Compression air energy storage warehouse sediment brine discharging well completion pipe string and process method

Abstract

The invention discloses a compressed air energy storage reservoir sediment and brine discharge well completion pipe string and a process method, the compressed air energy storage reservoir sediment and brine discharge well completion pipe string comprises a pipeline unit, a screen pipe unit, an oil pipe unit and an emergency cut-off unit; a screen pipe unit is arranged in the pipeline unit; an oil pipe unit is arranged in the screen pipe unit; and the oil pipe unit is connected with the emergency cut-off unit. Wellhead monitoring is moved downwards, the bottom open hole section pressure and gas detection function is achieved, gas upward returning at the brine discharging tail stage is predicted in advance, a ground wellhead emergency cut-off valve can be opened in time, safety of a ground pipeline is guaranteed, and stable operation of a sediment brine discharging well is guaranteed; the device is used in a sediment brine discharging well at the bottom of a salt cavern energy storage reservoir or a gas storage reservoir, and shaft blockage caused by well wall collapse or upward returning of insoluble substances is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of salt cavern underground storage construction, and particularly relates to a completion string and process method for a sediment drainage well in a compressed air energy storage cavern. Background Art

[0002] As one of the main types of gas storage caverns, salt cavern gas storage caverns have the advantages of high injection and production efficiency and large short-term throughput. Salt cavern gas storage caverns mainly utilize the characteristic that salt dissolves in water to establish a connection with the target formation (salt rock layer) from the surface through drilling. After the connection is formed, a cavity-forming string is lowered from the wellhead, and fresh water is injected into the salt layer using a surface injection water pump and supporting equipment. After the fresh water fully reacts with the salt rock layer, the fresh water will turn into brine and return to the surface. After a period of dissolution, a huge salt cavity is formed underground, and this salt cavity can be used for subsequent storage of compressed air. The current mainstream method of utilizing the salt cavity space is to lower an injection gas and drain brine string through the pre-drilled wellbore to displace the brine above the sediment in the salt cavity. Using this method will result in the inability to utilize the pore space of the insoluble matter at the bottom of the salt cavity.

[0003] Therefore, a new type of brine drainage method is innovated, that is, bypassing the upper cavity position, drilling a sediment drainage well at the sediment area in the middle and lower part of the cavity, and injecting gas through the original drilled wellbore and draining brine through the sediment drainage well for injection gas and drain brine. The project of entering the cavity with a directional sediment drainage well has been successfully implemented in salt cavern gas storage / energy storage caverns in Jiangsu, Hubei, etc. It provides a new solution for the utilization of the bottom sediment in salt cavern gas storage caverns. However, currently, the three-opening method uses an open-hole completion method to enter the cavity sediment. If the current open-hole method is used, the wellbore is extremely vulnerable to the influence of insoluble debris and the caving of the open-hole section wellbore wall during the process from well completion to injection gas and drain brine, resulting in blockage. At the same time, with this completion method, it is impossible to judge and prevent the upward flow of gas at the end of the injection gas and drain brine period. Therefore, there is an urgent need to develop a new completion string and process method to solve the above problems existing in the prior art. Summary of the Invention

[0004] The purpose of the present invention is to be used in the sediment drainage well at the bottom of a salt cavern energy storage cavern or gas storage cavern, reduce the wellbore blockage caused by wellbore collapse or the upward return of insoluble matter, and at the same time avoid the upward return of gas at the end of the injection gas and drain brine period in the completion string, ensure the safety of the surface pipeline, and ensure the stable operation of the sediment drainage well.

[0005] In view of the above problems, the present invention discloses a completion string for a sediment drainage well in a compressed air energy storage cavern, including: a pipeline unit, a screen pipe unit, a tubing unit, and an emergency cut-off unit;

[0006] The pipeline unit is internally provided with a screen pipe unit;

[0007] The screen pipe unit is internally provided with a tubing unit;

[0008] The tubing unit is connected to the emergency cut-off unit.

