Pressure-controlled shaft drainage device and system and drainage control method

Abstract

The invention provides a pressure-controlled shaft liquid drainage device and system and a liquid drainage control method.The liquid drainage device comprises a liquid drainage pipe, a top disc and a bottom disc, the top disc and the bottom disc are arranged at the two ends of the liquid drainage pipe respectively, the top disc is connected with the bottom end of an oil pipe, and a pressure-controlled switch part capable of blocking or opening the interior of the liquid drainage pipe under the action of internal pressure is arranged in the liquid drainage pipe; the chassis and the switch piece for blocking the liquid discharge pipe seal a shaft bottom space at the bottom of the shaft, so that the shaft bottom space is subjected to pressure building; when the pressure of the shaft bottom space is kept higher than the preset internal pressure of the switch piece, the switch piece is forced to open the liquid discharge pipe, so that gas in the shaft bottom space carries liquid to be discharged through the liquid discharge pipe and the oil pipe. Based on the technical scheme, the liquid drainage device is very simple in structure and actual operation, pressure building and liquid drainage can be automatically carried out based on the bottom hole pressure, and then a large amount of underground liquid is effectively prevented from being accumulated, so that continuous and stable liquid drainage production of a gas well is guaranteed, liquid accumulation of a shaft is prevented, and the production time rate of the gas well is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of gas well drainage and gas production, and in particular to a pressure-controlled wellbore drainage device, system and drainage control method. Background Art

[0002] During natural gas extraction, drainage is often necessary. Traditional methods, both domestically and internationally, typically involve optimizing tubing strings, gas lift, bubble drainage, plunger lift, mechanical pumping, electric submersible pumps, jet pumps, and combined processes (such as optimizing tubing strings-bubble drainage, gas lift-bubble drainage, or pressurization-gas lift-bubble drainage).

[0003] Among them, the optimal tubing string is to improve the water-carrying capacity of the airflow by optimizing the diameter of the oil pipe, so as to discharge the liquid accumulated at the bottom of the well; gas lift is to inject high-pressure natural gas into the well from the ground through the gas lift valve, and use the energy of the gas to lift the liquid in the wellbore to restore the production capacity of the well; foam drainage is to add a foaming agent from the wellhead to turn the downhole liquid into light foam, which is brought to the ground under the stirring of the airflow; plunger lift is to use the plunger as the mechanical interface between the gas and the liquid, relying on the original gas pressure of the gas well to move the piston up and down in the oil pipe to bring out the liquid in the well; mechanical pumping, submersible pump and jet pump are to use mechanical methods to achieve the purpose of pumping and draining water in the pipe.

[0004] However, the above-mentioned means currently widely used are mainly applicable when the bottom hole pressure is high or the wellbore liquid volume is not large. When the bottom hole energy of the gas well is insufficient, the bottom hole pressure is low, and the wellbore water volume is large, the gas production of the gas well is greatly reduced, and the above-mentioned gas-liquid separation, bubble drainage, gas lift and other methods cannot be used; and the preferred composite processes such as tubing-bubble drainage, gas lift-bubble drainage, pressurization-gas lift-bubble drainage are relatively complicated to use, with a large workload, cumbersome procedures and low efficiency. Summary of the Invention

[0005] In order to solve the problem that existing gas well drainage means cannot effectively drain water when the bottom hole pressure of the gas well is low and the wellbore water volume is large, the present invention proposes a pressure-controlled wellbore drainage device, system and drainage control method.

[0006] In a first aspect, the present invention provides a pressure-controlled wellbore drainage device, comprising a drainage pipe and a top plate and a bottom plate, respectively disposed at both ends of the drainage pipe, wherein the top plate is connected to the bottom end of the oil pipe, and the center of each of the top plate and the bottom plate is provided with a drainage port connected to the drainage pipe. The drainage pipe is provided with a pressure-controlled switch capable of blocking or opening the drainage pipe under the action of internal pressure;

[0007] Among them, when the drainage device is lowered into the bottom of the wellbore along with the oil pipe, the chassis and the switch component that blocks the drainage pipe isolate the bottom hole space at the bottom of the wellbore, so that the bottom hole space is pressurized; when the bottom hole space is pressurized to a pressure greater than the preset internal pressure of the switch component, the switch component is forced to open the drainage pipe, so that the gas in the bottom hole space carries the liquid and is discharged through the drainage pipe and the oil pipe.

[0008] In one embodiment, when the drainage device is lowered into the bottom of the wellbore along with the oil pipe, the top plate, the drainage pipe, the bottom plate and the casing of the wellbore form an annulus area, and the annulus area is connected to the pressure control equipment on the well via a pressurized pipeline;

[0009] Wherein, a pressure compensation port connecting the annular space and the bottom hole space is opened on the chassis, and a first one-way valve is provided at the pressure compensation port.

[0010] In one embodiment, the switch member is constructed as an annular pressure-controlling rubber sleeve that can be filled with a pressure medium. The pressure-controlling rubber sleeve can expand radially inward under the pressure of the pressure medium to block the drain pipe and can contract radially outward under external pressure to open the drain pipe.

[0011] In one embodiment, a pressure charging port communicating with the inner space of the pressure-controlling rubber sleeve is provided on the wall of the liquid discharge pipe, and a second one-way valve is provided at the pressure charging port.

[0012] In one embodiment, the top plate includes an upper plate body and a lower plate body respectively connected to the oil pipe and the drain pipe and capable of relative movement, one end of the pressure-control rubber sleeve abuts against the bottom plate, and the other end is partially embedded in the interior of the top plate and abuts against the inner side surface of the upper plate body;

[0013] Wherein, the upper plate body can move in the axial direction of the drain pipe in the direction away from the bottom plate as the oil pipe is lifted up, so that the pressure-controlling rubber sleeve can stretch in the axial direction of the drain pipe.

[0014] In one embodiment, a pressure-controlled clamping seat is provided at the edge of the chassis, and the pressure-controlled clamping seat can be released under a pressure greater than a release pressure value to clamp the casing of the wellbore, so that the drainage device is positioned at a predetermined position at the bottom of the well;

[0015] The pressure-controlled holder can also be retracted when the lifting body of the oil pipe reaches a retraction pressure value, so that the chassis and the drainage device are lifted up and out of the wellbore as a whole by the oil pipe.

[0016] In one embodiment, a third one-way valve is provided at the drain port of the chassis.

[0017] In one embodiment, the diameters of the drainage ports of the top plate and the bottom plate are both smaller than the inner diameter of the drainage pipe.

[0018] In one embodiment, the system further comprises at least three pressure detection units, which are respectively used to detect the pressure inside the drainage pipe, the internal pressure of the switch element, and the pressure of the bottom well space.

[0019] In a second aspect, the present invention provides a pressure-controlled wellbore fluid drainage system, which includes the above-mentioned fluid drainage device, an uphole control device, and a remote pressure detection device;

[0020] The uphole control device is connected to the oil pipe and is used to control the lowering and lifting of the oil pipe; the remote pressure detection device is electrically connected to the pressure detection unit in the liquid discharge device and is used to obtain the corresponding pressure value.

[0021] In a third aspect, the present invention provides a method for controlling liquid discharge, which comprises the following steps:

[0022] When the drainage device is lowered along the oil pipe to a predetermined position at the bottom of the wellbore, a pressure medium is injected into the annulus area surrounded by the casing of the wellbore and the top plate, drainage pipe and bottom plate of the drainage device;

[0023] The pressure medium is allowed to enter the pressure-controlling rubber sleeve inside the discharge pipe through the pressure charging port on the discharge pipe, so that the pressure-controlling rubber sleeve expands and the pressure reaches a preset internal pressure, and the preset internal pressure is not less than the minimum liquid-carrying pressure of the bottom hole gas;

[0024] The oil pipe is opened. When the pressure of the bottom hole space isolated by the chassis is greater than the preset internal pressure, the gas and water in the bottom hole space circulate and compress the pressure-control rubber sleeve and are discharged to the outside through the drainage pipe and the oil pipe. When the pressure of the bottom hole space is less than the preset internal pressure, the pressure is held until the pressure is greater than the preset internal pressure.

[0025] In one embodiment, the following steps are also included:

[0026] In response to detecting that the pressure of the bottom hole space is too low, the pressure medium is injected into the annulus area, so that the pressure medium enters the bottom hole space through the pressure compensation port on the bottom plate to increase the pressure of the bottom hole space.

[0027] In one embodiment, the following steps are also included:

[0028] In response to detecting that the pressure of the pressure-controlling rubber sleeve is too high, lifting the oil pipe;

[0029] The upper plate of the top plate moves away from the bottom plate along with the oil pipe, so that the end of the pressure-control rubber sleeve abutting the upper plate can stretch and expand the volume of the internal space along with the movement of the upper plate, thereby reducing the internal pressure.

