Opening-controllable differential pressure sliding sleeve for fracture acidizing of oil and gas well and pressure testing method

Abstract

The invention discloses an opening-controllable differential pressure sliding sleeve for fracture acidizing of an oil and gas well and a pressure testing method.The opening-controllable differential pressure sliding sleeve is provided with a central pipe, a reversing piston and a piston auxiliary springback mechanism, and the piston auxiliary springback mechanism is installed in an annulus formed by the central pipe and a spring outer barrel and located above the reversing piston; a reversing piston provided with a pressure test track is connected with the piston connecting sleeve and is arranged in a pressure operation cavity formed by the central pipe, the force transfer inner pipe, the piston outer cylinder and the sliding sleeve outer cylinder; the piston outer cylinder is connected with the reversing piston through a piston starting shear pin, a guide screw installed in the piston outer cylinder is connected with a pressure test rail of the reversing piston, and the sliding sleeve is connected with the sliding sleeve outer cylinder through a sliding sleeve starting shear pin. According to the controllable differential pressure sliding sleeve opening device, the controllable differential pressure sliding sleeve can only be opened after pressure relief after pressurizing is conducted on a wellhead once or more, the time of sleeve pressure testing is controllable, operation is easy, and working reliability is high. The use effect is obvious, and good economic benefits can be generated.

Description

Technical Field

[0001] The invention relates to a sliding sleeve for downhole stratified fracturing of an oil and gas well, in particular to an open controllable differential pressure sliding sleeve for fracturing and acidizing of an oil and gas well and a pressure testing method. Background Art

[0002] In the process of oil and gas field development, for the development of many low-permeability oil and gas reservoirs, fracturing, acidizing and other transformation measures are generally required. Downhole operation tools such as fracturing and acidizing generally need to withstand harsh downhole environments such as high pressure and high temperature. Especially for multi-stage fracturing completion projects, the process is complex, the types of downhole tools involved are many, and the technical requirements are high. The working performance of the supporting tools is crucial. For example: once a problem occurs with the sliding sleeve used for fracturing and acidizing, it is bound to cause downhole accidents and cause huge economic losses.

[0003] As the formation conditions of new wells become more and more complex, layered operations are becoming more and more common, and the working reliability of sliding sleeves used in downhole fracturing and acidizing is receiving more and more attention.

[0004] At present, conventional differential pressure opening fracturing sleeves are mainly used in the layered fracturing casing cementing completion string, installed at the very end of the string, and used for the first stage of fracturing. The sleeve can be directly opened for fracturing operations without perforating, with high operating efficiency and reduced operating costs. Therefore, it is widely used. At present, differential pressure sleeves mainly include direct opening differential pressure sleeves and delayed pressure testable differential pressure sleeves: direct opening differential pressure sleeves are directly opened by ground pressure, which cannot meet the pressure test requirements of the casing; delayed pressure testable differential pressure sleeves have a delay structure installed inside, and can be delayed when the ground is pressurized to the casing test pressure; after the pressure test, the sleeve is opened. However, due to changes in bottom hole conditions and construction and operation reasons, the delayed differential pressure sleeve has problems such as too short opening time or failure to open normally, which makes it unable to meet the construction requirements.

[0005] Through searching, the following related patent technologies have emerged to solve the above problems: Patent application No. 202123139997.3 discloses a toe end sliding sleeve capable of multiple pressure tests. The above utility model includes an upper joint, a center tube, a movable guide ring, a piston rod, a piston, a stop ring, a ball, a spring, a rupture disk and a lower joint.

[0006] The above-mentioned sliding sleeve can meet the function of two pressure tests. The piston rod and the piston are connected, and the hydraulic pressure on and off of the two ends of the piston are realized by changing the long and short tracks of the piston reversing structure.

[0007] However, the piston operating chamber is an air chamber, which will be affected by the internal and external pressure difference and air tightness, and the internal pressure of the tool will also be affected by the action of the piston rod. After the rupture disc ruptures, the test pressure will also be affected by the force bearing capacity of the reversing structure.

[0008] Patent application No. 201820152248.3 discloses a testable toe-end sleeve. The utility model includes a housing and an inner sleeve disposed in the housing. The inner sleeve includes an upper inner sleeve and a lower inner sleeve, the upper inner sleeve is provided with a flow limiting valve, and a rupture disk is provided on the side wall of the lower inner sleeve. When the rupture disk ruptures, the flow limiting valve limits the flow of grease in the oil chamber through the flow limiting valve, thereby realizing delayed opening of the sleeve.

