Underground self-excited pump and integrated tubular column

Abstract

The invention relates to an underground self-excitation pump and an integrated pipe column which are applied to well types such as highly-deviated wells and horizontal wells. The underground self-excitation pump comprises a working barrel and a self-excitation mandrel. And the main body of the working barrel is provided with a hole for communicating radial inner and outer spaces. The self-excitation mandrel comprises a clamping piece and a spraying piece. The clamping piece is provided with an axial through channel. A power air flow channel and a liquid accumulation channel are arranged in the spraying piece and communicate with the channel through the gap. The upper end of the power air flow channel can enable first fluid flowing into the power air flow channel from the hole to be sprayed out towards the channel, so that second fluid in the space below the self-excitation mandrel can flow upwards along the channel. The first fluid is mainly natural gas, and the second fluid is mainly gas-liquid two-phase fluid. The gas-liquid two-phase fluid is pumped away from the lower space of the self-excitation mandrel and flows upwards through the pressure difference generated when natural gas flows at a high speed, the flowing effect of a liquid film of an inclined shaft section is effectively improved, water accumulation is avoided, and the stable production period of an oil and gas well is further prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas exploitation, in particular to a downhole self-excited pump and an integrated pipe column. BACKGROUND

[0002] In the prior art, the integrated pipe column can complete multiple works such as separate layer fracturing, gas lift liquid discharge, and oil and gas reservoir protection, so that the process of oil and gas exploitation operation has good continuity. Using the integrated pipe column, continuous gas lift production can be realized without adjusting the pipe column, thereby simplifying the operation procedure and achieving the purpose of increasing production and efficiency. The integrated pipe column gas lift operation is carried out in a manner of external energy, and needs to use a matching device to pump high-pressure medium to carry accumulated liquid to the ground. Once the ground pump is stopped, the oil and gas well in the low-pressure and low-yield period faces the risk of re-accumulation of liquid.

[0003] At present, horizontal wells are the main development wells of gas reservoirs. However, the horizontal well has a greater risk of water production, and the special well structure often affects the liquid discharge of the gas well. The pressure drop loss makes the wellbore flow pressure gradient rise rapidly and leads to serious gas-liquid slip in the inclined well section. Therefore, the pressure drop loss is one of the reasons for the difficulty in liquid discharge of the horizontal well. The liquid film is thickest at the inclined well section of the horizontal well in the low-pressure and low-yield period, and the gas-liquid slip phenomenon is most serious at the 45° inclination angle. Therefore, the key to liquid discharge of the horizontal well must be placed on the liquid discharge of the inclined well section, so as to realize stable production of the horizontal well in the low-pressure stage under the condition of no external energy, thereby improving the recovery rate of oil and gas. SUMMARY

[0004] Based on the above problems existing in the prior art, the present application provides a downhole self-excited pump and an integrated pipe column applied to well types such as high-inclination wells and horizontal wells, which installs the downhole self-excited pump in the inclined well section, can effectively improve the flow effect of the liquid film in the inclined well section, and further prolong the stable production period of the oil and gas well.

[0005] In a first aspect of the present application, a downhole self-excited pump is provided, comprising:

[0006] a working barrel connected to the integrated pipe column, a main body of the working barrel being provided with an eye hole communicating with the radial inner and outer spaces thereof; and

[0007] a self-excited core shaft, comprising a clamping piece for clamping in the main body, and a jetting piece below and connected to the clamping piece, the clamping piece having an axially-through channel, the jetting piece being provided with a power airflow channel communicating with the upper space of the self-excited core shaft and the eye hole, and an accumulated liquid flow channel communicating with the upper and lower spaces of the self-excited core shaft, the power airflow channel and the accumulated liquid flow channel both communicating with the channel through the gap between the jetting piece and the clamping piece,

[0008] The upper end of the power airflow channel is configured to spray the first fluid flowing into the power airflow channel from the hole towards the passage, thereby forming a pressure difference between the gap and the space below the self-excited core shaft, so that the second fluid from the space below the self-excited core shaft can flow upwards along the passage with the first fluid through the hydrops flow channel.

[0009] Further, the lower end of the hydrops flow channel is provided with a plug installed on the spray member by a shear pin to block the communication between the hydrops flow channel and the space below the self-excited core shaft, and the plug is configured to fall off after the shear pin is sheared, thereby connecting the hydrops flow channel and the space below the self-excited core shaft.

[0010] Further, the lower end of the spray member is connected with a fishing barrel, and the lower end of the fishing barrel is configured to be clamped with the upper end of the clamping piece of another self-excited core shaft, so that several self-excited core shafts can be connected in sequence.

[0011] Further, the lower end of the spray member is provided with an extension for connecting the fishing barrel, and the extension and the fishing barrel jointly define a receiving cavity for receiving the fallen plug, and the extension is also provided with a communication hole for communicating the hydrops flow channel and the space below the self-excited core shaft.

[0012] Further, the upper end of the clamping piece is provided with a clamping portion capable of being clamped with the main body of the working barrel, and the clamping portion is provided with a guide protrusion extending radially outward and a bearing protrusion located above the guide protrusion,

[0013] The guide protrusion is configured to abut against the inner wall of the oil pipe of the integrated pipe column, so that the clamping portion elastically deforms radially inward and can be clamped in the guide groove on the inner wall of the main body,

[0014] The bearing protrusion is configured to be clamped in the bearing groove on the inner wall of the main body.

[0015] Further, the lower end of the clamping piece is provided with a connecting slot for being inserted into the spray member, and the gap is formed between the upper end surface of the spray member and the slot surface of the connecting slot.

