Bottom valve for immovable tubular column of hydraulic pump and immovable tubular column of hydraulic pump

Abstract

The invention provides a bottom valve for an immovable tubular column of a hydraulic pump and the immovable tubular column of the hydraulic pump, and belongs to the technical field of oil and gas exploitation. The bottom valve comprises a valve seat, a valve body, a valve element and a fishing head. A through hole penetrating through the bottom and the top of the valve seat is formed in the valve seat; the valve body is located in the through hole, a circulation channel is formed in the valve body, the valve body can move between a first position and a second position in the extending direction of the through hole, the valve element is movably located in the circulation channel, and the moving direction of the valve element is the extending direction of the circulation channel. The valve element is used for making sealing contact with the circulation channel at the third position, the fishing head is connected with the top of the valve body, and the fishing head is used for being connected with a mechanical fishing hand. The fishing success rate of the bottom valve of the hydraulic pump can be increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas exploitation, and in particular relates to a bottom valve for a fixed pipe string of a hydraulic pump and the fixed pipe string of the hydraulic pump. Background Art

[0002] In order to improve the recovery rate of oil and gas production, more and more oil fields choose to use multi-round carbon dioxide huff and puff oil production technology to produce oil and gas. Multi-round carbon dioxide huff and puff is generally achieved based on a hydraulic pump without moving the pipe string.

[0003] In the related art, the fixed pipe string of the hydraulic pump includes casing, tubing, packer and bottom valve. The casing is sleeved outside the tubing, and the packer is connected to the annulus between the tubing and the casing. The bottom valve is located at the bottom of the tubing, and the bottom valve includes a valve seat and a valve core. The valve seat is connected to the bottom of the tubing. The valve core is a spherical valve, which is movably connected in the valve seat and is used to seal with the valve seat to seal the tubing. A hydraulic pump is connected in the tubing. The pump barrel of the hydraulic pump is connected in the tubing, and the pump core of the hydraulic pump is movably connected in the pump barrel of the hydraulic pump. When injecting carbon dioxide into the formation, it is necessary to wash the pump core of the hydraulic pump out of the pump barrel of the hydraulic pump first, and then lower the strong magnetic salvage tool to the bottom of the tubing through the wire rope, and the strong magnetic salvage tool is adsorbed together with the spherical valve, and then the wire rope is pulled up to the wellhead, so that the spherical valve can be salvaged from the valve seat. In this way, the carbon dioxide injected at the wellhead can be injected into the formation along the oil pipe, hydraulic pump, etc.

[0004] However, when salvaging the spherical valve, the strong magnetic salvage tool is very likely to absorb iron impurities in the wellbore during the downhole process, causing the magnetic adsorption capacity of the strong magnetic salvage tool to weaken, making it difficult to adsorb the spherical valve. In addition, since the spherical valve is located at the bottom of the oil pipe, the spherical valve is easily blocked by formation sand, wellbore rust and other materials, which also makes it difficult for the strong magnetic salvage tool to adsorb the spherical valve. Therefore, the success rate of salvaging the spherical valve using the strong magnetic salvage tool is low, which ultimately affects the injection of carbon dioxide. Summary of the invention

[0005] The embodiment of the present disclosure provides a bottom valve for a hydraulic pump stationary pipe string and a hydraulic pump stationary pipe string, which can improve the success rate of salvaging the bottom valve of the hydraulic pump. The technical solution is as follows:

[0006] The disclosed embodiment provides a bottom valve for a fixed pipe column of a hydraulic pump, the bottom valve comprising a valve seat, a valve body, a valve core and a fishing head; the valve seat has a through hole that passes through the bottom and top of the valve seat; the valve body is located in the through hole, the interior of the valve body has a flow channel, the extension direction of the flow channel is the same as the extension direction of the through hole, the first port of the flow channel is located at the bottom end face of the valve body, the second port of the flow channel is located at the side wall of the valve body, the valve body can move between a first position and a second position along the extension direction of the through hole, the valve When the valve body is in the first position, the valve body is sealed and connected to the bottom of the valve seat, and when the valve body is in the second position, there is a gap between the valve body and the inner wall of the valve seat; the valve core is movably located in the circulation channel, and the moving direction of the valve core is the extension direction of the circulation channel. The valve core is used to be in sealing contact with the circulation channel at a third position, and the third position is located between the first port and the second port of the circulation channel in the extension direction of the circulation channel; the salvaging head is connected to the top of the valve body, and the salvaging head is used to be connected to a mechanical salvaging hand.

