Underground one-way flow valve and gas production 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 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 ball seat and the sealing ball are constructed to allow fluid to flow from bottom to top in a one-way mode; the elastic piece is arranged on the check valve element and can be fixedly connected with the check valve body; and the throttling mechanism is arranged in the shell.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, specifically relating to a downhole one-way flow valve and a gas extraction process. Background Technology

[0002] Oil and gas development is a systematic project covering geology, drilling, well completion, production enhancement, extraction, and transportation. With 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 often buried deep with low porosity, requiring hydraulic fracturing to establish oil and gas channels in the formation. To improve oil and gas recovery, the hydraulic fracturing operation involves increasing the flow rate, pumped fluid volume, and proppant quantity to crush the oil and gas reservoir as much as possible. As oil and gas well development progresses into the middle and later stages, formation energy gradually decreases, and more and more fluid accumulates within the well, leading to a rapid decline in oil and gas production. Conventional gas lift tubing, due to low formation energy, cannot remove the fluid accumulated in the casing to the surface; the injected gas enters the formation, failing to meet the requirement of lifting the fluid to the surface.

[0004] Therefore, there is an urgent need to develop a gas extraction technology and a corresponding downhole one-way flow valve. Summary of the Invention

[0005] To address the technical problems described above, this invention aims to provide a downhole one-way flow valve that can be used to implement the gas production process provided by this invention and improve gas lift efficiency.

[0006] The present invention also proposes a gas extraction process that can prevent the injected gas from entering the formation, thereby improving the efficiency of gas lift.

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

[0008] A single-flow valve body has a first flow passage along its central axis and a first flow guide hole on its side wall. In a first state, the first flow guide hole is closed, and in a second state, the first flow guide hole is open.

[0009] The one-way valve core disposed within the one-way valve body includes a housing, a second flow passage disposed along the central axis of the housing, a ball seat disposed within the housing, the ball seat being located below the first flow guide hole, and a sealing ball disposed within the ball seat. The ball seat and the sealing ball are configured to allow fluid to flow unidirectionally from bottom to top.

[0010] A spring clip disposed on the one-way valve core, the spring clip being configured to be fixedly connected to the one-way valve body; and

[0011] A throttling mechanism is disposed within the housing.

[0012] In one specific embodiment, a locking block is provided on the spring sheet, and a first locking groove for engaging with the locking block is provided on the inner wall of the one-flow valve body.

[0013] In one specific embodiment, a retrieval neck is provided above the locking block for adaptation to a retrieval tool. The retrieval tool is configured to fit over the outside of the retrieval neck and radially press the retrieval neck inward, thereby causing the locking block to radially retract and disengage from the first locking groove.

[0014] In one specific embodiment, a small-diameter shell is coaxially disposed at the upper end of the housing, the outer diameter of the small-diameter shell being smaller than the outer diameter of the housing, and the spring piece is disposed at the upper end of the housing and spaced out on the outside of the small-diameter shell.

[0015] In one specific embodiment, the throttling mechanism includes a throttling cylinder coaxially disposed within the housing, and a throttling nozzle disposed within the throttling cylinder, the throttling nozzle being located between the first guide hole and the ball seat.

[0016] In one specific embodiment, a fourth retaining ring is provided on the outer wall of the throttling cylinder, and a fourth retaining groove for engaging the fourth retaining ring is provided on the inner wall of the housing.

[0017] In one specific embodiment, the throttling cylinder includes a fifth cylindrical section and a sixth cylindrical section coaxially disposed at the upper end of the fifth cylindrical section. The outer diameter of the sixth cylindrical section is smaller than the inner diameter of the housing. A retrieval head is provided at the upper end of the fourth retaining spring. The retrieval tool can extend from top to bottom between the sixth cylindrical section and the housing, thereby adapting to the retrieval head and causing the fourth retaining spring to radially retract and disengage from the fourth retaining groove.

