iC1 ₂ ) (with a concentration of 0.01 M), then in an acidified solution of palladium chloride (PbC1 ₂ ) (with a concentration of 0.01 M), with washing with distilled water between the baths. After treatment with palladium chloride (PbC1 ₂ ), a 0.01 M solution of hydrogen chloride (HC1) is used to remove residual tin compounds (8i) from the surface. Processing in each of the baths is carried out at room temperature. See the dissertation by V. Seu1ai Ak1v, Rgeragaboi oG RB-Ld / R88 Sotrovye Metbgaev Gog Nubgodey 8erababoeiv, A Tbev1v, Aogsev! E Ro1u! Esbshs 1ivb! U! E (May 2004).

A functionalized polystyrene core sealed with palladium (Pb) can be placed in a flow bath with a flow rate of 73 cm ³ / min containing a solution for cladding with copper (Cu), consisting of copper sulfate (Cu8O ₄ x5H ₂ O), disodium dihydrate of ethylene diamine tetraacetic acid, caustic soda (No. YUN). ethylenediamine and triethanolamine activated with formic acid. See articles Υ. Lh and 8. Fey, Arrbeb 8gGase 8s1eise, t. 178, p. 116 (2001); A. Yi, N. Sbaid, 8gase aib Soabidv Tesbio1odu, v. 107, p. 48 (1998); 81 and e! A1., 1ib. Eid. Sb. Kev., T. 36, p. 1632 (1997); Naia e! A1., Ma! epa1b Lebegv, vol. 58, p. 104 (2003). Copper (Cu) can be deposited on a functionalized polystyrene rod sealed with palladium (Pb) at a temperature of 40 ° C for a 90-minute period, followed by washing with distilled water. Most of the surface can be coated with a layer of copper (Cu) having a thickness that varies from 0.3 to 0.6 microns.

Alternatively, if the foam matrix is an air-filled foam microcapsule having cells with a diameter of about 250 to 500 microns and a spherical shape, the manufacturing process may include functionalization and seeding with palladium (Pb) of the polystyrene sphere, as described above. Using the same solution for cladding with copper (Cu) and consumption, the functionalized and palladium-etched (Pb) polystyrene sphere can be clad at a temperature of 40 ° C for a 10-minute period, followed by washing with distilled water. As a result, the surface can be coated with a copper (Cu) film 0.1-0.2 microns thick, which follows the contours of the surface of the foam material.

As another example, the manufacturing process of a Nylon 6/6 ball having a diameter of 1/8 inch (3.175 mm) may include functionalization and palladium (Pb) seeding of the solid ball, as described above, using a 0.01 M HC1 solution for 10 min for the functionalization process. In addition, a nylon ball can be reacted in a flowing solution at a temperature of 40 ° C for 4 hours 5 minutes, followed by washing with distilled water, which can be the same solution for cladding with copper, with the activator discussed above. The cladding copper film may have a thickness of 10-25 μm over a nylon ball.

As yet another exemplary manufacturing method, a hollow gas-filled metal shell can be obtained using the Fraunhofer method for producing hollow metal objects, as shown in FIG. 11 A. For example, see an article by O. Aibegway, and. Aaad, b. 8cbne ^ ba ^, 6.88! Erbash, V. Klebask, No. 1 Me! And Shs No11o \ u 8rbege 8bis! Igev, Abuaiseb Yidsheepid Ma1epa1v, 2000, v. 2 (April 2000), pp. 192-195. In this embodiment 1100, the foam matrices 1102, which may be matrices of 81st foamed polystyrene matrices or any of the above described polymeric foam matrices, may be coated with metallic material 1104, which may include metal or metal alloy powder and a binder. The coating of foam matrices 1102 of a metal material and a binder 1104 can be accomplished by fluidized bed coating methods in a reactor 1106. The resulting polymer foam matrices coated with a layer 1108 of a metal or metal alloy and a binder can then be calcined in an oven 1110. In a furnace, the polymer foam matrix may be thermally decomposed or reacted to form volatile reaction products that are removed by diffusion through walls coming from partially sintered metal

- 26 016839 or a metal alloy. Then the temperature can be raised to remove the residual binder, and the metal material is sintered to obtain a dense shell of metal or a metal alloy. The resulting compressible objects 1112, after cooling, can be used as part of a variable density drilling fluid.

