RU2495360C1 - Method to generate jet stream and shaped charge of perforator for its realisation - Google Patents

Abstract

FIELD: blasting.

SUBSTANCE: method and device relate to perforation of well casing pipes for production of well, gas, water, and may be used in jet perforators that improve hydrodynamic connection of a bed and a well, and providing for increased well yield. A shaped charge comprises a body, inside of which there is an explosive cartridge. The cartridge gas a charge hollow coated with lining. Inside the lining there is an insert fixed with a layer of plastic material. The density of the plastic material layer is 0.8-2.4 g/cm³. The product of density by thickness of the plastic material layer is less than the thickness of the wall insert. The ratio of insert top thickness to the diameter of the lining base is from 0.1 to 0.3. The ratio of insert height to lining height is from 0.5 to 0.8. The explosive cartridge is exploded. Detonation products press the shaped lining, then the plastic material is pressed and heated. The impact wave energy is reduced. The speed of shaped lining pressing is reduced. The impact wave from collision of the insert and the lining is sent from the zone of collision along the lining material. Large amount of the lining and insert participates in generation of the jet stream. The jet stream is shaped.

EFFECT: original design of lining and increased efficiency of explosive energy takeoff by lining elements.

8 cl, 3 dwg, 4 tbl

Description

Technical field

The invention relates to methods and devices for perforating casing pipes of wells, more specifically to cumulative borehole drills that improve the hydrodynamic connection of the formation with the well, and providing increased net return (flow rate) of the well.

The invention is of general industrial importance for the extraction of oil, gas, water, or other minerals.

State of the art

Cumulative perforators are known (EM Vitseni “Cumulative perforators used in oil and gas wells”, M. “Nedra”, 1979), which are an effective means of opening productive formations in oil, gas, injection and water wells, allowing perforation work in wells with various geological and technical conditions.

In order to increase the flow rate of the well, it is required to improve or restore the hydrodynamic connection of the well with the remote sections of the formation. For this, high excess pressure is applied at the wellhead, as a result of which cracks form in the formation. In this case, hydraulic fracturing occurs and granular artificial sand (proppant) is injected into the cracks to prevent their closure. Punching a large diameter hole in the wall of the well casing is necessary. This requires increasing the diameter of the cumulative jet.

Known devices in which the increase in the diameter of the cumulative jet occurs due to an increase in the angle of collapse of the lining (edited by Orlenko AP “Explosion Physics”, volume 2, M. “Fizmatlit”, 2002).

The disadvantage of such devices is that the diameter of the cumulative punch charge is limited by the dimensions of the casing of the well, which does not allow to achieve the desired results.

Known devices in which an increase in the diameter of the cumulative jet is achieved by increasing the thickness of the lining (edited by Orlenko A.P. "Explosion Physics", volume 2, M. "Fizmatlit", 2002).

The disadvantage of such devices is that a simple increase in the wall thickness of the liner, from which the head of the cumulative jet is formed, does not give an obvious effect, since the speed of the cumulative jet decreases, and its diameter increases slightly, the diameter of the cumulative perforator charge and its mass are limited by the dimensions of the casing wells, which does not allow compressing the lining with the necessary speed, and does not allow to achieve the required results ..

Known cumulative charge (KZ), [patent DE 3116934 C1 from 04.29.1981; Messer-schmitt-Bolkow-Blohm GmbH; F42B 1/02] with an insert of a certain geometric shape inside the top of the cladding to obtain a large diameter hole in the punched barrier. An insert made of metal, Teflon, polymer or aluminum powder, in which, when sprayed in a shock wave, a reaction occurs with the release of gases and an increase in pressure in the channel.

The disadvantage of such a charge is that the cumulative jet formed from the cladding with an insert at the top of the cladding has a slight broadening in the head part, which quickly works and forms a large hole only on a thin final barrier. When the wall thickness of the well is 3 mm or more, a large hole is not formed.

The USSR author's certificate for the invention [SU No. 1753749 dated 12.19.89., ЕВВ 43/117; Cumulative charge of a perforator, authors Tebyakin V.M., Shipitsin L.A. et al.], Containing a housing, inside of which an axisymmetric shaped explosive block is placed, having a cumulative recess covered by a lining consisting of two layers, the outer of which is adjacent to the cumulative notch. Moreover, the outer layer is made in the form of a grid of thin narrow strips, and the specific gravity of the material of the outer layer is greater than the specific gravity of the material of the inner layer. When the cladding collapses, narrow strips of the outer layer cut the resulting pestle into several parts.

The disadvantage of such a charge is the direct dependence of the diameter of the cumulative jet and the breakdown ability of the charge on the high accuracy of performing a grid of narrow bands. At the slightest manufacturing inaccuracy, an asymmetry of the cumulative jet occurs, a decrease in the diameter of the jet, and therefore, the breakdown ability of the charge sharply decreases.