[0018] In one specific embodiment, the one-way valve body includes an upper connector and a lower connector.

[0019] The upper connector includes a first cylindrical section and a second cylindrical section coaxially fixed. The inner diameter of the second cylindrical section is larger than the inner diameter of the first cylindrical section, and the first guide hole is disposed on the second cylindrical section.

[0020] The lower connector includes a third cylindrical section and a fourth cylindrical section coaxially fixed, wherein the outer diameter of the fourth cylindrical section is smaller than the outer diameter of the third cylindrical section.

[0021] The second cylindrical section is coaxially sleeved on the outside of the fourth cylindrical section, thereby forming an annular cavity between the second cylindrical section and the fourth cylindrical section. An inner cylinder for sealing the first guide hole is provided in the annular cavity by means of a pin.

[0022] In one specific embodiment, the lower end of the inner cylinder is sealed to the fourth cylinder section and the second cylinder section on its inner and outer sides, respectively, and the upper end of the inner cylinder is connected to the first flow channel, so that the pressure-bearing surface of the upper end of the inner cylinder is greater than that of the lower end.

[0023] According to the present invention, a gas production process is also provided, using a downhole one-way flow valve provided according to the present invention, comprising the following steps:

[0024] S1. Connect the packer and the single-flow valve body in the first state to the tubing, with the packer located below the single-flow valve body. After the packer is inserted into the well, it is seated.

[0025] S2. The single-flow valve core with the throttling mechanism is fed into the single-flow valve body and pressurized to put the single-flow valve body into the second state.

[0026] S3. Inject gas into the annulus from the ground into the tubing or between the tubing and casing.

[0027] Compared with the prior art, the advantages of this application are as follows.

[0028] This invention involves running a downhole one-way flow valve and a packer together into the well. The packer is used to seal the annulus below the downhole one-way flow valve. In this way, after gas is injected into the annulus between the downhole one-way flow valve and the casing, the injected gas cannot pass through the packer to enter the formation. Instead, it can only enter the inner cavity of the downhole one-way flow valve through the first guide hole on the downhole one-way flow valve. Then, carrying the accumulated liquid, it moves upward along the tubing, thereby completing the drainage and gas production.

[0029] During normal production, the one-way valve body of this invention is inserted into the well in its first state. At this 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 a throttling mechanism is inserted 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, which can be used to implement production processes. When it is necessary to implement the gas production process provided by this invention, the first guide hole of the one-way valve body is opened by pressurizing the wellhead, and then gas is injected into the annulus between the downhole one-way flow valve and the casing to discharge the fluid accumulated at the bottom of the well. Attached Figure Description

[0030] The invention will now be described with reference to the accompanying drawings.

[0031] Figure 1A schematic diagram showing an embodiment of a downhole one-way flow valve in a first state according to the present invention;

[0032] Figure 2 A schematic diagram of one embodiment of the single-flow valve core according to the present invention is shown;

[0033] Figure 3 A schematic diagram of one embodiment of a single-flow valve body according to the present invention is shown;

[0034] Figure 4 A schematic diagram of an embodiment of the gas extraction process according to the present invention is shown;

[0035] Figure 5 A schematic diagram showing an embodiment of a downhole one-way flow valve in a second state according to the present invention is provided.

[0036] Figure 6 A schematic diagram of the structure of the throttling mechanism of the downhole one-way flow valve according to the present invention after it has been removed from the well is shown.