An alternative manufacturing method is shown in FIG. 11B. In FIG. 11B Regular or irregular hollow objects of a metal or metal alloy can be made by forming a layer of a metal or metal alloy, such as a nickel layer, on a foamed matrix by vapor deposition on a disposable foamed matrix. In Embodiment 1120, a foamed matrix 1122 is prepared, which may be a closed cell polymer foamed matrix. The foam matrix 1122 is coated with pigment 1124, such as carbon black or other pigments that absorb infrared radiation, to form a coated foam matrix 1126. The coated foam matrix 1126 is then placed in a reactor that is filled with gas 1128, such as gaseous nickel carbonyl. The coated foam matrix 1126 is then exposed to infrared radiation 1130, which heats the coated surface of the coated foam matrix 1126. As a result of exposure to infrared radiation 1130, carbonyl decomposes on the surface of the coated foam matrix 1126 to form a metal coating 1132, such as nickel on the foam matrix 1134. Metal coated the foamed matrix 1134 is then sintered in the furnace 1136 at a temperature high enough to decompose the foamed matrix, and the decomposition products are removed m diffusion through the metal layer during the sintering process. As a result, compressible objects 1138 with a hollow inner region are formed.

Modification of compressible objects to relieve local stress.

As an additional embodiment, the structure of compressible objects can be modified to distribute local stress arising in the expanded and compressed state. For example, finite element modeling in the case of the rotation ellipsoid discussed above demonstrates that the degree of instability of creasing of the apex increases with increasing wall thickness and a decrease in the initial ratio of geometric dimensions, while the degree of instability of equatorial protrusion increases with decreasing wall thickness and an increase in the ratio of geometric dimensions. To expand the degree of freedom in designing the architecture of a compressible object, the wall thickness of a compressible object can vary with thinning of the wall at the poles and thickening at the equator. This wall thickness adjustment can provide support in each embodiment to relieve local stresses in various areas of compressible objects. The variation of the wall thickness from the pole to the equator can be performed in a manner that is compatible with certain manufacturing methods, which are discussed above.

Alternatively, one or more structural elements, such as a flange, may be added to compressible objects. These structural elements, such as a flange, can reduce local stress in the shell of a compressible object. For example, if the structural element is a flange, it can be added at the equator of a compressible object to support the equatorial belt against protrusion. This flange can distribute the deforming force along the equator of the compressible object for the propagation of stress from the local zone. For example, as shown in FIG. 12A12C shows the effect of adding a flange 1202 to an elliptical object with a wall thickness of 10 microns (10 μm) in various states. In this example, an elliptical object can have an internal pressure-expanding pressure of 1,500 psi (10.335 MPa, excess) in this example and is formed from a pseudo-elastic material such as a shape memory alloy, alloy ΝίΤί with a phase transition temperature of about 0 from austenite to martensite ° C. In FIG. 12A shows a compressible object, which is an elliptical compressible object having a flange 1202 in the initial state 1200. The elliptical object is shown in the expanded state 1204 in FIG. 12B and in a compressed state 1206 in FIG. 12C. As shown in FIG. 12A-12C, flange 1202 distributes local stress to a level below the maximum strain experienced by the elliptical object. The benefits of adding a flange are discussed further in FIG. thirteen.

FIG. 13 is an exemplary graph regarding the addition of a flange to a compressible object in accordance with some aspects of the present technology. In FIG. 13, finite element modeling was used to create a graph 1300 of maximum strain 1302 versus compression ratio 1304 for a first compressible object having a flange and a second compressible object without a flange. Graph 1300 includes a first characteristic curve 1306 for a first compressible object having a wall thickness of 10 μm and a flange of width 125 μm, which may be the elliptical object of FIG. 12A-12C, and a second characteristic curve 1308 for a second compressible object having a wall thickness of 10 μm without a flange. In graph 1300, line 1310 indicates the approximate maximum reversible strain for формации alloy, and line 1312 shows the approximate maximum permissible strain required to achieve the desired volume fatigue life, which is discussed above.

As shown in graph 1300, adding a flange reduces the maximum stress experienced by elliptical objects having the same structure and wall thickness. Essentially equa

- 27 016839 a toric flange can be used to expand the degree of freedom in the design of compressible objects that are below the limits of permanent deformation.

The addition of the equatorial flange can be performed in a manner that is compatible with certain manufacturing methods, which are discussed above. As an example, the manufacture of compressible objects from a sheet metal alloy and the subsequent connection to the equatorial flange can be adapted to form a flange of a certain width by modifying existing production processes.

