Liquid drainage test system and liquid drainage test method

Abstract

The invention relates to the technical field of gas well liquid drainage, in particular to a liquid drainage testing system and a liquid drainage testing method, and aims to solve the technical problem that in the prior art, a power liquid drainage and mining technological process is complex. The liquid drainage testing system can achieve gas well liquid drainage with compressed natural gas as power, liquid drainage does not occupy an oil sleeve annulus, and a gas production channel is reserved; in addition, compressed natural gas is used as power, if the adjacent well has sufficient gas source, the natural gas of the adjacent well can be introduced to implement liquid drainage, and a natural gas compressor is not needed to pressurize, so that the construction cost is further reduced, and the gas production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid drainage in gas wells, and particularly to a liquid drainage test system and a liquid drainage test method. Background Art

[0002] With the continuous deepening of exploration, rich water-bearing gas reservoirs with low abundance, poor seepage capacity, large water production, and inability to form natural productivity have become the key and difficult points in exploration. At present, for such gas wells, the methods of draining water and producing gas mostly adopt the way of injecting power liquid on the ground, draining liquid inside the pipe, and producing gas outside the pipe. That is, a set of working pipe string is lowered into the gas well borehole to below the producing layer. The working pipe string usually consists of a working tubing, a corresponding pump drainage device, a casing anchor, a slotted liner, etc. The wellbore liquid is pumped out from the inside of the working tubing. When the wellbore liquid drops to a certain depth, the compressed natural gas in the formation can enter the wellbore, then return to the ground through the annulus between the tubing and the casing, and then enter the gas gathering pipeline. Conventional drainage and gas production require injecting power liquid on the ground for production, and the equipment is complex. Summary of the Invention

[0003] The purpose of the present invention is to provide a liquid drainage test system and a liquid drainage test method to solve the technical problem of the complex technological process of using power liquid for production in the prior art.

[0004] To solve the above technical problem, the technical solution provided by the present invention is as follows:

[0005] In a first aspect, the present invention provides a liquid drainage test system, including: a working pipe string and a liquid drainage pipe string;

[0006] The working pipe string includes a tubing and a tubing tee. The tubing tee has a first port, a second port, and a third port. One end of the tubing is fixedly connected to the first port;

[0007] The liquid drainage pipe string includes a central pipe, a gas lift valve, and a packer;

[0008] One end of the central pipe is inside the tubing, and the other end passes through the tubing, the first port, and the second port in sequence. The central pipe and the tubing as well as the tubing tee enclose a small annulus, and is also in sealing cooperation with the side wall of the second port;

[0009] Both the gas lift valve and the packer are inside the tubing and are both connected to the central pipe. Among them, there are multiple gas lift valves, and the multiple gas lift valves are spaced along the axial direction of the central pipe and are between the packer and the tubing tee. The packer is set in the tubing;

[0010] The gas lift valve includes an outer cylinder body and a sealing component. Among them, an air lift channel penetrating the side wall is provided on the outer cylinder body, and the sealing component is arranged inside the outer cylinder body and configured to block the air lift channel under the condition of no liquid in the outer cylinder body, and release the blockage of the air lift channel under the condition of the outer cylinder body being filled with liquid.

[0011] Further, the sealing component includes a slide valve and a reset unit;

[0012] The slide valve is slidably matched with the inner wall of the outer cylinder body so as to be slidable along the axial direction of the outer cylinder body;

[0013] The reset unit is arranged between the slide valve and the outer cylinder body, so that the slide valve has a tendency to slide towards the direction close to the air lift channel to block the air lift channel.

[0014] Further, along the circumferential direction of the outer cylinder body, an annular groove is recessed on the inner wall of the outer cylinder body, and the air lift channel is arranged on the side wall of the annular groove;

[0015] One end of the slide valve is located in the annular groove to block the air lift channel, and the other end is located outside the annular groove. An annular cavity is formed by enclosing the wall surface of the slide valve and the annular groove;

[0016] The reset unit includes nitrogen gas, and the nitrogen gas is arranged in the annular cavity.