[0007] In another implementation of the present disclosure, the valve body includes a connecting section and a sealing section; a first end of the connecting section is connected to the sealing section, a second end of the connecting section is connected to the fishing head, the second port passes through an outer wall of the connecting section, the connecting section has a first flow section extending along its own axial direction, the first flow section is connected to the second port; the sealing section has a second flow section passing through both ends of the sealing section, the second flow section is connected to the first flow section, the flow channel includes the first flow section and the second flow section; an outer diameter of the sealing section is larger than an outer diameter of the connecting section, and the sealing section is in sealing cooperation with the valve seat.

[0008] In another implementation of the present disclosure, at least a portion of the sealing section close to the connecting section is a first reducing section, and the inner diameter of the first reducing section gradually decreases along the direction from the connecting section to the sealing section; the valve core is a sealing sphere, and the first reducing section is used to seal with the valve core.

[0009] In another implementation of the present disclosure, at least a portion of the valve seat is a second variable diameter section, and the inner diameter of the second variable diameter section gradually decreases along the direction from the connecting section to the sealing section; when the valve body is in the first position, the sealing section is sealed and connected to the second variable diameter section.

[0010] In another implementation of the present disclosure, the valve body also includes an extension section, the extension section and the connecting section are respectively located at two ends of the sealing section, the extension section is connected to one end of the sealing section away from the connecting section, and the outer diameter of the extension section is smaller than the outer diameter of the sealing section; the circulation channel also includes a third circulation section, the third circulation section is in the extension section and passes through both ends of the extension section, and the third circulation section is connected to the second circulation section.

[0011] In yet another implementation of the present disclosure, the fishing head is a rod-shaped structure, and an outer wall of the fishing head has a plurality of barbs that cooperate with the mechanical fishing hand.

[0012] In yet another implementation of the present disclosure, the maximum outer diameter of the fishing head is smaller than the outer diameter of the valve body.

[0013] In another embodiment of the present disclosure, a fixed tubular column for a hydraulic pump is provided, the tubular column comprising casing, oil tubing, a packer and a bottom valve, the bottom valve being the bottom valve described above; the casing is sleeved outside the oil tubing and connected to the oil tubing, the oil tubing is used to be connected to the pump barrel of the hydraulic pump, the packer is located in the annulus between the casing and the oil tubing, the packer is respectively connected to the casing and the oil tubing; the bottom valve is located inside the oil tubing and close to the bottom of the oil tubing, the bottom valve is connected to the oil tubing.

[0014] In another implementation of the present disclosure, the fixed tubular column further includes a screen tube and a plug, wherein the screen tube is coaxially located in the bottom of the oil pipe and located on the side of the bottom valve facing the bottom of the oil pipe, and the screen tube is connected to the oil pipe; the plug is located at an end of the oil pipe away from the screen tube, and the plug is sealed at the end of the screen tube.

[0015] In another implementation of the present disclosure, the fixed tubing string also includes a leather cup, which is located on the side of the packer facing the top of the oil pipe, and the leather cup is sleeved on the outside of the oil pipe; the leather cup is a conical ring sleeve, and the end of the leather cup with a larger outer diameter is abutted against the casing, and the end of the leather cup with a larger outer diameter faces the top of the oil pipe.

[0016] The technical solution provided by the embodiments of the present disclosure has the following beneficial effects:

[0017] Since the bottom valve provided in the embodiment of the present disclosure includes a valve seat, and the valve seat is located in the oil pipe of the fixed pipe column of the hydraulic pump, the valve seat can provide an installation foundation for the valve body and the valve core.

[0018] Because the valve body is movably connected to the valve seat, when the valve body is in the first position, the valve body is sealed and connected to the valve seat, and the valve core is movably located in the circulation channel, and the valve core is used to be in sealing contact with the circulation channel at the third position, and the third position is located between the first port and the second port of the circulation channel in the extension direction of the circulation channel. In this way, the oil pipe can be sealed by the cooperation of the valve body with the valve seat and the valve core, so that when the pump core is backwashed, the power fluid is prevented from entering the formation.

[0019] Furthermore, when the valve body is in the second position, there is a gap between the valve body and the inner wall of the valve seat, and the first port of the circulation channel penetrates the bottom end face of the valve body, and the second port of the circulation channel penetrates the outer wall of the valve body. In this way, during normal production, under the suction action of the hydraulic pump, oil and gas can flow from the bottom of the oil pipe through the first port of the circulation channel, flow through the second port, enter the hydraulic pump, pass through the channel of the hydraulic pump, and then pass through the annulus between the oil pipe and the casing before being sucked to the ground.