[0009] However, the sliding sleeve still has the problem of short opening time or failure to open normally.

[0010] Patent application No. 201821811355.9 discloses a piston-type delayed opening toe end sliding sleeve. The utility model includes an upper joint, a shell, a delay mechanism, a central tube, an opening mechanism and a lower joint. When working, when the wellbore fluid reaches the set pressure value, the opening mechanism starts to drive the delay mechanism to start, and after the set time, the opening piston is pushed to move until the fracturing outer port is connected to the fracturing inner port.

[0011] However, the above utility model also has the problem of short opening time or failure to open normally.

[0012] In view of this, it is very necessary to provide an openable controllable pressure differential sliding sleeve for oil and gas well fracturing and acidizing to solve the above problems. Summary of the invention

[0013] The purpose of the present invention is to provide a controllable pressure differential sleeve and pressure test method for oil and gas well fracturing and acidizing, optimize the internal structure of the sleeve, control the opening time and number of sleeves, so as to solve the problem of short opening time or failure to open normally of the sleeves used in the downhole fracturing and acidizing completion engineering of existing oil and gas wells, ensure the smooth progress of the completion engineering, reduce production costs, and improve economic benefits.

[0014] The technical solution of the present invention is: an open controllable differential pressure sliding sleeve for oil and gas well fracturing and acidizing, provided with a center tube, a reversing piston and a piston auxiliary rebound mechanism, wherein: the upper end of a force transmission inner tube provided with a pressure transmission hole is connected to the center tube, and the lower end is inserted into the sliding sleeve, and the center tube, the force transmission inner tube and the sliding sleeve are installed in the inner hole between the upper joint and the lower joint; the spring outer tube provided with a piston balance hole, the piston outer tube and the sliding sleeve outer tube provided with a circulation port and a sliding sleeve balance hole are connected with the outer circles of the upper joint and the lower joint from top to bottom in sequence; the reversing piston provided with a pressure test track is connected to the piston connecting sleeve and is installed in a pressure operation chamber formed by the center tube, the force transmission inner tube, the piston outer tube and the sliding sleeve outer tube; the piston auxiliary rebound mechanism is installed in the annulus formed by the center tube and the spring outer tube and is located above the reversing piston; the piston outer tube is connected to the reversing piston through a piston starting shear pin, the guide screw installed in the piston outer tube is connected to the pressure test track of the reversing piston, and the sliding sleeve is connected to the sliding sleeve outer tube through the sliding sleeve opening shear pin.

[0015] Preferably, the reversing piston is a non-uniform diameter cylindrical body and the outer circle of the cylinder is provided with an external threaded connecting section, a piston starting shear nail groove, a pressure test track, a piston limiting connecting section and an external threaded connecting section in sequence from top to bottom; the piston starting shear nail groove can be inserted into the piston starting shear nail groove, and the guide screw can be inserted into the pressure test track, and sealing ring grooves are provided on the inner circle and the outer circle of the lower part of the piston limiting connecting section and seals are installed therein.

[0016] Preferably, piston limit blocks and piston limit grooves are evenly distributed and staggered above the sealing ring groove in the piston limit connecting section of the reversing piston; in the reversing piston, the outer diameter of the piston limit connecting section is larger than the outer diameter of the body where the pressure test track is located.

[0017] Preferably, the pressure test track is composed of a bent asymmetric track groove, and is provided with a track starting position, a track recovery position, a sleeve opening position and a device pressure test position. In the pressure test track, the track starting position and the track recovery position, the device pressure test position and the sleeve opening position are arranged in order according to the height of the position of the track groove, and are arranged in parallel from top to bottom. The device pressure test position is located higher than the sleeve opening position and is parallel to it in the longitudinal direction.

[0018] Preferably, at least one group of pressure test tracks is provided in the reversing piston and the length of the sleeve opening track groove where the sleeve opening position is located is greater than the length of the device pressure test track groove where the device pressure test position is located; the inner circle of the piston connecting sleeve threadedly connected to the reversing piston is a stepped inner circle and an internal threaded connecting section, a pressure transmission chamber and a limit step are provided from top to bottom, the internal threaded connecting section is threadedly connected to the reversing piston, the pressure transmission chamber corresponds to the pressure transmission hole in the force transmission inner tube, and the limit step cooperates with the limit step above the pressure transmission hole of the force transmission inner tube.