[0016] Further, the upper end of the power airflow channel is provided with an air nozzle, and the air nozzle is configured to spray the first fluid flowing into the power airflow channel through the one-way valve at the hole towards the passage.

[0017] Further, the self-energizing core shaft further comprises a leakage structure, the leakage structure comprises a mounting groove arranged on the side wall of the nozzle member and / or the clamping member, and a third sealing ring mounted in the mounting groove, the third sealing ring protrudes from the side wall of the nozzle member and / or the clamping member.

[0018] Further, the leakage structure can form a leakage annulus between the inner wall of the tubing of the integrated string, so that the fluid from above the self-energizing core shaft can flush the inner wall of the tubing through the leakage annulus.

[0019] Further, the inner wall of the main body is provided with a reduced diameter portion extending radially inwardly, and the third sealing ring is configured to form an interference fit with the reduced diameter portion after the self-energizing core shaft is clamped with the working barrel.

[0020] In a second aspect of the present application, an integrated string is provided, comprising a vertical shaft section, a horizontal shaft section, and an inclined shaft section connecting the vertical shaft section and the horizontal shaft section, wherein at least one downhole self-energizing pump as described above is arranged in the inclined shaft section.

[0021] Further, the self-energizing core shaft of the downhole self-energizing pump is pumped in the integrated string by liquid nitrogen to form a joint with the main body of the selected working barrel.

[0022] Further, the horizontal shaft section is provided with a circulating sliding sleeve, and an opening tool is clamped in the circulating sliding sleeve, the opening tool is configured to open the circulating sliding sleeve before pumping the self-energizing core shaft, so as to form a pressure difference between the space above and below the self-energizing core shaft.

[0023] Further, the circulating sliding sleeve comprises an outer barrel and an inner barrel slidingly arranged in the outer barrel, and the inner wall of the inner barrel is also provided with a guide groove and a bearing groove capable of being clamped with a guide protruding tooth and a bearing protruding tooth on the opening tool respectively, so that the opening tool can drive the inner barrel to move, so that the hole on the outer barrel is in communication with the inside of the tubing and the external annulus.

[0024] The application can realize the following beneficial effects: the downhole self-priming pump provided by the application comprises a working cylinder connected to an integrated pipe column and a self-priming core shaft arranged in the working cylinder. The main body of the working cylinder is provided with a hole communicating with the inner and outer spaces thereof. The self-priming core shaft comprises a clamping piece for clamping in the main body and a jetting piece connected to the lower part of the clamping piece. The clamping piece has an axial through channel. The jetting piece is provided with a power airflow channel communicating with the upper space of the self-priming core shaft and the hole and a liquid accumulation channel communicating with the upper and lower spaces of the self-priming core shaft, and the power airflow channel and the liquid accumulation channel both communicate with the channel through the gap between the jetting piece and the clamping piece. The upper end of the power airflow channel is configured to enable the first fluid flowing into the power airflow channel from the hole to be jetted towards the channel. Thus, a pressure difference is formed between the gap and the lower space of the self-priming core shaft, so that the second fluid from the lower space of the self-priming core shaft can flow upwards along the channel with the first fluid through the liquid accumulation channel. The first fluid is mainly natural gas, and the second fluid is mainly gas-liquid two-phase fluid. The pressure difference generated by the high-speed flow of natural gas enables the gas-liquid two-phase fluid to be extracted from the lower space of the self-priming core shaft and flow upwards, effectively improving the flow effect of the liquid film in the inclined well section, avoiding water accumulation and further prolonging the stable production period of the oil and gas well. BRIEF DESCRIPTION OF DRAWINGS

[0025] The application will be further described below in combination with the drawings and examples.

[0026] Figure 1 Fig. 1 shows a structural schematic diagram of an integrated pipe column.

[0027] Figure 2 Fig. 2 shows a structural sectional view of a self-priming core shaft in a pumping state in the integrated pipe column.

[0028] Figure 3 Fig. 3 shows a partial enlarged view of the self-priming core shaft in the pumping state in the integrated pipe column, wherein the flow direction of the fluid is indicated by arrows. Figure 2

[0029] Fig. 4 shows a structural sectional view of the self-priming core shaft in a to-position state in the integrated pipe column. Figure 4

[0030] Fig. 5 shows a partial enlarged view of the self-priming core shaft in the to-position state in the integrated pipe column, wherein the flow direction of the fluid is indicated by arrows. Figure 5 Figure 4 Fig. 6 shows a structural sectional view of the downhole self-priming pump 6 in a working state, wherein the flow direction of the fluid is indicated by arrows.

[0031] Figure 6

[0032] ​​Figure 7 Fig. 7 shows a structural sectional view of the circulating sliding sleeve and opening tool.

[0033] Figure 8 Fig. 8 shows a structural sectional view of the fishing tool.

[0034] In the figure, the reference numerals are as follows: 100, integrated pipe column; 1, vertical shaft section; 2, inclined shaft section; 3, horizontal shaft section; 4, oil pipe; 5, gas lift valve; 8, packer; 9, sliding sleeve; 10, ball seat; 11, fishing tool;

[0035] 6, downhole self-priming pump; 61, working barrel; 62, main body; 621, guide groove; 622, bearing groove; 623, eyelet; 624, reduced diameter portion; 63, first joint; 631, first sealing ring; 64, second joint;

[0036] 65, self-priming core shaft; 66, clamping member; 661, clamping portion; 662, guide protrusion; 663, bearing protrusion; 664, barb tooth; 665, connecting groove; 666, passage; 67, jetting member; 671, power airflow channel; 6711, air nozzle; 672, fluid accumulation flow channel; 6721, plug; 6722, second sealing ring; 6723, shear pin; 673, gap; 674, screw; 675, extension; 6751, communication hole; 6752, accommodating cavity; 68, fishing barrel; 681, barb tapered portion; 682, abutting portion;