[0017] Further, two groups of the first sealing rings are externally embedded at the one end of the slide valve, and the two groups of the first sealing rings are abutted against the side wall of the annular groove and are located on both sides of the air lift channel.

[0018] Further, the outer cylinder body includes an upper joint, a body and a lower joint;

[0019] Both ends of the body are respectively threadedly connected with the upper joint and the lower joint and are in sealing fit. The inner wall of the body and the end faces of the upper joint and the lower joint enclose to form the annular groove.

[0020] Further, the drain pipe string further includes a reverse circulation jet pump and a check valve;

[0021] The reverse circulation jet pump is connected to the central pipe and is located between the gas lift valve and the packer. The reverse circulation jet pump is configured to suck fluid into the central pipe under the air intake condition;

[0022] The check valve is connected to the reverse circulation jet pump and is located between the reverse circulation jet pump and the packer.

[0023] Further, the reverse circulation jet pump includes a throat tube, an outer cylinder, a nozzle, and a flow nipple;

[0024] The throat tube and the flow nipple are spaced apart;

[0025] The outer cylinder is sleeved on the throat tube and the flow nipple. One end of the outer cylinder is threadedly connected to the throat tube, and the other end is threadedly connected to the flow nipple;

[0026] The nozzle is threadedly connected to the flow nipple and is directed at the throat tube;

[0027] Along the axial direction of the flow nipple, the flow nipple is provided with a main channel. One end of the main channel is communicated with the nozzle, and the other end is closed. A side channel penetrating through the flow nipple itself is provided on the side wall of the flow nipple, and the side channel and the main channel are spaced apart;

[0028] Along the radial direction of the flow nipple, a transverse hole is provided on the side wall of the flow nipple, and the transverse hole is communicated with the main channel.

[0029] Further, the packer includes a packer, or the packer includes a setting joint and an insert seal;

[0030] The setting joint is arranged on the tubing, and the insert seal is inserted and matched with the setting joint, and a seal is arranged between the two;

[0031] Further, the work string further includes a casing;

[0032] The tubing passes through the casing, and a large annulus is formed between the tubing and the casing. One end of the tubing connected to the tubing tee is located outside the casing;

[0033] One end of the casing close to the tubing tee is sealed with the tubing, and an exhaust hole communicated with the large annulus is provided on the side wall of the casing.

[0034] In a second aspect, the present invention further provides a liquid drainage test method. This method is based on the above-mentioned liquid drainage test system and includes the following steps;

[0035] S1: Connect a plug, a central pipe tee, a sealing plug, a plurality of gas lift valves, a reverse circulation jet pump, a check valve, a packer, and a pressure gauge to the central pipe in sequence from one end to the other end of the central pipe to form a liquid drainage string;

[0036] S2: Lower the liquid drainage string into the tubing and set the packer with the tubing;

[0037] S3: Gas lift liquid drainage;

[0038] S301: Inject compressed natural gas from the third port;

[0039] S302: When the liquid accumulation in the well is pumped to the sand control screen pipe of the work string, stop draining the liquid. When the liquid accumulation in the well returns to the level that affects the gas well production, repeat step S301.

[0040] Based on the above technical solutions, the technical effects that can be achieved by the liquid drainage test system provided by the present invention are as follows:

[0041] In this liquid drainage test system, multiple gas lift valves cooperate to form a multi-stage gas lift valve. Among them, the one close to the tubing tee is the first-stage gas lift valve, and so on; when the well is filled with liquid, all the multi-stage gas lift valves are in the open state, that is, the gas lift channel is in the open state. At this time, the outer cylinder is connected to the small annulus; when compressed natural gas is injected into the small annulus through the third port, the compressed natural gas will enter the outer cylinder of the first-stage gas lift valve from the small annulus through the gas lift channel, thereby discharging the liquid in the wellbore from the first-stage gas lift valve in a reverse circulation to the ground and filling the space above the first-stage gas lift valve with gas, which further prompts the first-stage gas lift valve to close; after the first-stage gas lift valve closes, the compressed gas can only displace the liquid above the second-stage gas lift valve from the second-stage gas lift valve and then prompts the second-stage gas lift valve to close; in this way, the liquid accumulation in the wellbore can be gradually displaced step by step, and all the gas lift valves downhole are closed.