[0009] Furthermore, the pipeline unit includes: a conduit, a surface casing, and a production casing;

[0010] The surface casing is arranged inside the conduit;

[0011] The production casing is arranged inside the surface casing.

[0012] Furthermore, the screen unit includes: a screen and a liner hanger;

[0013] The liner hanger is fixedly installed on the production casing;

[0014] The liner hanger is connected to the screen.

[0015] Furthermore, the tubing unit includes: a tubing, a first pressure and gas detector, and a second pressure and gas detector;

[0016] The tubing is connected to the surface wellhead and is arranged inside the screen;

[0017] The first pressure and gas detector is arranged in the middle of the tubing;

[0018] The second pressure and gas detector is arranged at the end of the tubing.

[0019] Furthermore, the tubing unit further includes: a first bypass valve, a second bypass valve;

[0020] The first bypass valve is installed on the tubing and is located above the first pressure and gas detector;

[0021] The second bypass valve is installed on the tubing and is located above the second pressure and gas detector.

[0022] Furthermore, the emergency cut-off unit includes: an emergency cut-off valve, a power module, a signal receiving module, and a ground control cabinet;

[0023] The signal receiving module is electrically connected to the first pressure and gas detector and the second pressure and gas detector respectively;

[0024] The signal receiving module is electrically connected to the ground control cabinet;

[0025] The ground control cabinet is electrically connected to the power module;

[0026] The power module is connected to the emergency cut-off valve;

[0027] The emergency cut-off valve is installed at the surface wellhead.

[0028] Furthermore, the setting depth of the surface casing is lower than the depth of the surface water;

[0029] The distance between the end of the production casing and the top of the salt layer is greater than the first set threshold;

[0030] The material of the surface casing is ordinary carbon steel, and the steel grade is J55 or above;

[0031] The material of the production casing is ordinary carbon steel, and the steel grade is N80 or above.

[0032] The well completion process method of the sediment drainage well of the compressed air energy storage reservoir adopting the above-mentioned well completion string includes the following steps:

[0033] Determine the basic conditions of the salt cavity;

[0034] Based on the above basic conditions, make a comprehensive judgment to determine the ground wellhead position of the sediment drainage well;

[0035] Adopt a three-opening wellbore structure and complete the well with an open hole;

[0036] After drilling into the salt cavity with an open hole, lower the screen unit;

[0037] Lower the tubing unit.

[0038] Furthermore, the horizontal distance between the ground wellhead of the sediment drainage well and the boundary of the salt cavity is greater than the third set threshold.

[0039] Furthermore, the cavity entry point of the sediment drainage well is located in the sediment area at the bottom of the salt cavity body.

[0040] Furthermore, the kick-off point of the sediment drainage well is located below the salt layer.

[0041] Compared with the prior art, the embodiments of the present invention have at least the following advantages:

[0042] 1. Move the wellhead monitoring downward, have the function of detecting the pressure and gas in the bottom open hole section, predict in advance the gas upwelling at the end of the brine drainage, and can timely open the emergency cut-off valve at the ground wellhead to ensure the safety of the ground pipeline and the stable operation of the sediment drainage well;

[0043] 2. Used in the sediment drainage well at the bottom of the salt cavern energy storage reservoir or gas storage reservoir, reduce the wellbore blockage caused by wellbore collapse or the upwelling of insoluble substances, ensure the progress of the gas injection and brine drainage operation, and avoid project delays caused by wellbore blockage;

[0044] 3. Effectively prevent the instability of the wellbore during the period from the cavity entry of the sediment drainage well to the gas injection and brine drainage, and ensure the safety of equipment and construction.

