Pressure-maintaining gas injection and brine discharge system for salt-cavern gas storage and injection-production operation method

Abstract

The invention relates to a salt-cavern gas storage pressure-maintaining gas injection brine discharging system and an injection-production operation method. The salt-cavern gas storage pressure-maintaining gas injection and brine discharge system comprises a natural gas injection and production well communicated with the top of a salt-cavern gas storage, a brine injection and production well communicated with the bottom or the side edge of the salt-cavern gas storage, a natural gas conveying assembly and a brine conveying assembly, the natural gas conveying assembly is arranged in the natural gas injection and production well, and one end of the natural gas conveying assembly is connected with a natural gas source; the brine conveying assembly is arranged in the brine injection and production well, one end of the brine conveying assembly is communicated with the lower portion in the salt cavern gas storage, and the other end of the brine conveying assembly is connected with a brine injection and production pipeline. The device has the advantages that the process of'gas injection and brine discharge 'or'brine injection and exhaust' can be effectively realized, the constant pressure in the salt cavern gas storage can be realized, the available range of the brine mining old cavity is greatly expanded, bottom gas which is prevented from collapsing and shrinking and stored in the cavity for a long time can be completely utilized, and the working gas quantity of the salt cavern is greatly increased.

Description

Technical Field

[0001] The invention relates to the technical field of salt cavern gas storage, and in particular to a salt cavern gas storage pressure-maintaining gas injection and brine removal system and an injection-production operation method. Background Art

[0002] At present, there are two technical methods for the construction of salt cavern underground gas storage. One is to drill a new well, that is, to dissolve the salt rock layer by water dissolution method, and dissolve into a relatively stable pear-shaped artificial dissolution cavity underground. This kind of storage construction technology is a mature technology in Western developed countries and is also a commonly used storage construction method in my country; the other is to use the underground dissolution cavity formed by the existing salt mine brine wells. After strict screening and stability evaluation, the brine well body structure is transformed according to the technical requirements of the gas storage to store natural gas. Compared with the first salt cavern underground gas storage construction method, the second construction method can greatly shorten the construction cycle, reduce the construction investment, and relieve the pressure of the cavity brine outlet. However, the second construction method mainly uses the old cavity formed by salt mine brine. Most of the old cavities are difficult to use due to the complex morphology, cavity stability and sealing that cannot meet the construction needs of salt cavern gas storage. The utilization rate of old cavity resources is low. At the same time, after the renovation of the old cavity is completed, the conventional injection and production operation mode needs to preserve a part of the bottom gas in the cavity for a long time, and the bottom gas is difficult to produce in order to ensure the stability requirements of the salt cavity.

[0003] Based on this, it is necessary to develop a salt cavern gas storage pressure-maintaining gas injection and brine removal system and an injection-production operation method to overcome the above technical problems. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a salt cavern gas storage pressure-maintaining gas injection and brine removal system and an injection-production operation method, which effectively overcomes the defects of the prior art.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] A pressure-maintaining gas injection and brine removal system for a salt cavern gas storage reservoir comprises a natural gas injection and production well connected to the top of the salt cavern gas storage reservoir, a brine injection and production well connected to the bottom or side of the salt cavern gas storage reservoir, a natural gas transmission component and a brine transmission component. The natural gas transmission component is arranged in the natural gas injection and production well, one end of the natural gas transmission component is connected to a natural gas source, and the other end is connected to the upper part of the inner cavity of the salt cavern gas storage reservoir. The brine transmission component is arranged in the brine injection and production well, one end of the brine transmission component is connected to the lower part of the salt cavern gas storage reservoir, and the other end is connected to a brine injection and production pipeline.

[0007] Based on the above technical solution, the present invention can also be improved as follows.

