Underground one-way flow valve and drainage gas recovery process

Abstract

The invention belongs to the technical field of oil and gas production, and particularly relates to an underground one-way flow valve and a drainage gas production process. The underground one-way flow valve comprises a check valve body, a first flow passage is arranged along the central axis of the check valve body, a first flow guide hole is formed in the side wall of the check valve body, the first flow guide hole is in a closed state in a first state, and the first flow guide hole is in an open state in a second state; the check valve element is arranged in the check valve body and comprises a shell, a second flow passing channel is formed along the central axis of the shell, a ball seat is arranged in the shell and located below the first flow guide hole, a sealing ball is arranged in the ball seat, and the second flow passing channel is located below the first flow guide hole. The ball seat and the sealing ball are configured to allow fluid to flow from bottom to top in a one-way mode. And the throttling mechanism is arranged in the shell.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas exploitation, and particularly relates to a downhole one-way flow valve and a drainage gas recovery process. BACKGROUND

[0002] Petroleum and natural gas development is a systematic project covering geology, drilling, well completion, production stimulation, collection and transportation engineering. With the rapid economic development, energy demand is rising sharply, and oil and gas development has shifted from conventional oil and gas resources to unconventional oil and gas such as tight oil and gas, shale oil and gas, and coalbed methane. Horizontal well fracturing technology has become the mainstream technology.

[0003] Unconventional oil and gas resources are buried deep and have low porosity, and often need to be hydraulically fractured to establish oil and gas channels in the formation. In order to improve oil and gas recovery, the construction displacement, pump injection liquid volume, and support number of hydraulic fracturing are increased to crush the formation as much as possible. As oil and gas well exploitation enters the middle and late stages, the formation energy gradually decreases, and the liquid in the oil and gas well accumulates more and more, and the oil and gas production rapidly decreases. Due to the low formation energy, the conventional gas lift string cannot bring the liquid in the casing to the ground, and the injected gas enters the formation, which cannot meet the requirement of lifting the liquid to the ground.

[0004] Therefore, it is urgent to develop a drainage gas recovery process and a corresponding downhole one-way flow valve. SUMMARY

[0005] In view of the above technical problems, the present application aims to provide a downhole one-way flow valve which can be used to implement the drainage gas recovery process provided by the present application and improve the gas lift efficiency.

[0006] The present application also provides a drainage gas recovery process which can avoid the injected gas entering the formation, thereby improving the efficiency of gas lift.

[0007] According to the present application, a downhole one-way flow valve is provided, comprising:

[0008] A one-way valve body is provided with a first flow passage along the central axis of the one-way valve body, and a first flow guide hole is provided on the side wall of the one-way valve body. In the first state, the first flow guide hole is in the closed state, and in the second state, the first flow guide hole is in the open state;

[0009] A one-way valve core is arranged in the one-way valve body, the one-way valve core comprises a housing, a second flow passage is arranged along the central axis of the housing, a ball seat is arranged in the housing, the ball seat is located below the first flow guide hole, a sealing ball is arranged in the ball seat, and the ball seat and the sealing ball are configured to allow fluid to flow from bottom to top in one direction; and

[0010] A throttling mechanism is arranged in the housing.

[0011] In one specific embodiment, the throttling mechanism comprises a throttling barrel coaxially arranged in the housing, a throttling nozzle is arranged in the throttling barrel, and the throttling nozzle is located between the first flow guide hole and the ball seat.

[0012] In one specific embodiment, the throttling nozzle is fixed in the throttling barrel by a jackscrew.

[0013] In one specific embodiment, a fourth snap spring is arranged on the outer wall of the throttling barrel, and a fourth snap groove for clamping the fourth snap spring is arranged on the inner wall of the housing.

[0014] In one specific embodiment, the throttling barrel comprises a fifth barrel segment and a sixth barrel segment coaxially arranged on the upper end of the fifth barrel segment, the outer diameter of the sixth barrel segment is smaller than the inner diameter of the housing, a fishing head is arranged on the upper end of the fourth snap spring, and a fishing tool can be inserted from top to bottom between the sixth barrel segment and the housing to adapt to the fishing head and make the fourth snap spring radially contract and disengage from the fourth snap groove.

[0015] In one specific embodiment, the one-way valve core is fixed with the one-way valve body by a fixing mechanism, the fixing mechanism comprises a first snap spring coaxially arranged on the outer wall of the one-way valve core, and a first snap groove is arranged on the inner wall of the one-way valve body, and the first snap spring is clamped in the first snap groove.

[0016] In one specific embodiment, a contraction tooth is arranged on the upper end of the first snap spring, the outer diameter of the contraction tooth gradually increases from top to bottom, a release barrel is arranged on the outer side of the one-way valve core by a shear pin, in the release state, the release barrel shears the shear pin and moves downward, radially inwardly extruding the contraction tooth, so as to make the first snap spring contract, and then make the first snap spring disengage from the first snap groove.