[0019] Preferably, the piston outer tube is a non-uniform diameter cylindrical body and a radially penetrating piston starting shear pin hole and guide screw hole are arranged in the upper body. The piston starting shear pin hole and guide screw hole are both threaded holes and can respectively insert the piston starting shear pin and guide screw. The other end of the guide screw is inserted into the track starting position of the pressure test track.

[0020] Preferably, outer cylinder limit blocks and outer cylinder limit grooves are evenly distributed and staggered in the inner cavity of the piston outer cylinder below the piston starting shear pin and guide screw, and the outer cylinder limit blocks and outer cylinder limit grooves can be plugged into the piston limit grooves and piston limit blocks in the reversing piston.

[0021] Preferably, the sliding sleeve and the sliding sleeve outer tube are both non-uniform diameter cylindrical bodies and overlap each other. After the sliding sleeve and the sliding sleeve outer tube are overlapped, a pressure balance chamber is formed between the sliding sleeve and the lower joint, and the pressure balance chamber corresponds to the sliding sleeve balance hole; the sliding sleeve outer tube and the sliding sleeve are connected by the sliding sleeve opening shear nails.

[0022] Preferably, a sleeve starting shear pin is also installed between the upper end of the sleeve outer tube and the force transmission inner tube; at least two sleeve starting shear pins are provided, at least three sleeve opening shear pins are provided, and at least two pressure transmission holes are provided in the force transmission inner tube.

[0023] Preferably, the upper joint, spring outer tube, piston outer tube, sleeve outer tube and lower joint are threadedly connected in sequence from top to bottom; the piston auxiliary rebound mechanism is provided with a spacer ring, a spring, a support ring, a support ball and an adjustment ring, and the spacer ring, spring, support ring, support ball and adjustment ring are installed in sequence from top to bottom in the annulus formed by the center tube and the spring outer tube; the upper end surface of the adjustment ring and the lower end of the support ring are both provided with grooves, and the support ball is installed in the groove between the adjustment ring and the support ring; the lower inner circle of the adjustment ring is threadedly connected to the upper outer circle of the reversing piston and can move with the movement of the reversing piston.

[0024] The pressure testing method for opening a controllable differential pressure sliding sleeve for oil and gas well fracturing and acidizing comprises the following steps: A. applying pressure to the casing from the ground and breaking the piston start shear pins; B. releasing the pressure after the first casing pressure test; C. applying pressure again and opening the controllable differential pressure sliding sleeve after all pressure tests are completed.

[0025] Compared with the prior art, the present invention has the following significant use effects: the device of the present invention is a controllable pressure differential sleeve that can be opened only after the wellhead is pressurized once or more and the pressure is released. The time of the casing pressure test is controllable, the operation is simple, and the working reliability is high.

[0026] The device of the present invention can meet the requirements of the overall pressure test of the casing, and can change the position of the reversing sleeve in the device of the present invention by changing the long track groove-sleeve opening track groove and the short track groove-device pressure test track groove, complete the pressure test and sleeve opening operation, and its opening time is controllable. During the pressure test, the upper plane of the piston limit block in the reversing piston contacts the lower plane of the outer cylinder limit block set in the piston outer cylinder and is subjected to force, and the guide screw is not affected by the force generated during the pressure test, so the requirements of the casing high pressure test can be met.

[0027] In the device of the present invention, the pressure operation structure composed of the piston outer cylinder, the center tube, the reversing piston and the piston connecting sleeve, and the sleeve opening structure composed of the sleeve outer cylinder, the sleeve and the force transmission inner tube are all independently designed, and the pressure operation chamber is an independent chamber. During the pressure test operation, the sleeve in the present invention is not affected by the internal pressure. The sleeve not only does not move, but also due to the action of the external pressure, the sleeve is subjected to an upward force, which can also prevent the sleeve from opening prematurely. Therefore, the application of the present invention can prevent all hazards caused by premature opening of the sleeve due to factors such as misoperation. It solves the problem that the existing delayed pressure difference sleeve opens prematurely or cannot be opened due to changes in formation parameters and operations, as well as all the disadvantages caused by premature opening or failure to open, and can significantly improve economic benefits.

[0028] In summary, the present invention has significant use effect and good application value and can generate good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 It is a cross-sectional view of the schematic diagram of the structure of an open controllable differential pressure sleeve.