[0042] It can be seen that compared with the prior art, this liquid drainage test system can realize liquid drainage of gas wells with compressed natural gas as the power, and the liquid drainage does not occupy the tubing-casing annulus, retaining the gas production channel; in addition, using compressed natural gas as the power, if there is sufficient gas source in the adjacent well, the natural gas of the adjacent well can be introduced for liquid drainage without the need for natural gas compressor boosting, which will further reduce the construction cost and improve the gas production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0044] Figure 1 It is a cross-sectional view of an embodiment of the liquid drainage test system provided by the embodiment of the present invention;

[0045] Figure 2 It is a cross-sectional view of another embodiment of the liquid drainage test system provided by the embodiment of the present invention;

[0046] Figure 3 It is a half cross-sectional view of the gas lift valve provided by the embodiment of the present invention;

[0047] Figure 4 This is a cross-sectional view of the reverse circulation jet pump provided by the embodiment of the present invention.

[0048] Icon: 1 - tubing; 2 - tubing tee; 3 - central tube;

[0049] 4 - gas lift valve; 41 - outer cylinder; 42 - sliding valve; 43 - annular cavity; 44 - first sealing ring; 45 - second sealing ring; 411 - gas lift channel; 412 - upper joint; 413 - body; 414 - lower joint; 4141 - step;

[0050] 5 - small annulus;

[0051] 6 - reverse circulation jet pump; 61 - throat tube; 62 - outer barrel; 63 - nozzle; 64 - flow nipple; 65 - third sealing ring; 641 - main pore; 642 - side pore; 643 - transverse hole;

[0052] 7 - check valve; 8 - packer; 9 - setting joint; 10 - insert seal; 11 - casing; 12 - large annulus; 13 - plug; 14 - central tube tee; 15 - sealing plug; 16 - pressure gauge; 17 - sand control screen pipe; 18 - casing tee; 19 - tubing hanger. Specific embodiments

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0054] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0055] The following will describe in detail some embodiments of the present invention with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0056] Conventional drainage gas production requires ground injection of power fluid for drainage production, and the equipment is complex.

[0057] In view of this, the present invention provides a liquid drainage test system, which includes an operation string and a liquid drainage string; the operation string includes a tubing 1 and a tubing tee 2, and the tubing tee 2 has a first port, a second port and a third port, and one end of the tubing 1 is fixedly connected to the first port; the liquid drainage string includes a central pipe 3, a gas lift valve 4 and a packer; one end of the central pipe 3 is inside the tubing 1, and the other end passes through the tubing 1, the first port and the second port in sequence. The central pipe 3 and the tubing 1 and the tubing tee 2 enclose a small annulus 5, and are also in sealing cooperation with the side wall of the second port; both the gas lift valve 4 and the packer are inside the tubing 1 and are both connected to the central pipe 3. Among them, there are multiple gas lift valves 4, and the multiple gas lift valves 4 are spaced along the axial direction of the central pipe 3 and are between the packer and the tubing tee 2, and the packer is set in the tubing 1; the gas lift valve 4 includes an outer cylinder 41 and a closing assembly. Among them, a gas lift channel 411 is provided on the side wall of the outer cylinder 41, and the closing assembly is arranged inside the outer cylinder 41 and is configured to block the gas lift channel 411 under the condition of no liquid in the outer cylinder 41, and release the blockage of the gas lift channel 411 under the condition of full liquid in the outer cylinder 41.

