RU2802635C1 - Packer with a four-section hydraulic setting chamber - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: devices for selective hydraulic fracturing, repair and insulation works, used in the implementation of underground workover of wells in order to stimulate the flow of hydrocarbons. The packer with a four-section hydraulic setting chamber for hydraulic fracturing contains: three completely identical hydraulic sections, where the hydraulic section consists of an internal clamping piston having four holes for hydraulic communication between the hydraulic chamber, clamping cylinders and tubing, on which the packer lowers with cylinder seal and O-ring; one hydraulic section containing a clamping piston with a seal containing a retaining ring configured to limit the stroke of the clamping cylinders and control the compression of the packer element; clamping cylinder having a hole of a given diameter to ensure the communication of the annulus with the annulus of the tubing string; a seal on the pressure cylinder, configured to seal in the inside of the setting cylinder to ensure a hermetic separation of the two areas with different pressures. Between the tubular space in the tubing string and the annulus, a differential pressure arises, as it grows, an axial force appears, which is transmitted to the clamping cylinder and the outer cylinder and sets them in motion axially along the packer.

EFFECT: ensuring efficient and reliable activation of the packer by increasing the fluid flow through it.

1 cl, 11 dwg, 3 tbl

Description

TECHNICAL FIELD

This technical solution generally relates to the field of the oil and gas industry, namely to devices for selective hydraulic fracturing, repair and insulation work, and can be used when carrying out underground repairs of wells in order to intensify the influx of hydrocarbons.

BACKGROUND OF THE ART

There are many situations in which downhole tools must be selectively actuated. For example, for hydraulic fracturing, where there are wells with completions in multiple reservoirs, each zone is equipped with one or more tools, and each tool requires an actuation such that fluid is diverted for delivery from the tool to the outside of the fracturing wellbore. oil and gas containing formation. Actuation is often required in a sequence that allows for progressive fracturing along the length of the wellbore without leakage of fracturing fluid through previously fracturing zones.

Currently, all packer devices or, in other words, packers of various types are designed to separate the annular and intrapipe spaces of interlayer zones in order to limit the flow of fluid between zones. Despite the fact that the design components of various solutions may be present in different quantities and forms, all determine a single type of operation - the expansion of the packer element due to hydraulic or mechanical pressure.

Patent US5217077A “Resettable packer” is known from the prior art, patent holder: Baker Hughes Inc, publication date: 06/08/1993. This solution considers a drop-down bottomhole packer. Circulation from the surface creates back pressure behind the seal element, which expands the seal element into contact with the wellbore or casing. The tool can be moved to hold pressure behind the element to keep it in contact with the wellbore or casing while allowing flow to pass through the packer for procedures such as injection or stimulation. The tool includes a release mechanism to make it easier to remove the tubing string if for any reason the tool gets stuck. The design includes provisions to hold the packer in the retracted position for running and removal operations to avoid damage to the packer.

An analysis of technical solutions selected from patent and scientific-technical literature showed that a mechanical packer is known (see “Reference manual on the gas-lift method of operating wells.” Yu.V. Zaitsev, R.A. Maksutov, O.V. Chubanov and etc. M.: “Nedra”, 1984, p. 76). The packer consists of a shaft connected to a tubing string. An expansion cone and sealing collars between the last and upper stops are freely installed on the barrel.

To transmit torque to the packer barrel when it is seated, a spring lantern is used; there is a shaped bayonet groove in which the pin moves when the packer is seated. It is possible to disconnect the tubing string, if necessary, from the packer by left rotation. If it is necessary to reconnect the tubing string to the packer, it can be rotated inside the production string.

A mechanical packer is also known from the prior art (see RF patent No. 2204427, IPC E21B 33/12, published 02/10/2004). The packer contains a barrel, a coupling, an anchor assembly with rams and expansion cones, and a seal. The packer is equipped with an adapter and an extension connected to each other and to the barrel with carved elements, spring-loaded with nuts in the groove of the barrel. The connection, through a thread, of the lower expansion cone with the barrel is also known.

Based on the above and the patent research conducted, we can conclude that the level of technology does not contain technical solutions that are based on features that coincide with all the essential features of the proposed technical solution.

All existing cup packers have a high rate of wear while running in the well, have a high risk of damage to the cups during installation, are dependent on the integrity of the well, and are limited to withstand high pressures once activated.