[0008] Furthermore, the above-mentioned natural gas transmission component includes a natural gas injection and production pipe, a production casing of a gas injection and production well, a surface casing of the gas injection and production well and a first wellhead device. The surface casing of the gas injection and production well is sleeved in the wellhead of the above-mentioned natural gas injection and production well. The above-mentioned first wellhead device is installed in the wellhead of the above-mentioned natural gas injection and production well. The production casing of the gas injection and production well is sleeved in the well wall of the above-mentioned natural gas injection and production well. The above-mentioned natural gas injection and production pipe is penetrated in the production casing of the gas injection and production well. The above-mentioned first wellhead device has a natural gas port connected to its inner cavity. The above-mentioned natural gas port is connected to a natural gas source through a natural gas transmission pipeline. A packer assembly in contact with the production casing of the gas injection and production well is provided on the other end. The annulus between the production casing of the gas injection and production well and the above-mentioned natural gas injection and production pipe is filled with a wellbore annulus protection fluid.

[0009] Furthermore, the first wellhead device has a first detection port connected to the inner cavity thereof, and a first pressure gauge is connected to the first detection port.

[0010] Furthermore, a first control valve is provided at the natural gas inlet.

[0011] Furthermore, the brine transportation assembly includes a surface casing of a brine drainage well, a production casing of a brine drainage well, an open hole wellbore and a second wellhead device. The surface casing of the brine drainage well is sleeved in the wellhead of the brine injection and production well. The production casing of the brine drainage well is sleeved in the well wall of the brine injection and production well. The second wellhead device is installed in the wellhead of the brine injection and production well. The second wellhead device has a brine port connected to its inner cavity. The brine port is connected to the brine injection and production pipeline. The open hole wellbore is connected between one end of the production casing of the brine drainage well located underground in the brine injection and production well and the salt cavern gas storage reservoir.

[0012] Furthermore, a cut-off valve is provided on the above-mentioned brine injection and production pipeline.

[0013] Furthermore, a salt mine brine injection and production pump is provided on the above-mentioned brine injection and production pipeline.

[0014] Furthermore, the second wellhead device has a sampling port connected to its inner cavity, the sampling port is connected to a sampling tube, and the sampling tube is provided with a sampling valve.

[0015] Furthermore, the second wellhead device has a second detection port connected to its inner cavity, and a second pressure gauge is provided at the detection port.

[0016] The beneficial effects are: the design is simple and reasonable, and can effectively realize the process of "injecting gas to expel brine" or "injecting brine to expel gas", and can achieve constant pressure in the salt cavern gas storage reservoir, so that the old cavities that cannot be used according to the traditional gas storage reservoir construction standards can be further utilized, which greatly expands the available scope of the old cavities for brine extraction. Secondly, the bottom gas stored in the cavity for a long time to prevent the cavity from collapsing and shrinking can be fully utilized, which greatly increases the working gas volume of the salt cavern.

[0017] A pressure-maintaining injection and production operation method for a salt cavern gas storage is also provided, which is implemented by using a pressure-maintaining gas injection and brine removal system for a salt cavern gas storage, and includes the following steps:

[0018] During gas extraction, brine is transported into the salt cavern gas storage reservoir through the brine transport component to displace natural gas, and the natural gas is simultaneously exported to the outside through the natural gas transport component;

[0019] During gas injection, natural gas is transported into the salt cavern gas storage reservoir through the natural gas transportation component to displace brine, and brine is simultaneously output to the outside through the brine transportation component.

[0020] The beneficial effect is that the injection-production operation method is simple and can utilize the bottom gas stored in the cavity for a long time to prevent the cavity from collapsing and shrinking, thereby greatly increasing the working gas volume of the salt cavern. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the gas injection and brine removal of the pressure-maintaining gas injection and brine removal system of the salt cavern gas storage of the present invention;

[0022] Figure 2 This is a schematic diagram of the salt cavern gas storage pressure-maintaining gas injection and brine exhaust system of the present invention during brine injection and exhaust.