According to the hydrodynamic theory of cumulation, based on the model of an incompressible fluid, the cumulative jet is always formed during oblique collision of plates accelerated by an explosion or a thin conical shell. (“Explosion Physics” edited by A. Orlenko, Moscow, 2002, pp. 207-208,) which is given as an analogue to the method of forming a cumulative jet.

The process of symmetric collapse of two flat jets of compressible fluid at an angle of 2α with a speed U ₀ in the coordinate system associated with the collision point “0” is considered. The flow velocity vector before and after the oblique shock wave front u _0n and u _n is shown, which are decomposed into two components: normal u _0n and u _n and parallel to the front of yogis and Ur. Compressible supersonic flow with a speed u ₀ rotates through an angle α and slows down. Such inhibition of a supersonic flow is carried out using the front of an oblique shock wave. In this case, the flow in front of the front of the shock wave OM is not shock compressed. A sharp increase in pressure occurs behind the front of the OM oblique shock wave and a cumulative jet in the direction of the OX is not formed. According to the theory of oblique shock waves, between the angle of rotation of the supersonic flow α and the angle of inclination of the front of the oblique shock wave β for a given velocity u ₀ there is a dependence α = α (β).

With an increase in the angle a, the attached front of the OM shock wave can exist only up to a certain angle α <α _k . At angles α≥α _{to the} front of the OM, the oblique shock wave, departs towards the incident supersonic flow. In this case, the intensity of the shock front MM ′ increases. The liquid behind the shock front MM ′ is shock-compressed, but, due to the fact that the AMO surface is free of pressure, the liquid in the section of the OM front begins to flow to the right, forming a cumulative jet.

The disadvantage of this method can be considered the impossibility of changing the speed of the cumulative jet for the selected material, since only one material is used in the lining, and therefore the impossibility of changing the diameter of the cumulative jet.

As a prototype for the method, the USSR author's certificate for the invention was selected [SU No. 1753749 from 12.19.89., ЕВВ 43/117; Cumulative charge of a perforator, authors Tebyakin V.M., Shipitsin L.A. et al.], Including the detonation of a profiled piece of explosive, high-speed compression of the cumulative lining under the influence of detonation products, the formation of a cumulative jet.

The disadvantage of the prototype is the inability to increase the diameter of the cumulative jet when using this type of cumulative lining.

The diameter of the cumulative jet can be increased by increasing the radius of the outer surface of the cladding element and the thickness of the top of the cladding. The increase in the radius of the outer surface of the cladding element in the method of perforation allows you to:

- increase the speed of the leading elements of the cumulative jet due to the greater value of the velocity of the detonation wave on the cladding element, from which the head of the cumulative jet is formed;

- increase the diameter of the jet by reducing the speed of convergence of the cladding and increasing the resulting area of unloading of the surface of the cladding, and increasing the material involved in the formation of the head of the cumulative jet;

- increase the speed of the leading elements of the cumulative jet by increasing the acceleration base of the corresponding cladding elements;

- increase the angle of collapse of the cladding elements on the axis of symmetry of the charge, while the speed of the cumulative jet may increase, ceteris paribus.

As a disadvantage to achieve these positions, one can note the existing limitations in the dimensions of the well, which does not allow increasing the diameter of the charge and the mass of explosives to achieve the required parameter values.

Disclosure of invention

The problem to which the invention is directed is to create a method and a cumulative charge for punching a large diameter hole in the well casing without increasing the diameter of the charge.

The technical result achieved in solving this problem is to increase the diameter of the cumulative jet and participate in its formation of most of the cladding material.

To obtain the specified technical result in the method of forming a cumulative jet, including detonating an explosive, forming a shock wave front, compressing a cumulative lining under the influence of detonation products, forming a cumulative jet according to the invention, after blasting an explosive, slow down the compression speed of the cladding before the formation of a cumulative jet. , on the axis of symmetry and at the point of impact of the cladding form a shock wave moving along the cladding material with a speed ahead of which compresses the cladding, form the unloading zone of the cladding, which is involved in the formation of the cumulative jet, then form the cumulative jet.

The technical result is achieved by the fact that in the cumulative charge of the perforator containing the housing, inside of which there is an axisymmetric profiled explosive block having a cumulative recess covered by the cladding according to the invention, an insert is installed inside the cladding, with the profile of the outer surface corresponding to the inner surface of the cladding, mounted on the inner lining lining surface with a layer of plastic material, the thickness of which is not more than the thickness of the liner wall, and the product of the thickness of the pla material density by its density is less than 1.0 and more than 0.3, while the total wall thickness of the cladding and liner is selected experimentally within (0.04-0.12) of the inner radius R _{to the} base of the cladding.