[0045] Other features and advantages of the present invention will be set forth in the following description, and in part will be obvious from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention may be realized and attained by the structure particularly pointed out in the specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0047] Figure 1 FIG. shows a schematic structural diagram of a completion string for a sediment and brine drainage well of a compressed air energy storage reservoir according to an embodiment of the present invention;

[0048] Figure 2 FIG. shows a flowchart of a completion process method for a sediment and brine drainage well of a compressed air energy storage reservoir according to an embodiment of the present invention.

[0049] Reference numerals: 1, conduit; 2, surface casing; 3, production casing; 4, liner hanger; 5, first bypass valve; 6, first pressure and gas detector; 7, tubing; 8, open hole; 9, second bypass valve; 10, second pressure and gas detector; 11, screen pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the 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.

[0051] Figure 1 FIG. shows a schematic structural diagram of a completion string for a sediment and brine drainage well of a compressed air energy storage reservoir according to an embodiment of the present invention. As Figure 1 shown, a completion string for a sediment and brine drainage well of a compressed air energy storage reservoir proposed by the present invention includes: a pipeline unit, a screen pipe unit, a tubing unit, and an emergency cut-off unit;

[0052] The pipeline unit is internally provided with a screen pipe unit;

[0053] The screen pipe unit is internally provided with a tubing unit;

[0054] The tubing unit is connected to the emergency cut-off unit.

[0055] A pipeline unit for forming a communication channel between the ground and the sediment area at the bottom of the salt cavity

[0056] A screen pipe unit for protecting the open hole section at the bottom of the above communication channel and preventing the blockage of the brine drainage channel caused by the collapse of the open hole section wellbore or the precipitation of impurities during the long-term gas injection and brine drainage construction

[0057] A tubing unit for lowering the first pressure and gas detector 6 and the second pressure and gas detector 10 for gas and pressure monitoring during gas injection and brine drainage

[0058] An emergency cut-off unit, after the first pressure and gas detector 6 and the second pressure and gas detector 10 detect abnormal pressure or gas channeling, transmits the abnormal signal to the ground control cabinet, controls the activation of the power module to start the emergency cut-off valve, and finally realizes the closing of the wellhead to prevent the high-pressure gas from damaging the ground pipeline

[0059] A completion string for a sediment brine drainage well in a compressed air energy storage reservoir proposed by the present invention is used in the sediment brine drainage well at the bottom of a salt cavern energy storage reservoir or a gas storage reservoir, reduces the wellbore blockage caused by the collapse of the wellbore or the upward return of insoluble substances, ensures the progress of gas injection and brine drainage operations, and avoids project delays caused by wellbore blockage; effectively prevents the instability of the wellbore during the period from the sediment brine drainage well entering the cavity to gas injection and brine drainage, and ensures the safety of equipment and construction

[0060] In some embodiments, the pipeline unit includes: a conductor 1, a surface casing 2, and a production casing 3

[0061] The surface casing 2 is arranged inside the conductor 1

[0062] The production casing 3 is arranged inside the surface casing 2

[0063] The outer diameter of the surface casing 2 is smaller than the inner diameter of the conductor 1, and the outer diameter of the production casing 3 is smaller than the inner diameter of the surface casing 2, which is convenient for the rapid installation construction of the conductor 1, the surface casing 2, and the production casing 3 to form a stable pipeline unit

[0064] The conductor 1 is mainly used to isolate the soft soil layer on the ground

[0065] The surface casing 2 is used to isolate surface water and shallow formation water systems to prevent pollution

[0066] The production casing 3 is used to form a rigid communication channel above the salt layer section

[0067] Exemplarily, a sediment drainage well is drilled at a position 100 m outside the salt cavity boundary. A three-opening wellbore structure is adopted. The diameter of the conductor 1 is 406.4 mm, the diameter of the surface casing 2 for the first opening is 273.1 mm, the diameter of the production casing 3 for the second opening is 177.8 mm, the diameter of the screen pipe 11 is 139.7 mm, and the diameter of the internal tubing 7 is 48.3 mm with a pressure and gas detector and a bypass valve at the bottom.