[0058] In this liquid drainage test system, multiple gas lift valves 4 cooperate to form a multi-stage gas lift valve 4. Among them, the one close to the tubing tee 2 is the first-stage gas lift valve 4, and so on; when the well is full of liquid, the multi-stage gas lift valves 4 are all in the open state, that is, the gas lift channels 411 are in the open state. At this time, the outer cylinder 41 is communicated with the small annulus 5; when compressed natural gas is injected into the small annulus 5 through the third port, the compressed natural gas will enter the outer cylinder 41 of the first-stage gas lift valve 4 from the small annulus 5 through the gas lift channel 411, so as to reverse-circulate the liquid in the wellbore out of the ground from the first-stage gas lift valve 4 and make the upper part of the first-stage gas lift valve 4 full of gas, thereby prompting the first-stage gas lift valve 4 to close; after the first-stage gas lift valve 4 is closed, the compressed gas can only displace the liquid above the second-stage gas lift valve 4 from the second-stage gas lift valve 4 and then prompt the second-stage gas lift valve 4 to close; in this way, it can gradually displace the accumulated liquid in the wellbore step by step, and at the same time all the gas lift valves 4 in the well are closed.

[0059] It can be seen that compared with the prior art, this liquid drainage test system can realize liquid drainage of gas wells with compressed natural gas as the power, and the liquid drainage does not occupy the oil-casing annulus and retains the gas production channel; in addition, using compressed natural gas as the power, if there is sufficient gas source in the adjacent well, the natural gas of the adjacent well can be introduced for liquid drainage without the need for natural gas compressor boosting, which will further reduce the construction cost and improve the gas production efficiency.

[0060] The following combines Figures 1 to 4 to describe in detail the structure and shape of the liquid drainage test system provided in this embodiment:

[0061] Refer to Figure 1 and Figure 2, The liquid drainage test system can achieve reverse circulation gas lift and jet pump liquid drainage. It consists of two parts: the operation string and the liquid drainage string. These two parts are relatively independent and interconnected, forming an organic liquid drainage system.

[0062] For natural gas wells, and if the downhole operation string has been set up, there is no need to pull out the original string for re - setting. This avoids the operation and risks of pulling out and running in the original string. The liquid drainage string can be directly run into the original string. At this time, the liquid drainage string consists of a plug 13, a central pipe tee 14, a sealing plug 15, a central pipe 3, a multi - stage gas lift valve 4, a reverse circulation jet pump 6, a check valve 7, a tubing 1, a packer 8, a pressure gauge 16, etc. As Figure 1 shown, lower this liquid drainage string to the predetermined position of the operation string, then rotate and apply pressure to set the packer 8, and then connect the wellhead and surface pipelines to carry out gas lift liquid drainage. It should be added that if it is a new gas well, or the operation string can be pulled out and re - set, as Figure 2 shown, a landing joint 9 is set on the tubing 1. The landing joint 9 is inserted and cooperated with an insert seal 10 to form a seal. This is equivalent to the packer 8 being set in the tubing 1, thus replacing the packer 8.

[0063] Regarding the gas lift valve 4, specifically:

[0064] Referring to Figure 3 , the outer cylinder 41 includes an upper joint 412, a body 413 and a lower joint 414. The closing assembly includes a sliding valve 42 and a reset unit; both ends of the body 413 are respectively thread - connected to the upper joint 412 and the lower joint 414, and are hermetically fitted through a second sealing ring 45. The inner wall of the body 413 and the end faces of the upper joint 412 and the lower joint 414 enclose an annular groove; the sliding valve 42 and the wall surface of the annular groove enclose an annular cavity 43. Its upper end is located in the annular groove to block the gas lift channel 411. Two groups of first sealing rings 44 are embedded outside the upper end, and the two groups of first sealing rings 44 are abutted against the side wall of the annular groove and are located above and below the gas lift channel 411. The lower end is located outside the annular groove and is hermetically fitted with the lower joint 414 through a second sealing ring 45; preferably, the reset unit uses nitrogen, and nitrogen fills the annular cavity 43, about 2 Mpa. In addition, the reset unit can also use a spring.