[0037] In the picture:

[0038] 1. Single-flow valve body; 11. First flow passage; 12. First guide hole; 14. Pin; 15. Inner cylinder; 16. Upper connector; 161. First slot; 162. First cylinder section; 163. Second cylinder section; 17. Lower connector; 171. Protrusion; 172. Third cylinder section; 173. Fourth cylinder section; 174. Fifth guide hole; 18. Annular cavity;

[0039] 2. Single-flow valve core; 21. Second flow passage; 22. Second guide hole; 23. Housing; 231. First positioning step; 232. Fourth slot; 233. Stepped hole; 234. Small-diameter shell; 24. Ball seat; 25. Sealing ball; 26. Baffle plate; 261. Flow hole;

[0040] 4. Shrapnel; 41. Clamping block; 42. Salvage neck; 43. Hook groove;

[0041] 5. Throttling mechanism; 51. Throttling cylinder; 511. Sixth guide hole; 512. Second positioning step; 513. Fifth cylinder section; 514. Sixth cylinder section; 52. Throttling nozzle; 53. Set screw; 54. Fourth retaining ring; 55. Retrieval head; 56. Limiting step;

[0042] 100. Downhole one-way flow valve; 101. Tubing; 102. Packer; 103. Casing.

[0043] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0044] The invention will now be described with reference to the accompanying drawings.

[0045] It should be noted that in this application, the direction of the downhole one-way flow valve according to the present invention after entering the well near the wellhead is described as "up," "forward," or similar terms, i.e. Figure 1 The upper side; the direction away from the wellhead after the downhole one-way flow valve according to the present invention is described as "down", "back" or similar terms, i.e. Figure 1 The lower side.

[0046] Figure 1 The structure of a downhole one-way flow valve 100 according to the present invention is shown. Figure 1 As shown, the downhole one-way flow valve 100 includes a one-way valve body 1 and a one-way valve core 2. When implementing the gas production process provided by the present invention, the one-way valve body 1 is first lowered into the casing 103 in conjunction with a packer, and then the one-way valve core 2 is pumped into the one-way valve body 1. The specific structures of the one-way valve body 1 and the one-way valve core 2 are described below.

[0047] According to the present invention, such as Figure 2 As shown, the one-way valve core 2 is generally cylindrical in shape. The inner cavity of the one-way valve core 2 is the second flow channel 21, which runs through the one-way valve core 2 along its central axis. 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 channel 21; that is, fluid cannot flow downwards through the second flow channel 21 of the one-way valve core 2.

[0048] In one specific embodiment, a second flow guide hole 22 is provided on the side wall of the single-flow valve core 2, and the second flow guide hole 22 connects the second flow passage 21 with the outside of the single-flow valve core 2.

[0049] According to the present invention, such as Figure 3 As shown, the overall structure of the single-flow valve body 1 is roughly cylindrical. The inner cavity of the single-flow valve body 1 is the first flow passage 11, which is installed through the single-flow valve body 1 along the central axis of the single-flow valve body 1.

[0050] In this embodiment, as Figure 3 As shown, the single-flow valve body 1 includes an upper connector 16 and a lower connector 17 that are coaxially fixedly connected. An annular cavity 18 is formed between the parts of the upper connector 16 and the lower connector 17 that are nested together. A first guide hole 12 is provided on the side wall of the upper connector 16. In the first state, an inner cylinder 15 is provided in the annular cavity 18 by means of a pin 14 to block the first guide hole 12.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] In one specific embodiment, the one-way valve core 2 includes a housing 23 and a ball seat 24 disposed on the housing 23. For example... Figure 2 As shown, the inner cavity of the housing 23 is the second flow passage 21, the second guide hole 22 is provided on the side wall of the housing 23, the ball seat 24 is provided at the lower end of the housing 23, and a sealing ball 25 for sealing is provided inside the ball seat 24. The second guide hole 22 is located on the upper side of the ball seat 24. Further, the ball seat 24 is constructed as a conical surface, and the side of the ball seat 24 with a larger diameter faces upward, and the sealing ball 25 is located on the upper side of the ball seat 24. In this configuration, when the fluid flows from top to bottom through the ball seat 24 and the sealing ball 25, the fluid will push the sealing ball 25 downward, thereby blocking the ball seat 24 and 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 will push the sealing ball 25 upward, thereby moving the sealing ball 25 away from the ball seat 24, making the ball seat 24 open, thus enabling the one-way valve core 2 to have the function of allowing fluid to flow only from bottom to top.