[0068] Although the above has been exemplarily described with a three-opening wellbore structure as an example, the present invention is not limited thereto, and it can adopt various wellbore structures, such as a four-opening wellbore structure. Those skilled in the art can comprehensively consider according to the gas injection and brine drainage principle of the present invention and the actual application situation, as long as the principle of the present invention can be realized.

[0069] In some embodiments, the setting depth of the surface casing 2 is lower than the depth of the surface water;

[0070] The distance between the end of the production casing 3 and the top of the salt layer is greater than a first set threshold.

[0071] The surface casing 2 and the production casing 3 are set as required above to ensure the sealing and stability of the wellbore.

[0072] Exemplarily, the first set threshold is 30 m.

[0073] Although the above has been exemplarily described with the first set threshold being 30 m as an example, the present invention is not limited thereto, and it can be set to multiple values, such as 35 m, 40 m, 45 m, etc. Those skilled in the art can comprehensively consider according to the drilling principle of the sediment drainage well of the present invention and the actual application situation, as long as the principle of the present invention can be realized.

[0074] In some embodiments, the horizontal distance between the three-opening open hole section and the boundary of the salt cavity body reserves at least the length of a second set threshold.

[0075] The purpose is to prevent the second opening from prematurely entering the salt cavity body and causing difficulties in cementing, and at the same time reserve a sufficiently long small hole section for directional drilling.

[0076] Exemplarily, the second set threshold is 60 m.

[0077] Although the above has been exemplarily described with the second set threshold being 60 m as an example, the present invention is not limited thereto, and it can be set to multiple values, such as 65 m, 70 m, 75 m, etc. Those skilled in the art can comprehensively consider according to the drilling principle of the sediment drainage well of the present invention and the actual application situation, as long as the principle of the present invention can be realized.

[0078] In some embodiments, the drill bit used for drilling can be a roller cone bit or a PDC bit according to different formations.

[0079] In some embodiments, the material of the surface casing 2 is preferably ordinary carbon steel, and the steel grade of the surface casing 2 is J55 or above;

[0080] The material of the production casing 3 is preferably ordinary carbon steel, and the steel grade of the production casing 3 is N80 or above.

[0081] The material of the screen pipe 11 is preferably ordinary carbon steel.

[0082] Since the sediment drainage and brine well only contacts saturated brine during the subsequent gas injection and brine drainage process, therefore, the materials of the surface casing 2, the production casing 3 and the screen pipe 11 are preferably selected as ordinary carbon steel, which is easy to purchase and has a low cost. The ordinary carbon steel material is sufficient to meet the requirements of the working conditions in the sediment drainage and brine well of the energy storage reservoir.

[0083] Although the materials of the surface casing 2, the production casing 3 and the screen pipe 11 are exemplarily described above with ordinary carbon steel as an example, however, the present invention is not limited thereto, and it can adopt various types of steel, such as 3Cr, 13Cr, nickel-based alloy anti-corrosion materials, etc. Those skilled in the art can comprehensively consider according to the closing principle of the present invention and the actual application situation, as long as the principle of the present invention can be realized.

[0084] In some embodiments, the screen pipe unit includes: a screen pipe 11 and a liner hanger 4;

[0085] The liner hanger 4 is fixedly installed on the inner wall of the production casing 3; Exemplarily, the two can be connected by the method of slip hanging;

[0086] The liner hanger 4 is connected to the screen pipe 11. Exemplarily, the two can be connected by threads or the specified connection method of the liner hanger 4.

[0087] The screen pipe 11 is used to protect the smoothness of the open hole section at the bottom of the above-mentioned communication channel, prevent the collapse of the open hole section wellbore or the precipitation of impurities during the long-term gas injection and brine drainage construction process, resulting in the blockage of the brine drainage channel. At the same time, part of the communication channel is reserved in the screen hole part to increase the brine drainage volume and reduce the flow resistance;

[0088] The liner hanger 4 is used to connect and lower the screen pipe 11.