[0030] Figure 2 yes Figure 1 Schematic diagram of the three-dimensional structure of the middle reversing piston.

[0031] In the figure: upper joint 1; spring outer tube 2, piston balancing hole 2-1; spacer ring 3, spring 4, center tube 5, support ring 6, support ball 7, adjustment ring 8, piston starting shear pin 9, guide screw 10, piston outer tube 11; reversing piston 12, track recovery position 12-1, sleeve opening position 12-2, device pressure test position 12-3, piston limit block 12-4, piston limit slot 12-5, piston starting shear pin slot 12-6, track starting position 12-7; piston connecting sleeve 13; force transmission inner tube 14, pressure transmission hole 14-1; sleeve starting shear pin 15, sleeve opening shear pin 16; sleeve outer tube 17, circulation port 17-1, sleeve balancing hole 17-2; sleeve 18, lower joint 19. DETAILED DESCRIPTION

[0032] The accompanying drawings are for reference and illustration only and are not intended to limit the scope of protection of the present invention. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0035] See also Figure 1-Figure 2 As shown, an open controllable differential pressure sliding sleeve for oil and gas well fracturing and acidizing is provided with a central tube 5, a reversing piston 12 and a piston auxiliary rebound mechanism, wherein: the upper end of a force transmission inner tube 14 provided with a pressure transmission hole 14-1 is connected to the central tube 5, and the lower end is inserted into a sliding sleeve 18, and the central tube 5, the force transmission inner tube 14 and the sliding sleeve 18 are installed in the inner hole between the upper joint 1 and the lower joint 19; the spring outer tube 2 provided with a piston balance hole 2-1, the piston outer tube 11 and the sliding sleeve outer tube 17 provided with a circulation port 17-1 and a sliding sleeve balance hole 17-2 are connected to the upper joint 1 and the lower joint 19 in sequence from top to bottom. The reversing piston 12 provided with a pressure test track is connected to the piston connecting sleeve 13 and installed in the pressure operation chamber formed by the center tube 5, the force transmission inner tube 14, the piston outer tube 11 and the sliding sleeve outer tube 17; the piston auxiliary rebound mechanism is installed in the annulus formed by the center tube 5 and the spring outer tube 2 and is located above the reversing piston 12; the piston outer tube 11 and the reversing piston 12 are connected by the piston starting shear pin 9, the guide screw 10 installed in the piston outer tube 11 is connected to the pressure test track of the reversing piston 12, and the sliding sleeve 18 and the sliding sleeve outer tube 17 are connected by the sliding sleeve opening shear pin 16.

[0036] In order to overcome the problem of short opening time or failure to open normally in the existing sliding sleeve device, the present invention connects the reversing piston 12 with the piston connecting sleeve 13 and installs it in the pressure operation chamber formed by the central tube 5, the force transmission inner tube 14, the piston outer tube 11 and the sliding sleeve outer tube 17. The spring outer tube 2 is provided with a piston balance hole 2-1, the sliding sleeve outer tube 17 is provided with a circulation port 17-1 and a sliding sleeve balance hole 17-2, and the pressure operation chamber is an independent chamber.

[0037] Due to the piston balance hole 2-1 provided in the spring outer tube 2 and the sleeve balance hole 17-2 provided in the sleeve outer tube 17, no closed air cavity is formed in the device of the present invention. The device of the present invention will not be affected by the gas spring effect, nor will it be affected by the air tightness of the pressure operation chamber and the pressure balance chamber. The reversing piston is acted upon by the liquid pressure and the spring force, and the sleeve is only acted upon by the liquid pressure, so that the operating pressure of the reversing piston and the opening pressure of the sleeve are more stable.

[0038] During the pressure test operation, pressure is applied through the pressure transmission hole 14-1 in the force transmission inner tube 14, and the sliding sleeve 18 is not affected by the internal pressure and does not move. Moreover, due to the effect of the external pressure, the sliding sleeve 18 is subjected to an upward force, which can prevent the sliding sleeve 18 from opening.

[0039] Therefore, the present invention can prevent the sliding sleeve 18 from opening prematurely due to factors such as misoperation.

[0040] On the basis of the above-mentioned embodiment 1, the present invention also has the following embodiments: a preferred embodiment: the reversing piston 12 is a non-uniform diameter cylindrical body and the outer circle of the cylinder is provided with an external threaded connecting section, a piston starting shear nail groove 12-6, a pressure test track, a piston limiting connecting section and an external threaded connecting section in sequence from top to bottom; the piston starting shear nail groove 12-6 can be inserted into the piston starting shear nail groove 12-6, and the guide screw 10 can be inserted into the pressure test track, and sealing ring grooves are provided on the inner circle and the outer circle of the lower part of the piston limiting connecting section and seals are installed therein.

