Underground one-way flow valve and gas lift process

Abstract

The invention belongs to the technical field of oil and gas exploitation, and particularly relates to an underground one-way flow valve and a gas lift process. The underground one-way flow valve comprises a check valve body, a first flow passing channel is arranged along the central axis of the check valve body, the check valve body comprises an upper connector and a lower connector which are coaxially and fixedly connected, an annular cavity is formed between the parts, sleeved with each other, of the upper connector and the lower connector, a first flow guide hole is formed in the side wall of the upper connector, and in the first state, the annular cavity is communicated with the first flow guide hole; an inner cylinder for blocking the first flow guide hole is arranged in the annular cavity through a pin, and the inner cylinder is constructed to be capable of opening the first flow guide hole after being pressed; and in the second state, the check valve element is provided with a second flow passing channel along the central axis of the check valve element, the check valve element is constructed to allow fluid to flow from right to left in a one-way mode, 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, so that pressure can be transmitted to the inner barrel.

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 lift 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 lift process 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 lift process provided by this invention, thereby improving gas lift efficiency.

[0006] The present invention also proposes a gas lift 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. The single-flow valve body includes an upper connector and a lower connector that are coaxially fixedly connected. An annular cavity is formed between the parts of the upper connector and the lower connector that are nested together. A first flow guide hole is provided on the side wall of the upper connector. In a first state, an inner cylinder is provided in the annular cavity by means of a pin to block the first flow guide hole. The inner cylinder is configured to open the first flow guide hole when it is pressurized.

[0009] The one-way valve core has a second flow passage along its central axis. The one-way valve core is configured to allow fluid to flow unidirectionally from right to left. In the second state, the one-way valve core is sealed within the first flow passage of the one-way valve body, thereby enabling pressure to be transmitted to the inner cylinder.

[0010] In one specific embodiment, the fixing mechanism includes a first retaining ring coaxially disposed on the outer wall of the one-way valve core, and a first retaining groove disposed on the inner wall of the one-way valve body. In the second state, the first retaining ring is engaged in the first retaining groove.

[0011] In one specific embodiment, a retraction tooth is provided at the left end of the first retaining spring, and the outer diameter of the retraction tooth gradually increases from left to right. A release sleeve is provided on the outside of the single-flow valve core via a shear pin. In the release state, the release sleeve cuts the shear pin and moves to the right, radially and inwardly squeezing the retraction tooth, thereby causing the first retaining spring to retract and thus disengage the first retaining spring from the first retaining groove.

[0012] In one specific embodiment, a nozzle is coaxially arranged in the second flow channel, a third guide hole is provided in the nozzle, a second guide hole is provided on the side wall of the single-flow valve core, the two ends of the third guide hole respectively connect the second guide hole and the left end of the nozzle, and a fourth guide hole is provided in the nozzle, the fourth guide hole connecting the left and right ends of the nozzle.

[0013] In one specific embodiment, the third guide hole includes a first hole section disposed axially within the nozzle and a second hole section disposed radially within the nozzle, wherein the left end of the first hole section penetrates the nozzle and the right end of the first hole section connects to the second hole section;

[0014] Multiple fourth guide holes are uniformly arranged circumferentially inside the nozzle.

[0015] 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 to the left of the ball seat. The nozzle is coaxially and sealed inside the housing and is located to the left of the ball seat.

[0016] In one specific embodiment, the left end of the nozzle is configured as a conical surface, and the inner wall of the housing is configured as a conical surface adapted to the nozzle.

[0017] In one specific embodiment, the upper connector includes a first cylindrical section and a second cylindrical section fixed coaxially, the inner diameter of the second cylindrical section being larger than the inner diameter of the first cylindrical section, and the first guide hole being disposed on the second cylindrical section. The lower connector includes a third cylindrical section and a fourth cylindrical section fixed coaxially, the outer diameter of the fourth cylindrical section being smaller than the outer diameter of the third cylindrical section, and the second cylindrical section being 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.

[0018] In one specific embodiment, the inner cylinder's right end is sealed to the fourth cylinder section and the second cylinder section on its inner and outer sides, respectively, and the inner cylinder's left end is connected to the first flow channel, thereby making the pressure-bearing surface of the inner cylinder's left end larger than that of its right end.