The use of weighting agents and other fluids to obtain a given drilling fluid of variable density.

As noted above, variable density drilling fluid 118 (FIG. 1) may include compressible objects together with drilling fluid. The choice of drilling fluid may include the selection of the primary component of the liquid phase from a number of available fluids. These fluids include water, oil, or a combination of water and oil. The liquid phase is selected after considering several factors, including cost, compatibility with underground formations, environmental impact, etc. Weighting agents are added to adjust the density of the drilling fluid. Thickeners are added to stabilize the suspension of weighting agents and cuttings. Other additives provide filtration control to prevent leakage of the liquid phase into the formation or facilitate the emulsification of free water in the oil phase.

To balance compressible objects, drilling fluids may include weighting agents and other fluids to control the density of a variable density drilling fluid inside the borehole. Weighting agents may include barite (barium sulfate), hematite (ferric oxide), galena (lead sulfide) and other suitable materials, while other admixable agents may include formates, such as sodium, potassium and cesium formates, and other suitable materials .

Weighting agents are added to drilling fluids to increase the density of the drilling fluid above the density level of aqueous (water) or non-aqueous (oil or synthetic fluids) base fluids. For example, weighting agents may include barite (barium sulfate), hematite (ferric oxide), galena (lead sulfide) and other suitable materials. These weighting agents are used to create the desired density profile of the composite drilling fluid from the surface to a predetermined depth. Since the pressure inside the borehole generally increases with depth, low-density compressible objects, such as compressible objects, are in an uncompressed state close to the surface, and in a compressed state are located on the side of the bottomhole zone of the borehole. When the compressible objects are in a compressed state due to pressure in the bottomhole zone, the density of the composite drilling fluid of variable density can be maintained to prevent fluid outflow from the formation and limited so that it does not exceed the pressure gradient of the hydraulic fracturing. When the compressible objects are in an uncompressed state at shallow depths, the formation may be exposed to variable density drilling mud in rock layers that are not so strong and the pressure of the formation fluid is typically lower. Essentially, the uncompressed state of compressible objects can be used to reduce the density of a suspension of a variable density drilling fluid. Accordingly, a variety of weighting agents can be used in drilling fluid to increase density in shallow sections of the borehole to keep compressible objects from expanding.

For example, barite (barium sulfate) can be used to increase the density of drilling fluid 118 variable density. The advantage of using barite as a weighting agent in drilling fluid is the low cost and easy availability of this material. Barite in its purest form has a density of 4.5 g / cm ³ , and barite in the category for drilling has a density of at least 4.2 g / cm ³ to be classified as an American Petroleum Institute standard. To achieve high mud density, barite can be suspended in drilling fluid at a high concentration. For example, drilling fluid with a density of up to 19 pounds per gallon (2.3 g / cm ³ ) may contain approximately 40% barite by volume. As the volume percentage of solids increases, the viscosity of the drilling fluid, especially at high degrees of shear, becomes very high, and the frictional pressure drop in the circulation system or in the downhole equipment becomes very high.

Accordingly, drilling fluid with barite can be combined with compressible objects up to 40 vol.% Under surface conditions. The result of this combination provides higher viscosity values where compressible objects are uncompressed (at the surface and shallow depths).

Similar densities of a variable density drilling fluid can be achieved with a lower proportion in volume percent of a weighting agent using a higher density material such as hematite (ferric oxide) or galena (lead sulfide). Hematite has a minimum density of 5.5 g / cm ^{3 as} measured by the American Petroleum Institute and can increase the density of drilling fluid at a lower total solids concentration than barite. However, drilling fluids with hematite may be more abrasive than drilling fluids with

- 28 016839 with barite, which can lead to premature damage or deterioration of equipment, such as drilling mud pumps, surface equipment of a drilling rig, drill pipe lines and downhole tools (i.e. motors), registration and measuring equipment. Galena (lead sulfide) has a density of 7.5 g / cm ³ and can be used to achieve a high density with a solids content of about 40% less than barite. Galena is a relatively soft mineral and does not cause premature wear of equipment.