[0030] In one embodiment, when the fluid discharge device is lowered along the oil pipe to a predetermined position at the bottom of the wellbore, the method further comprises:

[0031] Injecting pressure medium into the annular space until the pressure reaches the release pressure of a pressure-controlled clamping seat provided at the edge of the bottom plate, so that the pressure-controlled clamping seat releases and clamps the casing, thereby positioning the drainage device at the predetermined position;

[0032] The pressure medium is continuously injected into the annular space to expand the pressure-controlling rubber sleeve and reach a preset internal pressure, which is greater than the release pressure.

[0033] The above technical features can be combined in various suitable ways or replaced by equivalent technical features, as long as the purpose of the present invention can be achieved.

[0034] The pressure-controlled wellbore fluid drainage device, system, and fluid drainage control method provided by the present invention have at least the following beneficial effects compared to the prior art:

[0035] The present invention provides a pressure-controlled wellbore fluid drainage device, system, and drainage control method. The drainage device is simple in both structure and operation, automatically maintaining pressure and draining fluid based on bottomhole pressure. The drainage device, along with the corresponding system and method, effectively prevents large amounts of fluid from accumulating downhole, thereby ensuring continuous and stable drainage and production in gas wells. This effectively avoids wellbore fluid accumulation and increases gas well production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0037] Figure 1 Shows a schematic structural diagram of the liquid discharge device of the present invention;

[0038] Figure 2 A schematic diagram showing the on / off state of the second one-way valve of the liquid discharge device of the present invention is shown;

[0039] Figure 3 A schematic diagram showing the on / off state of the first one-way valve of the liquid discharge device of the present invention is shown;

[0040] Figure 4 A schematic diagram showing the switching state of the third one-way valve of the liquid discharge device of the present invention is shown.

[0041] In the drawings, like reference numerals are used for like parts, but the drawings are not necessarily true to scale.

[0042] Reference numerals:

[0043] 1-drain pipe, 11-switch component, 12-second one-way valve, 2-top plate, 3-bottom plate, 31-third one-way valve, 32-first one-way valve, 33-pressure control seat, 4-oil pipe, 5-annulus area, 6-bottom hole space, 7-pressure control equipment, 8-pressure detection unit, 9-casing. DETAILED DESCRIPTION

[0044] Based on some of the existing means mentioned in the aforementioned background technology, some relevant specific technical solutions are also listed below to further understand the technical background and application scenarios of the present invention.

[0045] (1) A gas-liquid separation device for a certain gas well, including a wellbore, a submersible pump, a gas production and liquid drainage structure, a packer, etc. Taking advantage of the fact that the specific gravity of liquid is greater than that of gas, the liquid inlet is set below the gas inlet, and combined with the gas-liquid separation function of the submersible pump itself, the separation of gas and liquid phases is achieved, which can solve the problems of liquid accumulation and flooding in water-producing wells or oil-water-gas producing wells with weak supply capacity.

[0046] (2) A certain self-energizing drainage and gas production process first prepares a solid self-energizing agent, which is then added to the accumulated liquid in the wellbore through the self-energizing drainage and gas production system. The well is shut down for a period of time to allow the self-energizing agent to dissolve. After the self-energizing agent is completely dissolved, the well is opened. The dissolved self-energizing agent reacts to generate gas and heat, and generates foam, thereby achieving the purpose of drainage and gas production in the gas well.

[0047] (3) A certain oil and gas well drainage device, comprising a gas-liquid separation tank, which is arranged on a connecting pipeline between the wellhead gas tree and the gas gathering station transmission pipeline. The inner cavity of the gas-liquid separation tank is divided into an air-oil chamber and a liquid chamber. The air-oil chamber is connected to the gas main pipe and the wellhead gas tree, and the liquid chamber is connected to the liquid storage chamber of the gas-liquid isolation tank. The present invention can separate and discharge the liquid accumulated in the wellbore of the liquid-containing oil and gas well, thereby ensuring the ability of the natural gas in the wellbore to carry the liquid accumulated downhole.

[0048] (4) A certain U-tube gas lift drainage device mainly uses a U-tube structure to prevent liquid slippage. The device's liquid collection pipe consists of a liquid discharge control valve, a U-tube, an air injection valve, and a liquid inlet, which are connected to each other. The liquid outlet is connected to the liquid collection pipe of the liquid discharge control valve. The air inlet of the air supply pipe on the ground is connected to the air supply control valve, and the air outlet of the air supply pipe is connected to the wellbore or to the air injection valve on the liquid collection pipe in the wellbore. The whole constitutes a U-tube drainage structure that is easy to operate.

[0049] (5) A vortex drainage and gas production tool is designed with a protective shell. The side wall of the protective shell near the upper end is penetrated by a plurality of first separation holes. The inner wall of the upper end is provided with two annular grooves. A rotating rod is connected to the inside of the protective shell through a bearing. The tool quickly collects water and gas in the well through the connecting rod and fan blades. The turbulent water and gas are converted into a vortex flow through the rotating transport roller and guide groove. The rotating rod and threaded fan blades quickly raise the water and gas in the vortex device, and at the same time, the water is thrown out through the rotating separation cylinder. It is easy to use.

[0050] (6) Some intelligent drainage and gas production equipment, including a delivery pipe, a liquid cooling pipe, a T-shaped sleeve, a sealing head, a filter, a water pump, a plate-fin heat exchanger, a gas-liquid separation tank, etc. The equipment is provided with a filter to filter out mud and rock particles in the water, thereby preventing mud and rock particles from mixing into the gas-liquid separation tank and damaging the high-pressure water pump, thereby improving the protection of the high-pressure water pump; by installing a plate-fin heat exchanger, the coolant in the liquid cooling pipe is circulated through the water pump and the plate-fin heat exchanger for heat exchange, so that the coolant can always maintain a low temperature, thereby improving the cooling effect and reducing the time consumption caused by the replacement of the coolant.

[0051] The purpose of listing the above technical solutions is only to facilitate understanding of the relevant technical background of the present invention. The corresponding technical solutions are only the technical solutions understood by the people who made the present invention, and do not necessarily represent the public existing technology.

[0052] The present invention will be further described below with reference to the accompanying drawings.

[0053] Example 1

[0054] An embodiment of the present invention provides a pressure-controlled wellbore drainage device, including a drainage pipe 1 and a top plate 2 and a bottom plate 3 respectively arranged at both ends of the drainage pipe 1, and the top plate 2 is connected to the bottom end of the oil pipe 4. The centers of the top plate 2 and the bottom plate 3 are both provided with drainage ports connected to the drainage pipe 1, and a pressure-controlled switch 11 is provided in the drainage pipe 1, which can block or open the drainage pipe 1 under the action of internal pressure.

[0055] Among them, when the drainage device is lowered into the bottom of the wellbore along with the oil pipe 4, the chassis 3 and the switch component 11 that blocks the drainage pipe 1 seal off the bottomhole space 6 at the bottom of the wellbore, so that the bottomhole space 6 is pressurized; when the bottomhole space 6 is pressurized to a pressure greater than the preset internal pressure of the switch component 11, the switch component 11 is forced to open the drainage pipe 1, so that the gas in the bottomhole space 6 carries the liquid and is discharged through the drainage pipe 1 and the oil pipe 4.

[0056] Specifically, as shown in the accompanying drawings Figure 1As shown, the invented pressure-controlled wellbore drainage device is integrally arranged at the bottom of the oil pipe 4 and can be lowered into the well or pulled out from the well along with the oil pipe 4. The pressure-controlled wellbore drainage device mainly comprises three parts in structure, namely the drainage pipe 1 and the top plate 2 and bottom plate 3 respectively arranged at the two ends of the drainage pipe 1. The top plate 2 and the bottom plate 3 are both disc-shaped structures, with an outer diameter larger than the drainage pipe 1 and matching the radial size of the wellbore (specifically, matching the inner diameter of the casing 9 of the wellbore). The centers of the top plate 2 and the bottom plate 3 are connected to the ends of the drainage pipe 1, and the drainage ports (not specifically marked in the drawings) in the centers of the top plate 2 and the bottom plate 3 are correspondingly connected to the ports of the drainage pipe 1.

[0057] More importantly, the interior of the drainage tube 1 is equipped with a pressure-controlled switch element 11. This switch element 11 is a movable structure. As its name suggests, its primary function is to block or open the drainage tube 1 under pressure, that is, to block or open the passage within the drainage tube 1. The control principle of the switch element 11 is that the switch element 11 itself is preset with an internal pressure. This internal pressure acts to cause the switch element 11 to tend to block the drainage tube 1. In other words, if there is no sufficiently strong external force, the internal pressure of the switch element 11 will drive the switch element 11 to move, thereby blocking the drainage tube 1. The specific method for setting the internal pressure of the switch element 11 or the structure used to provide and achieve it can be selected as needed. For example, a preloaded spring or other structure capable of providing pressure can be installed on the switch element 11, with the pressure exerted on the switch element 11 by the spring's elastic force acting as the aforementioned internal pressure. Alternatively, the switch element 11 can be directly configured to have a deformable capacity, which can be achieved through an elastic structure or elastic material, with the elastic force generated by the deformation of the switch element 11 itself serving as its internal pressure.