[0041] A preferred embodiment: piston limit blocks 12-4 and piston limit grooves 12-5 are evenly distributed and staggered above the sealing ring groove in the piston limit connecting section of the reversing piston 12; in the reversing piston 12, the outer diameter of the piston limit connecting section is larger than the outer diameter of the body where the pressure test track is located.

[0042] A preferred embodiment: the pressure test track is composed of a bent asymmetric track groove, and a track starting position 12-7, a track recovery position 12-1, a sleeve opening position 12-2 and a device pressure test position 12-3 are provided in the pressure test track. In the pressure test track, the track starting position 12-7 and the track recovery position 12-1, the device pressure test position 12-3 and the sleeve opening position 12-2 are arranged in parallel from top to bottom according to the height of the position of the track groove. The position of the device pressure test position 12-3 is higher than the sleeve opening position 12-2 and parallel to it in the longitudinal direction.

[0043] A preferred embodiment: at least one group of pressure test tracks is provided in the reversing piston 12, and the length of the sleeve opening track groove where the sleeve opening position 12-2 is located is greater than the length of the device pressure test track groove where the device pressure test position 12-3 is located; the inner circle of the piston connecting sleeve 13 threadedly connected to the reversing piston 12 is a stepped inner circle and an internal threaded connecting section, a pressure transmission chamber and a limit step are provided from top to bottom, the internal threaded connecting section is threadedly connected to the reversing piston 12, the pressure transmission chamber corresponds to the pressure transmission hole 14-1 in the force transmission inner tube 14, and the limit step cooperates with the limit step above the pressure transmission hole 14-1 of the force transmission inner tube 14.

[0044] A preferred embodiment: the piston outer tube 11 is a non-uniform cylindrical body and a piston start shear pin hole and a guide screw hole are provided in the upper body. The piston start shear pin hole and the guide screw hole are threaded holes and can be respectively loaded with the piston start shear pin 9 and the guide screw 10. The other end of the guide screw 10 is inserted into the track start position 12-7 of the pressure test track. One end of the piston start shear pin 9 is threadedly connected to the piston start shear pin hole on the piston outer tube 11, and the other end is installed in the piston start shear pin groove 12-6 in the reversing piston 12, which is used for the reversing piston 12 and the piston connecting sleeve 13 to limit the position during the casing lowering and completion process and before the overall casing pressure test, so as to prevent the reversing piston 12 from moving in advance, thereby opening the sliding sleeve 18.

[0045] A preferred embodiment: the inner cavity of the piston outer cylinder 11 below the piston starting shear pin 9 and the guide screw 10 is evenly distributed and staggered with outer cylinder limiting card blocks and outer cylinder limiting card slots, and the outer cylinder limiting card blocks and outer cylinder limiting card slots can be plugged into the piston limiting card slot 12-5 and the piston limiting card block 12-4 in the reversing piston 12. During the pressure test, in order to prevent the guide screw 10 from being overstressed, when the thrust generated by the pressure acting on the reversing piston 12 is greater than the shear force of the piston starting shear pin 9, the piston starting shear pin 9 is sheared; the reversing piston 12 moves upward and rotates a certain angle under the action of the guide screw 10 and the pressure test reversing track groove, and enters the device pressure test track groove. When the guide screw 9 is about to reach the device pressure test position 13-3 of the pressure test track, the upper plane of the piston limiting card block 12-4 in the reversing piston 12 contacts the lower plane of the outer cylinder limiting card block set in the piston outer cylinder 11 and is subjected to force. At this time, the piston connecting sleeve 13 also moves upward with the reversing piston 12, and the limiting step at the lower part of its inner circle is close to the limiting step position above the pressure transmission hole 14-1 in the force transmission inner tube 14. During the casing pressure test, the guide screw 10 is not affected by the force generated during the pressure test and can meet the test requirements of higher pressure.