[0023] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0024] 1. Natural gas transmission assembly; 2. Brine transmission assembly; 3. Brine production pipeline; 11. Natural gas injection and production pipe; 12. Production casing of injection and production gas wells; 13. Surface casing of injection and production gas wells; 14. Natural gas transmission pipeline; 15. Packer assembly; 16. First control valve; 21. Surface casing of brine drainage well; 22. Production casing of brine drainage well; 23. Open hole wellbore; 24. Second wellhead device; 31. Shut-off valve; 32. Salt mine brine injection and production pump; 241. Sampling valve; 242. Second pressure gauge. DETAILED DESCRIPTION

[0025] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0026] Example: Figure 1 and 2As shown, the pressure-maintaining gas injection and brine removal system for the salt cavern gas storage reservoir of this embodiment includes a natural gas injection and production well connected to the top of the salt cavern gas storage reservoir, a brine injection and production well connected to the bottom or side of the salt cavern gas storage reservoir, a natural gas transmission component 1 and a brine transmission component 2. The natural gas transmission component 1 is arranged in the natural gas injection and production well, one end of the natural gas transmission component 1 is connected to the natural gas source, and the other end is connected to the upper part of the inner cavity of the salt cavern gas storage reservoir, and the brine transmission component 2 is arranged in the brine injection and production well, one end of the brine transmission component 2 is connected to the lower part of the salt cavern gas storage reservoir, and the other end is connected to the injection and production brine pipeline 3.

[0027] The pressure-maintaining gas injection and brine removal system of the salt cavern gas storage of this embodiment is connected to the salt cavern gas storage by setting up mutually independent natural gas injection and production wells and brine injection and production wells, so that gas extraction or gas injection operations can be realized through the natural gas injection and production wells, and brine can also be injected or output through the brine injection and production wells. Specifically, the pressure-maintaining injection and production operation method of the salt cavern gas storage is implemented by using the pressure-maintaining gas injection and brine removal system of the salt cavern gas storage, including the following steps:

[0028] When gas is produced, brine is transported into the salt cavern gas storage reservoir through the brine transport component 2 to replace the natural gas, and the natural gas is simultaneously exported to the outside through the natural gas transport component 1;

[0029] During gas injection, natural gas is transported into the salt cavern gas storage reservoir through the natural gas transport component 1 to displace brine, and brine is simultaneously output to the outside through the brine transport component 2.

[0030] It should be noted that: regardless of whether it is gas injection and brine production or brine injection and gas production, the pressure changes in the salt cavern gas storage should be monitored throughout the process to ensure that the internal pressure is constant and within a safe range.

[0031] The salt cavern gas storage pressure-maintaining gas injection and brine exhaust system of the present embodiment is simple and reasonable in design, and can effectively realize the process of "gas injection and brine exhaust" or "brine injection and exhaust", and can achieve constant pressure in the salt cavern gas storage, so that old cavities that cannot be used by the traditional gas storage construction standards can be further utilized, greatly expanding the scope of utilization of old cavities for brine extraction, and secondly, the bottom gas stored in the cavity for a long time to prevent cavity collapse and shrinkage can be fully utilized, greatly increasing the working gas volume of the salt cavern.

[0032] As a preferred embodiment, the natural gas transmission component 1 includes a natural gas injection and production pipe 11, a production casing 12 of a gas injection and production well, a surface casing 13 of the gas injection and production well and a first wellhead device (indicated by A in the figure), the surface casing 13 of the gas injection and production well is sleeved in the wellhead of the natural gas injection and production well, the first wellhead device is installed in the wellhead of the natural gas injection and production well, the production casing 12 of the gas injection and production well is sleeved in the well wall of the natural gas injection and production well, the natural gas injection and production pipe 11 is penetrated in the production casing 12 of the gas injection and production well, the first wellhead device has a natural gas port connected to its inner cavity, the natural gas port is connected to a natural gas source through a natural gas transmission pipeline 14, and a packer assembly 15 in contact with the production casing 12 of the gas injection and production well is provided on the other end, and the annulus between the production casing 12 of the gas injection and production well and the natural gas injection and production pipe 11 is filled with a wellbore annulus protection fluid.