[0058] When in use, the pressure-controlled wellbore drainage device is installed at the bottom of the oil pipe 4 through the connection between the top plate 2 and the bottom end of the oil pipe 4, and can then be lowered into the well bottom along with the oil pipe 4. After reaching the well bottom, since the size of the bottommost bottom plate 3 matches the size of the wellbore, the bottom plate 3 isolates a relatively independent well bottom space 6 at the well bottom, as shown in the figure Figure 1As shown. In the application scenario of the present invention, the state of the target wellbore is insufficient production (small amount of gas) and high amount of water, so the bottom hole pressure is small and the energy is insufficient. At this time, the gas cannot carry the liquid to discharge. Therefore, after the drainage device is lowered into the bottom of the well, the pressure of the isolated bottom hole space 6 is small, which is less than the internal pressure of the switch 11 (the internal pressure can be adjusted in advance according to the specific situation of the wellbore and the needs, but it is usually necessary to ensure that the preset internal pressure is not less than the minimum pressure at which the gas can carry the liquid to form a gas-water mixed fluid to flow, so as to ensure that the gas flow rate is always higher than the minimum liquid-carrying gas flow rate). Therefore, the switch 11 is in a state of blocking the drainage pipe 1 at this time, and then the bottom hole space 6 is completely and independently isolated to form a relatively closed cavity. Based on this relatively closed bottom hole space 6, although the gas production of the wellbore is small, it will continue to produce gas over time, so the gas volume in the bottom hole space 6 will gradually increase, thereby continuously holding back the pressure and the bottom hole pressure will also continue to increase. When the pressure in the bottom hole space 6 increases to a level greater than the internal pressure of the switch element 11, the internal pressure of the switch element 11 will be overcome, forcing the switch element 11 to move and open the drainage pipe 1. At this time, the bottom hole space 6 is connected to the oil pipe 4 through the opened drainage pipe 1, so the bottom hole gas with sufficient pressure can carry the bottom hole liquid out, realizing automatic drainage under pressure control.

[0059] From the above content, it can be seen that the drainage device of the present invention is very simple in structure and actual operation, and can automatically hold pressure and drain liquid based on the bottom hole pressure. After a drainage cycle is completed, a large amount of liquid at the bottom of the well can basically be effectively discharged, and the liquid accumulated at the bottom of the well in the subsequent production process can be carried out in real time as the production is carried out, which can effectively avoid the accumulation of a large amount of liquid in the well, thereby ensuring the continuous and stable drainage production of the gas well, effectively avoiding the occurrence of liquid accumulation in the wellbore, and improving the production time of the gas well. Even if the wellbore is accidentally filled with liquid again, a drainage cycle can be automatically repeated based on the same principle to drain the liquid again.

[0060] Preferably, a third one-way valve 31 is provided at the drain port of the chassis 3 .

[0061] Specifically, as shown in FIG. Figure 1 As shown, a third one-way valve is provided on the chassis at the drainage port for connecting the bottom well space to the drainage pipe. The main function of the third one-way valve is to prevent gas-liquid backflow. Based on the setting of the third one-way valve, in the initial state (i.e. the state where the switch component blocks the drainage pipe), the bottom well space is small and the third one-way valve is closed. At this time, the bottom well space forms an independent cavity (pressure is represented by P5), and the space inside the drainage pipe between the closed switch component and the chassis forms an independent cavity (pressure is represented by P4). Therefore, during the pressure holding process, the pressure P5 of the bottom well space must first be greater than P4 before the third one-way valve can be opened (the schematic diagram of the switching state of the third one-way valve is shown in the attached figure Figure 4Then, the pressure must be greater than the internal pressure of the switch (indicated by P3) to force the switch to open the drain pipe for drainage. That is, during normal drainage, P5>P4>P3.

[0062] Furthermore, the diameters of the drainage ports of the top plate 2 and the bottom plate 3 are both smaller than the inner diameter of the drainage pipe 1 .

[0063] Specifically, the purpose of the caliber size design is to facilitate the connection between the top plate 2 and the bottom plate 3 and the drain pipe 1, and to provide a structural basis for the arrangement of other components, such as facilitating the installation of the third one-way valve 31 at the drain port of the bottom plate 3.

[0064] Furthermore, a pressure-controlled clamp 33 is provided on the edge of the chassis 3. This clamp 33 can be released at a pressure greater than the release pressure to clamp the wellbore casing 9, thereby positioning the fluid discharge device at a predetermined position at the bottom of the well. Furthermore, the pressure-controlled clamp 33 can be retracted when the lifting element of the oil pipe 4 reaches a retraction pressure, allowing the chassis 3 and the fluid discharge device to be lifted up and out of the wellbore by the oil pipe 4.

[0065] Specifically, as shown in the accompanying drawings Figure 1 As shown, the edge of the chassis 3 is provided with a plurality of pressure-controlled clamping seats 33. The function of the pressure-controlled clamping seat 33 is to clamp with the casing 9 of the wellbore, thereby realizing the positioning of the drainage device in the wellbore and making the drainage device stable at the predetermined position of the wellbore. The principle of the pressure-controlled clamping seat 33 is to have a radially movable clamping part, which is retracted in the initial state and is restricted by a limiting structure inside the pressure-controlled clamping seat 33. When clamping is required, pressure must first be applied to the pressure-controlled clamping seat 33 so that the clamping part can break through the restriction of the limiting structure to extend and release, thereby clamping the corresponding casing 9. The specific structure of the pressure-controlled clamping seat 33 can refer to the existing technology, such as pressure-controlled packers, seat sealers, etc.

[0066] In this embodiment, after the drainage device is lowered into the well bottom, it and the wellbore casing 9 form an annulus area 5, as shown in the accompanying drawings. Figure 1 As shown, at this time, the pressure in the annular area 5 can be increased to act on the pressure-controlled cartridge 33, thereby controlling the release of the pressure-controlled cartridge 33. Specifically, the pressure-controlled device 7 connected to the annular area 5 via a pressure-charging pipeline is used to inflate the annular area 5 until the initial pressure P0 reaches P1, which is the critical pressure for the release of the pressure-controlled cartridge 33.

[0067] In addition, the pressure-controlled card seat 33 can also shrink and separate from the casing 9 under the action of a sufficiently large external force, so that the drainage device can be lifted up through the oil pipe 4. When the lifting force reaches T2 from the initial T0, the pressure-controlled card seat 33 shrinks and the casing 9 is separated. It is mainly used to meet the need to lift the drainage device out of the wellbore in the event of a failure.

[0068] Furthermore, the drainage device includes at least three pressure detection units 8, each for detecting the pressure inside the drainage pipe 1, the internal pressure of the switch 11, and the pressure in the bottom hole space 6. This facilitates real-time monitoring of the drainage device's operating status underground, allowing for timely adjustments or handling of unexpected situations.

[0069] Example 2

[0070] An embodiment of the present invention provides a pressure-controlled wellbore drainage device, including a drainage pipe 1 and a top plate 2 and a bottom plate 3 respectively arranged at both ends of the drainage pipe 1, and the top plate 2 is connected to the bottom end of the oil pipe 4. The centers of the top plate 2 and the bottom plate 3 are both provided with drainage ports connected to the drainage pipe 1, and a pressure-controlled switch 11 is provided in the drainage pipe 1, which can block or open the drainage pipe 1 under the action of internal pressure.

[0071] Among them, when the drainage device is lowered into the bottom of the wellbore along with the oil pipe 4, the chassis 3 and the switch component 11 that blocks the drainage pipe 1 seal off the bottomhole space 6 at the bottom of the wellbore, so that the bottomhole space 6 is pressurized; when the bottomhole space 6 is pressurized to a pressure greater than the preset internal pressure of the switch component 11, the switch component 11 is forced to open the drainage pipe 1, so that the gas in the bottomhole space 6 carries the liquid and is discharged through the drainage pipe 1 and the oil pipe 4.

[0072] Specifically, as shown in the accompanying drawings Figure 1 As shown, the invented pressure-controlled wellbore drainage device is integrally arranged at the bottom of the oil pipe 4 and can be lowered into the well or pulled out from the well along with the oil pipe 4. The pressure-controlled wellbore drainage device mainly comprises three parts in structure, namely the drainage pipe 1 and the top plate 2 and bottom plate 3 respectively arranged at the two ends of the drainage pipe 1. The top plate 2 and the bottom plate 3 are both disc-shaped structures, with an outer diameter larger than the drainage pipe 1 and matching the radial size of the wellbore (specifically, matching the inner diameter of the casing 9 of the wellbore). The centers of the top plate 2 and the bottom plate 3 are connected to the ends of the drainage pipe 1, and the drainage ports (not specifically marked in the drawings) in the centers of the top plate 2 and the bottom plate 3 are correspondingly connected to the ports of the drainage pipe 1.