[0020] Because the salvage head is located at the top of the valve body and connected to the top of the valve body, the salvage head is used to connect with the mechanical salvage hand. In this way, after backwashing the pump core, the mechanical salvage hand can be directly placed in the oil pipe. The mechanical salvage hand cooperates with the salvage head to salvage the salvage head together with the valve body to the outside of the wellhead.

[0021] It can be seen that the bottom valve disclosed in the present invention is not only convenient for salvage, but also will not affect the normal production of the oil well. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a structural schematic diagram of a hydraulic pump fixed pipe column of the related art;

[0024] Figure 2 is a structural schematic diagram of a bottom valve provided by an embodiment of the present disclosure when the valve body is located in a first position;

[0025] Figure 3 is a structural schematic diagram of a bottom valve provided by an embodiment of the present disclosure when the valve body is located in the second position;

[0026] Figure 4 It is a structural schematic diagram of a fixed pipe string for a hydraulic pump provided by an embodiment of the present disclosure.

[0027] The symbols in the figure mean the following:

[0028] 1. Valve seat; 10. Through hole; 11. Second reducing section;

[0029] 2. valve body; 20. circulation channel; 21. connecting section; 2001. first port; 2002. second port; 2100. first circulation section; 22. sealing section; 2200. second circulation section; 221. first diameter-reducing section; 23. extension section; 2300. third circulation section;

[0030] 3. Valve core;

[0031] 4. Salvage head; 41. Barb;

[0032] 201, casing; 202, oil pipe; 203, packer; 204, bottom valve; 205, screen; 206, plug; 207, leather cup; 200, hydraulic pump. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0034] With the gradual deepening of the development process of oil fields at home and abroad, more and more oil reservoirs have entered the medium-to-high water content development stage, and the trend of water drive effect deterioration is becoming increasingly serious. More and more oil fields choose gas injection and huff-and-puff oil production to replace water drive oil production. Generally speaking, the main gas injection medium is carbon dioxide. Carbon dioxide huff-and-puff oil production technology uses the interaction between carbon dioxide and crude oil in the formation to expand the volume of crude oil, increase reservoir pressure, reduce formation crude oil viscosity, improve crude oil fluidity, reduce interfacial tension, etc., thereby increasing the production of carbon dioxide huff-and-puff oil wells.

[0035] The hydraulic pump lifting technology is widely used in CO2 huff and puff wells in oil reservoirs because it can effectively solve the problems of rapid rod and pipe corrosion rate, severe corrosion, and sanding of thick oil after CO2 huff and puff in oil reservoirs. In other words, the hydraulic pump lifting technology is generally selected in the CO2 huff and puff oil production process in oil reservoirs.

[0036] The so-called hydraulic pump lifting process refers to the hydraulic pump using the power fluid to form negative pressure to suck out the oil and gas in the oil well. The hydraulic pump lifting process must be implemented with a hydraulic pump and a hydraulic pump fixed pipe column suitable for the hydraulic pump.

[0037] See also Figure 1The fixed string of the hydraulic pump in the related art includes a casing 201, a tubing 202, a packer 203 and a bottom valve 204. The casing 201 is sleeved outside the tubing 202 and connected to the tubing 202, and the packer 203 is located in the annulus between the casing 201 and the tubing 202, and the packer 203 is connected to the casing 201 and the tubing 202 respectively.

[0038] The bottom valve 204 is located in the bottom of the oil pipe 202 and is located on the side of the packer 203 facing the bottom of the oil pipe 202. The bottom valve 204 is spaced from the packer 203. The valve seat of the bottom valve 204 is connected to the oil pipe 202. The valve seat of the bottom valve 204 has a through hole inside. The valve core of the bottom valve 204 is located to seal with the through hole inside the valve seat of the bottom valve 204. The valve core of the bottom valve 204 is a spherical valve.

[0039] The hydraulic pump 200 is located in the oil pipe 202 and is located on the side of the packer 203 away from the bottom valve 204. The pump barrel of the hydraulic pump 200 is connected in the oil pipe 202, and the pump core of the hydraulic pump 200 is movably connected in the pump barrel of the hydraulic pump 200.

[0040] Thus, during normal production and oil production, after the hydraulic pump 200 is connected to the surface power fluid system, the pump core of the hydraulic pump 200 that meets the production needs is put into the pump barrel of the hydraulic pump 200. Then, the power fluid provided by the power fluid system enters the oil pipe 202, and after passing through the pump core of the hydraulic pump 200, it flows through the annulus between the casing 201 and the oil pipe 202. After the power fluid enters the pump core of the hydraulic pump 200, suction is generated, and the valve core of the bottom valve 204 is separated from the valve seat of the bottom valve 204 under the action of the suction force, and the formation production fluid is sucked out from the bottom of the oil pipe, and after passing through the hydraulic pump 200, it enters the annulus between the casing 201 and the oil pipe 202 together with the power fluid and is discharged from the wellbore.