[0058] During the work process, such as Figure 4 As shown, firstly, 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. The one-way valve body 1 is connected in series with the tubing 101, and the inner cavity of the tubing 101 is connected to the first flow passage 11 of the one-way valve body 1. The packer 102 is coaxially sleeved on the outside of the tubing 101, and is located behind the one-way valve body 1. After the tubing 101, one-way valve body 1, and packer 102 are connected, they are lowered into the casing 103. Once in place, 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, clearing the inner cavity of the tubing 101, at which point oil and gas extraction can begin.

[0059] A single-flow valve core 2 is inserted from the wellhead and pumped into the single-flow valve body 1 using a fluid pump. Figure 1 As shown, at this time, the one-way valve core 2 is axially fixed to the one-way valve body 1. The central axes of the second guide hole 22, the fifth guide hole 174, and the first guide hole 12 coincide. The ball seat 24 is located below the first guide hole 12. The one-way valve body 1 is still in the first state, that is, the first guide hole 12 is still closed. Continuing to pump pressure, since the one-way valve core 2 does not allow fluid to pass from top to bottom, the pumped pressure can only flow along... Figure 1The direction indicated by the middle arrow passes sequentially through the second guide hole 22, the gap between the outer wall of the shell 23 and the inner wall of the fourth cylinder section 173, and the gap between the end face of the fourth cylinder section 173 and the end face of the first cylinder section 162, to the upper end face of the inner cylinder 15. This causes the inner cylinder 15 to move downward relative to the first guide hole 12, thereby opening the first guide hole 12 and connecting it with the second guide hole 22. Figure 6 As shown. Subsequently, gas continues to be injected into the tubing 101 from the wellhead. The gas flows downward along the tubing 101. The sealing ball 25 and the ball seat 24 prevent the gas entering the casing 23 from flowing downward. Therefore, the gas can only flow through the first guide hole 12 into the annulus between the tubing 101 and the casing 103. The packer 102 blocks the annulus, and the gas cannot continue to flow downward. Thus, the gas can only carry the bottom fluid and flow upward along the annulus between the tubing 101 and the casing 103 until it exits the well, completing the drainage and gas production.

[0060] In another embodiment of the present invention, after the first guide hole 12 is opened, nitrogen, natural gas, or other gases can also be injected from the wellhead into the annulus between the tubing 101 and the casing 103. The gas flows downward along the annulus between the tubing 101 and the casing 103. Figure 4 As shown, since the packer 102 blocks the annulus, the gas cannot continue to flow downwards and will not enter the formation to affect the formation pressure. The gas can only enter the second flow passage 21 of the casing 23 through the first guide hole 12 and the second 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 casing 23 flow upwards. In the process of the gas flowing upwards, the accumulated liquid is carried out along the tubing 101, thus completing the drainage and gas production.

[0061] According to the present invention, in this embodiment, a throttling mechanism 5 is provided inside the housing 23, such as... Figure 1 As shown. By setting the throttling mechanism 5, a throttling effect can be achieved during the conventional gas extraction process.

[0062] During the work process, such as Figure 4As shown, firstly, 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. The one-way valve body 1 is connected in series with the tubing 101, and the inner cavity of the tubing 101 is connected to the first flow passage 11 of the one-way valve body 1. The packer 102 is coaxially sleeved on the outside of the tubing 101, and is located behind the one-way valve body 1. After the tubing 101, one-way valve body 1, and packer 102 are connected, they are lowered into the casing 103. Once in place, 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, clearing the inner cavity of the tubing 101, at which point oil and gas extraction can begin. Then, a single-flow valve core 2 equipped with a throttling mechanism 5 is inserted from the wellhead, and a fluid pump is used to deliver the single-flow valve core 2 into the single-flow valve body 1, such as... Figure 1 As shown, at this time, the single-flow valve core 2 is axially fixed to the single-flow valve body 1, the central axes of the second guide hole 22, the fifth guide hole 174, and the first guide hole 12 coincide, the ball seat 24 is located below the first guide hole 12, and the single-flow valve body 1 is still in the first state, that is, the first guide hole 12 is still in the closed state. At this time, conventional gas extraction operations can be carried out, and the presence of the throttling mechanism 5 can provide a throttling effect for conventional gas extraction operations.