[0089] In some embodiments, the tubing unit includes: a tubing 7, a first pressure and gas detector 6, and a second pressure and gas detector 10;

[0090] The tubing 7 is connected to the surface wellhead and is arranged inside the screen pipe 11;

[0091] The first pressure and gas detector 6 is arranged in the middle of the tubing 7;

[0092] The second pressure and gas detector 10 is arranged at the end of the oil pipe 7.

[0093] The oil pipe 7 is used for lowering the first pressure and gas detector 6 and the second pressure and gas detector 10, and is used for monitoring gas and pressure during the gas injection and brine discharging process.

[0094] The first pressure and gas detector 6 is used for detecting the pressure fluctuation in the middle of the oil pipe 7 and the change of gas content;

[0095] The second pressure and gas detector 10 is used for detecting the pressure fluctuation at the bottom of the oil pipe 7 and the change of gas content.

[0096] Moving the wellhead monitoring downward, with the function of detecting the pressure and gas in the bottom open hole section, predicting in advance the upward return of gas at the end of brine discharging, and being able to timely open the emergency cut-off valve at the ground wellhead to ensure the safety of the ground pipeline and the stable operation of the sediment brine discharging well.

[0097] In some embodiments, the oil pipe unit further includes: a first bypass valve 5 and a second bypass valve 9;

[0098] The first bypass valve 5 is installed on the oil pipe 7 and is located above the first pressure and gas detector 6;

[0099] The second bypass valve 9 is installed on the oil pipe 7 and is located above the second pressure and gas detector 10.

[0100] The first bypass valve 5 is used for leading out the signal transmission cable of the first pressure and gas detector 6 from the inside of the pipe string, and after the signal transmission cable is led out from the inside of the pipe string, it goes through the annulus between the oil pipe 7 and the screen pipe 11 until it is led out from the wellhead;

[0101] The second bypass valve 9 is used for leading out the signal transmission cable of the second pressure and gas detector 10 from the inside of the pipe string, and after the signal transmission cable is led out from the inside of the pipe string, it goes through the annulus between the oil pipe 7 and the screen pipe 11 until it is led out from the wellhead.

[0102] In some embodiments, the emergency cut-off unit includes: an emergency cut-off valve, a power module, a signal receiving module and a ground control cabinet;

[0103] The signal receiving module is electrically connected to the first pressure and gas detector 6 and the second pressure and gas detector 10 respectively;

[0104] The signal receiving module is electrically connected to the ground control cabinet;

[0105] The ground control cabinet is electrically connected to the power module;

[0106] The power module is connected to the emergency cut-off valve;

[0107] The emergency cut-off valve is installed at the ground wellhead.

[0108] An emergency cut-off valve is used to close the wellhead urgently after the first pressure and gas detector 6 and the second pressure and gas detector 10 detect abnormal pressure and gas channeling, preventing high-pressure gas from damaging surface pipelines and equipment;

[0109] A power module is used to provide a power source for the emergency cut-off valve, the first pressure and gas detector 6, and the second pressure and gas detector 10;

[0110] A signal receiving module is used to receive the uploaded signals from the first pressure and gas detector 6 and the second pressure and gas detector 10;

[0111] A ground control cabinet is used to control the entire system of the first pressure and gas detector 6, the second pressure and gas detector 10, the power module, and the emergency cut-off valve.

[0112] Exemplarily, the power module uses hydraulic power to control the opening or closing of the emergency cut-off valve.

[0113] Although the above has been described by taking the power module using hydraulic power as an example, however, the present invention is not limited thereto, and it can use a variety of power sources, such as pneumatic power, electric drive, etc. Those skilled in the art can comprehensively consider according to the closing principle of the present invention and the actual application situation, as long as the principle of the present invention can be realized.