[0073] More importantly, the interior of the drainage tube 1 is equipped with a pressure-controlled switch element 11. This switch element 11 is a movable structure. As its name suggests, its primary function is to block or open the drainage tube 1 under pressure, that is, to block or open the passage within the drainage tube 1. The control principle of the switch element 11 is that the switch element 11 itself is preset with an internal pressure. This internal pressure acts to cause the switch element 11 to tend to block the drainage tube 1. In other words, if there is no sufficiently strong external force, the internal pressure of the switch element 11 will drive the switch element 11 to move, thereby blocking the drainage tube 1. The specific method for setting the internal pressure of the switch element 11 or the structure used to provide and achieve it can be selected as needed. For example, a preloaded spring or other structure capable of providing pressure can be installed on the switch element 11, with the pressure exerted on the switch element 11 by the spring's elastic force acting as the aforementioned internal pressure. Alternatively, the switch element 11 can be directly configured to have a deformable capacity, which can be achieved through an elastic structure or elastic material, with the elastic force generated by the deformation of the switch element 11 itself serving as its internal pressure.

[0074] When in use, the pressure-controlled wellbore drainage device is installed at the bottom of the oil pipe 4 through the connection between the top plate 2 and the bottom end of the oil pipe 4, and can then be lowered into the well bottom along with the oil pipe 4. After reaching the well bottom, since the size of the bottommost bottom plate 3 matches the size of the wellbore, the bottom plate 3 isolates a relatively independent well bottom space 6 at the well bottom, as shown in the figure Figure 1 As shown. In the application scenario of the present invention, the state of the target wellbore is insufficient production (small amount of gas) and high amount of water, so the bottom hole pressure is small and the energy is insufficient. At this time, the gas cannot carry the liquid to discharge. Therefore, after the drainage device is lowered into the bottom of the well, the pressure of the isolated bottom hole space 6 is small, which is less than the internal pressure of the switch 11 (the internal pressure can be adjusted in advance according to the specific situation of the wellbore and the needs, but it is usually necessary to ensure that the preset internal pressure is not less than the minimum pressure at which the gas can carry the liquid to form a gas-water mixed fluid to flow, so as to ensure that the gas flow rate is always higher than the minimum liquid-carrying gas flow rate). Therefore, the switch 11 is in a state of blocking the drainage pipe 1 at this time, and then the bottom hole space 6 is completely and independently isolated to form a relatively closed cavity. Based on this relatively closed bottom hole space 6, although the gas production of the wellbore is small, it will continue to produce gas over time, so the gas volume in the bottom hole space 6 will gradually increase, thereby continuously holding back the pressure and the bottom hole pressure will also continue to increase. When the pressure in the bottom hole space 6 increases to a level greater than the internal pressure of the switch element 11, the internal pressure of the switch element 11 will be overcome, forcing the switch element 11 to move and open the drainage pipe 1. At this time, the bottom hole space 6 is connected to the oil pipe 4 through the opened drainage pipe 1, so the bottom hole gas with sufficient pressure can carry the bottom hole liquid out, realizing automatic drainage under pressure control.

[0075] From the above content, it can be seen that the drainage device of the present invention is very simple in structure and actual operation, and can automatically hold pressure and drain liquid based on the bottom hole pressure. After a drainage cycle is completed, a large amount of liquid at the bottom of the well can basically be effectively discharged, and the liquid accumulated at the bottom of the well in the subsequent production process can be carried out in real time as the production is carried out, which can effectively avoid the accumulation of a large amount of liquid in the well, thereby ensuring the continuous and stable drainage production of the gas well, effectively avoiding the occurrence of liquid accumulation in the wellbore, and improving the production time of the gas well. Even if the wellbore is accidentally filled with liquid again, a drainage cycle can be automatically repeated based on the same principle to drain the liquid again.

[0076] Preferably, a third one-way valve 31 is provided at the drain port of the chassis 3 .

[0077] Specifically, as shown in FIG. Figure 1 As shown, a third one-way valve is provided on the chassis at the drainage port for connecting the bottom well space to the drainage pipe. The main function of the third one-way valve is to prevent gas-liquid backflow. Based on the setting of the third one-way valve, in the initial state (i.e. the state where the switch component blocks the drainage pipe), the bottom well space is small and the third one-way valve is closed. At this time, the bottom well space forms an independent cavity (pressure is represented by P5), and the space inside the drainage pipe between the closed switch component and the chassis forms an independent cavity (pressure is represented by P4). Therefore, during the pressure holding process, the pressure P5 of the bottom well space must first be greater than P4 before the third one-way valve can be opened (the schematic diagram of the switching state of the third one-way valve is shown in the attached figure Figure 4 Then, the pressure must be greater than the internal pressure of the switch (indicated by P3) to force the switch to open the drain pipe for drainage. That is, during normal drainage, P5>P4>P3.

[0078] Furthermore, the diameters of the drainage ports of the top plate 2 and the bottom plate 3 are both smaller than the inner diameter of the drainage pipe 1 .

[0079] Specifically, the purpose of the caliber size design is to facilitate the connection between the top plate 2 and the bottom plate 3 and the drain pipe 1, and to provide a structural basis for the arrangement of other components, such as facilitating the installation of the third one-way valve 31 at the drain port of the bottom plate 3.

[0080] Furthermore, a pressure-controlled clamp 33 is provided on the edge of the chassis 3. This clamp 33 can be released at a pressure greater than the release pressure to clamp the wellbore casing 9, thereby positioning the fluid discharge device at a predetermined position at the bottom of the well. Furthermore, the pressure-controlled clamp 33 can be retracted when the lifting element of the oil pipe 4 reaches a retraction pressure, allowing the chassis 3 and the fluid discharge device to be lifted up and out of the wellbore by the oil pipe 4.

[0081] Specifically, as shown in the accompanying drawings Figure 1As shown, the edge of the chassis 3 is provided with a plurality of pressure-controlled clamping seats 33. The function of the pressure-controlled clamping seat 33 is to clamp with the casing 9 of the wellbore, thereby realizing the positioning of the drainage device in the wellbore and making the drainage device stable at the predetermined position of the wellbore. The principle of the pressure-controlled clamping seat 33 is to have a radially movable clamping part, which is retracted in the initial state and is restricted by a limiting structure inside the pressure-controlled clamping seat 33. When clamping is required, pressure must first be applied to the pressure-controlled clamping seat 33 so that the clamping part can break through the restriction of the limiting structure to extend and release, thereby clamping the corresponding casing 9. The specific structure of the pressure-controlled clamping seat 33 can refer to the existing technology, such as pressure-controlled packers, seat sealers, etc.

[0082] In this embodiment, after the drainage device is lowered into the well bottom, it and the wellbore casing 9 form an annulus area 5, as shown in the accompanying drawings. Figure 1 As shown, at this time, the pressure in the annular area 5 can be increased to act on the pressure-controlled cartridge 33, thereby controlling the release of the pressure-controlled cartridge 33. Specifically, the pressure-controlled device 7 connected to the annular area 5 via a pressure-charging pipeline is used to inflate the annular area 5 until the initial pressure P0 reaches P1, which is the critical pressure for the release of the pressure-controlled cartridge 33.

[0083] In addition, the pressure-controlled card seat 33 can also shrink and separate from the casing 9 under the action of a sufficiently large external force, so that the drainage device can be lifted up through the oil pipe 4. When the lifting force reaches T2 from the initial T0, the pressure-controlled card seat 33 shrinks and the casing 9 is separated. It is mainly used to meet the need to lift the drainage device out of the wellbore in the event of a failure.

[0084] Furthermore, the drainage device includes at least three pressure detection units 8, each for detecting the pressure inside the drainage pipe 1, the internal pressure of the switch 11, and the pressure in the bottom hole space 6. This facilitates real-time monitoring of the drainage device's operating status underground, allowing for timely adjustments or handling of unexpected situations.

[0085] Furthermore, in this embodiment, when the drainage device is lowered to the bottom of the wellbore along with the oil pipe 4, the top plate 2, drainage pipe 1, bottom plate 3, and wellbore casing 9 form an annulus 5. An annulus 5 is connected to the wellbore pressure control equipment 7 via a pressurized pipeline. A pressure-compensating port is provided on the bottom plate 3, connecting the annulus 5 with the bottomhole space 6. A first one-way valve 32 is installed at the pressure-compensating port.

[0086] Specifically, as shown in the accompanying drawings Figure 1As shown, the top plate 2, the drainage pipe 1, the bottom plate 3, and the wellbore casing 9 form an annulus 5. The top plate 2 and the bottom plate 3 are both sealed against the wellbore casing 9. This can be achieved by providing a sealing contact layer at the edges of the top plate 2 and the bottom plate 3. The annulus 5 is connected to the wellbore pressure control device 7 via a pressurized pipeline in the wellbore. The pressure control device 7 can control the pressure in the annulus 5. For example, the pressure in the annulus 5 can be controlled by controlling the injection or withdrawal of a pressure medium (gas or liquid, preferably gas in this embodiment) into or out of the annulus 5.