[0033] In the above-mentioned embodiment, the wellhead of the natural gas injection and production well is fixed by the surface casing 13 of the injection and production well. At the same time, a natural gas injection and production pipe 11 is arranged on the well wall of the natural gas injection and production well for reinforcement. A first wellhead device (a product belonging to the prior art, which will not be described here) is installed at the wellhead of the natural gas injection and production well. A production casing 12 of the injection and production well connected to the first wellhead device is arranged in the natural gas injection and production pipe 11. The end of the production casing 12 of the injection and production well is sealed with the inner wall of the natural gas injection and production pipe 11 by a packer assembly 15. Natural gas is transported inward or outward through the production casing 12 of the injection and production gas well. Its structural design is simple and can ensure the good transportation of natural gas.

[0034] In this embodiment, the first wellhead device has a first detection port connected to its inner cavity, and a first pressure gauge (indicated by b in the figure) is connected to the first detection port. The first pressure gauge can monitor the pressure information of natural gas injection or output in real time, indirectly reflect the pressure situation in the salt cavern gas storage, and adjust the flow rate of natural gas transmission in time to ensure that the pressure in the salt cavern gas storage is at a constant value.

[0035] In this embodiment, the natural gas inlet is provided with a first control valve 16. The first control valve 16 is used to control the delivery flow of the natural gas.

[0036] As a preferred embodiment, the brine transportation assembly 2 includes a surface casing 21 of a brine drainage well, a production casing 22 of a brine drainage well, a naked hole wellbore 23 and a second wellhead device 24. The surface casing 21 of the brine drainage well is sleeved in the wellhead of the brine injection and production well. The production casing 22 of the brine drainage well is sleeved in the well wall of the brine injection and production well. The second wellhead device 24 is installed in the wellhead of the brine injection and production well. The second wellhead device 24 has a brine port connected to its inner cavity. The brine port is connected to the brine injection and production pipeline 3. The naked hole wellbore 23 is connected between one end of the brine drainage well production casing 22 located underground in the brine injection and production well and the salt cavern gas storage reservoir.

[0037] In the above embodiment, the wellhead of the brine injection and production well is fixed by the surface casing 21 of the brine drainage well. At the same time, a second wellhead device 24 (a product of the prior art, which will not be described here) is installed at the wellhead of the brine injection and production well, and a brine drainage well production casing 22 is set on the well wall of the brine injection and production well to reinforce the well wall. The brine is transported inward or outward (transported outward to the salt chemical enterprise) through the brine drainage well production casing 22 and the open hole wellbore 23. The structural design is simple and can ensure the good transportation of the brine.

[0038] In this embodiment, a cut-off valve 31 is provided on the brine injection and production pipeline 3. The brine transportation in the pipeline can be cut off, or opened to keep it unobstructed.

[0039] In this embodiment, a salt mine brine injection and production pump 32 is provided on the brine injection and production pipeline 3, and the salt mine brine injection and production pump 32 ensures effective external transportation of brine.

[0040] In this embodiment, the second wellhead device 24 has a sampling port connected to its inner cavity, the sampling port is connected to a sampling tube, and the sampling tube is provided with a sampling valve 241. The sampling valve 241 is opened to sample the brine.

[0041] In this embodiment, the second wellhead device 24 has a second detection port connected to its inner cavity, and a second pressure gauge 242 is provided at the detection port. The second pressure gauge 242 can monitor the pressure information of brine injection or output in real time, indirectly reflect the pressure situation in the salt cavern gas storage reservoir, and adjust the flow rate of brine delivery in time to ensure that the pressure in the salt cavern gas storage reservoir is at a constant value.

[0042] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0043] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0044] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0046] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0047] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A pressure-maintaining gas injection and brine removal system for a salt cavern gas storage, characterized in that: The invention comprises a natural gas injection and production well connected to the top of a salt cavern gas storage reservoir, a brine injection and production well connected to the bottom or side of the salt cavern gas storage reservoir, a natural gas transmission component (1) and a brine transmission component (2), wherein the natural gas transmission component (1) is arranged in the natural gas injection and production well, one end of the natural gas transmission component (1) is connected to a natural gas source, and the other end is connected to the upper part of the inner cavity of the salt cavern gas storage reservoir, and the brine transmission component (2) is arranged in the brine injection and production well, one end of the brine transmission component (2) is connected to the lower part of the salt cavern gas storage reservoir, and the other end is connected to a brine injection and production pipeline (3).