[0017] In one specific embodiment, the one-way valve body comprises an upper joint and a lower joint,

[0018] The upper joint comprises coaxially fixed first and second barrel segments, the inner diameter of the second barrel segment is larger than the inner diameter of the first barrel segment, and the first flow guide hole is arranged on the second barrel segment,

[0019] The lower joint comprises coaxially fixed third and fourth barrel segments, the outer diameter of the fourth barrel segment is smaller than the outer diameter of the third barrel segment,

[0020] The second barrel segment coaxially sleeves the outer side of the fourth barrel segment, so as to form an annular cavity between the second barrel segment and the fourth barrel segment, and an inner barrel for plugging the first flow guide hole is arranged in the annular cavity by a pin.

[0021] In one specific embodiment, the lower end of the inner cylinder is sealed with the fourth cylinder segment and the second cylinder segment, and the upper end of the inner cylinder is in communication with the first flow passage, so that the pressure receiving surface of the upper end of the inner cylinder is larger than that of the lower end.

[0022] According to the present application, a water drainage gas production process is also provided, which uses the downhole one-way flow valve provided by the present application and comprises the following steps:

[0023] S1, connecting the packer and the one-way valve body in the first state on the tubing, the packer being below the one-way valve body, and setting the packer after being positioned in the well;

[0024] S2, sending the one-way valve core with the throttling mechanism into the one-way valve body and pressurizing, so that the one-way valve body is in the second state;

[0025] S3, injecting gas from the ground into the annulus between the one-way valve body and the casing.

[0026] Compared with the prior art, the present application has the following advantages.

[0027] The downhole one-way flow valve and the packer are lowered into the well together, and the annulus below the downhole one-way flow valve is sealed by the packer. In this way, after injecting gas into the annulus between the downhole one-way flow valve and the casing, the injected gas cannot enter the formation downward through the packer, but can only enter the inner cavity of the downhole one-way flow valve through the first flow hole on the downhole one-way flow valve, and then move upward along the tubing with the accumulated liquid, thereby completing the water drainage gas production.

[0028] In the normal production process, the one-way valve body of the present application is in the first state when it is lowered into the well, at which time the one-way valve body is equivalent to a section of conventional tubing and can be used to implement conventional downhole processes. After the one-way valve core with the throttling mechanism is lowered into the one-way valve body, the one-way valve core only allows fluid to flow from the bottom of the well to the wellhead, and the throttling structure has a throttling function and can be used to implement production processes. When the water drainage gas production process provided by the present application needs to be implemented, the first flow hole of the one-way valve body is opened by pressurizing at the wellhead, and then injecting gas into the annulus between the downhole one-way flow valve and the casing can discharge the accumulated liquid at the bottom of the well. BRIEF DESCRIPTION OF DRAWINGS

[0029] The present application will be described below with reference to the accompanying drawings.

[0030] Figure 1 shows a schematic view of one embodiment of the first state of the downhole one-way flow valve according to the present application;

[0031] Figure 2shows a schematic view of one embodiment of a single-flow valve core according to the present application;

[0032] Figure 3 shows a schematic view of one embodiment of a single-flow valve body according to the present application;

[0033] Figure 4 shows a schematic view of one embodiment of a drainage gas recovery process according to the present application;

[0034] Figure 5 shows a schematic view of one embodiment of a second state of a downhole one-way flow valve according to the present application;

[0035] Figure 6 shows a schematic view of one embodiment of a downhole one-way flow valve according to the present application after the throttle mechanism has been pulled out of the well.

[0036] in the drawings:

[0037] 1. single-flow valve body; 11. first flow passage; 12. first flow guide hole; 14. pin; 15. inner cylinder; 16. upper joint; 161. first clamping groove; 162. first cylinder segment; 163. second cylinder segment; 17. lower joint; 171. protrusion; 172. third cylinder segment; 173. fourth cylinder segment; 174. fifth flow guide hole; 18. annular cavity;

[0038] 2. single-flow valve core; 21. second flow passage; 22. second flow guide hole; 23. housing; 231. first positioning step; 232. fourth clamping groove; 24. ball seat; 25. sealing ball; 26. ball blocking plate; 261. flow hole;

[0039] 4. fixing mechanism; 41. first clamping spring; 42. fishing neck; 421. boss; 43. release cylinder; 431. abutting member; 44. cutting pin; 45. retraction tooth;

[0040] 5. throttle mechanism; 51. throttle cylinder; 511. sixth flow guide hole; 512. second positioning step; 513. fifth cylinder segment; 514. sixth cylinder segment; 52. throttle nozzle; 53. jackscrew; 54. fourth clamping spring; 55. fishing head; 56. limiting step;

[0041] 100. downhole one-way flow valve; 101. oil pipe; 102. packer; 103. casing.

[0042] In this application, all the drawings are schematic drawings and are only used to illustrate the principles of the present application and are not drawn to scale. DETAILED DESCRIPTION

[0043] The present application will be described below with reference to the drawings.

