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 a one-way flow valve and a drainage gas production process. The one-way flow valve comprises a one-way valve body, a first flow passing channel is arranged along the central axis of the one-way valve body, and a first flow guide hole is formed in the side wall of the one-way valve body; a second flow passage is arranged along the central axis of the check valve core, the check valve core is configured to allow the fluid to flow unidirectionally from bottom to top, and a second flow guide hole is formed in the side wall of the check valve core; the throttling mechanism is arranged in the check valve element, and the throttling mechanism can be taken out from the check valve element; the elastic sheet is arranged at the upper end part of the check valve core; in the first state, the first flow guide hole of the check valve body is in a closed state, and in the second state, the check valve element is arranged in the first flow passing channel of the check valve body in a sealed and sleeved mode and opens the first flow guide hole, so that the first flow guide hole is communicated with the second flow guide hole.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, specifically relating to a one-way flow valve and a drainage 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 drainage gas extraction process and a corresponding one-way flow valve. Summary of the Invention

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

[0006] The present invention also proposes a drainage 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 one-way flow valve is provided, comprising:

[0008] A single-flow valve body is provided with a first flow passage along the central axis of the single-flow valve body, and a first flow guide hole is provided on the side wall of the single-flow valve body;

[0009] A one-way valve core is provided with a second flow passage along the central axis of the one-way valve core. The one-way valve core is configured to allow fluid to flow unidirectionally from bottom to top. A second flow guide hole is provided on the side wall of the one-way valve core.

[0010] A throttling mechanism disposed within the one-way valve core, the throttling mechanism being configured to be removable from the one-way valve core; and

[0011] A spring sheet is provided at the upper end of the single-flow valve core, and a locking block is provided on the spring sheet. A first slot for engaging with the locking block is provided on the inner wall of the single-flow valve body.

[0012] In the first state, the first flow guide orifice of the single-flow valve body is closed.

[0013] In the second state, the single-flow valve core is sealed and fitted inside the first flow passage of the single-flow valve body, and the first flow guide hole is opened to connect the first flow guide hole with the second flow guide hole. The locking block is engaged in the first slot, thereby fixing the single-flow valve body and the single-flow valve core.

[0014] 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.

[0015] 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.

[0016] In one specific embodiment, the throttling mechanism includes a throttling cylinder coaxially disposed within the single-flow valve core, and a throttling nozzle disposed within the throttling cylinder, the throttling nozzle being located between the first guide hole and the ball seat.

[0017] 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 single-flow valve core.

[0018] In one specific embodiment, the single-flow valve core includes a housing and a ball seat disposed on the housing. A sealing ball for sealing is disposed inside the ball seat. A second flow guide hole is disposed on the side wall of the housing and is located above the ball seat. The throttling mechanism is coaxially and sealed inside the housing and is located above the ball seat.

[0019] In one specific embodiment, a ball baffle is provided inside the housing, the ball baffle is located between the ball seat and the throttling mechanism, and an axial flow hole is provided on the ball baffle.

[0020] In one specific embodiment, the one-way valve body includes:

[0021] The outer cylinder, wherein the first flow guide hole is disposed on the side wall of the outer cylinder; and

[0022] The inner cylinder is fixed inside the outer cylinder by pins;

[0023] In the first state, the inner cylinder seals the first guide hole.

[0024] In the second state, the single-flow valve core pushes the inner cylinder downward relative to the outer cylinder, and connects the first guide hole with the second guide hole.

[0025] In one specific embodiment, a second retaining groove is provided on the inner wall of the outer cylinder, and a second retaining spring is provided on the outer wall of the inner cylinder. In the second state, the second retaining spring is engaged in the second retaining groove.

[0026] According to the present invention, a drainage gas extraction process is also provided, using a one-way flow valve provided according to the present invention, comprising the following steps:

[0027] 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.

[0028] 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.

[0029] S3. Remove the throttling mechanism from the flow valve core and inject gas into the flow valve body or the annulus between the flow valve body and the sleeve from the ground.

[0030] Compared with the prior art, the advantages of this application are as follows.

[0031] 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.