[0063] In one specific embodiment, the throttling mechanism 5 includes a throttling cylinder 51 coaxially disposed within the housing 23, and a throttling nozzle 52 disposed within the throttling cylinder 51, the throttling nozzle 52 being located between the first guide hole 12 and the ball seat 24.

[0064] Furthermore, in this embodiment, the throttle nozzle 52 is disposed on the inner side of the lower end of the throttle cylinder 51. During the assembly process, the throttle nozzle 52 enters the inner cavity of the throttle cylinder 51 axially from bottom to top until the upper end face of the throttle nozzle 52 axially abuts against the inner wall of the throttle cylinder 51. Then, the set screw 53 is screwed into the inner cavity of the throttle cylinder 51 axially from bottom to top through the thread until the upper end face of the set screw 53 abuts against the lower end face of the throttle nozzle 52.

[0065] In one specific embodiment, a second positioning step 512 is provided on the outer wall of the throttle cylinder 51, and a first positioning step 231 for fitting the second positioning step 512 is provided on the inner wall of the housing 23. The first positioning step 231 is located below the second guide hole 22. During assembly, the throttle cylinder 51 enters the housing 23 axially from top to bottom until the second positioning step 512 of the throttle cylinder 51 axially abuts against the first positioning step 231 of the housing 23.

[0066] According to the present invention, a sixth guide hole 511 is provided on the side wall of the throttling cylinder 51, and the sixth guide hole 511 connects the inner cavity of the throttling cylinder 51 with the outside. After the throttling cylinder 51 is assembled into the housing 23, the central axes of the sixth guide hole 511 and the second guide hole 22 coincide.

[0067] In a specific embodiment, such as Figure 2 As shown, a stepped hole 233 is provided on the inner wall of the housing 23 corresponding to the second guide hole 22. Further, the stepped hole 233 is an annular groove provided on the inner wall of the housing 23.

[0068] In one specific embodiment, a small-diameter shell 234 is coaxially fixed at the upper end of the shell 23. The inner diameter of the small-diameter shell 234 is equal to the inner diameter of the shell 23, and the outer diameter of the small-diameter shell 234 is smaller than the outer diameter of the shell 23. A fourth slot 232 is provided on the inner wall of the small-diameter shell 234.

[0069] A fourth retaining ring 54 is provided on the outer wall of the throttle cylinder 51. When the second positioning step 512 of the throttle cylinder 51 axially abuts against the first positioning step 231 of the housing 23, the fourth retaining ring 54 of the throttle cylinder 51 is engaged in the fourth retaining groove 232 of the small diameter housing 234, thereby fixing the throttle cylinder 51 in the housing 23.

[0070] In a preferred embodiment, 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 spring 54. The outer diameter of the fourth retaining spring 54 is larger than the outer diameter of the retrieval head 55, thereby forming a limiting step 56 between the fourth retaining spring 54 and the retrieval head 55. The limiting step 56 can axially abut against the fourth retaining groove 232, thereby preventing the fourth retaining spring 54 from moving upward relative to the fourth retaining groove 232 and disengaging therefrom. The fourth retaining spring 54 and the retrieval head 55 are located at the connection between the fifth cylinder section 513 and the sixth cylinder section 514. When it is necessary to remove the throttling mechanism 5 from the single-flow valve core 2, the retrieval tool can extend from top to bottom between the sixth cylindrical section 514 and the housing 23, thereby adapting to the retrieval head 55, fitting around the outside of the retrieval head 55, and engaging the retrieval head. At the same time, it can also radially press the retrieval head 55 inward, thereby causing the fourth retaining spring 54 to radially retract and disengage from the fourth retaining groove 232. Afterward, the retrieval tool is lifted, and the retrieval tool can then remove the entire throttling mechanism 5 from the single-flow valve core 2 through the retrieval head 55.