[0065] Normally, that is, when there is no liquid in the outer cylinder 41, under the action of nitrogen pressure, the sliding valve 42 is in the top dead center position, as Figure 2As shown, at this time, the upper end of the slide valve 42 abuts against the upper joint 412, and the gas lift channel 411 is located between two groups of first sealing rings 44 and is closed. When the gas lift valve 4 descends into the well, if the liquid column pressure inside the valve overcomes the nitrogen pressure and the friction force of the first sealing ring 44, the slide valve 42 will be pushed to the bottom dead center and supported by the step 4141 inside the lower joint 414. In this way, the first sealing ring 44 on the slide valve 42 is located below the gas lift channel 411, thus opening the gas lift channel 411. At this time, the compressed gas can lift the liquid above the gas lift valve 4 to the ground.

[0066] Continuing from the above, when all the liquid above the gas lift valve 4 is discharged, both inside and outside the pipe are filled with gas, and the pressure inside the valve will drop to nearly 0. At this time, under the action of the nitrogen pressure, the slide valve 42 will be pushed to the top dead center position, thus closing the gas lift channel 411. Immediately afterwards, the compressed gas can lift the liquid above the next-stage gas lift valve 4. In this way, going down step by step, all the liquid in the wellbore can be lifted to the ground, and at the same time, all the gas lift valves 4 are automatically closed. Finally, the compressed gas is conveyed to the reverse circulation jet pump 6, and all the bottom-hole accumulated liquid is pumped out through the suction action of the reverse circulation jet pump 6.

[0067] Regarding the reverse circulation jet pump 6, specifically:

[0068] Refer to Figure 4 , the upper and lower parts of the reverse circulation jet pump 6 have threads. The upper end is hermetically connected to the central pipe 3, and the lower end is hermetically connected to the check valve 7. The reverse circulation jet pump 6 includes a throat 61, an outer cylinder 62, a nozzle 63, and a flow nipple 64; the throat 61 and the flow nipple 64 are distributed at intervals; the outer cylinder 62 is sleeved on the throat 61 and the flow nipple 64. One end of the outer cylinder 62 is threadedly connected to the throat 61 and is sealed with the throat 61 through a third sealing ring 65, and the other end is threadedly connected to the flow nipple 64 and is sealed with the flow nipple 64 through a third sealing ring 65; the nozzle 63 is threadedly connected to the flow nipple 64 and is sealed with the flow nipple 64 through a third sealing ring 65 and is directly opposite to the throat 61; along the axial direction of the flow nipple 64, the flow nipple 64 is provided with a main hole 641. One end of the main hole 641 is communicated with the nozzle 63, and the other end is closed. A side hole 642 penetrating through itself is provided on the side wall of the flow nipple 64, and the side hole 642 and the main hole 641 are distributed at intervals; along the radial direction of the flow nipple 64, a transverse hole 643 is provided on the side wall of the flow nipple 64, and the transverse hole 643 is communicated with the main hole 641.

[0069] During application, the motive gas input from the small annulus 5 enters the main passage 641 through the transverse hole 643 on the flow nipple 64, then enters the nozzle 63. Through the diameter reduction and flow resistance of the nozzle 63, the motive gas is pressurized and energy-accumulated, and a high-speed jet is formed at the outlet of the nozzle 63. Then it is sprayed into the throat 61, and through the diameter expansion and pressure reduction of the throat 61, a negative pressure suction area is formed between the nozzle 63 and the throat 61, so as to suck the fluid below the reverse circulation jet pump 6 into the central pipe 3 through the side passage 642 and lift it to the ground together with the motive gas.