The oil and gas industry has every incentive to improve the efficiency and reliability of packers that are deployed and operated in the downhole environment. This should ensure that the packers are operated with maximum efficiency, minimal risk of failure or inaccuracy, as flexible as possible to operator requirements and minimizing any repairs associated with time delays and costs.

SUMMARY OF THE INVENTION

The technical task or technical problem solved in this technical solution is the implementation of a packer with a four-section hydraulic installation chamber.

The technical result achieved by solving the above problem is an increase in the differential pressure between the tubular and annular space, which moves the packers to the activated position, which is caused by an increase in flow rate. Axial movements and axial loads are not required when activating/deactivating packers. Thus, the technical solution makes it possible to activate the packer system (upper and lower packer) by increasing the fluid flow.

When lowering to a given depth, as well as when extracting from the well, the packer system is in the transport position. The outer diameter of the packing elements is equal to the outer diameter of the steel part of the system. This prevents packer wear during tripping operations in the well. This is where this technical solution has a great advantage compared to two-packer cup-type systems.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present technical solution will become apparent from the detailed description below and the accompanying design drawings, in which:

In FIG. Figure 1 shows an implementation option for a hydraulic fracturing installation, which includes a lower packer, a circulation sub, and an upper packer mounted using a threaded connection on a tubing string from bottom to top.

In FIG. Figure 2 shows the design of a packer with a four-section hydraulic setting chamber.

In FIG. Figure 3 shows an example of the implementation of a pressure piston, which has four holes for communication with the hydraulic chamber of the pressure cylinder.

In FIG. Figure 4 shows an implementation option for the graphical interface of the calculator, which determines the flow rate of the working fluid required to create a differential pressure sufficient to activate the packing elements, which is determined by the set of areas in the nozzles installed in the circulation sub.

In FIG. Figure 5 shows holes with cylindrical threads located in the circulation sub.

In FIG. Figure 6 shows an embodiment of the packer design, where the yellow color is the pipe space and hydraulic chambers - area A, the turquoise color is the annulus - area B.

In FIG. Figure 7 shows an embodiment of a circulation sub.

In FIG. Figure 8 shows a diagram of how the movable external component of a hydraulic packer is subject to force F ₁ from pressure P ₁ and force F ₂ from pressure P _2.

In FIG. 9 shows an example of the implementation of pressing of the packing element by the external environment.

In FIG. 10 shows a diagram where the maximum load on the threaded connections between the pistons should not exceed the shear load on this type of threaded connection.

In FIG. Figure 11 shows a diagram in which the maximum load on the threaded connections between the pistons of the lower packer is calculated.

DETAILED DESCRIPTION OF THE INVENTION

Below we will discuss in detail the terms and their definitions used in the description of the technical solution, which will help to understand the essence of the technical solution.

A packer is a device in a borehole for blocking and sealing individual zones of wells (oil, gas, water, geological exploration). The axial action cup packer is part of the downhole assembly for repeated hydraulic fracturing.

Hydraulic fracturing is a method of intensifying the production of oil and gas wells and increasing the injectivity of injection wells. Hydraulic fracturing is carried out to create a highly conductive fracture in the target formation under the influence of a fluid injected under pressure. Hydraulic fracturing technology makes it possible to put into operation idle wells in which production by traditional methods is impossible or unprofitable. To prevent the cracks from closing, a proppant (proppant) is pressed into them.

The technical solution itself in the complex for hydraulic fracturing (hereinafter referred to as hydraulic fracturing) works functionally as follows.

The prototype device is an installation for the production of hydraulic fracturing, including tubing mounted using a threaded connection on a string of tubing from the bottom up, as shown in Fig. 1:

lower packer with a four-section hydraulic installation chamber;

a circulation sub, represented by a device body and holes with threaded connections for installing flushing nozzles of various diameters in them to ensure the required pressure drop, in quantities, for example, from four to six;

top packer with a four-section hydraulic installation chamber. The designs of the upper and lower packer with setting chamber may be identical or different.