[0041] When the carbon dioxide jacket needs to be injected, the pump core of the hydraulic pump 200 needs to be backwashed out first, and the valve core of the bottom valve also needs to be salvaged, so that a gas injection channel can be formed.

[0042] When backwashing the pump core, the surface power fluid system provides power fluid to enter the annulus between the casing 201 and the oil pipe 202. Since the packer is set in the annulus between the casing 201 and the oil pipe 202, the power fluid can only enter the hydraulic pump along the channel of the hydraulic pump. Since the bottom valve is located below the hydraulic pump, that is, the bottom valve seals the bottom of the oil pipe, the power fluid cannot enter the formation through the oil pipe, but the power fluid enters the hydraulic pump 200. The pump core of the hydraulic pump 200 is separated from the pump barrel of the hydraulic pump under the action of the power fluid, and the pump core reaches the ground under the support of the power fluid.

[0043] The valve core of the bottom valve is salvaged, and a strong magnetic salvage tool is lowered to the bottom of the oil pipe 202 through a steel wire rope. The strong magnetic salvage tool is adsorbed together with the spherical valve, and then the steel wire rope is pulled up to the wellhead.

[0044] Then inject carbon dioxide into the oil pipe according to the design requirements, and prepare for production after well soaking, blowout and other procedures.

[0045] It can be seen that when the valve core of the bottom valve in the related art is being salvaged, the success rate of salvaging will be affected because it is difficult for the strong magnetic salvaging tool to adsorb to the spherical valve, thereby affecting the injection of carbon dioxide.

[0046] The disclosed embodiment provides a bottom valve for a fixed pipe string of a hydraulic pump, which can greatly improve the success rate of salvaging the valve core of the bottom valve.

[0047] See also Figure 2 and 3 The bottom valve comprises a valve seat 1, a valve body 2, a valve core 3 and a fishing head 4. The valve seat 1 has a through hole 10 which passes through the bottom and the top of the valve seat 1.

[0048] The valve body 2 is located in the through hole 10. The valve body 2 has a flow channel 20 inside. The extension direction of the flow channel 20 is the same as the extension direction of the through hole 10. The first port 2001 of the flow channel 20 is located at the bottom end surface of the valve body 2. The second port 2002 of the flow channel 20 is located on the side wall of the valve body 2. The valve body 2 can be in the first position (see Figure 2 ) and the second position (see Figure 3 ) when the valve body 2 is in the first position (see Figure 2 ), the valve body 2 is sealed and connected to the bottom of the valve seat 1, and the valve body 2 is in the second position (see Figure 3 ), there is a gap between the valve body 2 and the inner wall of the valve seat 1.

[0049] The valve core 3 is movably located in the circulation channel 20, and the movement direction of the valve core 3 is the extension direction of the circulation channel 20. The valve core 3 is used to be in sealing contact with the circulation channel 20 at a third position, and the third position is located between the first port 2001 and the second port 2002 of the circulation channel 20 in the extension direction of the circulation channel 20. The fishing head 4 is connected to the top of the valve body 2, and the fishing head 4 is used to connect with a mechanical fishing hand.

[0050] Since the bottom valve provided in the embodiment of the present disclosure includes a valve seat 1 , and the valve seat 1 is located in the oil pipe of the fixed pipe string of the hydraulic pump, the valve seat 1 can provide an installation foundation for the valve body 2 and the valve core 3 .

[0051] Because the valve body 2 is movably connected to the valve seat 1, when the valve body 2 is in the first position, the valve body 2 is sealed and connected to the valve seat 1, and the valve core 3 is movably located in the circulation channel 20. The valve core 3 is in sealing contact with the circulation channel 20 at the third position, and the third position is located between the first port 2001 and the second port 2002 of the circulation channel 20 in the extension direction of the circulation channel 20. In this way, the oil pipe can be sealed by the cooperation of the valve body 2 with the valve seat 1 and the valve core 3, so that the power fluid is prevented from entering the formation when the pump core is backwashed. In addition, when the valve body 2 is in the second position, there is a gap between the valve body 2 and the inner wall of the valve seat 1, and the first port of the circulation channel 20 passes through the bottom end face of the valve body 2, and the second port of the circulation channel 20 passes through the side wall of the valve body 2. In this way, during normal production, under the suction action of the hydraulic pump, oil and gas can flow from the bottom of the oil pipe through the first port 2001 of the circulation channel 20, flow through the second port 2002, enter the hydraulic pump, pass through the channel of the hydraulic pump, and then pass through the annulus between the oil pipe and the casing and be sucked to the ground.