The profile of the outer surface of the liner, as a rule, is made corresponding to the inner surface of the cladding.

The liner material may be identical to the lining material, for example cast iron.

A layer of plastic material can be selected with a density of 0.8-2.4 g / cm ³ .

The profile of the inner surface of the liner is possibly conical.

The ratio of the thickness of the top of the liner and the diameter of the base of the cladding can be in the range from 0.1 to 0.3.

The ratio of the height of the liner and the height of the lining can be in the range from 0.5 to 0.8.

To form a cumulative jet from the greater part of the liner and liner, the shock wave generated on the axis of symmetry can be directed from the collision zone along the liner material at the point of collision of the liner, an enlarged discharge zone on the liner inner surface can be formed, and a larger part of the formation of the head part of the jet can be formed the amount of cladding material and liner.

In the process of compression due to the presence of the liner and plastic material between the lining and the liner, the reduction speed decreases and a cumulative jet of large diameter is formed. The diameter of the cumulative jet is directly proportional to the diameter of the punched hole in the wall of the casing pipe.

Brief Description of the Drawings

Figure 1 shows the cumulative charge with the liner, where

1 - case

2 - explosive (BB)

3 - cavity cumulative excavation,

4 - cumulative lining,

5 - liner

6 - plastic material

7 - intermediate detonator.

Figure 2 shows the liner.

Figure 3 shows the hole of maximum diameter in a steel plate simulating the wall of the casing pipe from a cumulative jet of large diameter.

In case 1, BB 2 and an intermediate detonator 7 are placed. The cavity 3 is covered with a lining 4, inside of which there is a liner 5. Between the lining 4 and the liner 5, plastic material 6 is placed. The liner 4 and the liner 5 are made of cast iron. The inner profile of the liner 5, as shown in figure 2, is a truncated cone in which the ratio of the thickness of the top S of the liner 5 to the outer diameter of the base D of the lining 4 is in the range from 0.1 to 0.3. Experimentally established the optimal ratio of the thickness of the top S of the liner to the outer diameter of the base D of the cladding, the data obtained experimentally are shown in table 1.

Table 1. The dependence of the thickness of the top S of the liner to the outer diameter of the base D of the cladding. S / d Diameter of a hole in a steel plate, d, mm 0,07 12 0.1 eighteen 0.2 17 0.3 17 0.4 10

Experimentally, the optimal ratio of the size of the lining and the liner was established to obtain the best values of the diameter of the cumulative jet. An indicator of the diameter of the jet is the diameter d of the hole in the wall of the casing pipe. The diameter of the punched hole in the wall of the casing pipe is directly proportional to the diameter of the cumulative jet.

The ratio of the height h _{on the} liner 5 to the height H _reg lining 4 is in the range from 0.5 to 0.8. The data were obtained experimentally and are shown in table 2.

Table 2. The dependence of the hole diameter d in the steel plate on the ratio h _on / N _reg h _on / N _reg Diameter of a hole in a steel plate, d, mm 0.39 12 0.5 fifteen 0.64 16 0.8 17 1,0 fourteen

The total wall thickness of the cladding 4 and the liner 5 should be within (0.04-0.12) of the inner radius R _{to the} base of the cumulative cladding 4.

Between the lining 4 and the liner 5 is a plastic material 6 with a density of from 0.8 g / cm ³ to 2.4 g / cm ³ . The data were obtained experimentally and are shown in table 3.

Table 3. The dependence of the diameter of the hole d in the steel plate on the density of the plastic material, ρ _pm The density of the plastic material ρ _pm , g / cm ³ Diameter of a hole in a steel plate, d, mm 0.7 fourteen 0.8 17 1,0 eighteen 1,5 17 2.0 16 2,4 16 2.7 fourteen

The thickness of the plastic material 6 should not exceed the wall thickness of the liner 5, and the density product ρ _pm . plastic material 6 to its thickness δ _pm should be in the range from 0.3 to 1.0. The data were obtained experimentally and are shown in table 4.

Table 4. Dependence of the diameter of the hole d in the steel plate on the product of the density of the plastic material by its thickness ρ _pm × δ _pm The product of the density of a plastic material by its thickness ρ _pm × δ _pm Diameter of a hole in a steel plate, d, mm 0.18 10 0.3 fifteen 0.48 fifteen 0.8 eighteen 1,0 16 1,2 12

The hole with a maximum diameter of 18 mm, obtained experimentally, when penetrating the simulator of the casing wall of the claimed cumulative charge is shown in figure 3. The result obtained of the maximum diameter of the hole from the claimed cumulative charge is 70% higher than the maximum diameter of the hole obtained from the cumulative charge without an insert.