[0037] 69, flow discharge structure; 691, mounting groove; 692, third sealing ring; 693, flow discharge annular gap;

[0038] 7, circulating sliding sleeve; 71, outer barrel; 711, third joint; 712, fourth joint; 713, hole; 714, shear pin; 72, inner barrel; 73, opening tool; 731, plug ball. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects of the present application more clear, the present application will be described in detail with reference to the accompanying drawings. The drawings are simplified schematic diagrams, and only schematically illustrate the basic structure of the present application, and thus only show the configurations related to the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0040] REFERENCE Figure 1As shown, the integrated tubing string 100 provided by the present invention can be roughly divided into three sections according to the angle when installed in a horizontal well: a vertical shaft section 1 extending vertically into the underground rock formation, a horizontal well section 3 extending horizontally in the underground rock formation, and an inclined shaft section 2 connecting the vertical shaft section 1 and the horizontal well section 3. The integrated tubing string 100 includes a plurality of tubing 4 arranged in series in the vertical shaft section 1, the inclined shaft section 2, and the horizontal well section 3. According to production needs, a plurality of gas lift valves 5 are provided between the plurality of tubing 4 in the vertical shaft section 1, and at least one, preferably a plurality of, downhole self-excited pumps 6 are installed between the plurality of tubing 4 in the inclined shaft section 1. In the direction from the inclined shaft section 2 to the end of the horizontal well, the horizontal well section 3 is sequentially provided with a connecting circulating sleeve 7, an alternately arranged packer 8 and a sleeve 9, and a ball seat 10 connected to the last sleeve 9. Preferably, multiple sets of alternately arranged packers 8 and sleeves 9 are provided.

[0041] refer to Figures 2-6 As shown, in some embodiments, the downhole self-excited pump 6 includes a working cylinder 61 coaxially connected to the tubing 4, and a self-excited mandrel 65 that can be snapped into the working cylinder 61. The working cylinder 61 is pre-installed on the inclined section 2 of the integrated tubing string 100. The self-excited mandrel 65 can be pumped to a predetermined depth into the working cylinder 61 by liquid nitrogen pumping, and the self-excited mandrel 65 and the working cylinder 61 at the predetermined depth form a snap-fit ​​engagement.

[0042] Combination Figure 4 and Figure 6 As shown, in some embodiments, the working cylinder 61 includes a main body 62 capable of engaging with the self-excited mandrel 65, a first connector 63 disposed at the upper end of the main body 62 and coaxially connected to the main body 62, and a second connector 64 disposed at the lower end of the main body 62 and coaxially connected to the main body 62. A first sealing ring 631 is provided between the first connector 63, the second connector 64, and the main body 62 to prevent fluid communication between the annular space outside the downhole self-excited pump 6 and the interior of the downhole self-excited pump 6 between the first connector 63 and the main body 62 and / or between the second connector 64 and the main body 62.

[0043] The inner wall of the main body 62 is provided with at least one circumferential guide groove 621 and at least one circumferential bearing groove 622. The guide groove 621 can engage with the guide protrusion 662 on the downhole self-excited pump 6, and the bearing groove 622 can engage with the bearing protrusion 663 on the downhole self-excited pump 6. Through the engagement of the guide groove 621 and the guide protrusion 662, and the engagement of the bearing groove 622 and the bearing protrusion 663, the working cylinder 61 at a predetermined depth can axially limit the corresponding self-excited mandrel 65. This ensures that the self-excited mandrel 65 can be accurately and reliably engaged in the corresponding working cylinder 61. In some embodiments, the grooves inside the working cylinder 61 (including the guide groove 621 and the bearing groove 622 in the main body 62) are made of erosion-resistant alloy parts to avoid high-speed sand-carrying fluid forming high-speed vortices in the grooves during construction, which would cause erosion damage to the groove surface and other parts, thereby ensuring that the self-excited mandrel 65 can be accurately and reliably engaged in the corresponding working cylinder 61.

[0044] Recombined Figure 6 As shown, the main body 62 is also provided with an eyelet 623 connecting the outer annulus of the working cylinder 61 and the interior of the main body 62. A one-way valve (not shown) is installed at the eyelet 623. The one-way valve ensures that fluid can only flow from the outer annulus of the working cylinder 61 to the interior of the working cylinder 61, and cannot flow in the reverse direction. In some embodiments, when the self-excited mandrel 65 is lowered into place in the integrated tubing 100 and forms an axial limit with the corresponding working cylinder 61, the eyelet 623 on the main body 62 can communicate with the power flow channel 671 (described below) on the self-excited mandrel 65, so that the fluid (e.g., natural gas) in the annulus of the integrated tubing 100 can flow into the power flow channel 671 of the self-excited mandrel 65 through the one-way valve at the eyelet 623. In some preferred embodiments, a gas lift valve core (not shown) can also be installed at the eyelet 623 to control the opening pressure of the one-way valve. Thus, before the self-excited mandrel 65 is assembled into the corresponding working cylinder 61, the working cylinder 61 can act as a gas lift valve. As the external pressure of the oil pipe 4 changes, the multiple working cylinders 61, which act as air lift valves, can be opened or closed in stages to achieve the function of staged air lift.

[0045] In some embodiments, the working cylinder 61 is adapted to a full-bore tubing 4, thereby achieving a full-bore wellbore and meeting the matching requirements of a full-bore fracturing string. The self-excited mandrel 65 can be retrieved using a retrieval tool. After retrieval, the self-excited mandrel 65 inside the working cylinder 61 can still achieve a full-bore wellbore, facilitating the smooth implementation of operations such as drainage and gas production.