[0087] Therefore, based on the annulus 5, whose pressure can be controlled by gas injection, a pressure-boosting port is further provided on the bottom plate 3, which can communicate with the bottomhole space 6. Then, gas can be introduced into the annulus 5 using the pressure control device 7 to increase the pressure of the annulus 5, thereby allowing the gas to enter the bottomhole space 6 through the pressure-boosting port, and ultimately, the bottomhole space 6 can be pressure-boosted. The purpose of pressure-boosting is to quickly increase the pressure of the bottomhole space 6 and shorten the pressure-holding process of the bottomhole space 6. In particular, when the initial pressure of the bottomhole space 6 is too low, the gas volume and corresponding energy in the bottomhole space 6 can be quickly replenished, thereby achieving rapid discharge of the bottomhole liquid in a short period of time.

[0088] In addition, the first one-way valve 32 provided at the pressure-compensating port can prevent the backflow of gas, that is, to prevent the gas or gas-liquid fluid in the bottom hole space 6 from entering the annular space 5 through the pressure-compensating port and affecting the normal structure and function of the drainage device. The switching state of the first one-way valve 32 is shown in the accompanying figure. Figure 3 During pressure replenishment, when the internal pressure of the annulus 5 (denoted by P2) is greater than the pressure P5 of the bottomhole space 6, the first one-way valve 32 can be opened. After pressure replenishment is completed, the internal pressure of the annulus 5 is rapidly reduced by the pressure control device 7, allowing the first one-way valve 32 to quickly close under the action of the reverse pressure difference, thereby avoiding affecting the drainage of the bottomhole space 6.

[0089] Example 3

[0090] An embodiment of the present invention provides a pressure-controlled wellbore drainage device, including a drainage pipe 1 and a top plate 2 and a bottom plate 3 respectively arranged at both ends of the drainage pipe 1, and the top plate 2 is connected to the bottom end of the oil pipe 4. The centers of the top plate 2 and the bottom plate 3 are both provided with drainage ports connected to the drainage pipe 1, and a pressure-controlled switch 11 is provided in the drainage pipe 1, which can block or open the drainage pipe 1 under the action of internal pressure.

[0091] Among them, when the drainage device is lowered into the bottom of the wellbore along with the oil pipe 4, the chassis 3 and the switch component 11 that blocks the drainage pipe 1 seal off the bottomhole space 6 at the bottom of the wellbore, so that the bottomhole space 6 is pressurized; when the bottomhole space 6 is pressurized to a pressure greater than the preset internal pressure of the switch component 11, the switch component 11 is forced to open the drainage pipe 1, so that the gas in the bottomhole space 6 carries the liquid and is discharged through the drainage pipe 1 and the oil pipe 4.

[0092] Specifically, as shown in the accompanying drawings Figure 1 As shown, the invented pressure-controlled wellbore drainage device is integrally arranged at the bottom of the oil pipe 4 and can be lowered into the well or pulled out from the well along with the oil pipe 4. The pressure-controlled wellbore drainage device mainly comprises three parts in structure, namely the drainage pipe 1 and the top plate 2 and bottom plate 3 respectively arranged at the two ends of the drainage pipe 1. The top plate 2 and the bottom plate 3 are both disc-shaped structures, with an outer diameter larger than the drainage pipe 1 and matching the radial size of the wellbore (specifically, matching the inner diameter of the casing 9 of the wellbore). The centers of the top plate 2 and the bottom plate 3 are connected to the ends of the drainage pipe 1, and the drainage ports (not specifically marked in the drawings) in the centers of the top plate 2 and the bottom plate 3 are correspondingly connected to the ports of the drainage pipe 1.

[0093] More importantly, the interior of the drainage tube 1 is equipped with a pressure-controlled switch element 11. This switch element 11 is a movable structure. As its name suggests, its primary function is to block or open the drainage tube 1 under pressure, that is, to block or open the passage within the drainage tube 1. The control principle of the switch element 11 is that the switch element 11 itself is preset with an internal pressure. This internal pressure acts to cause the switch element 11 to tend to block the drainage tube 1. In other words, if there is no sufficiently strong external force, the internal pressure of the switch element 11 will drive the switch element 11 to move, thereby blocking the drainage tube 1. The specific method for setting the internal pressure of the switch element 11 or the structure used to provide and achieve it can be selected as needed. For example, a preloaded spring or other structure capable of providing pressure can be installed on the switch element 11, with the pressure exerted on the switch element 11 by the spring's elastic force acting as the aforementioned internal pressure. Alternatively, the switch element 11 can be directly configured to have a deformable capacity, which can be achieved through an elastic structure or elastic material, with the elastic force generated by the deformation of the switch element 11 itself serving as its internal pressure.

[0094] When in use, the pressure-controlled wellbore drainage device is installed at the bottom of the oil pipe 4 through the connection between the top plate 2 and the bottom end of the oil pipe 4, and can then be lowered into the well bottom along with the oil pipe 4. After reaching the well bottom, since the size of the bottommost bottom plate 3 matches the size of the wellbore, the bottom plate 3 isolates a relatively independent well bottom space 6 at the well bottom, as shown in the figure Figure 1As shown. In the application scenario of the present invention, the state of the target wellbore is insufficient production (small amount of gas) and high amount of water, so the bottom hole pressure is small and the energy is insufficient. At this time, the gas cannot carry the liquid to discharge. Therefore, after the drainage device is lowered into the bottom of the well, the pressure of the isolated bottom hole space 6 is small, which is less than the internal pressure of the switch 11 (the internal pressure can be adjusted in advance according to the specific situation of the wellbore and the needs, but it is usually necessary to ensure that the preset internal pressure is not less than the minimum pressure at which the gas can carry the liquid to form a gas-water mixed fluid to flow, so as to ensure that the gas flow rate is always higher than the minimum liquid-carrying gas flow rate). Therefore, the switch 11 is in a state of blocking the drainage pipe 1 at this time, and then the bottom hole space 6 is completely and independently isolated to form a relatively closed cavity. Based on this relatively closed bottom hole space 6, although the gas production of the wellbore is small, it will continue to produce gas over time, so the gas volume in the bottom hole space 6 will gradually increase, thereby continuously holding back the pressure and the bottom hole pressure will also continue to increase. When the pressure in the bottom hole space 6 increases to a level greater than the internal pressure of the switch element 11, the internal pressure of the switch element 11 will be overcome, forcing the switch element 11 to move and open the drainage pipe 1. At this time, the bottom hole space 6 is connected to the oil pipe 4 through the opened drainage pipe 1, so the bottom hole gas with sufficient pressure can carry the bottom hole liquid out, realizing automatic drainage under pressure control.

[0095] From the above content, it can be seen that the drainage device of the present invention is very simple in structure and actual operation, and can automatically hold pressure and drain liquid based on the bottom hole pressure. After a drainage cycle is completed, a large amount of liquid at the bottom of the well can basically be effectively discharged, and the liquid accumulated at the bottom of the well in the subsequent production process can be carried out in real time as the production is carried out, which can effectively avoid the accumulation of a large amount of liquid in the well, thereby ensuring the continuous and stable drainage production of the gas well, effectively avoiding the occurrence of liquid accumulation in the wellbore, and improving the production time of the gas well. Even if the wellbore is accidentally filled with liquid again, a drainage cycle can be automatically repeated based on the same principle to drain the liquid again.

[0096] Preferably, a third one-way valve 31 is provided at the drain port of the chassis 3 .

[0097] Specifically, as shown in FIG. Figure 1 As shown, a third one-way valve is provided on the chassis at the drainage port for connecting the bottom well space to the drainage pipe. The main function of the third one-way valve is to prevent gas-liquid backflow. Based on the setting of the third one-way valve, in the initial state (i.e. the state where the switch component blocks the drainage pipe), the bottom well space is small and the third one-way valve is closed. At this time, the bottom well space forms an independent cavity (pressure is represented by P5), and the space inside the drainage pipe between the closed switch component and the chassis forms an independent cavity (pressure is represented by P4). Therefore, during the pressure holding process, the pressure P5 of the bottom well space must first be greater than P4 before the third one-way valve can be opened (the schematic diagram of the switching state of the third one-way valve is shown in the attached figure Figure 4Then, the pressure must be greater than the internal pressure of the switch (indicated by P3) to force the switch to open the drain pipe for drainage. That is, during normal drainage, P5>P4>P3.

[0098] Furthermore, the diameters of the drainage ports of the top plate 2 and the bottom plate 3 are both smaller than the inner diameter of the drainage pipe 1 .

[0099] Specifically, the purpose of the caliber size design is to facilitate the connection between the top plate 2 and the bottom plate 3 and the drain pipe 1, and to provide a structural basis for the arrangement of other components, such as facilitating the installation of the third one-way valve 31 at the drain port of the bottom plate 3.

[0100] Furthermore, a pressure-controlled clamp 33 is provided on the edge of the chassis 3. This clamp 33 can be released at a pressure greater than the release pressure to clamp the wellbore casing 9, thereby positioning the fluid discharge device at a predetermined position at the bottom of the well. Furthermore, the pressure-controlled clamp 33 can be retracted when the lifting element of the oil pipe 4 reaches a retraction pressure, allowing the chassis 3 and the fluid discharge device to be lifted up and out of the wellbore by the oil pipe 4.