[0019] According to the present invention, a gas lift process is also provided, using a downhole one-way flow valve provided according to the present invention, comprising the following steps:

[0020] S1. Connect the packer and the single-flow valve body in the first state to the tubing. The packer is located to the right of the single-flow valve body. After the packer is inserted into the well, it is seated.

[0021] S2. The single-flow valve core is sent into the single-flow valve body and pressurized, so that the single-flow valve body is in the second state;

[0022] S3. Inject air into the annular space between the single-flow valve body and the sleeve from the ground.

[0023] Compared with the prior art, the advantages of this application are as follows.

[0024] 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 to the right of 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 enter the formation to the right through the packer. Instead, it can only enter the inner cavity of the downhole one-way flow valve through the first and second guide holes 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.

[0025] In its first state, the one-way valve body of this invention is inserted into the well, where it functions as a section of conventional tubing and can be used for conventional downhole processes. After the one-way valve core is inserted into the one-way valve body, it only allows fluid to flow from the bottom of the well to the wellhead, and can be used for production processes. When the gas lift process provided by this invention needs to be implemented, 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.

[0026] Furthermore, the nozzle of the downhole one-way flow valve of the present invention can generate negative pressure when the injected gas flows upward, which will create a suction effect on the formation fluid, thereby bringing out as much fluid as possible from the right side of the downhole one-way flow valve, reducing the resistance of the accumulated liquid to the natural gas in the formation, and thus maximizing the release of production capacity. Attached Figure Description

[0027] The invention will now be described with reference to the accompanying drawings.

[0028] Figure 1A schematic diagram showing an embodiment of a downhole one-way flow valve in a first state according to the present invention is provided.

[0029] Figure 2 A schematic diagram of one embodiment of the single-flow valve core according to the present invention is shown;

[0030] Figure 3 The invention is shown Figure 2 Schematic diagram of the AA section;

[0031] Figure 4 The invention is shown Figure 2 Schematic diagram of the BB cross section;

[0032] Figure 5 A schematic diagram of one embodiment of a single-flow valve body according to the present invention is shown;

[0033] Figure 6 A schematic diagram of an embodiment of the air lift process according to the present invention is shown;

[0034] Figure 7 A schematic diagram of an embodiment of a downhole one-way flow valve according to the present invention is shown in its second state.

[0035] In the picture:

[0036] 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;

[0037] 2. Single-flow valve core; 21. Second flow passage; 22. Second flow guide hole; 23. Housing; 24. Ball seat; 25. Sealing ball;

[0038] 3. Nozzle; 31. Third guide hole; 311. First orifice section; 312. Second orifice section; 32. Fourth guide hole; 33. Tip;

[0039] 4. Fixing mechanism; 41. First retaining ring; 42. Retrieval neck; 421. Boss; 43. Disposal device; 431. Abutment; 44. Scissors pin; 45. Retraction tooth;

[0040] 100. Downhole one-way flow valve; 101. Tubing; 102. Packer; 103. Casing.

[0041] 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

[0042] The invention will now be described with reference to the accompanying drawings.

[0043] 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 "left", "front" or similar terms, that is... Figure 2 and Figure 5 The left side; the direction away from the wellhead after the downhole one-way flow valve according to the present invention is described as "right", "back" or similar terms, i.e. Figure 2 and Figure 5 On the right side.

[0044] 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 lift 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.

[0045] 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 right to left through the second flow channel 21; that is, fluid cannot flow from left to right through the second flow channel 21 of the one-way valve core 2.

[0046] 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.

[0047] According to the present invention, such as Figure 5 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.

[0048] In this embodiment, as Figure 5 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.

[0049] Specifically, the upper connector 16 includes a first cylindrical section 162 and a second cylindrical section 163 coaxially fixed. The first cylindrical section 162 is located on the left 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.

[0050] 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 to the right of 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.

[0051] 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 right end of the second cylindrical section 163 is provided with internal thread, and the right 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.

[0052] In one embodiment of the present invention, after the second cylindrical section 163 and the fourth cylindrical section 173 are fixedly connected, the left end face of the fourth cylindrical section 173 is located to the right of 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 right 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, and the pressure on the left end face of the inner cylinder 15 is greater than the pressure on the right end face, thereby causing the inner cylinder 15 to move to the right, opening the first guide hole 12, and enabling the first guide hole 12 to communicate with the first flow channel 11.

[0053] 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.