[0070] Furthermore, referring to Figure 1 , the work string further includes a casing 11, a tubing hanger 19 and a casing hanger tee. The casing 11 is flange-connected to the lower port flange of the casing hanger tee, the upper port of the casing hanger tee is connected to the joint flange, and the tubing hanger 19 is arranged between the joint and the tubing 1 to block the upper opening of the casing 11.

[0071] Referring to Figure 1 , when the liquid drainage test system provided by the present invention is draining liquid, natural gas is injected from the flank of the tubing tee 2, i.e., the third port, into the small annulus 5 between the tubing 1 and the central pipe 3. At this time, if the wellbore is full of liquid, all the multi-stage gas lift valves 4 are in the open state, and the compressed gas can reverse-circulate the liquid in the wellbore out of the ground from the first-stage gas lift valve 4, making the area above the first-stage gas lift valve 4 full of gas. Since the density of the gas is very low, the pressure inside the first-stage gas lift valve 4 will decrease, prompting the first-stage gas lift valve 4 to close; at this time, the compressed gas can only displace the liquid above the second-stage gas lift valve 4 from the second-stage gas lift valve 4, reducing the pressure inside the second-stage gas lift valve 4 and prompting the second-stage gas lift valve 4 to close. In this way, it can be gradually returned downward to displace all the accumulated liquid in the wellbore, and all the gas lift valves 4 in the well will be closed. During the gas lift process, due to the function of the check valve 7, the liquid entering the tubing 1 and the central pipe 3 cannot return to the wellbore again and will eventually be completely discharged.

[0072] Continuing from the above, finally, the compressed gas can only perform reverse circulation through the reverse circulation jet pump 6. The compressed gas will generate a suction effect through the reverse circulation jet pump 6, sucking the liquid below the packer 8 into the central pipe 3 and returning it to the ground from the flank of the central pipe tee 14 together with the natural gas; after being separated and metered on the ground, the natural gas is used as motive gas again and injected into the well for circulating liquid drainage, and the liquid in the large annulus 12 between the tubing 1 and the casing 11 is continuously discharged. When the liquid level in the large annulus 12 drops to a certain depth, the natural gas in the formation enters the wellbore and returns upward through the large annulus 12. Due to the blockage of the tubing hanger 19, the formation-produced gas can only return to the ground from the flank of the casing tee 18 and enter the gas gathering pipeline network.

[0073] Continuing with the above, when the wellbore liquid accumulation is pumped to the sand control screen pipe 17, the liquid flowing back in the central pipe 3 will rapidly decrease. At this time, the liquid drainage can be stopped, and in this way, the gas well can produce normally for a period of time. When the liquid accumulation in the well recovers to the level that affects the gas production of the gas well, it can be drained again.

[0074] With the above design, the problem that the existing liquid drainage system has a complex technological process due to the need for ground-injected fluid as the power source is solved, filling the gap in the gas well drainage using natural gas from adjacent wells or the gas gathering pipeline network as the power fluid.

[0075] In the present invention, a liquid drainage string is lowered into the tubing 1. The liquid drainage string is composed of a central pipe 3, multiple-stage gas lift valves 4, a reverse circulation jet pump 6, a check valve 7, a packer 8 or an insert seal 10, a pressure gauge 16, etc., forming a system of central pipe 3 reverse circulation gas lift + jet pump liquid drainage. Here, the multiple-stage gas lift valves 4 can gradually empty the wellbore liquid accumulation with a relatively low gas pressure until the bottom of the well. At this time, all the downhole gas lift valves 4 will be closed; the ultimate goal is to supply compressed natural gas to the downhole jet pump, and through the suction action of the jet pump, all the liquid accumulation at the bottom of the well is pumped out. The jet pump uses a reverse circulation jet pump 6, one is synchronous with the gas lift valve 4, and the other is that the gas lift liquid drainage in the pipe can form slug flow, improving the liquid drainage efficiency.