[0046] A preferred embodiment: the sliding sleeve 18 and the sliding sleeve outer tube 17 are both non-uniform diameter cylindrical bodies and overlap each other. After the sliding sleeve 18 and the sliding sleeve outer tube 17 are overlapped, a pressure balance chamber is formed between the sliding sleeve 18 and the sliding sleeve outer tube 17 and the lower joint 19, and the pressure balance chamber corresponds to the sliding sleeve balance hole 17-2; the sliding sleeve outer tube 17 and the sliding sleeve 18 are connected by the sliding sleeve opening shear nail 16.

[0047] A preferred embodiment: a sleeve starting shear pin 15 is also installed between the upper end of the sleeve outer tube 17 and the force transmission inner tube 14; at least two sleeve starting shear pins 15 are provided, at least three sleeve opening shear pins 16 are provided, and at least two pressure transmission holes 14-1 in the force transmission inner tube 14 are provided.

[0048] A preferred embodiment: the upper joint 1, the spring outer tube 2, the piston outer tube 11, the sleeve outer tube 17 and the lower joint 19 are threadedly connected in sequence from top to bottom; the piston auxiliary rebound mechanism is provided with a spacer ring 3, a spring 4, a support ring 6, a support ball 7 and an adjusting ring 8, and the spacer ring 3, spring 4, support ring 6, support ball 7 and adjusting ring 8 are installed in sequence from top to bottom in the annulus formed by the center tube 5 and the spring outer tube 2; the upper end surface of the adjusting ring 8 and the lower end of the support ring 6 are both provided with grooves, and the support ball 7 is installed in the groove between the adjusting ring 8 and the support ring 6; the lower inner circle of the adjusting ring 8 is threadedly connected to the upper outer circle of the reversing piston 12 and can move with the movement of the reversing piston 12, thereby assisting the reversing and resetting of the pressure test track in the reversing piston 12.

[0049] The pressure testing method for opening a controllable differential pressure sliding sleeve for oil and gas well fracturing and acidizing comprises the following steps: A. Pressurizing the inside of the casing from the ground and breaking the piston start shear pin 9; In this process: when the casing is pressure tested, the high-pressure fluid in the inner cavity of the device of the present invention enters the pressure operating cavity from the pressure transmission hole 14 - 1 of the force transmission inner tube 14 and acts on the lower part of the reversing piston 12 .

[0050] When the thrust generated by the pressure acting on the reversing piston 12 is greater than the shear force of the piston starting shear pin 9, the piston starting shear pin 9 is sheared off, the reversing piston 12 moves upward and rotates a certain angle under the action of the guide screw 10 and the track groove, and enters the pressure test reversing track groove.

[0051] When the guide screw 10 is about to reach the device pressure test position 12-3 in the pressure test reversing track groove, the upper plane of the piston limit block 12-4 in the reversing piston 12 contacts the lower plane of the outer cylinder limit block set in the piston outer cylinder 11. At this time, the piston connecting sleeve 13 also moves up with the reversing piston 12, and the limit step at the lower part of its inner circle is close to the limit step position above the pressure transmission hole 14-1 in the force transmission inner tube 14. When the device of the present invention is tested on the casing, the guide screw 10 is not affected by the force generated during the pressure test, so it can meet the test requirements of higher pressure.

[0052] B. After the first casing pressure test is completed, the pressure is released; under the elastic force of the spring 4 in the piston auxiliary rebound mechanism, the reversing piston 12 moves downward, and rotates a certain angle under the action of the guide screw 10 and the track groove in the pressure test track, and the guide screw 10 enters the track recovery position 12-1 in the reversing piston 12. The number of pressure test tracks is at least one set, and can also be set according to the number of pressure tests. Regardless of how many sets of pressure test tracks are set, each time a pressure test is performed, the upper plane of the piston limit block 12-4 in the reversing piston 12 is in contact with the lower plane of the outer cylinder limit block set in the piston outer cylinder 11.

[0053] C. After all pressure tests are completed, pressurize again and open the controllable pressure differential sleeve.

[0054] When all the pressure tests are completed, the pressure is applied again to allow the reversing piston 12 to move upward, and under the action of the guide screw 10 and the track groove in the pressure test track, it rotates a certain angle to enter the sleeve opening track groove and the sleeve opening position 12-2 to open the device of the present invention.

[0055] Because in the present invention, the length of the sliding sleeve opening track groove is longer than the device pressure test track groove, at this time, the piston limit block 12-4 in the reversing piston 12 corresponds to the outer tube limit groove in the inner circle of the piston outer tube 11. Therefore, the piston limit block 12-4 in the reversing piston 12 enters the outer tube limit groove in the piston outer tube 11, and the piston connecting sleeve 13 also continues to move upward with the reversing piston 12, so that the limit step in the piston connecting sleeve 13 contacts the limit step in the force transmission inner tube 14 to bear force.