[0044] It should be noted that in the present application, the direction of the downhole one-way flow valve according to the present application after entering the well close to the wellhead is described as "up", "front" or similar terms, i.e. Figure 1 the upper side of the well; the direction of the downhole one-way flow valve according to the present application after entering the well away from the wellhead is described as "down", "back" or similar terms, i.e. Figure 1 the lower side of the well.

[0045] Figure 1 The structure of the downhole one-way flow valve 100 according to the present application is shown. As Figure 1 shown, the downhole one-way flow valve 100 comprises a one-way valve body 1 and a one-way valve core 2, and in the implementation of the water drainage gas recovery process provided by the present application, the one-way valve body 1 is first matched with the packer and lowered into the casing 103, and then the one-way valve core 2 is pumped into the one-way valve body 1. The specific structure of the one-way valve body 1 and the one-way valve core 2 will be described below.

[0046] According to the present application, as Figure 2 shown, the one-way valve core 2 is generally cylindrical in overall structure, and the inner cavity of the one-way valve core 2 is the second flow passage 21, which is provided through the one-way valve core 2 along the central axis of the one-way valve core 2. In this embodiment, the one-way valve core 2 is configured to allow fluid to flow unidirectionally from bottom to top through the second flow passage 21, that is, fluid cannot flow from top to bottom through the second flow passage 21 of the one-way valve core 2.

[0047] In a specific embodiment, a second flow guide hole 22 is provided on the side wall of the one-way valve core 2, and the second flow guide hole 22 communicates the second flow passage 21 with the outside of the one-way valve core 2.

[0048] According to the present application, as Figure 3 shown, the one-way valve body 1 is generally cylindrical in overall structure, and the inner cavity of the one-way valve body 1 is the first flow passage 11, which is provided through the one-way valve body 1 along the central axis of the one-way valve body 1.

[0049] In this embodiment, as Figure 3 shown, the one-way valve body 1 comprises an upper joint 16 and a lower joint 17 fixedly connected coaxially, and an annular cavity 18 is formed between the mutually sleeved portions of the upper joint 16 and the lower joint 17, a first flow guide hole 12 is provided on the side wall of the upper joint 16, and in the first state, an inner cylinder 15 is provided in the annular cavity 18 by a pin 14 to block the first flow guide hole 12.

[0050] Specifically, the upper connector 16 includes a first cylindrical section 162 and a second cylindrical section 163 that are coaxially fixed. The first cylindrical section 162 is located on the upper side of the second cylindrical section 163. The outer diameters of the first cylindrical section 162 and the second cylindrical section 163 are equal, and the inner diameter of the second cylindrical section 163 is greater than the inner diameter of the first cylindrical section 162. The first guide hole 12 is located on the second cylindrical section 163.

[0051] The lower connector 17 includes a third cylindrical section 172 and a fourth cylindrical section 173 that are coaxially fixed. The third cylindrical section 172 is located below the fourth cylindrical section 173. The inner diameters of the third cylindrical section 172 and the fourth cylindrical section 173 are equal, and the outer diameter of the fourth cylindrical section 173 is smaller than the outer diameter of the third cylindrical section 172.

[0052] The second cylindrical section 163 is coaxially sleeved on the outside of the fourth cylindrical section 173 by means of threaded connection. That is, the lower end of the second cylindrical section 163 is provided with internal thread, and the lower end of the fourth cylindrical section 173 is provided with external thread, thereby forming an annular cavity 18 between the second cylindrical section 163 and the fourth cylindrical section 173.

[0053] In one embodiment of the present invention, after the second cylindrical section 163 and the fourth cylindrical section 173 are fixedly connected, the upper end face of the fourth cylindrical section 173 is located below the first guide hole 12. The inner cylinder 15 is fixedly disposed in the annular cavity 18 by a pin 14, and the inner cylinder 15 blocks the first guide hole 12. Sealing rings for sealing with the fourth cylindrical section 173 and the second cylindrical section 163 are respectively provided on the inner and outer sides of the lower end of the inner cylinder 15. Under this arrangement, when the pressure in the first flow channel 11 increases, the pressure is transmitted to the inner cylinder 15. The pressure on the upper end face of the inner cylinder 15 is greater than the pressure on the lower end face, thereby causing the inner cylinder 15 to move downward and open the first guide hole 12, allowing the first guide hole 12 to communicate with the first flow channel 11.

[0054] In a preferred embodiment, a backstop mechanism, such as a ratchet, a retaining ring, or a retaining groove, is provided between the inner cylinder 15 and the upper connector 16 (or the lower connector 17) to prevent the inner cylinder 15 from resetting after opening the first guide hole 12.