[0046] refer to Figure 2 , Figure 4 and Figure 6As shown, in some embodiments, the self-excited mandrel 65 includes a jetting element 67, a snap-fit ​​element 66 mounted on the upper end of the jetting element 67 and axially communicating therewith, and a retrieval cylinder 68 mounted on the lower end of the jetting element 67. The snap-fit ​​element 66 has an axially communicating channel 666, and its upper end has an elastic snap-fit ​​portion 661 capable of radially inward elastic deformation. The guide teeth 662 and the bearing teeth 663, as described above, extend radially outward along the snap-fit ​​portion 661, allowing the snap-fit ​​portion 661 to engage with the body 62. The guide teeth 662 are located below the bearing teeth 663. In some embodiments, when the self-excited mandrel 65 is pumped in the integrated tubing string 100, the snap-fit ​​portion 661 can undergo radially inward elastic deformation under the action of the inner wall of the tubing 4 or the inner wall of the body 62. When the guide tooth 662 encounters a protruding obstacle on the inner wall of the oil pipe 4, the locking part 661 can further undergo radially inward elastic deformation, thereby further reducing the circumferential dimension of the locking part 66 and improving the passability of the self-excited mandrel 65. When the guide tooth 662 and the bearing tooth 663 are aligned with the corresponding guide groove 621 and the bearing groove 622, respectively, the locking part 661 returns to its original shape under its own elastic action, so that the guide tooth 662 and the bearing tooth 663 enter the corresponding guide groove 621 and the bearing groove 622, respectively, to achieve axial positioning of the self-excited mandrel 65.

[0047] In some embodiments, the guide tooth 662 has a trapezoidal cross-section, and the size of the base of the guide tooth 662 is larger than the size of the top of the guide tooth 662. That is, the downward and upward sidewalls of the guide tooth 662 are inclined towards each other, making it easier for the guide tooth 662 to enter the guide groove 621 of the corresponding working cylinder 61. The cross-section of the bearing tooth 663 is preferably a rectangular cross-section, so that the bearing tooth 663 can form an axial engagement with the corresponding bearing groove 622, especially when subjected to large forces, it can still maintain the engagement.

[0048] In some embodiments, multiple working tubes 61 may be pre-installed at different depths of the integrated tubing string 100. These working tubes 61 have different shapes and / or sizes and / or spacings of the bearing grooves 622 and guide grooves 621 to distinguish them from each other. Subsequently, depending on the production status of the horizontal well, technicians can selectively lower a self-excited mandrel 65 into the working tube 61 at the desired depth. At this point, a self-excited mandrel 65 with guide teeth 662 and bearing teeth 663 that conform to the shape, size, and spacing of the bearing grooves 622 and guide grooves 621 on the working tube 61 at the predetermined depth is selected for pumping. This ensures that the self-excited mandrel 65 only forms axial restraint with the corresponding working tube 61 when pumped to the desired well depth. This is well known to those skilled in the art.

[0049] Recombined Figure 2 , Figure 4 and Figure 6 As shown, in some embodiments, the top end of the snap-fit ​​portion 661 is also provided with barbed teeth 664. The barbed teeth 664 can form an axial snap-fit ​​engagement with the retrieval cylinder 68 of another self-excited mandrel 65, thereby facilitating the serial retrieval of the self-excited mandrels 65 and improving retrieval efficiency.

[0050] Refer again Figures 2-6 As shown, in some embodiments, the power airflow channel 671 of the jet member 67 extends from the center of the upper end face of the jet member 67 to the side wall of the jet member 67. Furthermore, the jet member 67 is also provided with a through liquid accumulation channel 672, which extends from the edge of the upper end face of the jet member 67 to the center of the lower end face of the jet member 67. The upper end of the jet member 67 is inserted into the connecting groove 665 located at the bottom of the snap-fit ​​member 66, such that a gap 673 connecting the power airflow channel 671 and the liquid accumulation channel 672 is formed between the upper end face of the jet member 67 and the bottom of the connecting groove 665. In some embodiments, the jet member 67 and the snap-fit ​​member 66 are connected by a screw 674 screwed onto the side wall of the connecting groove 665. In a preferred embodiment, the screw 674 is a ball joint screw, which allows for a certain degree of axial deflection between the jet member 67 and the snap-fit ​​member 66, reducing the connection stiffness between the jet member 67 and the snap-fit ​​member 66, thereby improving the passability of the self-excited mandrel 65. In a preferred embodiment, when the self-excited mandrel 65 encounters a protruding obstacle during pumping in the integrated column 100, the jet 67 will deflect relative to the snap-fit ​​66 under the action of the obstacle and pass through the narrow part caused by the obstacle first, and then the snap-fit ​​661 will pass through the narrow part.

[0051] The lower end of the spraying component 67 is also provided with a hollow extension 675, and a connecting hole 6751 is formed on the circumferential sidewall of the extension 675. The connecting hole 6751 can connect the liquid accumulation channel 672 and the space below the self-excited mandrel 65 in the working cylinder 61. The extension 675 can also be used to connect with the retrieval cylinder 68. In some embodiments, the extension 675 and the retrieval cylinder 68 are connected by means of screwing, bolting, riveting or welding.