[0076] Continuing with the above, whether to use a packer 8 or an insert seal 10 in the liquid drainage string depends on the specific well conditions. If the work string has been set in the well and cannot be retrieved and reset, then a tubing 1 packer 8 is used; if it is a new well or the work string can be retrieved and reset, then a setting joint 9 should be set in the work string, and an insert seal 10 is used in the liquid drainage string.

[0077] The effects of the present invention are as follows:

[0078] The present invention can realize gas well liquid drainage using compressed natural gas as the power. The liquid drainage does not occupy the annulus between the tubing and the casing, retaining the gas production channel; at the same time, the combination of the gas lift of the multiple-stage gas lift valves 4 and the reverse circulation jet pump 6 reduces the gas source pressure, improving the safety and reliability of gas use; at the same time, due to the suction action of the reverse circulation jet pump 6, all the liquid accumulation at the bottom of the well can be pumped out, fully liberating the gas-producing formation and increasing the gas production.

[0079] Using compressed natural gas as the power, if there is sufficient gas source in the adjacent well, the natural gas of the adjacent well can be introduced to implement this process without the need for natural gas compressor boosting, which will greatly reduce the construction cost and improve the gas production efficiency. Adopting the reverse circulation liquid drainage method, with liquid drainage in the central pipe 3, it is easier to form slug flow, which can effectively avoid gas slippage, improve the liquid-carrying capacity of gas lift, and improve the liquid drainage efficiency.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A liquid discharge testing system, characterized in that, include: Working string and drainage string; The working pipe string comprises an oil pipe (1) and an oil pipe tee (2), wherein the oil pipe tee (2) has a first opening, a second opening and a third opening, and one end of the oil pipe (1) is fixedly connected to the first opening; The drainage pipe string comprises a central pipe (3), a gas lift valve (4) and a packing member; One end of the center pipe (3) is located in the oil pipe (1), and the other end passes through the oil pipe (1), the first opening and the second opening in sequence. The center pipe (3), the oil pipe (1) and the oil pipe tee (2) form a small annulus (5) and are also sealed with the side wall of the second opening. The gas lift valve (4) and the packing are both located in the oil pipe (1) and are both connected to the center pipe (3), wherein a plurality of gas lift valves (4) are provided, and the plurality of gas lift valves (4) are distributed at intervals along the axial direction of the center pipe (3) and are located between the packing and the oil pipe tee (2), and the packing is sealed with the oil pipe (1); The gas lift valve (4) comprises an outer cylinder (62) body (41) and a sealing component, wherein the outer cylinder (62) body (41) is provided with a gas lift passage (411) penetrating its side wall, and the sealing component is arranged in the outer cylinder (62) body (41) and is configured to block the gas lift passage (411) when there is no liquid in the outer cylinder (62) body (41), and to release the blockage of the gas lift passage (411) when the outer cylinder (62) body (41) is filled with liquid.

2. The liquid discharge test system according to claim 1, wherein The closure assembly includes a slide valve (42) and a reset unit; The slide valve (42) is slidably matched with the inner wall of the outer cylinder (62) body (41) so as to be able to slide along the axial direction of the outer cylinder (62) body (41); The reset unit is arranged between the slide valve (42) and the outer cylinder (62) body (41), so that the slide valve (42) has a tendency to slide toward the gas lift passage (411) to block the gas lift passage (411).

3. The liquid discharge testing system according to claim 2, wherein Along the circumference of the outer cylinder (62) body (41), the inner wall of the outer cylinder (62) body (41) is recessed to form an annular groove, and the gas lift channel (411) is arranged on the side wall of the annular groove; One end of the slide valve (42) is located in the annular groove to block the gas lift channel (411), and the other end is located outside the annular groove. The slide valve (42) and the wall surface of the annular groove enclose an annular cavity (43); The resetting unit comprises nitrogen, and the nitrogen is arranged in the annular cavity (43).