[0054] In a preferred embodiment, to make the inner cylinder 15 more securely installed, such as Figure 5 As shown, in this embodiment, the left end face of the fourth cylindrical section 173 extends to the left side of the first guide hole 12, so that both the left and right 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 to the right 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.

[0055] 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 channel 21, the second flow guide hole 22 is disposed on the side wall of the housing 23, the ball seat 24 is disposed at the right end of the housing 23, and a sealing ball 25 for sealing is disposed inside the ball seat 24. The second flow guide hole 22 is located on the left 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 to the left, and the sealing ball 25 is located on the left side of the ball seat 24. In this configuration, when fluid flows from left to right through the ball seat 24 and the sealing ball 25, the fluid pushes the sealing ball 25 to the right, thereby blocking the ball seat 24 and preventing the fluid from flowing from left to right through the ball seat 24. When fluid flows from right to left through the ball seat 24 and the sealing ball 25, the fluid pushes the sealing ball 25 to the left, thereby moving the sealing ball 25 away from the ball seat 24 and keeping the ball seat 24 in the open state. This allows the one-way valve core 2 to have the function of allowing fluid to flow unidirectionally from right to left.

[0056] During the work process, such as Figure 6 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.

[0057] 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 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 to the right of 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 left to right, 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 left end face of the inner cylinder 15. This causes the inner cylinder 15 to move to the right relative to the first guide hole 12, thereby opening the first guide hole 12 and connecting it with the second guide hole 22. Figure 7 As shown. Subsequently, nitrogen, natural gas, and other gases are injected from the wellhead into the annulus between tubing 101 and casing 103. The gases flow downwards along the annulus between tubing 101 and casing 103, as... Figure 6 As shown, since the packer 102 blocks the annulus, the gas cannot continue to flow to the right 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 right end of the second flow passage 21 make the gas entering the casing 23 flow only to the left. In the process of the gas flowing to the left, the accumulated liquid is carried out along the tubing 101, thus completing the drainage and gas production.

[0058] In a preferred embodiment, a nozzle 3 is provided in the housing 23. For example... Figure 2 As shown, the nozzle 3 is coaxially fixed in the second flow channel 21 of the housing 23, and the nozzle 3 is located above the ball seat 24.

[0059] A third guide hole 31 and a fourth guide hole 32 are provided inside the nozzle 3. The two ends of the third guide hole 31 connect the second guide hole 22 on the housing 23 and the upper end of the nozzle 3, respectively, while the fourth guide hole 32 connects the upper and lower ends of the nozzle 3.

[0060] In one specific embodiment, the third guide hole 31 includes a first orifice section 311 disposed axially within the nozzle 3 and a second orifice section 312 disposed radially within the nozzle 3. For example... Figure 3 As shown, in this embodiment, the left end of the first orifice 311 penetrates the nozzle 3, while the right end of the first orifice 311 does not penetrate the nozzle 3, and the right end of the first orifice 311 connects to the second orifice 312. In this embodiment, four second orifice 312s are provided, and correspondingly, four second guide holes 22 are also provided on the housing 23. The four second orifice 312s are arranged in a radiating pattern inside the nozzle 3, and one end of each of the four second orifice 312s converges on the central axis of the nozzle 3 and connects to the right end of the first orifice 311. The other ends of the four second orifice 312s are respectively connected to their corresponding second guide holes 22.

[0061] In one specific embodiment, a plurality of fourth guide holes 32 are uniformly arranged circumferentially within the nozzle 3. For example... Figure 4As shown, this embodiment is provided with four fourth guide holes 32. The four fourth guide holes 32 are evenly arranged in the nozzle 3 along the circumference and do not intersect with the second hole segment 312.