[0052] Combination Figure 6As shown, in some embodiments, a nozzle 6711 is provided at the upper opening of the power airflow channel 671, and the upper inner diameter of the nozzle 6711 is smaller than the lower inner diameter. The lower opening of the power airflow channel 671 can communicate with the corresponding orifice 623 on the working cylinder 61, so that the fluid in the annulus outside the working cylinder 61 can flow into the power airflow channel 671 of the injector 67 through the one-way valve at the orifice 623. Since the inner diameter of the nozzle 6711 gradually decreases from bottom to top, the fluid velocity increases when passing through the nozzle 6711. Therefore, even in a horizontal well in a low-pressure, low-production period, the fluid in the annulus of the integrated tubing string 100 can flow into the power airflow channel 671 through the orifice 623 and then be ejected at high speed from the nozzle 6711.

[0053] In some embodiments, a plug 6721 is provided at the lower opening of the liquid flow channel 672, and the plug 6721 is connected to the spray member 67 by a shear pin 6723. A second sealing ring 6722 is provided on the circumferential sidewall of the plug 6721, thereby enhancing the sealing between the plug 6721 and the lower opening of the liquid flow channel 672.

[0054] In some embodiments, the retrieval tube 68 is generally a hollow cylindrical structure open at both ends. The upper end of the retrieval tube 68 is connected to the extension 675, and the lower end of the retrieval tube 68 is provided with a barb cone 681 that can engage with the barb teeth 664 at the tip of the engaging part 661. In this embodiment, the barb cone 681 is provided on the inner wall of the retrieval tube 68 and extends radially inward, while the barb teeth 664 extend radially outward on the engaging part 661. The opposing end faces of the barb cone 681 and the barb teeth 664 are both provided as guide surfaces inclined in the same direction, thereby facilitating the insertion of the engaging part 661 into the retrieval tube 68, thereby forming an axial engagement between the retrieval tube 68 and the engaging part 661.

[0055] Combination Figures 3-6As shown, in some embodiments, the retrieval cylinder 68 is further provided with a supporting portion 682 located on the end face of the extension 675. The supporting portion 682 and the circumferential sidewall of the extension 675 together define a receiving cavity 6752 located within the extension 675. In some embodiments, during the pumping of the self-excited mandrel 65 through the integrated tubing 100 using liquid nitrogen, most of the fluid passes through the channel 666 of the snap-fit ​​member 66 and enters the power airflow channel 671 and the liquid accumulation channel 672 within the jet member 67. This portion of fluid exerts a small force on the inner walls of the power airflow channel 671 and the liquid accumulation channel 672, while the majority of the force is exerted on the end face of the plug 6721, thereby pushing the self-excited mandrel 65 to move rapidly to a predetermined position within the integrated tubing 100. After the self-excited mandrel 65 forms an axial limit with the corresponding working cylinder 61, continued pressure is applied to break the shear pin 6723, thereby allowing the plug 6721 to enter the receiving cavity 6752. At this time, the liquid flow channel 672 is connected to the space below the self-excited mandrel 65 through the connecting hole 6751 on the extension 675.

[0056] Combination Figure 3 As shown, in some embodiments, the self-excited mandrel 65 is further provided with a venting structure 69 located on the circumferential sidewall of the injection member 67 and / or the snap-fit ​​member 66. The venting structure 69 includes an annular mounting groove 691 formed on the circumferential sidewall of the injection member 67 and / or the snap-fit ​​member 66, and a third sealing ring 692 disposed within the mounting groove 691. The third sealing ring 692 protrudes from the circumferential sidewall of the injection member 67 and / or the snap-fit ​​member 66, so that the venting structure 69 can play a boosting role in the pumping of the self-excited mandrel 65, thereby improving the pumping efficiency of the self-excited mandrel 65. The outer diameter of the third sealing ring 692 is smaller than the inner diameter of the integrated tubing string 100 (or the tubing 4 or the working cylinder 61), so that the venting structure 69 can form a venting annular gap 693 between itself and the inner wall of the tubing 4 or the working cylinder 61. This allows the high-pressure fluid to form a high-speed fluid after passing through the drain ring gap 693, thereby flushing away dirt such as sand adhering to the inner wall of the oil pipe 4 or the working cylinder 61, so as to avoid affecting the pumping of the self-excited mandrel 65.

[0057] In some embodiments, the third sealing ring 692 protrudes 0-1.0 mm from the circumferential sidewall of the injection element 67 and / or the snap-fit ​​element 66, and the outer diameter of the third sealing ring 692 is 0-1.0 mm smaller than the inner diameter of the oil pipe 4 or the working cylinder 61, such that the width of the venting annular gap 693 between the venting structure 69 and the inner wall of the oil pipe 4 or the working cylinder 61 is in the range of 0-1.0 mm. In one specific embodiment, the outer diameter of the third sealing ring 692 is 5.3 mm, and the diameter of the groove opening of the mounting groove 691 is 4.3 mm, such that the third sealing ring 692 protrudes 1.0 mm from the circumferential sidewall of the injection element 67 and / or the snap-fit ​​element 66. The width of the venting annular gap 693 between the venting structure 69 and the inner wall of the oil pipe 4 or the working cylinder 61 is 1.0 mm.

[0058] Combination Figure 5 As shown, in some embodiments, a reduced-diameter portion 624 is further provided inside the working cylinder 61 corresponding to the self-excited mandrel 65, located on the inner wall of the main body 62. The reduced-diameter portion 624 extends radially inward along the working cylinder 61. In some embodiments, after the self-excited mandrel 65 is engaged with the corresponding working cylinder 61 and forms a circumferential limit, the third sealing ring 692 forms an interference fit with the reduced-diameter portion 624, thereby forming a seal between the venting structure 69 on the self-excited mandrel 65 and the reduced-diameter portion 624. The upper end of the reduced-diameter portion 624 is provided as a conical surface with an angle not exceeding 15° to ensure that the third sealing ring 692 remains intact when passing through the upper end of the reduced-diameter portion 624, thereby improving the sealing performance. In some preferred embodiments, the reduced diameter portion 624 extends radially inward from the inner wall of the working cylinder 61 by 1.0 mm to 2.0 mm, so that while ensuring that the integrated tubing 100 has a full bore state, a good seal can be formed between the venting structure 69 on the self-excited mandrel 65 and the reduced diameter portion 624.