[0055] In a preferred embodiment, to make the inner cylinder 15 more securely installed, such as Figure 3 As shown, in this embodiment, the upper end face of the fourth cylindrical section 173 extends to the upper side of the first guide hole 12, so that both the upper and lower ends of the inner cylinder 15 can be supported by the fourth cylindrical section 173 and the second cylindrical section 163. Furthermore, a fifth guide hole 174 is provided at the position corresponding to the first guide hole 12 in the fourth cylindrical section 173. When the inner cylinder 15 moves downward and opens the first guide hole 12, the first guide hole 12 can communicate with the first flow channel 11 through the fifth guide hole 174.

[0056] In a specific embodiment, the single-flow valve core 2 comprises a housing 23 and a ball seat 24 arranged on the housing 23. As shown in Figure 2 the inner cavity of the housing 23 is the second flow passage 21, the second flow guide hole 22 is arranged on the side wall of the housing 23, the ball seat 24 is arranged at the lower end of the housing 23, a sealing ball 25 for sealing is arranged in the ball seat 24, and the second flow guide hole 22 is located on the upper side of the ball seat 24. Further, the ball seat 24 is configured as a conical surface, and the side with a larger diameter of the ball seat 24 faces the upper side, and the sealing ball 25 is located on the upper side of the ball seat 24. In this arrangement, when the fluid flows from top to bottom through the ball seat 24 and the sealing ball 25, the fluid pushes the sealing ball 25 to move downward, so that the sealing ball 25 blocks the ball seat 24, thereby preventing the fluid from flowing from top to bottom through the ball seat 24; when the fluid flows from bottom to top through the ball seat 24 and the sealing ball 25, the fluid pushes the sealing ball 25 to move upward, so that the sealing ball 25 moves away from the ball seat 24, and the ball seat 24 is in an open state, thereby enabling the single-flow valve core 2 to allow the fluid to flow only in one direction from bottom to top.

[0057] In the working process, as shown in Figure 4 first, the packer 102 and the single-flow valve body 1 in the first state of the downhole one-way flow valve 100 are connected to the oil pipe 101. The single-flow valve body 1 is in series with the oil pipe 101, and the inner cavity of the oil pipe 101 communicates with the first flow passage 11 of the single-flow valve body 1. The packer 102 is coaxially sleeved on the outside of the oil pipe 101, and the packer 102 is located behind the single-flow valve body 1. After the oil pipe 101, the single-flow valve body 1 and the packer 102 are connected, they are lowered into the casing 103, and after being lowered into position, the packer 102 is set, so that the packer 102 blocks the annulus between the oil pipe 101 and the casing 103. After setting the packer 102, the ball seat or other downhole tool used to set the packer 102 is broken, so that the inner cavity of the oil pipe 101 is unobstructed, and at this time, oil and gas exploitation can be carried out.

[0058] The single-flow valve core 2 is put into the wellhead, and the single-flow valve core 2 is pumped to the single-flow valve body 1 by fluid, as shown in Figure 1 at this time, the single-flow valve core 2 is axially fixed with the single-flow valve body 1, the second flow guide hole 22 coincides with the center axis of the fifth flow guide hole 174 and the first flow guide hole 12, the ball seat 24 is located on the lower side of the first flow guide hole 12, and the single-flow valve body 1 is still in the first state, i.e., the first flow guide hole 12 is still in the closed state. Continue to pump the pressure, because the single-flow valve core 2 does not allow fluid to pass from top to bottom, so the pressure of the pump can only pass through Figure 1The arrow points to the direction, in turn, through the second flow guide hole 22, the gap between the outer wall of the shell 23 and the inner wall of the fourth cylinder segment 173, the gap between the end face of the fourth cylinder segment 173 and the end face of the first cylinder segment 162, and then to the upper end face of the inner cylinder 15, so as to make the inner cylinder 15 move downward relative to the first flow guide hole 12, and then open the first flow guide hole 12, and make the first flow guide hole 12 communicate with the second flow guide hole 22, as shown in Figure 6 Subsequently, continue to inject gas into the oil pipe 101 from the wellhead, and the gas flows downward along the oil pipe 101. The sealing ball 25 and the ball seat 24 make the gas entering the shell 23 unable to flow downward, so that the gas can only flow to the annulus between the oil pipe 101 and the casing 103 through the first flow guide hole 12. The packer 102 blocks the annulus, so the gas cannot continue to flow downward, and thus the gas can only flow upward along the annulus between the oil pipe 101 and the casing 103 with the bottom hole fluid, until the well, to complete the drainage gas recovery.

[0059] In another embodiment provided by the present application, after the first flow guide hole 12 is opened, nitrogen, natural gas or other gas can also be injected from the wellhead to the annulus between the oil pipe 101 and the casing 103. The gas flows downward along the annulus between the oil pipe 101 and the casing 103, as shown in Figure 4 Because the packer 102 blocks the annulus, the gas cannot continue to flow downward and cannot enter the formation to affect the formation pressure. The gas can only enter the second flow passage 21 of the shell 23 through the first flow guide hole 12 and the second flow guide hole 22 of the downhole one-way flow valve 100. The sealing ball 25 and the ball seat 24 at the lower end of the second flow passage 21 make the gas entering the shell 23 flow upward, and thus the gas flows upward with the fluid to complete the drainage gas recovery.