The design of a packer with a four-section hydraulic setting chamber, as shown in Fig. 2, consists of three completely identical hydraulic sections and one section, which is distinguished by the presence of a locking ring (pos.10) on the pressure piston (pos.6) to limit the stroke of the pressure cylinder (pos.7) and the outer cylinder (pos.5). The section consists of a pressure piston (pos.6), pressure cylinder (pos.7), seals on the pressure piston (pos.13) and seals on the pressure cylinder (pos.14). When pressure is created inside the packer, each section creates a force. The combined force of 4 sections compresses the rubber packing element (pos.12), which is compressed enough to create a seal between the body of the two-packer assembly (as shown in Fig. 1) and the well wall. The packer has a top sub (pos.1) And lower sub (pos.2) for connection to a tubing string or other downhole tool.

In an approximate implementation, the material of all metal products in a two-packer arrangement is steel, the seals are rubber.

The locking ring (pos. 10 ) serves to limit the stroke of the pressure cylinders and thereby regulates the compression of the packing element (pos. 12 ).

The pressure cylinder (item 7 ) and the outer cylinder (item 5 ) have holes of a certain diameter to ensure communication between area B and the annulus of the tubing string, otherwise the movement of the pressure cylinders to compress the packer element will be impossible, since there is no there will be a hydraulic channel for communication. The design provides several standard sizes for use in wells with different open hole (or cased hole) diameters. The layout design does not change. Only the packer dimensions change. For an open barrel in the range of 143-159 mm, the hole diameter is 6 mm.

The hydraulic installation section consists of an internal pressure piston (key 6 ) with a piston seal (key 13 ) and an O-ring (key 16 ). The pressure piston has four holes for communication with the hydraulic chamber of the pressure cylinder (item 7 ), as shown in Fig. 3. The holes are designed for hydraulic communication between the hydraulic chamber, pressure cylinders and tubing pipes on which the packer is lowered. Due to this message, as the flow rate increases, a differential pressure is created, which pushes the cylinders to compress the packer element. Hydraulic chamber A, formed between the pressure piston (item 6 ) and the pressure cylinder (item 7 ), is sealed by cylinder seals (item 14 ) in the interior of the installation cylinder to provide a hermetically sealed separation of the two areas in which the pressure is different.

When pumping working fluid at a flow rate (fracturing fluid (linear gel, cross-linked gel, mixture of cross-linked gel and proppant), 13-24% HCL acid, process water), which is determined by the area of the holes of the flushing nozzles of the circulation sub, a differential pressure arises (can take the value from 0 to 200 atm depending on the flow rate and the total flow area of 4 nozzles installed in the circulation sub) between the tubular space in the tubing string (hydraulic chamber A) and the annulus space (area B), as shown in Fig. 6. Yellow color – pipe space and hydraulic chambers – area A, turquoise color – annulus – area B. The flow rate of the working fluid required to create a differential pressure sufficient to activate the packing elements is determined by the set of areas in the nozzles installed in the circulation sub. The selection is carried out using a specially designed calculator, as shown in Fig. 4. The circulation sub has four straight threaded holes. Nozzles are screwed into these holes (Fig. 5). The nozzles have different flow areas, which allows you to change the nozzles and adjust the total flow area for the liquid to exit the circulation sub. As the differential pressure increases, an axial force arises, which is transmitted to the pressure cylinder (item 7 ) and the outer cylinder (item 5 ) and causes them to move axially along the packer. The force is calculated based on the difference in cylinder area, the number of hydraulic chambers and differential pressure. And they, in turn, exert force on the intermediate ring (pos. 9 ), which compresses the packing element (pos. 12 ), hermetically separating the intervals under and above the packing element. The packing element begins to compress under the influence of the axial force created by the hydraulic chambers. The packer moves from the transport position to the activated one. The rubber expands in diameter and fits tightly against the walls of the open hole or casing. In this way, the annulus space is divided into the space under the packer element and the space above the packer element. These two areas are not connected hydraulically. The packer, designed for an open hole of 142.9-158.8 mm, has an outer diameter of 139.7 mm in the transport position. The packing element can withstand a differential pressure of 68 MPa. The packing element (pos. 12 ) is connected to the locking ring (pos. 3 ) with a threaded connection. The retaining ring (pos. 3 ) is connected to the inner hollow body (pos. 4 ) by a threaded connection, which is secured with screws (pos. 15 ). And in the lower part, the packer structure is fixed using the lower cone (item 11 ) (this is a structure for attaching the packer element to the packer body). The limit ring (pos. 8 ) limits the movement of the pressure cylinder (pos. 7 ).