[0059] The following combination Figures 2-6 This document provides a detailed description of the pumping and positioning states of the self-excited mandrel 65, as well as the working state of the downhole self-excited pump 6.

[0060] Figure 2 and Figure 3The pumping state of the self-excited mandrel 65 within the tubing 4 is shown. The snap-fit ​​portion 661 of the snap-fit ​​member 66 undergoes radially inward elastic deformation under the resistance of the inner wall of the tubing 4, causing the guide teeth 662 and / or the bearing teeth 663 to abut against the inner wall of the tubing 4. Liquid nitrogen injected from the wellhead into the integrated tubing string 100 forms a high-pressure fluid above the self-excited mandrel 65, creating a pressure difference between the upper and lower ends of the self-excited mandrel 65, thereby pumping the self-excited mandrel 65 within the integrated tubing string 100. Part of the high-pressure fluid enters the gap 673 through the channel 666 of the snap-fit ​​member 66, and then is diverted to the power flow channel 671 and the liquid accumulation channel 672, while another part of the high-pressure fluid enters the venting annular gap 693 between the venting structure 69 and the inner wall of the tubing 4 along the outside of the snap-fit ​​member 66. The high-pressure fluid diverted to the power airflow channel 671 merges with the high-pressure fluid in the drain annular gap 693 at the lower opening of the power airflow channel 671, and then flushes the inner wall of the integrated tubing column 100, effectively preventing sand and other dirt on the inner wall of the integrated tubing column 100 from affecting the pumping of the self-excited mandrel 65. Meanwhile, the high-pressure fluid diverted to the liquid accumulation channel 672 acts on the end face of the plug 6721, thereby effectively improving the pumping speed of the self-excited mandrel 65. At the same time, the high-pressure fluid in the drain annular gap 693 also acts on the portion of the third sealing ring 692 that protrudes from the circumferential sidewall of the jet member 67 and / or the snap-fit ​​member 66, thereby further improving the pumping efficiency of the self-excited mandrel 65.

[0061] Figure 4 , Figure 5 and Figure 6 The image shows the self-excited mandrel 65 in its positioned position within the working cylinder 61. At this point, the self-excited mandrel 65 is axially confined to the working cylinder 61 at a predetermined depth. A seal is formed between the venting structure 69 on the self-excited mandrel 65 and the reduced-diameter portion 624 on the inner wall of the working cylinder 61, and the lower opening of the power airflow passage 671 connects to the orifice 623 on the main body 62. Because of the one-way valve installed at the orifice 623, fluid can only flow from the annular space outside the working cylinder 61 to the inside of the working cylinder 61, and cannot flow in the opposite direction. Therefore, continued pressurization at the wellhead allows high-pressure fluid to act on the upper surface of the plug 6721, causing the plug 6721 to break the shear pin 6723 and enter the receiving cavity 6752 of the extension 675. Thus, the downhole self-excited pump 6 enters its working state.

[0062] Figure 6This indicates that the downhole self-excited pump 6 is in operation. At this time, the lower opening of the power flow channel 671 connects to the orifice 623 on the main body 62, and the liquid flow channel 672 connects to the space below the self-excited mandrel 65 through the connecting hole 6751 on the side wall of the extension 675, so that both the power flow channel 671 and the liquid flow channel 672 are open. The first fluid (mainly low-pressure natural gas) in the annulus outside the integrated tubing string 100 can enter the power flow channel 671 through the one-way valve at the orifice 623, and then be ejected at high speed through the nozzle 6711 at the upper opening of the power flow channel 671, reducing the pressure in the gap 673 between the upper end face of the injector 67 and the bottom of the connecting groove 665. Under the action of the pressure difference, the second fluid (mainly gas-liquid two-phase fluid) located in the space below the self-excited mandrel 65 passes through the connecting hole 6751 on the extension 675 and enters the liquid flow channel 672, and then enters the gap 673 from the liquid flow channel 672. The first fluid carries the second fluid within the gap 673 and flows along the channel 666 toward the wellhead, thereby effectively improving the liquid film flow effect in the inclined section 2 and extending the self-flowing period of the horizontal well.

[0063] In some specific implementations, based on production parameters such as gas production, liquid production, and gas-liquid ratio of the horizontal well, the self-excited mandrel 65 is pumped to a well section with an inclination angle between 30° and 60° and engaged with the corresponding working cylinder 61, thereby turning on this stage of the downhole self-excited pump 6 and putting it into operation. All other stages of self-excited pumps above this stage remain shut down.

[0064] In some specific embodiments, based on production parameters such as gas production, fluid production, and gas-liquid ratio of the horizontal well, multiple self-excited mandrels 65 can be sequentially pumped into the inclined section 2 of the horizontal well and engaged with multiple corresponding working cylinders 61, thereby opening the multi-stage downhole self-excited pumps 6 and putting them into operation, further improving the liquid film flow effect of the inclined section 2 and extending the self-flowing period of the horizontal well. Specifically, since one-way valves and / or gas lift valve cores with specific opening pressures are installed at the orifice 623, when the pressure outside the tubing 4 is greater than the opening pressure of some one-way valves and / or gas lift valve cores, the downhole self-excited pumps 6 containing these one-way valves and / or gas lift valve cores are in the open state. When the pressure outside the tubing 4 is less than the opening pressure of some one-way valves and / or gas lift valve cores, the downhole self-excited pumps 6 containing these one-way valves and / or gas lift valve cores are in the closed state. Thus, selective opening of one or more stages of downhole self-excited pumps 6 is achieved.