[0052] Because the fishing head 4 is located at the top of the valve body 2 and connected to the top of the valve body 2, the fishing head 4 is used to connect with the mechanical fishing hand. In this way, after backwashing the pump core, the mechanical fishing hand can be directly placed in the oil pipe and cooperate with the fishing head 4 to fish the fishing head 4 together with the valve body 2 to the outside of the wellhead.

[0053] It can be seen that the bottom valve disclosed in the present invention is not only convenient for salvage, but also will not affect the normal production of the oil well.

[0054] That is to say, when the bottom valve of the present invention is in use, if during normal oil production, the power fluid provided by the power fluid system enters the oil pipe 202 and enters the pump core of the hydraulic pump 200, causing the hydraulic pump 200 to generate suction, the upper pressure of the bottom valve 204 is less than the lower pressure, and the formation production fluid reaches the valve core 3 through the circulation channel 20. The valve core 3 moves upward under the upward force of the formation production fluid, and the valve core 3 is no longer in sealing contact with the circulation channel 20. The formation production fluid enters through the circulation channel 20 and enters the hydraulic pump through the second port 2002 of the circulation channel 20 and is lifted to the ground.

[0055] When the hydraulic pump stops producing and the suction effect disappears, the upper pressure of the bottom valve 204 is greater than the lower pressure, and the valve core 3 moves downward under the action of gravity and contacts the circulation channel 20 in a sealed manner. At this time, the oil pipe can be sealed when the pump core is backwashed. If the pump core is backwashed, the power fluid enters the annulus between the casing 201 and the oil pipe 202, and enters the hydraulic pump from the annulus along the channel of the hydraulic pump. Since the bottom valve 204 is located below the hydraulic pump, that is, the bottom valve 204 closes the bottom of the oil pipe, the power fluid cannot enter the formation through the oil pipe, but the power fluid enters the hydraulic pump 200. The pump core of the hydraulic pump 200 is separated from the pump barrel of the hydraulic pump under the action of the power fluid, and the pump core reaches the ground under the support of the power fluid.

[0056] The valve core 3 of the salvage bottom valve 204 is lowered to the bottom of the oil pipe 202 by a mechanical salvage hand through a steel wire rope. After the mechanical salvage hand is snap-fitted and assembled with the salvage head 4, the steel wire rope is pulled up to the wellhead. At this time, only the valve seat 1 is left in the oil pipe, and the valve seat 1 has a through hole 10 therein. Therefore, carbon dioxide can be injected into the oil pipe through the through hole 10.

[0057] Optionally, the valve body 2 includes a connecting section 21 and a sealing section 22. The first end of the connecting section 21 is connected to the sealing section 22, the second end of the connecting section 21 is connected to the fishing head 4, the second port 2002 passes through the outer wall of the connecting section 21, the interior of the connecting section 21 has a first flow section 2100 extending along its own axial direction, and the first flow section 2100 is connected to the second port 2002. The interior of the sealing section 22 has a second flow section 2200 passing through both ends of the sealing section 22, the second flow section 2200 is connected to the first flow section 2100, and the flow channel 20 includes the first flow section 2100 and the second flow section 2200. The outer diameter of the sealing section 22 is greater than the outer diameter of the connecting section 21, and the sealing section 22 is in sealing cooperation with the valve seat 1.

[0058] In the above implementation, the sealing section 22 is used to seal with the valve seat 1, and the connecting section 21 is used to connect the flow channel 20 with the outside of the valve body 2. Moreover, the outer diameter of the sealing section 22 is larger than the outer diameter of the connecting section 21, so that only the sealing section 22 of the valve body 2 can seal with the valve seat 1, reducing the sealing contact area between the valve body 2 and the valve seat 1, thereby reducing the salvage force when salvaging the valve body 2.

[0059] In this embodiment, the connecting section 21 and the sealing section 22 are both made of 304L stainless steel, which can prevent corrosion from the formation produced fluid containing carbon dioxide. The connecting section 21 and the sealing section 22 are connected by threads.

[0060] Optionally, at least a portion of the sealing section 22 close to the connecting section 21 is a first diameter reducing section 221, and the inner diameter of the first diameter reducing section 221 gradually decreases along the direction from the connecting section 21 to the sealing section 22. The valve core 3 is a sealing sphere, and the first diameter reducing section 221 is used to seal with the valve core 3.