[0060] According to the present application, in the present embodiment, the throttling mechanism 5 in the shell 23, as shown in Figure 1 By setting the throttling mechanism 5, the throttling effect can be achieved during the conventional gas recovery process.

[0061] In the working process, as Figure 4As shown, first, the packer 102 and the one-way flow valve body 1 of the downhole one-way flow valve 100 in the first state are connected to the tubing 101. Among them, the one-way flow valve body 1 is in series with the tubing 101, and the inner cavity of the tubing 101 is in communication with the first flow passage 11 of the one-way flow valve body 1. The packer 102 is coaxially sleeved outside the tubing 101, and the packer 102 is located behind the one-way flow valve body 1. After the tubing 101, the one-way flow valve body 1 and the packer 102 are connected, they are lowered into the casing 103, and after being lowered into position, the packer 102 is set, so that the packer 102 blocks the annulus between the tubing 101 and the casing 103. After setting the packer 102, the ball seat or other downhole tool used to set the packer 102 is broken, so that the inner cavity of the tubing 101 is unobstructed, and at this time, oil and gas exploitation can be carried out. Then, the one-way valve core 2 provided with the throttling mechanism 5 is put from the wellhead, and the one-way valve core 2 is pumped into the one-way flow valve body 1 by fluid, as shown in the figure Figure 1 At this time, the one-way valve core 2 is axially fixed with the one-way flow valve body 1, the second flow guide hole 22 is coincident with the central axis of the fifth flow guide hole 174 and the first flow guide hole 12, the ball seat 24 is located on the lower side of the first flow guide hole 12, and the one-way flow valve body 1 is still in the first state, that is, the first flow guide hole 12 is still in the closed state. At this time, the conventional gas production operation can be carried out, and the presence of the throttling mechanism 5 can provide throttling effect for the conventional gas production operation.

[0062] In a specific embodiment, the throttling mechanism 5 includes a throttling cylinder 51 coaxially arranged in the shell 23, and a throttling nozzle 52 is arranged in the throttling cylinder 51, and the throttling nozzle 52 is located between the first flow guide hole 12 and the ball seat 24.

[0063] Further, in this embodiment, the throttling nozzle 52 is arranged inside the lower end of the throttling cylinder 51, and in the assembly process, the throttling nozzle 52 enters the inner cavity of the throttling cylinder 51 from below to above along the axial direction, until the upper end surface of the throttling nozzle 52 is in abutment with the inner wall of the throttling cylinder 51 along the axial direction, and then the top wire 53 is screwed into the inner cavity of the throttling cylinder 51 along the axial direction from below to above, until the upper end surface of the top wire 53 is in abutment with the lower end surface of the throttling nozzle 52.

[0064] In a specific embodiment, a second positioning step 512 is arranged on the outer wall of the throttling cylinder 51, and a first positioning step 231 for adapting with the second positioning step 512 is arranged on the inner wall of the shell 23, and the first positioning step 231 is located below the second flow guide hole 22. In the assembly process, the throttling cylinder 51 enters the shell 23 from above to below along the axial direction, until the second positioning step 512 of the throttling cylinder 51 is in abutment with the first positioning step 231 of the shell 23 along the axial direction.

[0065] According to the present application, a sixth flow guide hole 511 is arranged on the side wall of the throttling cylinder 51, and after the throttling cylinder 51 is assembled into the shell 23, the sixth flow guide hole 511 is coincident with the central axis of both the second flow guide hole 22.

[0066] In a specific embodiment, as shown in FIG. 2, a stepped hole 233 is provided on the inner wall of the housing 23 corresponding to the outer position of the second flow guide hole 22. Further, the stepped hole 233 is an annular groove provided on the inner wall of the housing 23. Figure 2

[0067] In a specific embodiment, a fourth spring 54 is provided on the outer wall of the throttle cylinder 51, and a fourth clamping groove 232 is provided on the inner wall of the housing 23 (or the fishing neck 42) for clamping the fourth spring 54. When the second positioning step 512 of the throttle cylinder 51 axially abuts the first positioning step 231 of the housing 23, the fourth spring 54 of the throttle cylinder 51 is clamped in the fourth clamping groove 232 of the housing 23, thereby fixing the throttle cylinder 51 in the housing 23.