[0056] When the applied force is greater than the shear force of the sleeve starting shear pin 15, the sleeve starting shear pin 15 is sheared off, and the piston connecting sleeve 13 drives the force transmission inner tube 14 to move upward; when the force transmission inner tube 14 moves upward to allow the sealing ring set in the inner hole of the sleeve 18 to be exposed, the pressure of the inner cavity in the device of the present invention will act on the upper part of the sleeve 18.

[0057] When the thrust generated by the pressure acting on the sleeve 18 is greater than the shear force of the sleeve opening shear pins 16, the sleeve opening shear pins 16 are sheared off, the sleeve 18 moves downward and opens the circulation port 17-1 in the sleeve outer tube 17, the fracturing channel of the device of the present invention is opened, and the fracturing construction can begin.

[0058] The embodiments described above are only typical embodiments, but the present invention is not limited to these embodiments, and those skilled in the art can make modifications without departing from the spirit and enlightenment of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the creative spirit and creative concept of the present invention should be included in the protection scope of the present invention. Therefore, the protection scope is not limited to the above description.

Claims

1. An openable controllable differential pressure sleeve for oil and gas well fracturing and acidizing, comprising a central tube (5), a reversing piston (12) and a piston auxiliary rebound mechanism, characterized in that: The upper end of a force transmission inner tube (14) provided with a pressure transmission hole (14-1) is connected to a center tube (5), and the lower end is inserted into a sliding sleeve (18); the center tube (5), the force transmission inner tube (14) and the sliding sleeve (18) are installed in the inner hole between an upper joint (1) and a lower joint (19); a spring outer tube (2) provided with a piston balance hole (2-1), a piston outer tube (11) and a sliding sleeve outer tube (17) provided with a circulation port (17-1) and a sliding sleeve balance hole (17-2) are connected to the outer circles of the upper joint (1) and the lower joint (19) in sequence from top to bottom; a reversing piston (12) provided with a pressure test track is connected to the piston The sleeve (13) is connected and installed in a pressure operation chamber formed by a central tube (5), a force transmission inner tube (14), a piston outer tube (11) and a sliding sleeve outer tube (17); the piston auxiliary rebound mechanism is installed in an annulus formed by the central tube (5) and the spring outer tube (2) and is located above the reversing piston (12); the piston outer tube (11) and the reversing piston (12) are connected through a piston starting shear pin (9), a guide screw (10) installed in the piston outer tube (11) is connected to the pressure test track of the reversing piston (12), and the sliding sleeve (18) and the sliding sleeve outer tube (17) are connected through a sliding sleeve opening shear pin (16).

2. The openable controllable differential pressure sleeve for oil and gas well fracturing and acidizing as claimed in claim 1, characterized in that: The reversing piston (12) is a non-uniform-diameter cylindrical body, and the outer circle of the cylinder is provided with an external threaded connection section, a piston starting shearing nail groove (12-6), a pressure test track, a piston limiting connection section and an external threaded connection section in sequence from top to bottom; the piston starting shearing nail groove (12-6) can be inserted into the piston starting shearing nail groove (12-6), and the guide screw (10) can be inserted into the pressure test track; the inner circle and the outer circle of the lower part of the piston limiting connection section are both provided with sealing ring grooves and sealing members are installed therein.

3. The openable controllable differential pressure sleeve for oil and gas well fracturing and acidizing as claimed in claim 2, characterized in that: A piston limiting block (12-4) and a piston limiting groove (12-5) are evenly distributed and staggered above the sealing ring groove in the piston limiting connection section of the reversing piston (12); in the reversing piston (12), the outer diameter of the piston limiting connection section is larger than the outer diameter of the body where the pressure test track is located.

4. The openable controllable differential pressure sliding sleeve for oil and gas well fracturing and acidizing as claimed in claim 3, characterized in that: The pressure test track is composed of a bent asymmetric track groove. A track starting position (12-7), a track recovery position (12-1), a sleeve opening position (12-2) and a device pressure test position (12-3) are arranged in the pressure test track. The track starting position (12-7), the track recovery position (12-1), the device pressure test position (12-3) and the sleeve opening position (12-2) are arranged in parallel from top to bottom according to the height of the position of the track groove. The device pressure test position (12-3) is located higher than the sleeve opening position (12-2) and is parallel to it in the longitudinal direction.