This is the optimal implementation option from the point of view of production, assembly and operation of the packer. In general, in other embodiments, the locking ring (item 3 ) and the inner hollow body (item 4 ) can be manufactured in a single design, but this will significantly complicate the work with the packer.

The next element in the arrangement is the circulation sub, as shown in Fig. 7. This layout element is one-piece and consists of a body (item 17 ) with six holes to allow for work with high flow rates with an internal threaded connection for mounting flushing nozzles (item 18 ) of a fixed diameter. The diameters of the nozzles (item 18 ) are selected depending on the planned fluid flow. The threaded connection makes it easy to change attachments. The flushing nozzles (pos. 18 ) are hermetically installed in the housing (pos. 17 ) using a threaded connection and O-rings (pos. 19 ). The internal diameter of the flushing nozzles is selected based on calculations of the required cross-sectional area of the hole and the pressure drop that they provide, as shown in Fig. 4. Using formulas for calculating pressure losses in Excel, a program was compiled to calculate the flow rate and diameter of nozzles.

The Hydra Raptor assembly runs on a tubing string with intermittent or continuous circulation or coiled tubing. The entire device, according to the prototype, is an installation for the production of hydraulic fracturing, including the following, mounted using a threaded connection on a tubing string from bottom to top: a) a lower packer with a four-section hydraulic installation chamber; b) a circulation sub represented by the body of the device and holes with threaded connections for installing flushing nozzles of various diameters in them to ensure the required pressure drop, in an amount from four to six; c) an upper packer with a four-section hydraulic installation chamber. The designs of the upper and lower packer with the installation chamber are identical. Having reached the required stimulation interval, the movement of the column stops, and the pumping of working fluid into the tubing space of the pump-compressor pipes begins. Tubing is not part of the invention. These are well-known pipes that are widely used in the oil industry. In this context, they are used exclusively for lowering the assembly into the well. Stimulation interval is an interval in a well where hydraulic fracturing (fracturing) is planned. Usually measured along the length of the wellbore, starting from the mouth, for example, 2340-2345 m along the wellbore. The layout includes a circulation sub with flushing nozzles (item 18 ) , which is the local resistance of the hydraulic system with a significant amount of hydraulic losses to create differential pressure, due to which the system is activated. Due to the hydraulic losses that are created when pumping liquid through the flushing nozzles, a differential pressure arises between the pipe and annulus. When liquid is pumped through the flushing nozzles (item 18 ), a pressure drop occurs due to local hydraulic resistance, as shown in Fig. 4. Flow rate 4000 l/min, 2 blind nozzles, 2 nozzles with a bore diameter of 18/32", 2 nozzles with a bore diameter of 20/32". The differential pressure that arises in this case is 45 atm. A differential pressure arises between the pipe (hydraulic chamber A) and the annular space of the assembly (area B). As the differential pressure increases, the packing element (item 12 ) is compressed, ensuring the necessary tightness of the annulus of the tubing between the upper and lower packer.

The claimed device successfully passed factory tests at one of the applicant’s enterprises and confirmed its performance and reliability.

Although the foregoing description has discussed some embodiments of the packer and methods of operating it, various improvements will be apparent to those skilled in the art. All such improvements coming within the scope of the appended claims are intended to be included in the foregoing description.

Below is an example of the implementation of a packer to ensure isolation of an open hole with a diameter of 142.88–158.75 mm, as well as an example of calculating the forces acting on a two-packer assembly with an outer diameter of 139.7 mm.

Table 1

Parameter Meaning Inner diameter, mm 61.98 Internal bore diameter, mm 58.80 Max outer diameter, mm 139.70 Min. open barrel diameter mm 142.88 Max. open trunk diameter, mm 158.75 Max. torque, kN * m 4.96 Maximum stretch per packer, t 98.73 Max. torsion on packer, kN*m 9.39 Differential pressure, MPa 68.95 Bursting pressure, MPa / Psi 68.95 Bearing pressure, MPa / Psi 68.95 Minimum operating temperature, C/F 21.11 Maximum operating temperature, C/F 148.89

The movable external component of the hydraulic packer is subject to force F ₁ from pressure P ₁ and force F ₂ from pressure P ₂ (see Fig. 8).