[0068] In a preferred embodiment, the throttle cylinder 51 includes a fifth cylinder segment 513 and a sixth cylinder segment 514 coaxially arranged on the upper end of the fifth cylinder segment 513, the outer diameter of the sixth cylinder segment 514 is smaller than the inner diameter of the housing 23, a fishing head 55 is arranged on the upper end of the fourth spring 54, and the outer diameter of the fourth spring 54 is greater than the outer diameter of the fishing head 55, thereby forming a limiting step 56 between the fourth spring 54 and the fishing head 55, which can axially abut the fourth clamping groove 232, thereby preventing the fourth spring 54 from moving upward and disengaging from the fourth clamping groove 232. The fourth spring 54 and the fishing head 55 are located at the connection between the fifth cylinder segment 513 and the sixth cylinder segment 514. When it is necessary to remove the throttling mechanism 5 from the spool 2, a fishing tool can be inserted between the sixth cylinder segment 514 and the housing 23 from top to bottom, thereby fitting with the fishing head 55, being sleeved on the outside of the fishing head 55, clamping the fishing head, and also being able to radially inwardly press the fishing head 55, thereby making the fourth spring 54 radially contract and disengage from the fourth clamping groove 232. Then the fishing tool can be lifted up, and the fishing tool can remove the entire throttling mechanism 5 from the spool 2 through the fishing head 55.

[0069] In a preferred embodiment, a ball blocking plate 26 is arranged in the housing 23, and the distance between the ball blocking plate 26 and the ball seat 24 can accommodate the sealing ball 25 and provide a certain moving space for the sealing ball 25 in the axial direction, thereby enabling the sealing ball 25 to move upward away from the ball seat 24, so that the fluid below can move upward through the ball seat 24. By arranging the ball blocking plate 26, the sealing ball 25 can be limited in the vicinity of the ball seat 24.

[0070] In a specific embodiment, the pin 14 is arranged on the lower side of the first flow guide hole 12.

[0071] In a specific embodiment, a protrusion 171 is arranged on the inner wall of the lower connector 17, and the spool 2 can be inserted into the interior of the lower connector 17, as shown in FIG. 2. Figure 1 ​As shown, after the single flow spool 2 extends into the inside of the lower joint 17, the ball seat 24 of the single flow spool 2 can axially abut the protrusion 171 of the lower joint 17, so as to realize the axial positioning of the first flow guide hole 12 and the second flow guide hole 22.

[0072] According to the present application, as Figure 2 As shown, the fixed mechanism 4 is coaxially fixed on the upper end of the single flow spool 2. As Figure 1 As shown, the fixed mechanism 4 can be clamped with the single flow valve body 1, so as to fix the single flow spool 2 in the single flow valve body 1.

[0073] Specifically, as Figure 2 As shown, the fixed mechanism 4 includes a first clamping spring 41 coaxially arranged on the outer wall of the shell 23 of the single flow spool 2. Correspondingly, as Figure 3 As shown, a first clamping groove 161 is arranged on the inner wall of the upper joint 16, and in the second state, as Figure 6 As shown, the first clamping spring 41 is clamped in the first clamping groove 161, so as to relatively fix the single flow valve body 1 and the single flow spool 2.

[0074] In a preferred embodiment, as Figure 2 As shown, a contraction tooth 45 is arranged on the upper end of the first clamping spring 41, the outer diameter of the contraction tooth 45 gradually increases from top to bottom, and the outer diameter of the upper end of the first clamping spring 41 is greater than the outer diameter of the lower end of the contraction tooth 45, so as to form a step at the upper end of the first clamping spring 41, so that after the first clamping spring 41 moves downward with the single flow spool 2 to be clamped with the first clamping groove 161, the first clamping spring 41 cannot be reset, thereby fixing the single flow valve body 1 and the single flow spool 2.

[0075] Further, a release cylinder 43 is fixedly arranged on the outer wall of the shell 23 through a shear pin 44, the release cylinder 43 is located on the upper side of the contraction tooth 45, and the inner diameter of the release cylinder 43 is greater than the outer diameter of the uppermost end of the contraction tooth 45. When it is necessary to take out the single flow spool 2 later, a fishing tool is lowered into the oil pipe 101, and the fishing tool finally abuts against the upper end face of the release cylinder 43 during downward movement, and continues to apply pressure to the fishing tool, so as to push the release cylinder 43 from top to bottom through the fishing tool, so that the release cylinder 43 shears the shear pin 44, and then the release cylinder 43 moves downward relative to the shell 23. The inner diameter of the release cylinder 43 is greater than the outer diameter of the uppermost end of the contraction tooth 45, and the outer diameter of the contraction tooth 45 gradually increases from top to bottom, so that the release cylinder 43 can be sleeved on the outer side of the contraction tooth 45 during downward movement, and exerts a radial inward extrusion force on the contraction tooth 45, so that the first clamping spring 41 is radially contracted inward and separated from the first clamping groove 161.

[0076] Furthermore, a retrieval neck 42 is coaxially fixed at the upper end of the housing 23, and a boss 421 is coaxially fixed at the upper end of the retrieval neck 42. When the retrieval tool pushes the release sleeve 43, the first retaining spring 41 retracts radially and disengages from the first retaining groove 161, and the boss 421 can engage with the retrieval tool. At this time, if the retrieval tool is moved upward, the retrieval neck 42 can drive the single-flow valve core 2 to move upward relative to the single-flow valve body 1, thereby separating the single-flow valve core 2 from the single-flow valve body 1.