[0061] In the above implementation, the above structure can form a one-way flow channel between the sealing section 22 and the valve core 3, so that the liquid flows from bottom to top and is sealed from top to bottom.

[0062] That is, if the valve core 3 is subjected to an upward force, the valve core 3 will be separated from the first diameter-changing section 221 , and the valve core 3 will no longer seal the flow channel 20 , so that the flow channel 20 is in an up-and-down flow state.

[0063] If the valve core 3 is not subjected to an upward force, the valve core 3 will fall back into the first diameter-changing section 221 under the action of its own gravity, and the valve core 3 will seal the flow channel 20, so that the flow channel 20 is in an upper and lower cut-off state.

[0064] In this embodiment, the valve core 3 is a corrosion-resistant sphere, which can prevent corrosion from the formation produced fluid containing carbon dioxide.

[0065] Optionally, at least a portion of the valve seat 1 is the second diameter reducing section 11, and the inner diameter of the second diameter reducing section 11 gradually decreases along the direction from the connecting section 21 to the sealing section 22. When the valve body 2 is in the first position, the sealing section 22 is sealed and connected to the second diameter reducing section 11.

[0066] In the above implementation, at least a portion of the valve seat 1 is the second diameter-reducing section 11, so that a one-way flow channel can be formed between the valve body 2 and the valve seat 1, and the liquid flows from bottom to top and is sealed from top to bottom.

[0067] If the valve body 2 is subjected to an upward force, the valve body 2 will be separated from the second diameter-changing section 11 and located at the second position, and the valve seat 1 is in an up-and-down flow state.

[0068] If the valve body 2 is not subjected to an upward force, at this time, the valve body 2 will be located in the first position under the action of its own gravity, that is, it is in sealing contact with the second diameter-changing section 11, and the valve body 2 seals the interior of the valve seat 1, and the interior of the valve seat 1 is in an upper and lower cut-off state.

[0069] In addition, in order to further improve the sealing performance between the valve body 2 and the valve seat 1, the outer peripheral wall of the sealing section 22 is provided with two spaced annular sealing grooves along its own axial direction, and a sealing rubber ring is provided in the annular sealing groove.

[0070] Optionally, the valve body 2 further includes an extension section 23 , the extension section 23 and the connecting section 21 are respectively located at two ends of the sealing section 22 , the extension section 23 is connected to one end of the sealing section 22 away from the connecting section 21 , and the outer diameter of the extension section 23 is smaller than the outer diameter of the sealing section 22 .

[0071] The circulation channel 20 further includes a third circulation section 2300, which is in the extension section 23 and passes through both ends of the extension section 23. The third circulation section 2300 is in communication with the second circulation section 2200. The second port 2002 is located at one end of the third circulation section 2300 away from the second circulation section 2200.

[0072] In the above implementation, the extension section 23 can further increase the weight of the valve body 2, so that the valve body 2 can quickly seal with the valve seat 1 when it is dropped into the well.

[0073] Exemplarily, the inner wall of the end of the extension section 23 away from the sealing section 22 (that is, the second port 2002) is a bell-mouth structure, and the inner diameter of the bell-mouth structure gradually decreases in the direction from the third flow section 2300 to the second flow section 2200. This can play a guiding role in entering the flow channel 20.

[0074] Optionally, the salvage head 4 is a rod-shaped structure, and the outer wall of the salvage head 4 has a plurality of barbs 41 that cooperate with the mechanical salvage hand.

[0075] In the above implementation, the barb 41 is an inverted triangle, which is used to cooperate with a common mechanical fishing claw so that the fishing head 4 can be fished by a fishing device.

[0076] Optionally, the maximum outer diameter of the fishing head 4 is smaller than the outer diameter of the valve body 2. This can reduce the space occupied by the fishing head 4.

[0077] The present disclosure also provides a fixed pipe string for a hydraulic pump, see Figure 4 The fixed tubing string includes a casing 201, a tubing 202, a packer 203 and a bottom valve 204. The bottom valve 204 is the bottom valve mentioned above.

[0078] The casing 201 is sleeved outside the oil pipe 202 and connected to the oil pipe 202. The oil pipe 202 is used to connect to the pump barrel of the hydraulic pump 200. The packer 203 is located in the annulus between the casing 201 and the oil pipe 202, and the packer 203 is connected to the casing 201 and the oil pipe 202 respectively. The bottom valve 204 is located in the oil pipe 202 and close to the bottom of the oil pipe 202, and the bottom valve 204 is connected to the oil pipe 202.

[0079] The hydraulic pump 200 is connected to the oil pipe 202 and is located on the top side of the bottom valve 204 facing the oil pipe.