[0062] After setting nozzle 3, the air lift process provided by this invention is implemented. Figure 6 When injecting gas into the annulus between tubing 101 and casing 103, combine Figure 7 The gas enters the third guide hole 31 through the first guide hole 12 and the second guide hole 22. Guided by the second section 312 and the first section 311 of the third guide hole 31, the gas is finally ejected to the left along the axis of the nozzle 3. When the high-pressure gas is ejected at the left end of the nozzle 3, a negative pressure zone can be formed there. That is to say, the pressure in the inner cavity of the housing 23 located on the left side of the nozzle 3 will be less than the pressure in the inner cavity of the housing 23 located on the right side of the nozzle 3. Under the action of negative pressure, such as Figure 6 and Figure 7 As shown, the formation fluid on the right side of the downhole one-way flow valve 100 enters the downhole one-way flow valve 100 through the ball seat 24, then flows through the fourth guide hole 32 of the nozzle 3 to the left side of the nozzle 3, and follows the high-pressure gas ejected from the nozzle 3 along the tubing 101 to the left, eventually being carried out of the well. In the prior art, it is usually necessary to wait until the accumulated fluid exceeds the gas lift valve before the gas lift process can be implemented, and only the accumulated fluid above the gas lift valve can be discharged at a time, thus requiring multiple interval gas lifts. With this setting of the present invention, the accumulated fluid on the right side of the downhole one-way flow valve 100 can be carried out at once, thereby extending the interval time of gas lift and simplifying the operation process.

[0063] In a preferred embodiment, the left end of the nozzle 3 is configured as a conical surface, specifically, as shown in the example below. Figure 2 As shown, a tip 33 is provided at the left end of the nozzle 3. The outer diameter of the tip 33 gradually decreases from right to left, and the inner wall of the housing 23 is set as a conical surface adapted to the nozzle 3. With this configuration, when high-pressure gas is ejected from the tip 33, the conical surface of the tip 33 and the housing 23 can enhance the negative pressure, thereby enhancing the airlift effect.

[0064] In one specific embodiment, the pin 14 is disposed on the right side of the first guide hole 12.

[0065] 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.

[0066] According to the present invention, such as Figure 2As shown, a fixing mechanism 4 is coaxially fixed to the left end of the one-way valve core 2. In the second state, the fixing mechanism 4 can engage with the one-way valve body 1, thereby fixing the one-way valve core 2 inside the one-way valve body 1.

[0067] Specifically, such as Figure 2 As shown, the fixing mechanism 4 includes a first retaining ring 41 coaxially mounted on the outer wall of the housing 23 of the single-flow valve core 2. Correspondingly, as... Figure 5 As shown, a first slot 161 is provided on the inner wall of the upper connector 16. In the second state, as... Figure 7 As shown, the first snap ring 41 is snapped into the first snap groove 161, thereby fixing the single-flow valve body 1 and the single-flow valve core 2 relative to each other.

[0068] In a preferred embodiment, such as Figure 2 As shown, a contraction tooth 45 is provided at the left end of the first retaining spring 41. The outer diameter of the contraction tooth 45 gradually increases from left to right, and the outer diameter of the left end of the first retaining spring 41 is larger than the outer diameter of the right end of the contraction tooth 45, thereby forming a step at the left end of the first retaining spring 41. After the first retaining spring 41 moves from left to right with the single-flow valve core 2 and engages with the first retaining groove 161, the first retaining spring 41 cannot be reset, thereby fixing the single-flow valve body 1 and the single-flow valve core 2.

[0069] Furthermore, a dropper 43 is fixedly installed on the outer wall of the housing 23 by shear pins 44. The dropper 43 is located to the left of the retraction tooth 45, and the inner diameter of the dropper 43 is larger than the outer diameter of the leftmost end of the retraction tooth 45. When it is necessary to remove the single-flow valve core 2 later, a retrieval tool is lowered into the oil pipe 101. During the downward movement of the retrieval tool, it eventually comes into contact with the left end face of the dropper 43. Pressure is continued to be applied to the retrieval tool, and the dropper 43 is pushed from left to right by the retrieval tool, thereby causing the dropper 43 to cut the shear pins 44. This causes the dropper 43 to move to the right relative to the housing 23. The inner diameter of the dropper 43 is larger than the outer diameter of the leftmost end of the retraction tooth 45, and the outer diameter of the retraction tooth 45 gradually increases from left to right. Therefore, during the movement to the right, the dropper 43 can be fitted onto the outside of the retraction tooth 45 and apply radially inward compressive force to the retraction tooth 45, thereby causing the first retaining spring 41 to retract radially inward and disengage from the first retaining groove 161.

[0070] Furthermore, a retrieval neck 42 is coaxially fixed at the left end of the housing 23, and a boss 421 is coaxially fixed at the left 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, moving the retrieval tool to the left will cause the single-flow valve core 2 to move to the left relative to the single-flow valve body 1 through the retrieval neck 42, thereby separating the single-flow valve core 2 from the single-flow valve body 1.