[0071] In a preferred embodiment, a baffle plate 26 is provided inside the housing 23. The distance between the baffle plate 26 and the ball seat 24 is sufficient to accommodate the sealing ball 25, and allows the sealing ball 25 a certain amount of axial movement space, enabling the sealing ball 25 to move upward away from the ball seat 24, thereby allowing the fluid below to move upward through the ball seat 24. By providing the baffle plate 26, the sealing ball 25 can be confined to the vicinity of the ball seat 24.

[0072] In one specific embodiment, the ball seat 24 is screwed into the housing 23 from bottom to top by a threaded connection, and the upper and lower end faces of the ball baffle 26 axially abut against the housing 23 and the ball seat 24 respectively, and the ball baffle 26 is fixed in the housing 23 by the ball seat 24.

[0073] In one specific embodiment, the pin 14 is disposed on the lower side of the first guide hole 12.

[0074] In one specific embodiment, a protrusion 171 is provided on the inner wall of the lower connector 17, allowing the one-way valve core 2 to extend into the interior of the lower connector 17, such as... Figure 1 As shown, after the single-flow valve core 2 extends into the interior of the lower connector 17, the ball seat 24 of the single-flow valve core 2 can axially abut against the protrusion 171 of the lower connector 17, thereby achieving axial positioning of the first guide hole 12 and the second guide hole 22.

[0075] According to the present invention, such as Figure 2 and Figure 3 As shown, a first slot 161 is provided on the inner wall of the upper connector 16, and a spring piece 4 is fixedly provided on the upper end of the single-flow valve core 2. A locking block 41 for engaging with the first slot 161 is provided on the spring piece 4. The spring piece 4 is elastic and can apply a radially outward preload force to the locking block 41. Figure 1 As shown, the locking block 41 of the spring piece 4 is engaged in the first locking groove 161 of the upper connector 16, restricting the relative axial movement of the single-flow valve core 2 and the single-flow valve body 1.

[0076] According to the present invention, a retrieval neck 42 for adapting to a retrieval tool is provided above the locking block 41. Further, the retrieval neck 42 is located at the uppermost end of the spring piece 4, and is configured such that its outer diameter gradually increases from top to bottom. With this configuration, when the locking block 41 is engaged in the first locking groove 161, a gap exists between the upper end of the retrieval neck 42 and the inner wall of the upper connector 16, allowing the retrieval tool to be inserted. When the single-flow valve core 2 needs to be removed later, the retrieval tool is lowered into the oil pipe 101. During its downward movement, the retrieval tool inserts into the gap between the retrieval neck 42 and the upper connector 16, causing the spring piece 4 to radially contract, thereby causing the locking block 41 to radially contract and disengage from the first locking groove 161.

[0077] Furthermore, a hook groove 43 is provided between the retrieval neck 42 and the locking block 41. After the retrieval tool is inserted to the outside of the retrieval neck 42, it continues to move to the right and eventually engages with the hook groove 43. This allows the retrieval tool to move together with the spring 4 and the single-flow valve core 2 during the process of pulling the retrieval tool out of the well, thus retrieving the single-flow valve core 2 from the well.

[0078] In one specific embodiment, the lower end of the spring piece 4 is fixedly connected to the housing 23, and the upper end of the spring piece 4 is spaced out on the outside of the small-diameter housing 234. That is, there is a gap between the inner wall of the upper end of the spring piece 4 and the outer wall of the small-diameter housing 234, thereby providing space for the spring piece 4 to retract radially.