[0080] The above fixed pipe string has the same beneficial effects as mentioned above, which will not be described in detail here.

[0081] Optionally, the fixed pipe string further includes a screen 205 and a plug 206, wherein the screen 205 is coaxially located in the bottom of the oil pipe 202 and located on the bottom side of the bottom valve 204 facing the oil pipe 202, and the screen 205 is connected to the oil pipe 202. The plug 206 is located at one end of the oil pipe 202 away from the screen 205, and the plug 206 is sealed at the end of the screen 205.

[0082] In the above implementation, the plug 206 is used to block the bottom of the screen tube 205, and the screen tube 205 is used to connect the inside of the oil pipe 202 with the outside, so that the formation production fluid can enter the oil pipe, while blocking the sand and gravel.

[0083] Optionally, the fixed tubing string further includes a leather cup 207 , which is located on the top side of the packer 203 facing the oil pipe 202 , and the leather cup 207 is sleeved on the outside of the oil pipe 202 .

[0084] The leather cup 207 is a conical ring sleeve, and the end of the leather cup 207 with a larger outer diameter abuts against the sleeve 201 , and the end of the leather cup 207 with a larger outer diameter faces the top of the oil pipe 202 .

[0085] In the above implementation, the leather cup 207 is used to further seal the annulus between the tubing and the casing, and can prevent the sand from burying the packer. Once the sand is buried, the well repair operation may cause the pipe string to be lifted with great force, and the pipe string cannot be lifted.

[0086] The following briefly introduces the working method of the bottom valve and the fixed pipe string provided in the embodiment of the present disclosure:

[0087] During normal production and oil extraction, the power fluid provided by the power fluid system enters the oil pipe 202 and enters the pump core of the hydraulic pump 200, which causes the hydraulic pump 200 to generate suction. The upper pressure of the bottom valve 204 is less than the lower pressure, and the formation production fluid reaches the valve core 3 through the circulation channel 20. The valve core 3 moves upward when the formation production fluid acts upward, and the valve core 3 is no longer in sealed contact with the circulation channel 20. The formation production fluid passes through the first port 2001 of the circulation channel 20 and enters the hydraulic pump through the second port 2002 and is lifted to the ground. When the hydraulic pump stops production and the suction effect disappears, the upper pressure of the bottom valve 204 is greater than the lower pressure, and the valve core 3 moves downward under the action of gravity and is in sealed contact with the circulation channel 20.

[0088] When backwashing the pump core, the power fluid enters the annulus between the tubing 202 and the casing 201. Since the annulus between the tubing 202 and the casing 201 is sealed by the packer 203, the power fluid can only enter the hydraulic pump from the annulus between the tubing 202 and the casing 201 along the channel of the hydraulic pump. Since the bottom valve 204 is located below the hydraulic pump, that is, the bottom valve 204 seals the bottom of the tubing 202, the power fluid cannot enter the formation through the tubing, but enters the hydraulic pump 200. The pump core of the hydraulic pump 200 is separated from the pump barrel of the hydraulic pump under the action of the power fluid, and the pump core is lifted by the power fluid and reaches the ground.

[0089] The valve core 3 of the bottom valve 204 is salvaged by lowering a mechanical salvage hand to the bottom of the oil pipe 202 through a steel wire rope. After the mechanical salvage hand is snap-fitted and assembled with the salvage head 4, the steel wire rope is pulled up to the outside of the wellhead.

[0090] After the valve core 3 is salvaged, only the valve seat 1 is left in the oil pipe 202 , and the valve seat 1 has a through hole 10 therein, so that carbon dioxide can be injected into the oil pipe through the through hole 10 .

[0091] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A bottom valve for a fixed pipe column of a hydraulic pump, characterized in that: The bottom valve comprises a valve seat (1), a valve body (2), a valve core (3) and a fishing head (4); The valve seat (1) has a through hole (10) penetrating the bottom and top of the valve seat (1); The valve body (2) is located in the through hole (10), and the valve body (2) has a circulation channel (20) inside. The extension direction of the circulation channel (20) is the same as the extension direction of the through hole (10). The first port (2001) of the circulation channel (20) is located at the bottom end surface of the valve body (2), and the second port (2002) of the circulation channel (20) is located at the side wall of the valve body (2). The valve body (2) can move between a first position and a second position along the extension direction of the through hole (10). When the valve body (2) is in the first position, the valve body (2) is sealed and connected to the valve seat (1). When the valve body (2) is in the second position, there is a gap between the valve body (2) and the inner wall of the valve seat (1). The valve core (3) is movably located in the circulation channel (20); the movement direction of the valve core (3) is the extension direction of the circulation channel (20); the valve core (3) is used to be in sealing contact with the circulation channel (20) at a third position; the third position is located between the first port (2001) and the second port (2002) of the circulation channel (20) in the extension direction of the circulation channel (20); The salvaging head (4) is connected to the top of the valve body (2), and the salvaging head (4) is used to be connected to a mechanical salvaging hand.