[0032] 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 drainage and 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

[0033] The invention will now be described with reference to the accompanying drawings.

[0034] Figure 1 A schematic diagram showing an embodiment of a one-way flow valve in a first state according to the present invention is provided.

[0035] Figure 2 A schematic diagram of one embodiment of the single-flow valve core according to the present invention is shown;

[0036] Figure 3 A schematic diagram of one embodiment of a single-flow valve body according to the present invention is shown;

[0037] Figure 4 A schematic diagram of an embodiment of the drainage gas extraction process according to the present invention is shown;

[0038] Figure 5 A schematic diagram showing an embodiment of a one-way flow valve in a second state according to the present invention is provided.

[0039] Figure 6 A schematic diagram of the throttling mechanism of the one-way flow valve according to the present invention after it has been removed from the well is shown.

[0040] In the picture:

[0041] 1. Single-flow valve body; 11. First flow passage; 12. First guide hole; 13. Outer cylinder; 131. Second slot; 14. Pin; 15. Inner cylinder; 151. Second snap ring; 152. Step; 16. Upper connector; 161. First slot; 17. Lower connector;

[0042] 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;

[0043] 4. Shrapnel; 41. Clamping block; 42. Salvage neck; 43. Hook groove;

[0044] 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;

[0045] 100. One-way flow valve; 101. Oil pipe; 102. Packer; 103. Casing.

[0046] 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

[0047] The invention will now be described with reference to the accompanying drawings.

[0048] It should be noted that in this application, the direction of the 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 one-way flow valve according to the invention is introduced into the well is described as "down", "back" or similar terms, i.e. Figure 1 The lower side.

[0049] Figure 1 The structure of a one-way flow valve 100 according to the present invention is shown. Figure 1 As shown, the one-way flow valve 100 includes a one-way valve body 1 and a one-way valve core 2. When implementing the drainage and gas extraction process provided by the present invention, the one-way valve body 1 is first lowered into the casing 103 in conjunction with the 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 will be described below.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] A first guide hole 12 is provided on the side wall of the one-way valve body 1. In the first state, the first guide hole 12 of the one-way valve body 1 is closed, and the fluid in the first flow channel 11 cannot exchange fluid with the outside of the one-way valve body 1 through the first guide hole 12. In the second state, such as Figure 5As shown, the single-flow valve core 2 is sealed inside the first flow passage 11 of the single-flow valve body 1 and opens the first guide hole 12. The first guide hole 12 of the single-flow valve core 2 is connected to the second guide hole 22. At this time, the fluid outside the single-flow valve body 1 can exchange with the fluid in the second flow passage 21 through the first guide hole 12 and the second guide hole 22.

[0054] 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.

[0055] During the work process, such as Figure 4 As shown, firstly, the packer 102 and the one-way flow valve 100 in its first state are connected to the tubing 101. The one-way valve 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 1. The packer 102 is coaxially sleeved on the outside of the tubing 101, and is located behind the one-way valve 1. After the tubing 101, one-way valve 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 for oil and gas extraction.

[0056] When there is excessive fluid accumulation at the bottom of the well and the formation energy is low, making it impossible to carry the fluid from the casing to the surface, a single-flow valve core 2 is inserted from the wellhead. A fluid pump is then used to deliver the single-flow valve core 2 into the single-flow valve body 1. Figure 1 As shown, at this time, the one-way valve body 1 is still in the first state, that is, the first guide hole 12 is still in the closed state. Continue pumping the one-way valve core 2, causing the one-way valve core 2 to move downwards relative to the one-way valve body 1, thereby opening the first guide hole 12 and connecting the first guide hole 12 with the second guide hole 22, as shown. Figure 5 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.

[0057] 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.

[0058] According to the present invention, in this embodiment, the throttling mechanism 5 within the housing 23, such as Figure 1 and Figure 2 As shown. By setting the throttling mechanism 5, a throttling effect can be achieved during the conventional gas extraction process.

[0059] 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. 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 5As shown, at this time, the single-flow valve core 2 is axially fixed to the single-flow valve body 1, the first guide hole 12 is opened, the central axis of the second guide hole 22 coincides with that of the first guide hole 12, and the ball seat 24 is located below the first guide hole 12. 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] In one specific embodiment, 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 (or the retrieval neck 42). 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 housing 23, thereby fixing the throttle cylinder 51 inside the housing 23.