[0114] At the end of the gas injection and brine drainage operation, when the first pressure and gas detector 6 and the second pressure and gas detector 10 located underground receive pressure fluctuation signals, they will respectively transmit the pressure fluctuation signals to the signal receiving module through cables. After the signal receiving module receives the above pressure fluctuation signals sent by the first pressure and gas detector 6 and the second pressure and gas detector 10, it analyzes the pressure fluctuation signals. When the pressure signal threshold is exceeded, it will send an alarm signal to the ground control cabinet. The ground control cabinet sends an instruction to close the wellhead to the power module according to the alarm signal. When the power module receives the above instruction to close the wellhead, it closes the emergency cut-off valve at the ground wellhead according to the instruction, realizing the well closure operation and preventing gas from returning upward.

[0115] The basic conditions for a completion string of a compressed air energy storage reservoir brine drainage well can be adopted:

[0116] (1) The old well conditions of the old salt mine cavity are relatively good (the original wellhead sealing performance and the wellbore integrity are good);

[0117] (2) The salt cavity can at least conduct convective circulation through two old wells;

[0118] (3) One of the old wells has the function of closing the well (or has been plugged), to meet the subsequent sealing requirements;

[0119] (4) The wellhead position of the sediment drainage well can be adjusted according to the salt cavity conditions and ground conditions;

[0120] (5) The ground conditions can ensure that the sediment drainage well has a sufficient pre-target distance. The wellbore trajectory is adjusted according to different salt cavity shapes and formation conditions, and the ground conditions meet the drilling requirements.

[0121] Principles of the wellbore trajectory of the completion string of the sediment drainage well in a compressed air energy storage reservoir:

[0122] (1) It is recommended that the horizontal distance between the ground wellhead position of the sediment drainage well and the salt cavity boundary be greater than the third set threshold and meet the trajectory orientation requirements;

[0123] (2) Keep the verticality of the wellbore above the salt layer as much as possible, and control the kick-off point below the salt layer;

[0124] (3) The setting of the target point needs to be comprehensively judged by combining factors such as the shape of the salt cavity, historical cavity formation / salt extraction data, wellbore structure of old wells, and formation conditions;

[0125] (4) The target point should at least follow the principle of grasping the cavity entry point within the range of the sediment area at the bottom of the salt cavity. Otherwise, the sediment drainage well will lose its maximum application value;

[0126] (5) During the setting of the wellbore trajectory, it is also necessary to pay attention to avoiding the upper space of the salt cavity as much as possible to prevent the open hole section from entering the cavity in advance, which will bring difficulties to subsequent cementing and plugging of the sediment drainage well.

[0127] Determining the wellbore using the above wellbore trajectory principles can avoid the upper cavity of the salt cavity to prevent premature entry into the cavity; the casing is run into the salt layer section to isolate the upper non-salt rock layer section, reducing the influence of the upper formation on the brine drainage channel; effectively reducing the target distance leaves more space for the selection of the wellhead position; retaining a sufficient length of the open hole section to prevent premature entry into the cavity during the second drilling and unable to complete the cementing operation.

[0128] Exemplarily, the third set threshold is 100m.

[0129] Although the above text has taken the third set threshold of 100m as an example for exemplary illustration, however, the present invention is not limited thereto, and it can be set to multiple values, such as 105m, 110m, 115m, etc. Those skilled in the art can comprehensively consider according to the drilling principle of the sediment drainage well of the present invention and the actual application situation, as long as the principle of the present invention can be realized.