[0101] Specifically, as shown in the accompanying drawings Figure 1 As shown, the edge of the chassis 3 is provided with a plurality of pressure-controlled clamping seats 33. The function of the pressure-controlled clamping seat 33 is to clamp with the casing 9 of the wellbore, thereby realizing the positioning of the drainage device in the wellbore and making the drainage device stable at the predetermined position of the wellbore. The principle of the pressure-controlled clamping seat 33 is to have a radially movable clamping part, which is retracted in the initial state and is restricted by a limiting structure inside the pressure-controlled clamping seat 33. When clamping is required, pressure must first be applied to the pressure-controlled clamping seat 33 so that the clamping part can break through the restriction of the limiting structure to extend and release, thereby clamping the corresponding casing 9. The specific structure of the pressure-controlled clamping seat 33 can refer to the existing technology, such as pressure-controlled packers, seat sealers, etc.

[0102] In this embodiment, after the drainage device is lowered into the well bottom, it and the wellbore casing 9 form an annulus area 5, as shown in the accompanying drawings. Figure 1 As shown, at this time, the pressure in the annular area 5 can be increased to act on the pressure-controlled cartridge 33, thereby controlling the release of the pressure-controlled cartridge 33. Specifically, the pressure-controlled device 7 connected to the annular area 5 via a pressure-charging pipeline is used to inflate the annular area 5 until the initial pressure P0 reaches P1, which is the critical pressure for the release of the pressure-controlled cartridge 33.

[0103] In addition, the pressure-controlled card seat 33 can also shrink and separate from the casing 9 under the action of a sufficiently large external force, so that the drainage device can be lifted up through the oil pipe 4. When the lifting force reaches T2 from the initial T0, the pressure-controlled card seat 33 shrinks and the casing 9 is separated. It is mainly used to meet the need to lift the drainage device out of the wellbore in the event of a failure.

[0104] Furthermore, the drainage device includes at least three pressure detection units 8, each for detecting the pressure inside the drainage pipe 1, the internal pressure of the switch 11, and the pressure in the bottom hole space 6. This facilitates real-time monitoring of the drainage device's operating status underground, allowing for timely adjustments or handling of unexpected situations.

[0105] Furthermore, in this embodiment, when the drainage device is lowered to the bottom of the wellbore along with the oil pipe 4, the top plate 2, drainage pipe 1, bottom plate 3, and wellbore casing 9 form an annulus 5. An annulus 5 is connected to the wellbore pressure control equipment 7 via a pressurized pipeline. A pressure-compensating port is provided on the bottom plate 3, connecting the annulus 5 with the bottomhole space 6. A first one-way valve 32 is installed at the pressure-compensating port.

[0106] Specifically, as shown in the accompanying drawings Figure 1 As shown, the top plate 2, the drainage pipe 1, the bottom plate 3, and the wellbore casing 9 form an annulus 5. The top plate 2 and the bottom plate 3 are both sealed against the wellbore casing 9. This can be achieved by providing a sealing contact layer at the edges of the top plate 2 and the bottom plate 3. The annulus 5 is connected to the wellbore pressure control device 7 via a pressurized pipeline in the wellbore. The pressure control device 7 can control the pressure in the annulus 5. For example, the pressure in the annulus 5 can be controlled by controlling the injection or withdrawal of a pressure medium (gas or liquid, preferably gas in this embodiment) into or out of the annulus 5.

[0107] Therefore, based on the annulus 5, whose pressure can be controlled by gas injection, a pressure-boosting port is further provided on the bottom plate 3, which can communicate with the bottomhole space 6. Then, gas can be introduced into the annulus 5 using the pressure control device 7 to increase the pressure of the annulus 5, thereby allowing the gas to enter the bottomhole space 6 through the pressure-boosting port, and ultimately, the bottomhole space 6 can be pressure-boosted. The purpose of pressure-boosting is to quickly increase the pressure of the bottomhole space 6 and shorten the pressure-holding process of the bottomhole space 6. In particular, when the initial pressure of the bottomhole space 6 is too low, the gas volume and corresponding energy in the bottomhole space 6 can be quickly replenished, thereby achieving rapid discharge of the bottomhole liquid in a short period of time.

[0108] In addition, the first one-way valve 32 provided at the pressure-compensating port can prevent the backflow of gas, that is, to prevent the gas or gas-liquid fluid in the bottom hole space 6 from entering the annular space 5 through the pressure-compensating port and affecting the normal structure and function of the drainage device. The switching state of the first one-way valve 32 is shown in the accompanying figure. Figure 3 During pressure replenishment, when the internal pressure of the annulus 5 (denoted by P2) is greater than the pressure P5 of the bottomhole space 6, the first one-way valve 32 can be opened. After pressure replenishment is completed, the internal pressure of the annulus 5 is rapidly reduced by the pressure control device 7, allowing the first one-way valve 32 to quickly close under the action of the reverse pressure difference, thereby avoiding affecting the drainage of the bottomhole space 6.

[0109] Furthermore, in this embodiment, the switch member 11 is constructed as an annular pressure-controlling rubber sleeve that can be filled with pressure medium. The pressure-controlling rubber sleeve can expand radially inward under the pressure of the pressure medium to block the drain pipe 1 and can contract radially outward under the action of external pressure to open the drain pipe 1.

[0110] Specifically, the switch element 11 adopts a rubber sleeve structure that has deformation capability in both structure and material, as shown in the accompanying drawings. Figure 1 As shown, the switch element 11 is constructed as an annular pressure-controlling rubber sleeve, the outer circumference of which is in contact with and partially fixed to the inner wall of the drain pipe 1. When the pressure-controlling rubber sleeve contracts, a via hole on its inner side allows access to the interior of the drain pipe 1, effectively opening the drain pipe 1. When the pressure-controlling rubber sleeve expands under the action of internal pressure, it expands radially inward, thereby blocking the via hole and thus blocking the drain pipe 1.

[0111] Because switch element 11 utilizes a pressure-controlled rubber sleeve, the internal pressure of switch element 11 can be controlled by the amount of pressure medium introduced into the pressure-controlled rubber sleeve. In this embodiment, the internal pressure is provided by injecting pressurized gas into the pressure-controlled rubber sleeve, and the internal pressure is controlled by controlling the amount of gas to achieve a desired internal pressure.

[0112] Furthermore, a pressure charging port communicating with the inner space of the pressure-controlling rubber sleeve is provided on the wall of the liquid discharge pipe 1 , and a second one-way valve 12 is provided at the pressure charging port.

[0113] Specifically, as shown in the accompanying drawings Figure 1 As shown, the pressure charging port on the wall of the discharge pipe 1 can be connected to the internal space of the pressure control rubber sleeve to realize the charging of pressurized gas, and a second one-way valve 12 is provided to prevent the reverse outflow of gas after charging, thereby realizing the maintenance of the internal pressure of the pressure control rubber sleeve. The switching state of the second one-way valve 12 is shown in the accompanying figure. Figure 2 As shown. As required, the pressure-controlled rubber sleeve can be pressurized on the surface of the well or after being lowered into the well bottom. The latter requires the annular space 5 and the pressure-controlled device 7 of the above-mentioned embodiment.

[0114] Specifically, after the drainage device is lowered to the bottom of the well, it forms an annulus 5 with the wellbore casing 9. In addition to cooperating with the pressure control device 7 on the wellbore to replenish the pressure of the bottomhole space 6 as in the second embodiment, the annulus 5 can also be pressurized by the pressure-controlling rubber sleeve through the pressure-charging port on the drainage pipe 1. Pressure replenishment and pressure charging can also be performed simultaneously in the structure.

[0115] Furthermore, top plate 2 comprises an upper plate body and a lower plate body, each connected to oil pipe 4 and drain pipe 1, and capable of relative movement. One end of the pressure-controlling rubber sleeve abuts bottom plate 3, while the other end is partially embedded in top plate 2 and abuts the inner side of the upper plate body. The upper plate body can move axially away from bottom plate 3 in response to the upward movement of oil pipe 4, thereby allowing the pressure-controlling rubber sleeve to extend axially in drain pipe 1.

[0116] Specifically, referring to the accompanying drawings Figure 1 As shown, according to the above content, the normal drainage of the bottom hole space 6 needs to meet the pressure relationship: P5>P4>P3. However, when P3>P4 or P3 is too large in value, even if the bottom hole space 6 is pressurized to P5 to meet the pressure conditions for gas-carrying liquid discharge, due to P3 being too large, the switch 11 is still in a state of blocking the drainage pipe 1, so it is necessary to reduce the internal pressure P3 of the switch 11. Based on the design of the switch 11 using a pressure-controlled rubber sleeve, since the pressure-controlled rubber sleeve is equipped with a second one-way valve 12 at the pressure-controlled rubber sleeve's charging port, it is impossible to achieve the external discharge of the internal gas, so it is necessary to find other ways to reduce its internal pressure P3. Therefore, this embodiment has carried out the above-mentioned optimization design in structure to reduce the internal pressure P3 of the pressure-controlled rubber sleeve.