[0077] In a preferred embodiment, a ratchet is provided on the inner wall of the lower end of the dropper 43 for matching the retraction tooth 45. When the dropper 43 is sleeved on the outside of the retraction tooth 45, the ratchet of the dropper 43 can engage with the retraction tooth 45, so that the dropper 43 cannot move upward relative to the retraction tooth 45, thereby preventing the dropper 43 from resetting.

[0078] In a preferred embodiment, an abutment 431 is coaxially fixed to the upper end of the hand-dropping device 43. The cross-sectional area of ​​the abutment 431 is larger than that of the hand-dropping device 43, thereby increasing the contact area with the retrieval tool and making it easier for the retrieval tool to push the hand-dropping device 43 downward.

[0079] According to the present invention, a drainage gas extraction process is also provided, comprising the following steps:

[0080] S1, such as Figure 4 As shown, the packer 102 and the one-way valve body 1 of the downhole one-way flow valve 100 in its first state are connected to the tubing 101 to form a tubing string. The one-way valve body 1 remains axially unobstructed and is connected in series with the tubing 101. The packer 102 is located below the one-way valve body 1 and is fitted over the outside of the tubing 101. After the tubing string is inserted into the well to the designed well depth, the packer 102 is set, sealing the annulus between the tubing 101 and the casing 103. After setting the packer 102, the ball seat or other downhole tools used to set the packer 102 are removed to keep the tubing string unobstructed.

[0081] S2. The single-flow valve core 2 equipped with the throttling mechanism 5 is sent into the single-flow valve body 1 and pressurized, so that the single-flow valve body 1 is in the second state.

[0082] Specifically, a single-flow valve core 2 equipped with a throttling mechanism 5 is inserted from the wellhead, and a liquid or gas pump is used to pump the single-flow valve core 2 to the single-flow valve body 1, such as... Figure 1 As shown, the ball seat 24 is brought into axial contact with the protrusion 171 of the lower connector 17. The wellhead continues to be pressurized, with the pressure according to... Figure 1The arrow direction shown passes through the sixth flow guide hole 511 of the throttling mechanism 5, the second flow guide hole 22, the gap between the outer wall of the shell 23 and the inner wall of the fourth cylinder segment 173, the gap between the end face of the fourth cylinder segment 173 and the end face of the first cylinder segment 162 in turn to the upper end face of the inner cylinder 15, so that the inner cylinder 15 shears the pin 14 and moves downward relative to the first flow guide hole 12, thereby opening the first flow guide hole 12 and making the first flow guide hole 12 communicate with the second flow guide hole 22. At the same time, the first snap spring 41 of the fixing mechanism 4 and the first clamping groove 161 of the upper joint 16 jointly limit the movement of the one-way valve core 2 and the one-way valve body 1.

[0083] In the normal production process, the formation capacity is sufficient, the sealing ball 25 leaves the ball seat 24 under the action of the formation pressure, and the formation gas or liquid passes through the lower joint 17, the ball seat 24, the flow hole 261 on the ball blocking plate 26, the top wire 53, the throttling nozzle 52, the inner cavity of the throttling cylinder 51 in turn, and finally flows out of the well along the oil pipe 101.

[0084] S3, when the well bottom liquid loading increases and the formation energy is insufficient to bring the liquid loading in the casing 103 to the ground to affect the production efficiency, the fishing tool is used to take out the throttling mechanism 5 from the one-way valve core 2 and move out of the well, and then gas is injected into the annulus between the oil pipe 101 and the casing 103 from the ground.

[0085] Specifically, the gas such as nitrogen and natural gas flows from the wellhead along the annulus between the oil pipe 101 and the casing 103 to the well bottom, passes through the first flow guide hole 12, the fifth flow guide hole 174 and the second flow guide hole 22 of the downhole one-way flow valve 100 into the inner cavity (second flow passage 21) of the shell 23, and drives the liquid loading in the second flow passage 21 to flow upward along the oil pipe 101 and be discharged from the wellhead, thereby reducing the liquid column pressure inside the oil pipe 101 and achieving the purpose of low-pressure production.

[0086] In another embodiment provided according to the application, in step S3, when the well bottom liquid loading increases and the formation energy is insufficient to bring the liquid loading in the casing 103 to the ground to affect the production efficiency, the fishing tool is used to take out the throttling mechanism 5 from the one-way valve core 2 and move out of the well, and then gas is injected into the oil pipe 101 from the ground.