[0071] In a preferred embodiment, a ratchet is provided on the inner wall of the right 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 to the left relative to the retraction tooth 45, thereby preventing the dropper 43 from resetting.

[0072] In a preferred embodiment, an abutment 431 is coaxially fixed to the left 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 to the right.

[0073] According to the present invention, an air lift process is also provided, comprising the following steps:

[0074] S1, such as Figure 6 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 to the right of 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.

[0075] S2. Insert the single-flow valve core 2 into the single-flow valve body 1 and pressurize it to put the single-flow valve body 1 into the second state.

[0076] 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 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 direction is transmitted sequentially through the third guide hole 31 of the nozzle 3, the second guide hole 22, the gap between the outer wall of the housing 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 left end face of the inner cylinder 15. This causes the inner cylinder 15 to shear the pin 14 and move to the right 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 first retaining spring 41 of the fixing mechanism 4 and the first retaining 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.

[0077] 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 fourth guide hole 32 of the nozzle 3, and the upper connector 16 in sequence, and finally flows out of the well along the tubing 101.

[0078] 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.

[0079] 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 third guide hole 31 of the nozzle 3 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. Guided by the third guide hole 31, high-pressure gas is ejected axially from the left end of the nozzle 3. The ejected high-pressure gas forms a negative pressure through the housing 23, thereby causing the sealing ball 25 to detach from the ball seat 24. The gas or liquid in the formation passes sequentially through the lower connector 17, the ball seat 24, and the fourth guide hole 32 of the nozzle 3. Together with the high-pressure gas ejected from the third guide hole 31 of the nozzle 3, it is carried out of the well through the inner cavity of the tubing 101, thereby accelerating the removal of liquid below the downhole one-way flow valve 100 and extending the gas lift interval time.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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). 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). The inner cylinder (15) is configured to open the first guide hole (12) when it is pressurized. 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 right to left. 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), so that pressure can be transmitted to the inner cylinder (15).

2. The downhole one-way flow valve according to claim 1, characterized in that, The fixing mechanism (4) includes a first retaining ring (41) coaxially disposed on the outer wall of the single-flow valve core (2), and a first retaining groove (161) is provided on the inner wall of the single-flow valve body (1). In the second state, the first retaining ring (41) is engaged in the first retaining groove (161).

3. The downhole one-way flow valve according to claim 2, characterized in that, A retraction tooth (45) is provided at the left end of the first snap ring (41). The outer diameter of the retraction tooth (45) gradually increases from left to right. 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 to the right, 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).

4. The downhole one-way flow valve according to claim 1, characterized in that, A nozzle (3) is coaxially arranged in the second flow channel (21). A third guide hole (31) is provided inside the nozzle (3), and a second guide hole (22) is provided on the side wall of the single-flow valve core (2). The two ends of the third guide hole (31) connect the second guide hole (22) and the left end of the nozzle (3), respectively. A fourth guide hole (32) is provided inside the nozzle (3), and the fourth guide hole (32) connects the left and right ends of the nozzle (3).

5. The downhole one-way flow valve according to claim 4, characterized in that, The third guide hole (31) includes a first hole section (311) arranged axially in the nozzle (3) and a second hole section (312) arranged radially in the nozzle (3). The left end of the first hole section (311) passes through the nozzle (3), and the right end of the first hole section (311) is connected to the second hole section (312). Multiple fourth guide holes (32) are uniformly arranged circumferentially inside the nozzle (3).

6. The downhole one-way flow valve according to claim 4, 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 inside the ball seat (24). The second flow guide hole (22) is disposed on the side wall of the housing (23) and is located to the left of the ball seat (24). The nozzle (3) is coaxially and sealed inside the housing (23) and is located to the left of the ball seat (24).

7. The downhole one-way flow valve according to claim 6, characterized in that, The left end of the nozzle (3) is configured as a conical surface, and the inner wall of the housing (23) is configured as a conical surface adapted to the nozzle (3).

8. The downhole one-way flow valve according to any one of claims 1 to 7, characterized in that, 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).

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

10. An air-lift 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 to the right of the single-flow valve body (1). After the packer is inserted into the well, it is seated. S2. The single-flow valve core (2) 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 single-flow valve body (1) and the sleeve from the ground.

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