[0130] Completion string structure: 139.7mm screen pipe 11 + tubing 7 + liner hanger 4. The main purpose is to divide the open hole section from the bottom inlet point to the casing shoe depth, reducing the impact of wellbore sloughing on brine drainage. Then, lower the 48.3mm tubing 7 with a pressure and gas detector and a bypass valve at the bottom into the well. Two pressure and gas detectors need to be installed in the completion string. The position of the second pressure and gas detector 10 is at the end of the 48.3mm tubing 7, near the inlet point of the sediment brine drainage well. The position of the first pressure and gas detector 6 is in the middle of the entire 48.3mm tubing 7. One or two casings above the two pressure and gas detectors need to be connected to the bypass valve. The main function of the bypass valve is to lead out the signal transmission cable of the pressure and gas detector from the inside of the string. After the signal transmission cable is led out from the inside of the string, it goes through the annulus between the 48.3mm tubing 7 and the 139.7mm screen pipe 11 until it is led out from the wellhead, mainly for facilitating the subsequent connection of the upper tubing 7. The accuracy of the pressure and gas detector needs to be less than 3%.

[0131] Functions and roles of the completion string: When it comes to the end stage of gas injection and brine drainage, at the beginning, a small amount of gas enters the sediment brine drainage well from the inlet point. The pressure and gas detectors at the bottom and middle of the tubing 7 detect the pressure fluctuations and changes in gas content, and transmit the electrical signals to the wellhead emergency cut-off valve. The emergency cut-off valve immediately opens and closes the wellhead, thus achieving the function of protecting the ground low-pressure pipeline.

[0132] Embodiment

[0133] Adopt the conventional three-opening wellbore structure, open-hole completion, bit program: Ф374.6mm bit + Ф241.3mm bit + Ф152.4mm bit; casing program: Ф273.1mm casing + Ф177.8mm casing; during the actual drilling process, in the salt layer section, that is, the lower part of the second opening and the third opening well section, a saturated brine drilling fluid system is used for drilling; it is recommended to use N80 casing for the production casing 3, and conventional cementing method is adopted, with a brine cement slurry system, and the cement returns to the surface. After drilling into the salt cavity with the open hole 8, lower the 139.7mm screen pipe 11 + tubing 7 + liner hanger 4. The main purpose is to divide the open hole section from the bottom inlet point to the casing shoe depth, reducing the impact of wellbore sloughing on brine drainage. Then, lower the 48.3mm tubing 7 with a pressure and gas detector and a bypass valve at the bottom into the well. When it comes to the end stage of gas injection and brine drainage, at the beginning, a small amount of gas enters the sediment brine drainage well from the inlet point. The pressure and gas detectors at the bottom and middle of the tubing 7 detect the pressure fluctuations and changes in gas content, and transmit the electrical signals to the wellhead emergency cut-off valve. The emergency cut-off valve immediately opens and closes the wellhead, thus achieving the function of protecting the ground low-pressure pipeline.

[0134] Figure 2The flowchart of the completion process method of the sediment drainage well for a compressed air energy storage reservoir according to an embodiment of the present invention is shown. As Figure 2 shown, the completion process method of the completion string of the sediment drainage well for a compressed air energy storage reservoir as described above includes the following steps:

[0135] Determine the basic conditions of the salt cavity;

[0136] Based on the above basic conditions, make a comprehensive judgment to determine the ground wellhead position of the sediment drainage well;

[0137] Adopt a three-opening wellbore structure and complete the well with an open hole;

[0138] After the open hole 8 drills into the salt cavity, lower the screen unit;

[0139] Lower the tubing unit.

[0140] Among them, the basic conditions include the depth where the cavity is located, the cavity boundary, the depth of the sediment surface, the sediment accumulation situation, adjacent wells (mainly referring to the wellbore trajectories of adjacent wells), adjacent cavities (mainly referring to the positions and sizes of adjacent cavities), and the ground conditions.

[0141] Among them, after the open hole 8 of the sediment drainage well drills into the sediment area of the salt cavity, first conduct a bottom exploration operation and record the bottom exploration data. Understand the formation conditions near the cavity entry point through the bottom exploration operation. After waiting for the pressure to stabilize, lower the completion string of the sediment drainage well for a compressed air energy storage reservoir.