[0065] refer to Figure 7As shown, the present invention also provides a circulating sleeve 7 installed on an integrated tubing string 100, and an opening tool 73 for opening the circulating sleeve 7. The circulating sleeve 7 includes an outer cylinder 71 coaxial with the integrated tubing string 100, and an inner cylinder 72 sleeved inside the outer cylinder 71. The upper end of the outer cylinder 71 is sealed with a third connector 711 for connecting to an oil pipe 4, and the lower end of the outer cylinder 71 is sealed with a fourth connector 712 for connecting to a packer 8. A hole 713 for communicating between the inside and outside annulus of the oil pipe 4 is installed on the side wall of the outer cylinder 71, and a shear pin 714 for fixing the inner cylinder 72 is also installed on the outer cylinder 71.

[0066] In some embodiments, the inner wall of the inner cylinder 72 is also provided with a guide groove 621 and a bearing groove 622 for engaging the corresponding opening tool 73, and the outer wall of the inner cylinder 72 is in sealing contact with the inner wall of the outer cylinder 71. When the inner cylinder 72 blocks the hole 713 on the circulating sleeve 7, the upper end face of the inner cylinder 72 abuts against the end face of the third connector 711. When the inner cylinder 72 does not block the circulating sleeve 7, the lower end face of the inner cylinder 72 abuts against the end face of the fourth connector 712.

[0067] In some embodiments, the opening tool 73 is generally a hollow cylindrical structure open at both ends. The opening tool 73 has a plugging ball 731 inside for sealing, and guide teeth 662 and bearing teeth 663 on the outside that can engage with the corresponding circulating sleeve 7. The upper end of the opening tool 73 also has barbed teeth 664.

[0068] In some embodiments, the opening tool 73 can be pumped to the corresponding circulating sleeve 7 using liquid nitrogen pumping, and then engage with the circulating sleeve 7 to form an axial limit. With continued pressurization at the wellhead, the plugging ball 731 pushes the inner cylinder 72 through the opening tool 73 to cut off the shear pin 714, and then the lower end face of the inner cylinder 72 abuts against the end face of the fourth connector 712. At this time, the upper end face of the inner cylinder 72 is located below the hole 713. The circulating sleeve 7 is opened, and the hole 713 connects the inside and outside annulus of the tubing 4.

[0069] refer to Figure 8As shown, the present invention also provides a retrieval tool 11 for retrieving the self-excited mandrel 65 or the opening tool 73. The structure of the retrieval tool 11 is roughly the same as that of the retrieval cylinder 68, and the lower end of the retrieval tool 11 is also provided with a barbed cone 681 for engaging with the barbed teeth 664. The upper end of the retrieval tool 11 is used to connect to a steel wire or a continuous tubing, thereby facilitating the lowering of the retrieval tool 11 into the integrated tubing string 100. The difference is that the retrieval tool 11 does not have a retaining part 682 inside, to ensure that the axial flow of the retrieval tool 11 is unobstructed. This allows the top end of the self-excited mandrel 65 to be easily inserted into the retrieval tool 11, thereby improving the success rate of retrieving the self-excited mandrel 65 individually or in a series. On the other hand, it also allows the retrieval operation to be carried out while the integrated tubing string 100 is circulating fluid with the pump running.

[0070] Based on the integrated tubular column 100 provided above, the present invention also provides a construction method, comprising the following steps:

[0071] In step S1, the underground rock strata are subjected to graded fracturing.

[0072] In step S2, rapid liquid removal is achieved by air lift using the integrated tubing 100.

[0073] In step S3, the gas well begins to produce gas.

[0074] In step S4, the gas well enters a low-pressure, low-production period and gradually begins to produce liquid accumulation. At an appropriate time, self-excited drainage gas production is carried out.

[0075] In the process of self-excited drainage and gas production, the opening tool 73 is first pumped to a predetermined position using liquid nitrogen. The opening tool 73 engages with and opens the circulating sleeve 7, connecting the internal and external annulus of the tubing 4. Then, one or more self-excited mandrels 65 are sequentially pumped to predetermined positions using liquid nitrogen and engaged with their respective working cylinders 61, thus assembling a downhole self-excited pump 6. During the pumping of the self-excited mandrel 65, the gas in the space below the self-excited mandrel 65 enters the external annulus of the integrated tubing string 100 through the holes 713 of the circulating sleeve 7, creating a pressure difference above and below the self-excited mandrel 65, thereby successfully pumping the self-excited mandrel 65 into position. Finally, the downhole self-excited pump 6 is activated for drainage and gas production.

[0076] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0077] It should be understood that the terms "length", "width", "up", "down", "front and back", "left and right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0078] The above description, based on the preferred embodiments of the present invention, provides guidance. Those skilled in the art can make various changes and modifications without departing from the scope of the invention. The technical scope of this invention is not limited to the contents of the specification but must be determined according to the claims.