2. A salt cavern gas storage pressure-maintaining gas injection and brine removal system according to claim 1, characterized in that: The natural gas transmission assembly (1) comprises a natural gas injection and production pipe (11), a production casing (12) of a gas injection and production well, a surface casing (13) of the gas injection and production well and a first wellhead device. The surface casing (13) of the gas injection and production well is sleeved in the wellhead of the natural gas injection and production well. The first wellhead device is installed in the wellhead of the natural gas injection and production well. The production casing (12) of the gas injection and production well is sleeved in the well wall of the natural gas injection and production well. The natural gas injection and production pipe (11) is penetrated in the production casing (12) of the gas injection and production well. The first wellhead device has a natural gas port connected to its inner cavity. The natural gas port is connected to a natural gas source through a natural gas transmission pipeline (14). A packer assembly (15) in contact with the production casing (12) of the gas injection and production well is provided on the outside of the other end. The annulus between the production casing (12) of the gas injection and production well and the natural gas injection and production pipe (11) is filled with a wellbore annulus protection fluid.

3. A salt cavern gas storage pressure-maintaining gas injection and brine removal system according to claim 2, characterized in that: The first wellhead device has a first detection port connected to the inner cavity thereof, and the first detection port is connected to a first pressure gauge.

4. A salt cavern gas storage pressure-maintaining gas injection and brine removal system according to claim 2, characterized in that: A first control valve (16) is provided at the natural gas inlet.

5. A salt cavern gas storage pressure-maintaining gas injection and brine removal system according to any one of claims 1 to 4, characterized in that: The brine transport assembly (2) comprises a surface casing (21) of a brine drainage well, a production casing (22) of a brine drainage well, an open-hole wellbore (23) and a second wellhead device (24); the surface casing (21) of the brine drainage well is sleeved in the wellhead of the brine injection and production well; the production casing (22) of the brine drainage well is sleeved in the well wall of the brine injection and production well; the second wellhead device (24) is installed in the wellhead of the brine injection and production well; the second wellhead device (24) has a brine port connected to its inner cavity; the brine port is connected to the brine injection and production pipeline (3); the open-hole wellbore (23) is connected between one end of the brine drainage well production casing (22) located underground in the brine injection and production well and a salt cavern gas storage reservoir.

6. A salt cavern gas storage pressure-maintaining gas injection and brine removal system according to claim 5, characterized in that: The brine injection and production pipeline (3) is provided with a cut-off valve (31).

7. The salt cavern gas storage pressure-maintaining gas injection and brine removal system according to claim 5, characterized in that: The brine injection and production pipeline (3) is provided with a salt mine brine injection and production pump (32).

8. The pressure-maintaining gas injection and brine removal system for salt cavern gas storage according to claim 5 is characterized by: The second wellhead device (24) has a sampling port connected to its inner cavity, the sampling port is connected to a sampling tube, and the sampling tube is provided with a sampling valve (241).

9. The salt cavern gas storage pressure-maintaining gas injection and brine removal system according to claim 5, characterized in that: The second wellhead device (24) has a second detection port connected to its inner cavity, and a second pressure gauge (242) is provided at the detection port.

10. A method for pressure-maintaining injection and production operation of a salt cavern gas storage, implemented using the pressure-maintaining gas injection and brine removal system of a salt cavern gas storage as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: When gas is extracted, brine is transported into the salt cavern gas storage reservoir through the brine transport component (2) to replace the natural gas, and the natural gas is simultaneously output to the outside through the natural gas transport component (1); During gas injection, natural gas is transported into the salt cavern gas storage reservoir through the natural gas transport component (1) to displace brine, and the brine is simultaneously output to the outside through the brine transport component (2).

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