[0087] In the description of the present application, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0088] In this application, unless otherwise clearly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0089] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0090] Finally, it should be noted that the above only describes the preferred embodiments of the present application and does not constitute any limitation on the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or replace some technical features with equivalent ones. Any modification, equivalent replacement, improvement and the like made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A downhole one-way flow valve, characterized in that, include: A single-flow valve body (1) is provided with a first flow passage (11) along the central axis of the single-flow valve body (1), and a first flow guide hole (12) is provided on the side wall of the single-flow valve body (1). In a first state, the first flow guide hole (12) is in a closed state, and in a second state, the first flow guide hole (12) is in an open state. A one-way valve core (2) is disposed in the one-way valve body (1). The one-way valve core (2) includes a housing (23). A second flow passage (21) is provided along the central axis of the housing (23). A ball seat (24) is provided in the housing (23). The ball seat (24) is located below the first flow guide hole (12). A sealing ball (25) is provided in the ball seat (24). The ball seat (24) and the sealing ball (25) are configured to allow fluid to flow unidirectionally from bottom to top. as well as A throttling mechanism (5) is disposed within the housing (23).

2. The downhole one-way flow valve according to claim 1, characterized in that, The throttling mechanism (5) includes a throttling cylinder (51) coaxially disposed in the housing (23), and a throttling nozzle (52) is disposed in the throttling cylinder (51). The throttling nozzle (52) is located between the first guide hole (12) and the ball seat (24).

3. The downhole one-way flow valve according to claim 2, characterized in that, The throttle nozzle (52) is fixed inside the throttle cylinder (51) by a set screw (53).

4. The downhole one-way flow valve according to claim 2, characterized in that, A fourth retaining ring (54) is provided on the outer wall of the throttle cylinder (51), and a fourth retaining groove (232) for engaging the fourth retaining ring (54) is provided on the inner wall of the housing (23).

5. The downhole one-way flow valve according to claim 4, characterized in that, The throttling cylinder (51) includes a fifth cylinder section (513) and a sixth cylinder section (514) coaxially disposed at the upper end of the fifth cylinder section (513). The outer diameter of the sixth cylinder section (514) is smaller than the inner diameter of the housing (23). A retrieval head (55) is provided at the upper end of the fourth retaining ring (54). The retrieval tool can extend from top to bottom between the sixth cylinder section (514) and the housing (23), thereby adapting to the retrieval head (55) and causing the fourth retaining ring (54) to radially retract and disengage from the fourth retaining groove (232).

6. The downhole one-way flow valve according to any one of claims 1 to 5, characterized in that, The single-flow valve core (2) is fixed to the single-flow valve body (1) by a fixing mechanism (4). The fixing mechanism (4) includes a first snap ring (41) coaxially disposed on the outer wall of the single-flow valve core (2) and a first slot (161) disposed on the inner wall of the single-flow valve body (1). The first snap ring (41) is engaged in the first slot (161).

7. The downhole one-way flow valve according to claim 6, characterized in that, A retraction tooth (45) is provided at the upper end of the first snap ring (41). The outer diameter of the retraction tooth (45) gradually increases from top to bottom. A release sleeve (43) is provided on the outside of the single-flow valve core (2) through a shear pin (44). In the release state, the release sleeve (43) cuts the shear pin (44) and moves downward, radially and inwardly squeezing the retraction tooth (45), thereby causing the first snap ring (41) to retract, and then causing the first snap ring (41) to disengage from the first snap groove (161).

8. The downhole one-way flow valve according to any one of claims 1 to 7, characterized in that, The single-flow valve body (1) includes an upper connector (16) and a lower connector (17). The upper connector (16) includes a first cylindrical section (162) and a second cylindrical section (163) coaxially fixed. The inner diameter of the second cylindrical section (163) is larger than the inner diameter of the first cylindrical section (162). The first guide hole (12) is disposed on the second cylindrical section (163). The lower connector (17) includes a third cylindrical section (172) and a fourth cylindrical section (173) fixed coaxially, wherein the outer diameter of the fourth cylindrical section (173) is smaller than the outer diameter of the third cylindrical section (172). The second cylindrical section (163) is coaxially sleeved on the outside of the fourth cylindrical section (173), thereby forming an annular cavity (18) between the second cylindrical section (163) and the fourth cylindrical section (173). An inner cylinder (15) for sealing the first guide hole (12) is provided in the annular cavity (18) by means of a pin (14).

9. The downhole one-way flow valve according to claim 8, characterized in that, The lower end of the inner cylinder (15) is sealed to the fourth cylinder section (173) and the second cylinder section (163) on both the inner and outer sides, respectively. The upper end of the inner cylinder (15) is connected to the first flow channel (11), so that the pressure surface of the upper end of the inner cylinder (15) is greater than that of the lower end.

10. A drainage gas extraction process, characterized in that, Using the downhole one-way flow valve according to any one of claims 1 to 9 includes the following steps: S1. Connect the packer and the single-flow valve body (1) in the first state to the tubing. The packer is located below the single-flow valve body (1). After the packer is inserted into the well, it is seated. S2. The single-flow valve core (2) with throttling mechanism (5) is sent into the single-flow valve body (1) and pressurized to put the single-flow valve body (1) into the second state. S3. Inject air into the annulus between the one-flow valve body (1) and the sleeve from the ground.

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