[0067] 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. Simultaneously, it can radially press the retrieval head 55 inward, causing the fourth retaining spring 54 to radially retract and disengage from the fourth retaining groove 232. Afterward, by lifting the retrieval tool, the entire throttling mechanism 5 can be removed from the single-flow valve core 2 through the retrieval head 55. Figure 6 As shown.

[0068] 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.

[0069] Furthermore, at least one axially penetrating flow hole 261 is provided on the ball baffle 26 to allow fluid to flow.

[0070] In a specific embodiment, such as Figure 3As shown, the one-way valve body 1 includes an outer cylinder 13 and an inner cylinder 15 coaxially sleeved within the outer cylinder 13. Both the outer cylinder 13 and the inner cylinder 15 are generally cylindrical in shape, and a first flow guide hole 12 is provided on the side wall of the outer cylinder 13. In a first state, the inner cylinder 15 is fixed inside the outer cylinder 13 by a pin 14, sealing the first flow guide hole 12. In a second state, the one-way valve core 2 can push the inner cylinder 15 downward relative to the outer cylinder 13, opening the first flow guide hole 12 and connecting it with the second flow guide hole 22 of the one-way valve core 2.

[0071] In one specific embodiment, the pin 14 is disposed on the lower side of the first guide hole 12.

[0072] Specifically, the single-flow valve core 2 can be fitted inside the inner cylinder 15, and a step 152 is provided on the inner wall of the inner cylinder 15. For example... Figure 1 As shown, after the one-way valve core 2 extends into the inner cylinder 15, the ball seat 24 of the one-way valve core 2 can axially abut against the step 152 of the inner cylinder 15. Figure 5 As shown, in Figure 1 On this basis, the single-flow valve core 2 is pumped, and the single-flow valve core 2 axially abuts against the step 152 of the inner cylinder 15, thereby pushing the inner cylinder 15 to move downward relative to the outer cylinder 13, and finally opening the first guide hole 12 and connecting the first guide hole 12 with the second guide hole 22.

[0073] In a preferred embodiment, a second retaining groove 131 is provided on the inner wall of the outer cylinder 13, and a second retaining spring 151 is provided on the outer wall of the inner cylinder 15. In a first state, the second retaining spring 151 is located above the second retaining groove 131. In a second state, after the inner cylinder 15 moves downward relative to the outer cylinder 13 to open the first guide hole 12, the second retaining spring 151 engages in the second retaining groove 131. By providing the second retaining spring 151 and the second retaining groove 131, the inner cylinder 15 can be prevented from resetting.

[0074] Preferably, the second snap ring 151 is located below the pin 14, thereby preventing the second snap ring 151 from interfering with the pin 14.

[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 lower connector 17 is provided at the lower end of the outer cylinder 13 by means of a threaded connection, and the upper end of the lower connector 17 extends into the interior of the outer cylinder 13.

[0080] According to the present invention, a drainage gas extraction process is also provided, comprising the following steps:

[0081] S1, such as Figure 4 As shown, the packer 102 and the one-way flow valve 100 in its first state are connected to the tubing 101 to form a tubing string. The one-way flow valve 1 remains axially unobstructed and is connected in series with the tubing 101. The packer 102 is located below the one-way flow valve 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.

[0082] 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.

[0083] Specifically, a flow valve core 2 is inserted from the wellhead, and a liquid or gas pump is used to deliver the flow valve core 2 to the flow valve body 1, such as... Figure 1As shown, the ball seat 24 is brought into axial contact with the step 152 of the inner cylinder 15. Continued pressurization at the wellhead provides a downward thrust to the single-flow valve core 2, shearing off the pin 14, as... Figure 5 As shown, the inner cylinder 15 and the one-way valve core 2 move downwards together until the lower end face of the inner cylinder 15 abuts against the upper end face of the lower connector 17, thereby opening the first guide hole 12 and connecting the first guide hole 12 with the second guide hole 22. At this time, the second snap ring 151 springs open and engages in the second slot 131, preventing the inner cylinder 15 from moving relative to the outer cylinder 13, thus preventing the inner cylinder 15 from resetting. At the same time, the locking block 41 on the spring piece 4 and the first slot 161 of the upper connector 16 work together to restrict the movement of the one-way valve core 2 relative to the one-way valve body 1.