Forces act on area S ₁ :

S ₁ – area of influence of pressure injected inside the packer and pressure in the well, [m ² ];

D ₁ – internal diameter of the smaller cylinder seal, [m];

D ₂ – outer diameter of the piston seal, [m].

Force F ₁ from one cylinder:

F ₁ – force created by pressure P ₁ on area S ₁ , [N];

P ₁ – pressure injected inside the packer, [Pa].

Force F ₂ from one cylinder:

F ₂ – force created by pressure P ₂ on area S ₁ , [N];

P ₂ – pressure inside the well, [Pa].

Depending on the number of cylinders, the resulting compression force of the packing element:

F – resultant force applied to the packing element, [N];

n is the number of cylinders used in the packer assembly.

Table 2 – Calculation of packer force

element when assembling a packer with 3 cylinders

Name Inner seal diameter Outer seal diameter Pressure inside the packer Well pressure Resultant force on the packer element Designation D1 D2 P1 P2 F Dimension mm mm MPa MPa kN Meaning 95.3 120.7 70 10 776 20 646 thirty 517

Table 3 – Calculation of packer force

element when assembling a packer with 4 cylinders

Name Inner seal diameter Outer seal diameter Pressure inside the packer Well pressure Resultant force on the packer element Designation D1 D2 P1 P2 F Dimension mm mm MPa MPa kN Meaning 95.3 120.7 70 10 1034 20 862 thirty 689

Let's calculate the possibility of pressing the packing element by the external environment (see Fig. 10).

The maximum load on the threaded connections between the pistons should not exceed the shear load on this type of threaded connection shown in Fig. eleven.

Fpage – shear force of this type of thread, [N].

The calculation of the maximum load on the threaded connections between the pistons of the lower packer is carried out according to the diagram shown in Fig. eleven:

S ₃ – area of influence on the packer plug, [m ² ].

Fres.n2 – resultant force applied to the threaded connection of the lower packer on the nth cylinder, [N].

The maximum load on threaded connections between pistons should not exceed the shear load on this type of threaded connection

Claims (5)

A packer with a four-section hydraulic installation chamber for hydraulic fracturing, containing: three completely identical hydraulic sections, each of which consists of: a pressure cylinder (7) and an internal pressure piston (6), having four holes for hydraulic communication of the hydraulic chamber formed between the pressure cylinder (7) and the internal pressure piston (6), with the internal space of the packer, while there is a seal (14) between the pressure cylinder (7) and the internal pressure piston (6) on the pressure cylinder (7), and between the internal pressure piston (6) and the adjacent internal pressure piston (6) attached to it an o-ring (16) is installed in the adjacent hydraulic section, forming a sealing of the said hydraulic chamber, while the pressure cylinder (7) has holes with the ability to communicate the space behind the internal pressure piston (6) with the space between the packer and the well wall; one hydraulic section containing: an external cylinder (5) and an internal pressure piston (6), containing a locking ring (10) installed on it, with the possibility of limiting the stroke of the pressure cylinders (7) and the external cylinder (5) connected in series, and regulating the compression of the packing element (12), while the internal pressure piston (6) has four holes for hydraulic communication of the hydraulic chamber formed between the outer cylinder (5) and the internal pressure piston (6), with the internal space of the packer, and between the outer cylinder (5) and the internal pressure piston (6) there is a seal (14) on the outer cylinder (5), and an o-ring (16) is installed between the internal pressure piston (6) and the adjacent internal pressure piston (6) attached to it of the adjacent hydraulic section. , forming a sealing of the mentioned hydraulic chamber, while the outer cylinder (5) has a hole with the ability to communicate the space behind the inner pressure piston (6) with the space between the packer and the well wall; internal hollow body (4), on one side connected to the internal pressure piston (6) of one hydraulic section, and on the other hand, configured to be connected to the tubing string on which the packer is lowered, while the internal pressure pistons (6 ) each hydraulic section is connected in series, forming the internal space of the packer, communicating with the pipe space in the tubing string; Moreover, on the outer side of the inner hollow body (4) through a locking ring (3) a packing element (12) is connected to it at one end, the other end of which is articulated with the intermediate ring (9) and the outer cylinder (5) with the possibility of compressing the packing element (12 ) when moving along the axis along the packer the sequentially interconnected clamping cylinders (7) and the outer cylinder (5) under the action of an axial force that arises as the differential pressure between the internal space of the packer and the space between the packer and the well wall increases.