Claims

1. A downhole self-excited pump, comprising: A working cylinder (61) connected to an integrated tubular column (100), the main body (62) of the working cylinder (61) having an aperture (623) communicating with its radially inner and outer spaces; and The self-excited mandrel (65) includes a snap-fit ​​member (66) for snapping into the body (62), and an injection member (67) located below and connected to the snap-fit ​​member (66). The snap-fit ​​member (66) has an axially penetrating channel (666). The injection member (67) has a power airflow channel (671) connecting the upper space of the self-excited mandrel (65) and the orifice (623), and a liquid accumulation channel (672) connecting the upper space and the lower space of the self-excited mandrel (65). Both the power airflow channel (671) and the liquid accumulation channel (672) are connected to the channel (666) through a gap (673) located between the injection member (67) and the snap-fit ​​member (66). The upper end of the power airflow channel (671) is configured to allow the first fluid flowing into the power airflow channel (671) through the orifice (623) to be ejected toward the channel (666), thereby creating a pressure difference between the gap (673) and the space below the self-excited mandrel (65), so that the second fluid from the space below the self-excited mandrel (65) can flow upward along the channel (666) with the first fluid through the liquid accumulation channel (672).

2. The downhole self-excited pump according to claim 1, characterized in that, The lower end of the liquid flow channel (672) is provided with a plug (6721) installed on the spray member (67) by a shear pin (6723) to block the communication between the liquid flow channel (672) and the space below the self-excited mandrel (65). The plug (6721) is configured to fall off after the shear pin (6723) is cut off, thereby allowing communication between the liquid flow channel (672) and the space below the self-excited mandrel (65).

3. The downhole self-excited pump according to claim 2, characterized in that, The lower end of the spraying component (67) is connected to a retrieval tube (68), the lower end of which is configured to engage with the upper end of the snap-fit ​​component (66) of another self-excited spindle (65), so that a number of self-excited spindles (65) can be connected in sequence.

4. The downhole self-excited pump according to claim 3, characterized in that, The lower end of the spraying component (67) is provided with an extension (675) for connecting the retrieval tube (68). The extension (675) and the retrieval tube (68) together define a receiving cavity (6752) for receiving the fallen plug (6721). The extension (675) is also provided with a connecting hole (6751) for connecting the liquid flow channel (672) and the space below the self-excited mandrel (65).

5. The downhole self-excited pump according to claim 1, characterized in that, The upper end of the snap-fit ​​member (66) is provided with a snap-fit ​​part (661) that can snap into the main body (62) of the working cylinder (61). The snap-fit ​​part (661) is provided with a guide tooth (662) extending radially outward and a bearing tooth (663) located above the guide tooth (662). The guide tooth (662) is configured to abut against the inner wall of the oil pipe (4) of the integrated tubing string (100), causing the locking part (661) to undergo radial inward elastic deformation and engage with the guide groove (621) on the inner wall of the main body (62). The bearing protrusion (663) is configured to engage with the bearing groove (622) on the inner wall of the body (62).

6. The downhole self-excited pump according to claim 1, characterized in that, The lower end of the snap-fit ​​member (66) is provided with a connecting groove (665) for inserting the spray member (67), and the gap (673) is formed between the upper end surface of the spray member (67) and the groove surface of the connecting groove (665).

7. The downhole self-excited pump according to claim 1, characterized in that, The upper end of the power airflow channel (671) is provided with a nozzle (6711), which is configured to spray the first fluid that flows into the power airflow channel (671) through the one-way valve at the orifice (623) toward the channel (666).

8. The downhole self-excited pump according to any one of claims 1-7, characterized in that, The self-excited mandrel (65) further includes a drainage structure (69), which includes a mounting groove (691) disposed on the side wall of the jetting member (67) and / or the snap-fit ​​member (66), and a third sealing ring (692) installed in the mounting groove (691), the third sealing ring (692) protruding from the side wall of the jetting member (67) and / or the snap-fit ​​member (66).

9. The downhole self-excited pump according to claim 8, characterized in that, The venting structure (69) can form a venting annular gap (693) between itself and the inner wall of the oil pipe (4) of the integrated tubing string (100), so that fluid from above the self-excited mandrel (65) can pass through the venting annular gap (693) and flush the inner wall of the oil pipe (4).

10. The downhole self-excited pump according to claim 8, characterized in that, The inner wall of the main body (62) is provided with a radially inwardly extending reduced diameter portion (624), and the third sealing ring (692) is configured to form an interference fit with the reduced diameter portion (624) after the self-excited mandrel (65) is engaged with the working cylinder (61).

11. An integrated tubing string, comprising a vertical shaft section (1), a horizontal shaft section (3), and an inclined shaft section (2) connecting the vertical shaft section (1) and the horizontal shaft section (3), wherein, At least one downhole self-excited pump (6) according to any one of claims 1 to 9 is provided in the inclined section (2).

12. The integrated tubular column according to claim 11, characterized in that, The self-excited mandrel (65) of the downhole self-excited pump (6) is pumped with liquid nitrogen within the integrated tubing string (100) to form an engagement with the body (62) of the selected working barrel (61).

13. The integrated tubular column according to claim 11, characterized in that, The well section (3) is provided with a circulating sleeve (7), and an opening tool (73) is engaged inside the circulating sleeve (7). The opening tool (73) is configured to open the circulating sleeve (7) before pumping the self-excited mandrel (65), so that a pressure difference is formed between the space above and below the self-excited mandrel (65).

14. The integrated tubular column according to claim 13, characterized in that, The circulating sleeve (7) includes an outer cylinder (71) and an inner cylinder (72) slidably disposed within the outer cylinder (71). The inner wall of the inner cylinder (72) is also provided with a guide groove (621) and a bearing groove (622) that can respectively engage with the guide protrusion (662) and the bearing protrusion (663) on the opening tool (73), so that the opening tool (73) can drive the inner cylinder (72) to move, so that the hole (713) on the outer cylinder (71) connects the interior and exterior annulus of the oil pipe (4).

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