[0142] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is 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 orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0143] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0144] In the present invention, unless otherwise clearly specified or defined, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication between two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0145] In the present invention, unless otherwise clearly specified or defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0146] In the description of the present invention, the descriptions with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In the present invention, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine the different embodiments or examples described in the present invention and the features of different embodiments or examples.

[0147] 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 recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A completion string for a sediment drainage and brine well in a compressed air energy storage reservoir, characterized in that, it includes: a pipeline unit, a screen pipe unit, a tubing unit, and an emergency cut-off unit; a screen pipe unit is arranged inside the pipeline unit; a tubing unit is arranged inside the screen pipe unit; the tubing unit is connected to the emergency cut-off unit.

2. The completion string for a sediment drainage and brine well in a compressed air energy storage reservoir according to claim 1, characterized in that, the pipeline unit includes: a conductor (1), a surface casing (2), and a production casing (3); the surface casing (2) is arranged inside the conductor (1); the production casing (3) is arranged inside the surface casing (2).

3. The completion string for a sediment drainage and brine well in a compressed air energy storage reservoir according to claim 2, characterized in that, the screen pipe unit includes: a screen pipe (11) and a liner hanger (4); the liner hanger (4) is fixedly installed on the production casing (3); the liner hanger (4) is connected to the screen pipe (11).

4. The completion string for a sediment drainage and brine well in a compressed air energy storage reservoir according to claim 3, characterized in that, the tubing unit includes: a tubing (7), a first pressure and gas detector (6), and a second pressure and gas detector (10); the tubing (7) is connected to the surface wellhead and is arranged inside the screen pipe (11); the first pressure and gas detector (6) is arranged in the middle of the tubing (7); the second pressure and gas detector (10) is arranged at the end of the tubing (7).

5. The completion string for a sediment drainage and brine well in a compressed air energy storage reservoir according to claim 4, characterized in that, the tubing unit further includes: a first bypass valve (5), a second bypass valve (9); the first bypass valve (5) is installed on the tubing (7) and is located above the first pressure and gas detector (6); the second bypass valve (9) is installed on the tubing (7) and is located above the second pressure and gas detector (10).

6. The completion string for a sediment drainage and brine well in a compressed air energy storage reservoir according to claim 4, characterized in that, the emergency cut-off unit includes: an emergency cut-off valve, a power module, a signal receiving module, and a surface control cabinet; the signal receiving module is electrically connected to the first pressure and gas detector (6) and the second pressure and gas detector (10) respectively; the signal receiving module is electrically connected to the surface control cabinet; the surface control cabinet is electrically connected to the power module; the power module is connected to the emergency cut-off valve; the emergency cut-off valve is installed at the surface wellhead.

7. The completion string for a sediment drainage and brine well in a compressed air energy storage reservoir according to claim 2, characterized in that, the depth of the surface casing (2) is lower than the depth of the surface water; the distance between the end of the production casing (3) and the top of the salt layer is greater than a first set threshold; the material of the surface casing (2) is ordinary carbon steel, and the steel grade is J55 or above; the material of the production casing (3) is ordinary carbon steel, and the steel grade is N80 or above.

8. A completion process method using the completion string for a sediment drainage and brine well in a compressed air energy storage reservoir according to any one of claims 1-7, characterized in that, it includes the following steps: determine the basic conditions of the salt cavity; Based on the above basic conditions, comprehensively judge to determine the ground wellhead position of the sediment drainage well; Adopt a three-opening wellbore structure and complete the well with an open hole; After drilling into the salt cavity in the open hole (8), lower the screen unit; Lower the tubing unit.

9. The well completion process method according to claim 8, characterized in that, the horizontal distance between the ground wellhead of the sediment drainage well and the salt cavity boundary is greater than the third set threshold.

10. The well completion process method according to claim 8, characterized in that, the cavity entry point of the sediment drainage well is located in the sediment area at the bottom of the salt cavity.

11. The well completion process method according to claim 8, characterized in that, the kick-off point of the sediment drainage well is located below the salt layer.

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