[0079] According to the present invention, a 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 1 The arrows indicate that the flow is transmitted sequentially through the sixth guide hole 511, the second guide hole 22, the gap between the outer wall of the housing 23 and the inner wall of the fourth cylindrical section 173, and the gap between the end face of the fourth cylindrical section 173 and the end face of the first cylindrical section 162 to the upper end face of the inner cylinder 15. This causes the inner cylinder 15 to shear the pin 14 and move downward relative to the first guide hole 12, thereby opening the first guide hole 12 and connecting it with the second guide hole 22. At the same time, the locking block 41 on the spring plate 4 and the first locking groove 161 of the upper connector 16 work together to restrict the movement of the single-flow valve core 2 and the single-flow valve body 1.

[0083] During normal production, the formation capacity is sufficient. Under the action of formation pressure, the sealing ball 25 leaves the ball seat 24. Formation gas or liquid passes through the lower connector 17, the ball seat 24, the flow hole 261 on the ball baffle plate 26, the top screw 53, the throttle nozzle 52, and the inner cavity of the throttle cylinder 51 in sequence, and finally flows out of the well along the tubing 101.

[0084] S3. When the fluid accumulation at the bottom of the well increases and the formation energy is insufficient to carry the fluid in the casing 103 to the surface, affecting the production efficiency, use a retrieval tool to remove the throttling mechanism 5 from the single-flow valve core 2 and remove it from the well. Then, inject gas into the annulus between the tubing 101 and the casing 103 from the surface.

[0085] Specifically, gases such as nitrogen and natural gas flow from the wellhead along the annulus between the tubing 101 and the casing 103 towards the bottom of the well. They enter the inner cavity (second flow channel 21) of the casing 23 through the first guide hole 12, the fifth guide hole 174, and the second guide hole 22 of the downhole one-way flow valve 100, and drive the accumulated liquid in the second flow channel 21 upward along the tubing 101 and out of the wellhead, thereby reducing the pressure of the liquid column inside the tubing 101 and achieving the purpose of low-pressure production.

[0086] In another embodiment provided by the present invention, in step S3, when the fluid accumulation at the bottom of the well increases and the formation energy is insufficient to carry the fluid in the casing 103 to the surface and affect the production efficiency, a retrieval tool is used to remove the throttling mechanism 5 from the single-flow valve core 2 and remove it from the well, and then gas is injected into the tubing 101 from the surface.

[0087] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0088] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0089] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0090] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

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. A spring (4) is disposed on the one-way valve core (2), the spring (4) being configured to be fixedly connected to the one-way valve body (1); and A throttling mechanism (5) is disposed within the housing (23).

2. The downhole one-way flow valve according to claim 1, characterized in that, A locking block (41) is provided on the spring piece (4), and a first locking groove (161) for engaging with the locking block (41) is provided on the inner wall of the single-flow valve body (1).

3. The one-way valve according to claim 2, characterized in that, A retrieval neck (42) is provided above the locking block (41) for use with a retrieval tool. The retrieval tool is configured to fit over the outside of the retrieval neck (42) and press the retrieval neck (42) radially inward, thereby causing the locking block (41) to retract radially and disengage from the first locking groove (161).

4. The downhole one-way flow valve according to claim 3, characterized in that, A small-diameter shell (234) is coaxially disposed at the upper end of the housing (23). The outer diameter of the small-diameter shell (234) is smaller than the outer diameter of the housing (23). The spring piece (4) is disposed at the upper end of the housing (23) and is located on the outside of the small-diameter shell (234) in a spaced manner.

5. The downhole one-way flow valve according to any one of claims 1 to 4, 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).

6. The downhole one-way flow valve according to claim 5, 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).

7. The downhole one-way flow valve according to claim 6, 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).

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 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 gas into the annulus from the ground into the tubing or between the tubing and casing.

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