4. The liquid discharge test system according to claim 3, characterized in that, Two groups of the first sealing rings (44) are embedded on one end of the sliding valve (42), and the two groups of the first sealing rings (44) are in contact with the side walls of the annular groove and are located on both sides of the gas lift channel (411).

5. The liquid discharge testing system according to claim 3, wherein, The outer cylinder (62) body (41) comprises an upper joint (412), a main body (413) and a lower joint (414); Both ends of the body (413) are threadedly connected to and sealingly fitted with the upper joint (412) and the lower joint (414) respectively. An annular groove is formed by enclosing the inner wall of the body (413), the end face of the upper joint (412), and the end face of the lower joint (414).

6. The liquid discharge test system according to claim 1, wherein The drain pipe string further includes a reverse circulation jet pump (6) and a check valve (7); The reverse circulation jet pump (6) is connected to the central pipe (3) and is located between the gas lift valve (4) and the packer. The reverse circulation jet pump (6) is configured to suck fluid into the central pipe (3) under the intake condition; The check valve (7) is connected to the reverse circulation jet pump (6) and is located between the reverse circulation jet pump (6) and the packer.

7. The liquid discharge test system according to claim 6, wherein, The reverse circulation jet pump (6) includes a throat pipe (61), an outer cylinder (62), a nozzle (63), and a flow nipple (64); The throat pipe (61) and the flow nipple (64) are spaced apart; The outer cylinder (62) is sleeved on the throat pipe (61) and the flow nipple (64). One end of the outer cylinder (62) is threadedly connected to the throat pipe (61), and the other end is threadedly connected to the flow nipple (64); The nozzle (63) is threadedly connected to the flow nipple (64) and is aligned with the throat pipe (61); Axially along the flow nipple (64), a main hole (641) is provided in the flow nipple (64). One end of the main hole (641) is communicated with the nozzle (63), and the other end is closed. A side hole (642) penetrating through the flow nipple (64) is provided on the side wall of the flow nipple (64). The side hole (642) and the main hole (641) are spaced apart; Radially along the flow nipple (64), a transverse hole (643) is provided on the side wall of the flow nipple (64). The transverse hole (643) is communicated with the main hole (641).

8. The liquid discharge testing system according to claim 1, wherein The packer includes a packer (8), or the packer includes a setting joint (9) and an insert seal (10); The setting joint (9) is arranged on the tubing (1). The insert seal (10) is inserted and fitted with the setting joint (9), and a seal is provided therebetween.

9. The liquid discharge test system according to any one of claims 1 to 8, characterized in that, The work string further includes a casing (11); The tubing (1) passes through the casing (11), and an outer annulus (12) is formed between the tubing (1) and the casing (11). One end of the tubing (1) connected to the tubing tee (2) is located outside the casing (11); One end of the casing (11) close to the tubing tee (2) is sealingly arranged with the tubing (1). An exhaust hole communicated with the outer annulus (12) is provided on the side wall of the casing (11).

10. A liquid discharge test method, characterized in that, Based on the drain test system according to any one of claims 1 to 9, the method includes the following steps: S1: Connect a plug (13), a central pipe tee (14), a seal plug (15), a plurality of gas lift valves (4), a reverse circulation jet pump (6), a check valve (7), a packer, and a pressure gauge (16) to the central pipe (3) in sequence from one end to the other end of the central pipe (3) to form a drain pipe string; S2: Lower the drain pipe string into the tubing (1) and set the packer on the tubing (1). S3: Drain the liquid by gas lift. S301: Inject compressed natural gas through the third through-port. S302: When the accumulated liquid in the well is pumped to the sand control screen pipe (17) of the work string, stop draining the liquid. When the accumulated liquid in the well returns to the level that affects the gas well production, repeat step S301.

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