In an alternative embodiment with compressible objects, mixture components may be used instead of or in addition to weighting agents. These components of the mixture may include formates, such as sodium, potassium, and cesium formates. For example, a solution of cesium formate in water can give a density of about 2.4 g / cm ³ without solids (without weighting agents). The density of the cesium formate solution is almost equal to that of a typical rock or rock fragments. As a result, rock fragments are not inclined to sink in drilling fluid with such a component of the mixture. When a cesium formate solution is mixed with compressible objects, a variable density drilling fluid can provide high density at high pressures where the compressible objects are in a compressed state (i.e. deep in the borehole). However, at shallow depths, where the compressible objects are in an expanded state, the density of the drilling fluid of variable density decreases. With such a liquid, an increase in the volume percentage of expanded compressible objects naturally increases the bulk density and contributes to the removal of rock fragments.

Additional viscosity can be achieved by adding thickeners, such as naturally occurring bentonite clay or synthetic polymers, to reduce the rate at which rock fragments and compressible objects tend to settle due to the difference in density between the fragments / compressible objects and the drilling fluid. These types of thickeners contribute to the removal of debris during the circulation of the drilling fluid and contribute to the gelation of the drilling fluid when the flow is suspended, thereby reducing the sedimentation rate of the debris and the sedimentation rate of compressible objects. Compressible objects may tend to float or sink inside the drilling fluid, depending on the state of their compression and the density of the compressible objects inside the borehole. At external pressures lower than those required to compress objects or particles, compressible objects generally have a lower density than drilling fluid. Here, compressible objects tend to float inside the fluid until the viscosity is sufficient to prevent movement. When the external pressures are high enough to ensure proper compression of the objects, the density of the compressible objects can reach or exceed the density of the drilling fluid. In this embodiment, the compressible objects may not move relative to the liquid or may even tend to sink inside the liquid, unless the viscosity is sufficient to prevent movement.

While the present technology according to the invention may be susceptible to various modifications and alternative forms, the exemplary embodiments discussed above have been shown by way of example. However, again, it should be understood that the invention is not intended to be limited to the specific embodiments presented herein. Indeed, the present methods according to the invention should cover all modifications, equivalents and alternatives falling within the meaning and scope of the invention, as defined by the following appended claims.

Claims (66)