Embodiments of the invention

The installation of the cone-shaped insert 5 in the cumulative charge liner 4 allows the head part of an enlarged cumulative jet to pierce a large diameter hole in the casing of the well, which ensures the creation of a higher pressure in the perforation channel when applying excess pressure to the wellhead and thereby allows the formation of cracks of great length. In addition, the obtained hole provides unhindered injection into the sand cracks formed in the formation, which prevents crack closure, thereby providing high-quality hydrodynamic communication between the formation regions remote from the well and the well.

The explosive charge 2 is initiated through an intermediate detonator 7. A shock wave compression of the liner 4 and the liner 5 takes place, which slam on the axis of symmetry of the cumulative charge. On the axis, at the point of impact of the cladding 4 and the liner 5, an oblique shock wave occurs, which begins to propagate along the material of the cladding 4 and the liner 5. The material behind the front of the shock wave is shock-compressed, but due to the fact that the inner surface of the cone of the liner 4 with the liner 5 is free from pressure, then the material of the cladding 4 and the liner 5 begins to unload and expire in the axial direction of the inner surface of the cone of the liner 5, forming the head of the cumulative jet. When the shock wave passes through the cladding 4, the plastic material 6, the liner 5, the material of the shock wave 6 decreases as a result of energy loss in compression and heating of the material 6, which reduces the compression rate of the liner 4 and the liner 5.

Thus, the collision speed of the lining 4 with the liner 5 is reduced due to the loss of energy for heating and compression of the plastic material 6, and the speed of the shock wave in the material of the liner 4 and the liner 5 remains constant and close to the speed of sound. As a result of this, the shock wave that occurred during the collision of the walls of the liner 5 and the lining 4 on the axis of symmetry rushes out from the collision zone along the material of the liner 4 and the liner 5 with the speed of sound, forming a large discharge zone on the inner surface of the liner 5, necessary for the formation of a cumulative jet .

Thus, by reducing the convergence rate of the liner 4 and the liner 5, due to the loss of energy for compression and heating of the plastic material 6, the shock wave front from the impact point will move a greater distance along the liner 4 and the liner 5. After that, the large inner surface of the liner has time to unload 4 and liner 5. This ensures the participation in the formation of the head of the jet of an increased amount of cladding material 4 and liner 5, which leads to the formation of a cumulative jet of increased diameter.

The device and method expand the arsenal of technical tools for perforating casing wells with an increased diameter of the cumulative jet. The method allows to increase the diameter of the cumulative stream, thereby improving the hydrodynamic connection of the formation with the well, and to increase the flow rate of the well.

Industrial applicability

The most effective is the use of the proposed cumulative charge and the method of forming a cumulative jet in cumulative downhole perforators during hydraulic fracturing for oil, gas, water, or other minerals. You can effectively use the present invention when perforating wells for pumping water into the reservoir. The method and device can improve the hydrodynamic connection of the reservoir with the well, and to increase the flow rate of the well. The considered embodiment of the invention can be implemented on existing equipment. This shows its performance, and confirms industrial applicability.

Claims (8)

1. A method of forming a cumulative jet, including detonating an explosive, forming a shock wave front, compressing a cumulative cladding under the action of detonation products, forming a cumulative jet, characterized in that after the explosive is blown up, the cladding compression speed is slowed down on the axis symmetries and at the point of collapse of the cladding form a shock wave moving along the cladding material at a speed ahead of the speed of compression of the cladding, form a zone of Booting cladding, which is involved in the formation of shaped-charge jet, jet cumulative further formed. 2. The cumulative charge of the perforator, containing a housing inside which an axisymmetric shaped explosive block is placed, having a cumulative recess coated with a cladding, characterized in that a liner is installed inside the cladding with an external surface profile corresponding to the inner surface of the cladding, fixed to the inner surface of the cladding with a plastic layer material whose thickness is not more than the wall thickness of the liner, and the product of the thickness of the layer of plastic material on its density is less than 1.0 and more than 0.3, while the total wall thickness of the cladding and liner is selected within (0.04-0.12) of the inner radius R _{to the} base of the cumulative cladding. 3. The cumulative charge according to claim 2, characterized in that the material of the liner is identical to the material of the lining. 4. The cumulative charge according to claim 3, characterized in that cast iron is selected as the material of the liner and lining. 5. The cumulative charge according to claim 2, characterized in that the layer of plastic material is made with a density of 0.8-2.4 g / cm ³ . 6. The cumulative charge according to claim 2, characterized in that the profile of the inner surface of the liner is conical. 7. The cumulative charge according to claim 2, characterized in that the ratio of the thickness of the top of the liner to the diameter of the base of the cladding is made in the range from 0.1 to 0.3. 8. The cumulative charge according to claim 2, characterized in that the ratio of the height of the liner to the height of the cladding is made in the range from 0.5 to 0.8.

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