5. The openable controllable differential pressure sliding sleeve for oil and gas well fracturing and acidizing as claimed in claim 4, characterized in that: At least one group of pressure test tracks is provided in the reversing piston (12), and the length of the sleeve opening track groove where the sleeve opening position (12-2) is located is greater than the length of the device pressure test track groove where the device pressure test position (12-3) is located; the inner circle of the piston connecting sleeve (13) threadedly connected to the reversing piston (12) is a stepped inner circle and is provided with an inner thread connecting section, a pressure transmission chamber and a limit step from top to bottom, the inner thread connecting section is threadedly connected to the reversing piston (12), the pressure transmission chamber corresponds to the pressure transmission hole (14-1) in the force transmission inner tube (14), and the limit step matches the limit step above the pressure transmission hole (14-1) of the force transmission inner tube 14.

6. The openable controllable differential pressure sleeve for oil and gas well fracturing and acidizing as claimed in claim 4, characterized in that: The piston outer cylinder (11) is a non-uniform diameter cylindrical body and is provided with a radially penetrating piston starting shear nail hole and a guide screw hole in the upper body. The piston starting shear nail hole and the guide screw hole are both threaded holes and can be respectively loaded with the piston starting shear nail (9) and the guide screw (10). The other end of the guide screw (10) is inserted into the track starting position (12-7) of the pressure test track.

7. The openable controllable differential pressure sleeve for oil and gas well fracturing and acidizing as claimed in claim 6, characterized in that: The inner cavity of the piston outer cylinder (11) below the piston starting shear pin (9) and the guide screw (10) is evenly distributed and staggered with outer cylinder limit card blocks and outer cylinder limit card grooves, and the outer cylinder limit card blocks and outer cylinder limit card grooves can be plugged into the piston limit card groove (12-5) and the piston limit card block (12-4) in the reversing piston (12).

8. The controllable opening differential pressure sleeve for oil and gas well fracturing and acidizing as claimed in claim 2, characterized in that: The sliding sleeve (18) and the sliding sleeve outer tube (17) are both unequal diameter cylindrical bodies and overlap each other. After the sliding sleeve (18) and the sliding sleeve outer tube (17) are overlapped, a pressure balance chamber is formed between the sliding sleeve (18) and the lower joint (19), and the pressure balance chamber corresponds to the sliding sleeve balance hole (17-2); the sliding sleeve outer tube (17) and the sliding sleeve (18) are connected via a sliding sleeve opening shear nail (16).

9. The openable controllable differential pressure sliding sleeve for oil and gas well fracturing and acidizing as claimed in claim 8, characterized in that A sleeve starting shear pin (15) is also arranged between the upper end of the sleeve outer tube (17) and the force transmission inner tube (14); at least two sleeve starting shear pins (15) are arranged, at least three sleeve opening shear pins (16) are arranged, and at least two pressure transmission holes (14-1) are arranged in the force transmission inner tube (14).

10. The controllable opening differential pressure sleeve for oil and gas well fracturing and acidizing as claimed in claim 9, characterized in that: The upper joint (1), the spring outer tube (2), the piston outer tube (11), the sleeve outer tube (17) and the lower joint (19) are threadedly connected in sequence from top to bottom; the piston auxiliary rebound mechanism is provided with a spacer ring (3), a spring (4), a support ring (6), a support ball (7) and an adjustment ring (8), and the spacer ring (3), the spring (4), the support ring (6), the support ball (7) and the adjustment ring (8) are installed in sequence from top to bottom in the annulus formed by the center tube (5) and the spring outer tube (2); the upper end surface of the adjustment ring (8) and the lower end of the support ring (6) are both provided with grooves, and the support ball (7) is installed in the groove between the adjustment ring (8) and the support ring (6); the lower inner circle of the adjustment ring (8) is threadedly connected to the upper outer circle of the reversing piston (12) and can move following the movement of the reversing piston (12).

11. A pressure testing method for opening a controllable differential pressure sleeve for oil and gas well fracturing and acidizing as claimed in any one of claims 1 to 10, characterized in that: The following steps are involved: A. Pressurize the casing from the ground and break the piston start shear pin (9); B. Release the pressure after the first casing pressure test is completed; C. After all pressure tests are completed, pressurize again and open the controllable pressure differential sleeve.

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