CLAIM 1. Compressible object to change the density of the drilling fluid, containing a shell that has an internal region in which the compressible object has an internal pressure, while the shell has a structure that can compensate for local stresses in the compressible object during its expansion and contraction. 2. The compressible object of claim 1, wherein the inner region is at least partially filled with foam material. 3. The compressible object according to claim 1, wherein the internal pressure exceeds a value of about 13,790 bar (200 pounds per square inch) at atmospheric external pressure and temperature and is selected for predetermined external pressures, while external pressures exceeding the internal pressure reduce volume of compressible object. 4. The compressible object according to claims 1, 2 or 3, in which the shell is able to experience less deformation with an approximate equality of external pressure and internal pressure than when the external pressure is greater or less than the specified compression interval of the compressible object. 5. A compressible object according to claims 1, 2 or 3, which has an internal pressure greater than about 34,470 bar (500 psi) at atmospheric external pressure and temperature, more preferably about 103400 bar (1,500 psi). inch) at atmospheric external pressure and temperature, and most preferably about 137900 bar (2000 pounds per - 29 016839 sq. Inch) at atmospheric external pressure and temperature. 6. Compressible object according to claims 1, 2 or 3, in which the shell has at least one structural element to reduce local stress. 7. The compressible object according to claim 6, in which at least one structural element includes a flange. 8. Compressible object according to claims 1, 2 or 3, in which the wall thickness of the shell varies within the surface of the compressible object to reduce local stress. 9. Compressible object according to claims 1, 2 or 3, in which the shell wall thickness is greater at the equator of the compressible object to reduce local stress. 10. Compressible object according to claims 1, 2 or 3, which has the shape of an ellipsoid with a ratio of geometric dimensions in the range between about 2 and about 5 with an approximate equality of external and internal pressure and more preferably with a ratio of geometric dimensions in the range between about 3 and about 4 with an approximate equality of external and internal pressure. 11. Compressible object according to claims 1, 2 or 3, in which the shell has a ratio of equivalent diameter to wall thickness in the range from about 20 to about 200, and more preferably in the range from about 50 to about 100. 12. Compressible object according to claims 1, 2 or 3, in which the shell includes a stratifying inorganic mineral as a reinforcing material or as a gas-tight barrier in the polymer matrix. 13. Compressible object according to claims 1, 2 or 3, in which the shell is made with nanofibrous reinforcement in the polymer matrix to achieve specific properties of the material of the wall. 14. The compressible object according to claims 1, 2 or 3, in which the shell includes a gas-tight barrier layer and a carrier layer. 15. The compressible object according to claim 14, in which the gas-tight barrier layer includes a layer of metal or a metal alloy and the carrier layer includes a polymer layer. 16. A compressible object according to claims 1, 2 or 3, which has an equivalent diameter in the range of between about 0.1 and about 50 mm and more preferably between about 0.1 and about 5.0 mm when the external pressure is less than the internal pressure. 17. A compressible object according to claims 1, 2 or 3, in which the inner region contains at least one non-liquefied gas selected to precisely adjust the deformation characteristics of the compressible object in response to changes in external pressure and temperatures. 18. A compressible object according to claims 1, 2 or 3, in which the inner region contains at least one liquefiable gas selected to precisely adjust the deformation characteristics of the compressible object in response to changes in external pressure and temperatures. 19. Drilling fluid containing compressible objects according to any one of claims 1-18 and basic drilling fluid, in which the density of the drilling fluid changes due to a change in the volume of compressible objects in response to changes in pressure and temperature as the drilling fluid and compressible objects move to the surface of the well . 20. The drilling fluid according to claim 19, further comprising weighting agents for controlling the density of the base drilling fluid. 21. The drilling fluid of claim 20, wherein the weighting agents include one of barite, hematite, galena, and any combination thereof. 22. The drilling fluid of claim 19, further comprising formates for regulating the density of the drilling fluid and reducing the addition of insoluble weighting agents capable of increasing the viscosity of the drilling fluid and compressible objects. 23. The method of drilling wells, which use the drilling fluid according to any one of PP-22. 24. A method of manufacturing a compressible object to change the density of the drilling fluid having a shell that includes an internal region having an internal pressure in which a compressible object structure is selected that is able to compensate for local stresses on the compressible object during its expansion and contraction, form a polymeric object and form a layer of metal or metal alloy on the polymer object with the formation of the specified shell. 25. The method of claim 24, wherein an internal pressure greater than about 13,790 bar (200 psi) at atmospheric pressure is selected for a predetermined external pressure at which the object begins to compress, and is selected based on at least least one or more characteristics of the structure or wall material. 26. The method according to paragraph 24, in which the wall material for the compressible object is chosen so that it can withstand local stress in the compressible object during its expansion and contraction. 27. The method according to p. 26, in which the structure of the compressible object and the wall material of the compressible object is selected on the basis of modeling by analysis using the finite element method. 28. The method according to paragraph 24, in which the polymer object is cooled to reduce the internal pressure before a metal or metal alloy layer is deposited on it. 29. The method according to PP.24-27, which is carried out using a chamber under pressure. - 30 016839 30. The method according to PP.24-27, in which a flat polymeric sheet formed as parts of a compressible object is selected as a polymer object, and after forming a layer of metal or a metal alloy on these parts, they are joined using at least one of mechanical, chemical and thermal methods with the formation of a compressible object. 