[0117] Specifically, as shown in the attached figure Figure 1 As shown, the top plate 2 is structurally connected to both the oil pipe 4 and the drainage pipe 1, so the top plate 2 is set to a movable structure, that is, the top plate 2 is composed of an upper plate body connected to the oil pipe 4 and a lower plate body connected to the drainage pipe 1, and the upper plate body and the lower plate body can move relative to each other within a certain range (that is, they will not be completely separated). After the drainage device is positioned at the predetermined position of the wellbore casing 9 along with the pressure-controlled socket 33 of the bottom plate 3, the lower plate body of the top plate 2 remains fixed to the casing 9, while the upper plate body can move relatively. In addition, the top part of the pressure-control rubber sleeve in the drainage pipe 1 is embedded in the interior of the top plate 2, that is, the top end of the pressure-control rubber sleeve passes through the notch opened on the lower plate body to enter the interior of the top plate 2 and abuts against the inner side surface of the upper plate body.

[0118] Therefore, under normal conditions, the two ends of the pressure-controlling rubber sleeve are respectively restricted by the chassis 3 and the upper disc body due to the abutment, so that the expansion of the pressure-controlling rubber sleeve is mainly carried out in the radial direction, or in other words, the pressure-controlling rubber sleeve is difficult to further expand in the axial direction of the discharge pipe 1. Therefore, based on the need to reduce the internal pressure P3 of the pressure-controlling rubber sleeve, the upper disc body is set to a movable structure. Therefore, when the upper disc body moves a certain distance away from the chassis 3 as the oil pipe 4 is lifted, the distance between the upper disc body and the chassis 3 becomes larger, thereby providing the pressure-controlling rubber sleeve with expansion space in the axial direction of the discharge pipe 1. At this time, the end of the pressure-controlling rubber sleeve corresponding to the upper disc body can further expand in the axial direction of the discharge pipe 1 as the upper disc body moves, thereby expanding the internal space size of the pressure-controlling rubber sleeve. When the internal gas volume is constant, the expansion of the space is bound to lead to a reduction in the internal pressure, so the need to reduce the internal pressure P3 of the pressure-controlling rubber sleeve can be achieved. Of course, to implement the above solution, it is necessary to ensure that the pressure-controlling rubber sleeve has a certain expansion margin when the upper disc body is in the initial position (i.e., before it moves with the oil pipe 4).

[0119] In addition, the internal pressure P3 of the pressure-controlling rubber sleeve can be adjusted based on the above-mentioned structural design of the top plate 2, and the structural design can also improve the drainage effect.

[0120] Specifically, according to the drainage principle of the present invention, the pressure in the bottomhole space 6, after being built up, is greater than the internal pressure of the switch member 11, forcing the switch member 11 to open the drainage pipe 1. In actual applications, however, the pressure in the bottomhole space 6 may be just greater than the internal pressure of the switch member 11. As the pressure forces the switch member 11 to open the drainage pipe 1, the gas and water in the bottomhole space 6 are discharged. However, as the gas and water are discharged, the pressure in the bottomhole space 6 may drop to just below the internal pressure of the switch member 11 within a short period of time, causing the switch member 11 to block the drainage pipe 1 again. This can cause the switch member 11 to repeatedly open and close the drainage pipe 1 multiple times within a short period of time, resulting in intermittent discharge of the gas and water, making it difficult to discharge continuously over a long period of time, thus affecting the drainage effect. Therefore, based on the above-mentioned structural design of the top plate 2, the internal pressure P3 of the pressure-controlling rubber sleeve can be adjusted. Therefore, the internal pressure of the pressure-controlling rubber sleeve is actually within a numerical range, for example, [P3", P3'], with P3'>P3">minimum liquid carrying pressure.

[0121] In the initial state, the internal pressure of the pressure-controlling sleeve is P3', at which time the pressure-controlling sleeve blocks the drainage pipe 1; when the bottom hole space 6 is pressurized to a pressure P5 just greater than P3', the pressure-controlling sleeve is compressed and contracts, thereby opening the drainage pipe 1, and the gas and water in the bottom hole space 6 are discharged; as the gas and water are discharged, the oil pipe 4 is gradually lifted up (the lifting force is T1, T1 < T2), so that the internal pressure of the pressure-controlling sleeve drops to P3"; even if the pressure P5 of the bottom hole space 6 may gradually decrease as the gas and water are discharged, as long as the pressure P5 is greater than P3", the drainage can still proceed normally. Therefore, the pressure range [P3", P3'] can be further targeted by adjusting the structure, and combined with the pressure drop rate of the bottom hole space 6, the drainage of the bottom hole space 6 can be carried out continuously for a longer period of time, thereby ensuring the exhaust effect.

[0122] In general, the structure of the drainage device of the present invention allows the bottomhole space 6 to be pressurized, and drainage can only be performed when the pressure is maintained at a pressure no less than the internal pressure of the pressure-controlling rubber sleeve. In this way, by controlling the internal pressure of the pressure-controlling rubber sleeve, the pressure of the bottomhole space 6 can be guaranteed to meet the minimum pressure required for gas to carry liquid, thereby ensuring that the gas can carry the liquid for drainage. At the same time, the internal pressure of the pressure-controlling rubber sleeve can be flexibly adjusted as needed, thereby indirectly controlling the specific pressure value of the bottomhole space 6 during drainage.

[0123] Example 4

[0124] According to the structural design and principles of the aforementioned embodiments, the drainage device was assembled in an indoor laboratory. The top plate, drainage pipe, bottom plate, pressure control equipment, one-way valve, pressure control rubber sleeve, pressure detection unit and other components were connected and installed in sequence. The connected drainage device was fixed at the bottom of the simulated wellbore. The drainage and gas production process of the gas well was simulated indoors and the performance of the device was tested.

[0125] (1) Gas is injected into the annulus through the pressure control device until the pressure P0 reaches the value P1, the pressure control seat of the chassis is released, and the device is fixed at the predetermined position in the wellbore;

[0126] (2) Continue to inject gas into the annular space until the second one-way valve opens under the action of the pressure difference, the pressure control rubber sleeve is filled with gas and the pressure increases until the pressure reaches the design value P3;

[0127] (3) Open the wellhead. When the pressure P5>P4>P3, the gas and water in the bottom hole space flow from the bottom hole to the drainage pipe through the third one-way valve, and then flow to the wellhead through the oil pipe;

[0128] When the pressure P5<P4≤P3, the pressure control rubber sleeve expands and blocks the drainage pipe, the third one-way valve closes, and the bottom hole pressure P5 gradually recovers. When the pressure P5>P4>P3, the pressure control rubber sleeve contracts under the action of pressure, the third one-way valve also opens, and the device resumes operation.

[0129] (4) Continue to inject gas into the annular space, so that the first one-way valve opens, and the pressure P5 of the bottom hole space increases under the action of the pressure compensation until it reaches the required value; then quickly reduce the pressure of the annular space, and the first one-way valve and the second one-way valve automatically close;

[0130] (5) Lift the oil pipe. When the lifting force reaches T1, the upper plate of the top plate gradually moves upward, the expandable space of the pressure control rubber sleeve in the axial direction of the discharge pipe increases, and the pressure P3 gradually decreases until it reaches the required value;

[0131] (6) Continue to lift the tubing. When the pulling force reaches T2, the pressure-controlled clamping seat on the chassis contracts and the device can be lifted to the wellhead.

[0132] During normal operation, the device maintained pressures P1 < P2 < P3 < P4 < P5, and tension T1 < T2. P1 was set to 2-5 MPa based on the typical pressure requirements of the pressure-controlled cartridge, while P2, P3, P4, and P5 varied dynamically depending on the device's operating conditions and requirements. Throughout the experimental testing, the device performed well, and the drainage performance met the expected design.

[0133] Furthermore, in this embodiment, if P5 is required to be maintained above 12 MPa, P3 can be set to 12 MPa. In this case, the pressure-control sleeve closes when P4 is below 12 MPa and opens when it exceeds 12 MPa. Furthermore, if P5 needs to be adjusted to above 15 MPa, P2 needs to be adjusted to increase the pressure to 15 MPa, thereby increasing P3 to 15 MPa. If P5 needs to be adjusted to above 10 MPa, the top plate needs to be raised by lifting the oil pipe, thereby reducing P3 to 10 MPa. In this embodiment, the distance the oil pipe is raised to reduce P3 is no more than 1 meter, preferably 0.5 to 1 meter. T1 is the pulling force required to reduce P3 by lifting the oil pipe. Its specific value is based on the ability to pull the top plate through the oil pipe. Similarly, T2 has a specific value based on the ability to pull the drain device through the oil pipe, thereby contracting the chassis' pressure-controlled clamp.

[0134] Example 5

[0135] An embodiment of the present invention provides a pressure-controlled wellbore fluid drainage system, comprising a fluid drainage device according to any one or more of the above-described embodiments, an uphole control device, and a remote pressure detection device. The uphole control device is connected to the oil pipe 4 for controlling the lowering and raising of the oil pipe 4; the remote pressure detection device is electrically connected to the pressure detection unit 8 in the fluid drainage device for obtaining corresponding pressure values.