2. The bottom valve according to claim 1, characterized in that: The valve body (2) comprises a connecting section (21) and a sealing section (22); The first end of the connecting section (21) is connected to the sealing section (22), the second end of the connecting section (21) is connected to the fishing head (4), the second port (2002) passes through the outer wall of the connecting section (21), the connecting section (21) has a first flow section (2100) extending along its own axial direction, and the first flow section (2100) is connected to the second port (2002); The sealing section (22) has a second flow section (2200) inside that passes through both ends of the sealing section (22), the second flow section (2200) is in communication with the first flow section (2100), and the flow channel (20) includes the first flow section (2100) and the second flow section (2200); The outer diameter of the sealing section (22) is greater than the outer diameter of the connecting section (21), and the sealing section (22) is in sealing cooperation with the valve seat (1).

3. The bottom valve according to claim 2, characterized in that: At least a portion of the sealing section (22) close to the connecting section (21) is a first diameter-changing section (221), and the inner diameter of the first diameter-changing section (221) gradually decreases along the direction from the connecting section (21) to the sealing section (22); The valve core (3) is a sealing sphere, and the first diameter-reducing section (221) is used for sealingly cooperating with the valve core (3).

4. The bottom valve according to claim 2, characterized in that: At least a portion of the valve seat (1) is a second diameter-changing section (11), and the inner diameter of the second diameter-changing section (11) gradually decreases along the direction from the connecting section (21) to the sealing section (22); When the valve body (2) is in the first position, the sealing section (22) is sealedly connected to the second diameter-changing section (11).

5. The bottom valve according to claim 2, characterized in that: The valve body (2) further comprises an extension section (23), wherein the extension section (23) and the connecting section (21) are respectively located at two ends of the sealing section (22), the extension section (23) is connected to an end of the sealing section (22) away from the connecting section (21), and the outer diameter of the extension section (23) is smaller than the outer diameter of the sealing section (22); The circulation channel (20) further comprises a third circulation section (2300), wherein the third circulation section (2300) is in the extension section (23) and passes through both ends of the extension section (23), and the third circulation section (2300) is in communication with the second circulation section (2200).

6. The bottom valve according to any one of claims 1 to 5, characterized in that: The salvaging head (4) is a rod-shaped structure, and the outer wall of the salvaging head (4) has a plurality of barbs (41) that cooperate with the mechanical salvaging hand.

7. The bottom valve according to claim 7, characterized in that: The maximum outer diameter of the fishing head (4) is smaller than the outer diameter of the valve body (2).

8. A stationary pipe string for a hydraulic pump, characterized in that: The fixed tubular column comprises a casing (201), a tubing (202), a packer (203) and a bottom valve (204), wherein the bottom valve (204) is the bottom valve according to any one of claims 1 to 7; The casing (201) is sleeved outside the oil pipe (202) and connected to the oil pipe (202). The oil pipe (202) is used to be connected to the pump barrel of a hydraulic pump. The packer (203) is located in the annulus between the casing (201) and the oil pipe (202). The packer (203) is connected to the casing (201) and the oil pipe (202) respectively. The bottom valve (204) is located inside the oil pipe (202) and close to the bottom of the oil pipe (202). The bottom valve (204) is connected to the oil pipe (202).

9. The stationary pipe string according to claim 8, characterized in that: The fixed pipe string further comprises a screen tube (205) and a plug (206), wherein the screen tube (205) is coaxially located in the bottom of the oil pipe (202) and located on the bottom side of the bottom valve (204) facing the bottom of the oil pipe (202), and the screen tube (205) is connected to the oil pipe (202); The plug (206) is located at one end of the oil pipe (202) away from the screen tube (205), and the plug (206) blocks the end of the screen tube (205).

10. The immovable pipe string according to claim 8, characterized in that: The fixed pipe string further comprises a leather cup (207), the leather cup (207) is located on the top side of the packer (203) facing the oil pipe (202), and the leather cup (207) is sleeved outside the oil pipe (202); The leather cup (207) is a conical ring sleeve, and the end of the leather cup (207) with a larger outer diameter abuts against the sleeve (201), and the end of the leather cup (207) with a larger outer diameter faces the top of the oil pipe (202).

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