31. The method according to paragraphs.24-27, in which a matrix is selected as the polymer object on which a layer of metal or a metal alloy is formed, and the matrix covered with the specified layer is heated. 32. The method according to p, in which the matrix contains capable of depolymerization of a hollow polymer or foamed polymer. 33. The method according to p, in which the heating of the matrix is carried out for its decomposition and diffusion of decomposition products through the shell of a compressible object. 34. The method according to paragraphs.24-27, in which a foamed matrix is selected as the polymer object on which a layer of metal or a metal alloy is formed. 35. The method according to clause 34, in which a layer of metal or metal alloy is formed on the foamed matrix by means of physical vapor deposition, or chemical vapor deposition, or electrochemical deposition, or non-electric deposition, or metallization, or sputtering, or evaporation or epitaxial molecular beam. 36. The method according to clause 34, in which prior to the formation of a layer of metal or metal alloy on the foamed matrix, it is cooled to a temperature below which the foamed material inside the shell is condensed. 37. The method according to clause 34, in which a layer of metal or metal alloy on the foamed matrix is formed by electroplating. 38. The method according to clause 34, in which a layer of metal or metal alloy is formed on the foamed matrix by non-electric cladding. 39. The method according to paragraphs.24-27, in which a polymer matrix is selected as the polymer object and an exfoliating inorganic mineral is formed in the polymer matrix. 40. The method according to § 39, in which the shell is made with nanofiber reinforcement in the polymer matrix to achieve the specific characteristics of the shell material. 41. The method according to PP.24-27, in which a polymer object is formed in a chamber having a first pipe located inside the second pipe, thus forming a polymer bubble of a polymer material in the second pipe and a gas in the first pipe, affect the outer surface of the polymer bubble cross-linking fluid with the formation of a polymeric object and remove the cross-linking fluid after curing of the polymeric object. 42. The method according to claim 41, wherein a sufficient pressure difference is created in the annular space formed between the first pipe and the second pipe to form the polymeric material into the polymeric object. 43. The method according to paragraph 41, wherein the chamber is a pressure chamber having an internal pressure greater than atmospheric pressure. 44. The method according to claim 43, wherein the pressure in the chamber is reduced to expand the polymer bubble to its expanded state. 45. The method according to claim 41, wherein the opening of the first pipe is additionally heated to reduce the melt viscosity in order to achieve the desired values of the flow properties of the polymeric material. 46. The method according to paragraph 41, in which the surface of the polymer bubble after separation from the first pipe and the second pipe is polymerized using ultraviolet radiation, or free radical polymerization, or thermochemical polymerization. 47. The method according to PP.24-27, in which a polymeric object is formed in an installation having a lower chamber with a nozzle for introducing gas and an upper chamber with a nozzle for admitting a liquid and a nozzle for releasing a liquid, in which the nozzle for introducing a gas is separated by a plate with perforations from the liquid inlet and outlet of the liquid, place the polymer sheet on the plate, create a pressure in the lower chamber that exceeds the pressure in the upper chamber, and form polymer objects from the polymer sheet. 48. The method of claim 47, wherein the polymeric object is removed from the upper chamber through the outlet. 49. The method according to p. 47, in which the perforations of the plate are made in the form of a set of alternative geometric contours for the formation of different sized polymer objects. 50. The method according to paragraphs.24-27, in which a foamed matrix is selected as the polymer object, on which a layer of metal or a metal alloy is formed, and then the foamed matrix coated with the specified layer is fired. 51. The method according to claim 50, in which the foamed matrix is a matrix of expanded polystyrene. 52. The method according to claim 50, in which the firing of the foamed matrix leads to its decomposition by diffusion through the shell of the compressible object. 53. The method of claim 50, further comprising using a binder material to bind a metal or metal alloy layer with a foamed matrix. - 31 016839 54. The method according to PP.24-27, in which a foamed matrix is selected as a polymeric object, the foamed matrix is coated with a layer of pigment, a foamed matrix coated with pigment is placed in a gas-filled reactor, irradiated with a metal layer and foamed with a metal coated the matrix. 55. The method according to item 54, in which the foam matrix is an object with an irregular shape. 56. The method according to item 54, in which the foam matrix includes a foamed polymeric material with closed cells. 57. The method according to claim 54, wherein the pigment layer comprises carbon black. 58. The method of claim 54, wherein the gas is nickel carbonyl gas. 59. The method according to item 54, in which the firing of the foamed matrix leads to its decomposition by diffusion through the shell of the compressible object. 60. The method according to any of claims 24 to 54, in which the compressible object in the expanded state has an equivalent diameter in the range of between about 0.1 and about 50 mm, and more preferably between about 0.1 and about 5.0 mm. 61. The method according to any of claims 24 to 54, in which the compressible object at atmospheric pressure has an internal pressure greater than about 103400 bar (1500 psi) and more preferably about 137900 bar (2000 psi ). 62. The method according to any of paragraphs.24-54, in which the compressible object has at least one structural element to reduce local stress. 63. The method according to § 57, in which at least one structural element contains a flange. 64. The method according to any of paragraphs.24-54, in which the wall thickness of the shell of a compressible object varies within the surface of the compressible object to reduce local stress. 65. The method according to any of paragraphs.24-54, in which the compressible object has the shape of an ellipsoid with a ratio of geometric dimensions in the range between about 2 and about 5, and more preferably between about 3 and about 4 with an approximate equality of external and internal pressure. 66. The method according to any of paragraphs.24-54, in which the shell has a ratio of equivalent diameter to wall thickness in the range from about 20 to about 200, and more preferably in the range from about 50 to about 100.