[0084] 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, ball seat 24, and throttling mechanism 5 in sequence, and finally flows out of the well along the tubing 101.

[0085] 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 extraction efficiency, gas is injected from the surface into the annulus between the tubing 101 and the casing 103.

[0086] Specifically, firstly, the throttling mechanism 5 is removed from the one-way valve core 2 using a fishing tool. Then, 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 one-way flow valve 100 through the first guide hole 12 and the second guide hole 22, and drive the accumulated liquid in the one-way flow valve 100 upward along the tubing 101 and out of the tubing 101, thereby reducing the liquid column pressure inside the tubing 101 and achieving the purpose of low-pressure production.

[0087] In another embodiment provided by the present invention, in step S3, when the bottom fluid 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. Then, gas is injected from the surface into the tubing 101, and finally the bottom fluid is discharged from the annulus between the tubing 101 and the casing 103.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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 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). A single-flow valve core (2) is provided with a second flow passage (21) along the central axis of the single-flow valve core (2). The single-flow valve core (2) is configured to allow fluid to flow unidirectionally from bottom to top. A second flow guide hole (22) is provided on the side wall of the single-flow valve core (2). A throttling mechanism (5) disposed within the single-flow valve core (2), the throttling mechanism (5) being configured to be removable from the single-flow valve core (2); and A spring plate (4) is provided at the upper end of the single-flow valve core (2), and a locking block (41) is provided on the spring plate (4). 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). In the first state, the first guide hole (12) of the single-flow valve body (1) is in the closed state. In the second state, the single-flow valve core (2) is sealed in the first flow passage (11) of the single-flow valve body (1) and the first flow guide hole (12) is opened, so that the first flow guide hole (12) communicates with the second flow guide hole (22). The locking block (41) is locked in the first locking groove (161), thereby fixing the single-flow valve body (1) and the single-flow valve core (2).

2. The one-way flow valve according to claim 1, 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).

3. The one-way flow valve according to claim 2, 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.

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

5. The one-way flow valve according to claim 4, 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 single-flow valve core (2).

6. The one-way flow valve according to claim 5, characterized in that, The single-flow valve core (2) includes a housing (23) and a ball seat (24) disposed on the housing (23). A sealing ball (25) for sealing is disposed in the ball seat (24). The second flow guide hole (22) is disposed on the side wall of the housing (23) and is located above the ball seat (24). The throttling mechanism (5) is coaxially and sealed in the housing (23) and is located above the ball seat (24).

7. The one-way flow valve according to claim 6, characterized in that, A ball baffle (26) is provided inside the housing (23). The ball baffle (26) is located between the ball seat (24) and the throttling mechanism (5). An overflow hole (261) is provided on the ball baffle (26) along the axial direction.

8. The one-way flow valve according to any one of claims 1 to 7, characterized in that, The single-flow valve body (1) includes: The outer cylinder (13), wherein the first guide hole (12) is disposed on the side wall of the outer cylinder (13); and The inner cylinder (15) is fixed inside the outer cylinder (13) by a pin (14); In the first state, the inner cylinder (15) seals the first guide hole (12). In the second state, the single-flow valve core (2) pushes the inner cylinder (15) down relative to the outer cylinder (13) and connects the first guide hole (12) with the second guide hole (22).

9. The one-way flow valve according to claim 8, characterized in that, A second slot (131) is provided on the inner wall of the outer cylinder (13), and a second retaining spring (151) is provided on the outer wall of the inner cylinder (15). In the second state, the second retaining spring (151) is engaged in the second slot (131).

10. A drainage gas extraction process, characterized in that, Using the 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. Remove the throttling mechanism (5) from the single-flow valve core (2) and inject air into the annulus between the single-flow valve body (1) or the sleeve from the ground.

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