[0136] Example 6

[0137] An embodiment of the present invention provides a liquid discharge control method, which includes the following steps:

[0138] S100: When the drainage device is lowered to a predetermined position at the bottom of the wellbore along with the oil pipe 4, pressure medium is injected into the annulus 5 surrounded by the wellbore casing 9 and the top plate 2, drainage pipe 1 and bottom plate 3 of the drainage device.

[0139] S200: By injecting pressure medium into the annular space 5 until the pressure reaches the release pressure of the pressure control seat 33 set at the edge of the bottom plate 3, the pressure control seat 33 is released and the casing 9 is clamped to position the drainage device at a predetermined position.

[0140] S300: Continue to inject pressure medium into the annulus area 5. Make the pressure medium enter the pressure-controlling rubber sleeve inside the drainage pipe 1 through the pressure charging port on the drainage pipe 1, so that the pressure-controlling rubber sleeve expands and the pressure reaches the preset internal pressure, which is not less than the minimum liquid-carrying pressure of the bottom hole gas.

[0141] S400: Open the oil pipe 4. When the pressure of the bottom hole space 6 isolated by the chassis 3 is greater than the preset internal pressure, the gas and water in the bottom hole space 6 flow through the compressed pressure control rubber sleeve and are discharged through the drainage pipe 1 and the oil pipe 4. When the pressure of the bottom hole space 6 is less than the preset internal pressure, the pressure is held until the pressure is greater than the preset internal pressure.

[0142] Furthermore, the discharge control method further comprises the following steps:

[0143] S10 : In response to detecting that the pressure of the bottom hole space 6 is too low, a pressure medium is injected into the annulus 5 , so that the pressure medium enters the bottom hole space 6 through the pressure compensation port on the bottom plate 3 to increase the pressure of the bottom hole space 6 .

[0144] Specifically, step S10 can be performed at any appropriate time to replenish the pressure of the bottom hole space 6. Therefore, step S10 is performed after the aforementioned step S100, but there is no necessary order with other steps.

[0145] Furthermore, the discharge control method further comprises the following steps:

[0146] S1: In response to detecting that the pressure of the pressure control rubber sleeve is too high, the oil pipe 4 is lifted;

[0147] S2: The upper plate of the top plate 2 moves away from the bottom plate 3 along with the oil pipe 4, so that the end of the pressure-control rubber sleeve abutting the upper plate can stretch and expand the volume of the internal space along with the movement of the upper plate, thereby reducing the internal pressure.

[0148] Specifically, steps S1 and S2 can be performed at any appropriate time. Except for the necessary pre-steps (such as step S100), there is no necessary order with the other steps mentioned above.

[0149] In the description of the present invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "back", "inside", "outside", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0150] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. A pressure-controlled wellbore drainage device, characterized in that: The device comprises a drain pipe and a top plate and a bottom plate respectively arranged at both ends of the drain pipe, wherein the top plate is connected to the bottom end of the oil pipe, and the center of each of the top plate and the bottom plate is provided with a drain port connected to the drain pipe. The drain pipe is provided with a pressure-controlled switch member capable of blocking or opening the drain pipe under the action of internal pressure; Among them, when the drainage device is lowered into the bottom of the wellbore along with the oil pipe, the chassis and the switch component that blocks the drainage pipe isolate the bottom hole space at the bottom of the wellbore, so that the bottom hole space is pressurized; when the bottom hole space is pressurized to a pressure greater than the preset internal pressure of the switch component, the switch component is forced to open the drainage pipe, so that the gas in the bottom hole space carries the liquid and is discharged through the drainage pipe and the oil pipe.

2. The pressure-controlled wellbore drainage device according to claim 1, characterized in that: When the drainage device is lowered into the bottom of the wellbore along with the oil pipe, the top plate, the drainage pipe, the bottom plate and the casing of the wellbore form an annulus area, and the annulus area is connected to the pressure control equipment on the well through a pressurized pipeline; Wherein, a pressure compensation port connecting the annular space and the bottom hole space is opened on the chassis, and a first one-way valve is provided at the pressure compensation port.

3. The pressure-controlled wellbore drainage device according to claim 1 or 2, characterized in that: The switch member is constructed as an annular pressure-controlling rubber sleeve that can be filled with pressure medium. The pressure-controlling rubber sleeve can expand radially inward under the pressure of the pressure medium to block the drain pipe and can contract radially outward under external pressure to open the drain pipe.

4. The pressure-controlled wellbore drainage device according to claim 3, characterized in that: A pressure charging port communicating with the inner space of the pressure-controlling rubber sleeve is provided on the wall of the liquid discharge pipe, and a second one-way valve is provided at the pressure charging port.

5. The pressure-controlled wellbore drainage device according to claim 3, characterized in that: The top plate includes an upper plate body and a lower plate body respectively connected to the oil pipe and the drain pipe and capable of relative movement, one end of the pressure-control rubber sleeve abuts against the bottom plate, and the other end is partially embedded in the interior of the top plate and abuts against the inner side surface of the upper plate body; Wherein, the upper plate body can move in the axial direction of the drain pipe in the direction away from the bottom plate as the oil pipe is lifted up, so that the pressure-controlling rubber sleeve can stretch in the axial direction of the drain pipe.

6. The pressure-controlled wellbore drainage device according to claim 1 or 2, characterized in that: The edge of the chassis is provided with a pressure-controlled clamping seat, which can be released under a pressure greater than a release pressure value to clamp the casing of the wellbore, so that the drainage device is positioned at a predetermined position at the bottom of the well; The pressure-controlled holder can also be retracted when the lifting body of the oil pipe reaches a retraction pressure value, so that the chassis and the drainage device are lifted up and out of the wellbore as a whole by the oil pipe.

7. The pressure-controlled wellbore drainage device according to claim 1, characterized in that: A third one-way valve is provided at the drain port of the chassis.

8. The pressure-controlled wellbore drainage device according to claim 1, characterized in that: The diameters of the drainage ports of the top plate and the bottom plate are both smaller than the inner diameter of the drainage pipe.

9. The pressure-controlled wellbore drainage device according to claim 1, characterized in that: It also includes at least three pressure detection units, which are used to detect at least the pressure inside the drainage pipe, the internal pressure of the switch component, and the pressure of the bottom well space.

10. A pressure-controlled wellbore drainage system, characterized in that: It comprises the liquid discharge device according to any one of claims 1 to 9, as well as an uphole control device and a remote pressure detection device; The uphole control device is connected to the oil pipe and is used to control the lowering and lifting of the oil pipe; the remote pressure detection device is electrically connected to the pressure detection unit in the liquid discharge device and is used to obtain the corresponding pressure value.

11. A method for controlling liquid discharge, characterized in that: The following steps are involved: When the drainage device is lowered along the oil pipe to a predetermined position at the bottom of the wellbore, a pressure medium is injected into the annulus area surrounded by the casing of the wellbore and the top plate, drainage pipe and bottom plate of the drainage device; The pressure medium is allowed to enter the pressure-controlling rubber sleeve inside the discharge pipe through the pressure charging port on the discharge pipe, so that the pressure-controlling rubber sleeve expands and the pressure reaches a preset internal pressure, and the preset internal pressure is not less than the minimum liquid-carrying pressure of the bottom hole gas; The oil pipe is opened. When the pressure of the bottom hole space isolated by the chassis is greater than the preset internal pressure, the gas and water in the bottom hole space circulate and compress the pressure-control rubber sleeve and are discharged to the outside through the drainage pipe and the oil pipe. When the pressure of the bottom hole space is less than the preset internal pressure, the pressure is held until the pressure is greater than the preset internal pressure.

12. The liquid discharge control method according to claim 11, characterized in that: The following steps are also included: In response to detecting that the pressure of the bottom hole space is too low, the pressure medium is injected into the annulus area, so that the pressure medium enters the bottom hole space through the pressure compensation port on the bottom plate to increase the pressure of the bottom hole space.

13. The liquid discharge control method according to claim 11, wherein: The following steps are also included: In response to detecting that the pressure of the pressure-controlling rubber sleeve is too high, lifting the oil pipe; The upper plate of the top plate moves away from the bottom plate along with the oil pipe, so that the end of the pressure-control rubber sleeve abutting the upper plate can stretch and expand the volume of the internal space along with the movement of the upper plate, thereby reducing the internal pressure.

14. The liquid discharge control method according to claim 11, wherein: When the fluid discharge device is lowered along the oil pipe to a predetermined position at the bottom of the wellbore, the method further includes: Injecting pressure medium into the annular space until the pressure reaches the release pressure of a pressure-controlled clamping seat provided at the edge of the bottom plate, so that the pressure-controlled clamping seat releases and clamps the casing, thereby positioning the drainage device at the predetermined position; The pressure medium is continuously injected into the annular space to expand the pressure-controlling rubber sleeve and reach a preset internal pressure, which is greater than the release pressure.

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