Sediment type salt cavern gas storage gas-water interface detection device and detection method

Abstract

The invention relates to a sediment type salt cavern gas storage gas-water interface detection device and method. The device comprises a cavity, an underground brine discharging well, a ground manifold, an optical fiber interface instrument and a sound wave gas-water interface instrument, and the bottom of the underground brine discharging well is communicated with the bottom of the cavity; the ground manifold is horizontally arranged and is communicated with one end of the natural gas pipeline; a brine discharging sleeve is vertically and fixedly installed in the underground brine discharging well, the upper end of the brine discharging sleeve extends out of the underground brine discharging well and is communicated with a ground manifold, and the top of the cavity is communicated with the ground manifold through a branch sleeve. A brine discharging pipe is vertically and fixedly mounted in the brine discharging sleeve, and the lower end of the brine discharging pipe extends to the bottom of the underground brine discharging well; the sound wave gas-water interface instrument is installed at the upper end of the halogen discharging pipe, and the optical fiber interface instrument is connected with the optical fiber in the halogen discharging sleeve. The gas-water interface depth in the sediment can be conveniently and effectively detected, and the risk that gas enters a brine discharging well to damage a wellhead and even inflammable gas leaks during later gas injection and brine discharging is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of salt cavern storage of natural gas, hydrogen, helium and the like, and in particular to a gas-water interface detection device and a detection method for a sediment-type salt cavern gas storage. Background Art

[0002] Salt cavern gas storage is an important type of gas storage facility, suitable for storing natural gas, hydrogen, helium, compressed air, and other gases, and plays a vital role in energy storage. China's salt mines are continental lake deposits. The salt rock formations contain high levels of intercalated layers of insoluble materials such as anhydrite and mudstone. As a result, the spaces released by the dissolution of halite are largely filled with high-porosity, massive sediment. For example, at one salt mine in my country, the proportion of insoluble intercalated layers is as high as 50%. Sonar cavity measurements revealed that 90% of the salt caverns are buried by sediment, reaching a height of approximately 110 meters. Therefore, the sediment voids are required for gas storage.

[0003] At present, the salt cavern gas storage facilities built at home and abroad all adopt the salt cavern net space (space measured by sonar instruments) construction model. In order to avoid the danger of natural gas being discharged from the brine discharge pipe during the gas injection and brine discharge stage, the gas-water interface needs to be tested in the later stage of brine discharge.

[0004] Currently, a common detection method uses neutron logging. First, a brine drainage string is lowered 1-2 meters above the sediment surface in the salt cavity. Then, a detection instrument is lowered through the string to the gas-water interface within the salt cavity. The gas-water interface is identified by the different neutron absorption characteristics of the gas and brine. However, in sediment-type salt cavern gas storage, most of the salt cavity is buried by sediment, and the brine drainage string cannot penetrate the sediment to the bottom of the salt cavity. Therefore, during the gas injection and brine drainage process in sediment-type gas storage, when the gas-water interface is within the sediment, neutron logging cannot be used to detect it. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a gas-water interface detection device and detection method for a sediment-type salt cavern gas storage, aiming to solve the problems in the prior art.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] A gas-water interface detection device for a sediment-type salt cavern gas storage reservoir comprises a mold cavity, an underground brine drainage well, a surface manifold and an interface detector, wherein the bottom of the underground brine drainage well is connected to the bottom of the mold cavity; the surface manifold is horizontally fixedly installed above the mold cavity and the underground brine drainage well, and is connected to one end of a natural gas pipeline; a brine drainage casing is vertically fixedly installed in the underground brine drainage well, the upper end of the brine drainage casing extends to the outside of the underground brine drainage well and is connected to the surface manifold, and the top of the mold cavity is connected to the surface manifold through a branch casing; a brine drainage pipe is vertically fixedly installed in the brine drainage casing, the lower end of the brine drainage pipe extends to the bottom of the underground brine drainage well, and the upper end extends to the outside of the brine drainage casing; the interface detector is used to detect the interface depth of brine in the brine drainage casing.

[0008] The beneficial effects of the present invention are as follows: during the detection process, first, natural gas is injected into the mold cavity through the natural gas pipeline, and brine is discharged to the ground through the brine discharge pipe; then, the mold cavity and the annular cavity between the brine discharge pipe and the brine discharge casing are connected to pressure balance, and the interface depth in the brine discharge casing, that is, the gas-liquid interface in the mold cavity, is measured by the interface detector.

[0009] The present invention can conveniently and effectively detect the depth of the gas-water interface in the sediment, thereby preventing gas from entering the brine drainage well during the subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, the cavity is a single cavity, and the underground brine drainage well is located on one side of the single cavity.

[0012] The beneficial effect of adopting the above further scheme is that the depth of the gas-water interface in the sediment in the single cavity can be conveniently and effectively detected, thereby preventing gas from entering the brine drainage well during the subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage.

[0013] Furthermore, the cavity is a U-shaped cavity, the underground brine drainage well is located on one side of the U-shaped cavity, and both sides of the top of the U-shaped cavity are connected to the ground manifold through the branch casing respectively.

[0014] The beneficial effect of adopting the above further scheme is that the depth of the gas-water interface in the sediment in the U-shaped cavity can be conveniently and effectively detected, thereby preventing gas from entering the brine drainage well during the subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage.

[0015] Furthermore, the cavity is a U-shaped cavity, the underground brine drainage well is located between two sides of the U-shaped cavity, and both sides of the top of the U-shaped cavity are connected to the ground manifold through the branch casing respectively.

[0016] The beneficial effect of adopting the above further scheme is that the depth of the gas-water interface in the sediment in the U-shaped cavity can be conveniently and effectively detected, thereby preventing gas from entering the brine drainage well during the subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage.

[0017] Furthermore, valve three and valve five are fixedly installed on the two branch sleeves respectively.

[0018] The beneficial effects of adopting the above further solution are simple structure and reasonable design. The two branch casings can be connected and disconnected respectively through valve three and valve five, and detection is more convenient.

[0019] Furthermore, a pressure gauge is fixedly installed on the upper end of the brine discharge sleeve and / or the two branch sleeves.

[0020] The beneficial effects of adopting the above further solution are simple structure, reasonable design, and the use of a pressure gauge to monitor the pressure at the wellhead of the underground brine drainage well and the pressure in the two branch casings in real time, which is safe and reliable.

[0021] Furthermore, a valve 1 is fixedly installed on the upper end of the brine exhaust pipe.

[0022] The beneficial effects of adopting the above further solution are simple structure, reasonable design, the brine discharge pipe can be opened and closed by valve 1, and the brine discharge is convenient.

[0023] Furthermore, a valve 2 is fixedly installed on one end of the surface manifold close to the underground brine drainage well.

[0024] The beneficial effect of adopting the above further scheme is simple structure and reasonable design. The ground manifold can be opened and closed through valve 2, thereby realizing the connection or disconnection between the cavity and the brine discharge pipe and the annular cavity between the brine discharge sleeve, which is convenient for interface detection.

[0025] Furthermore, a valve four is fixedly installed on the natural gas pipeline.

[0026] The beneficial effects of adopting the above further solution are simple structure and reasonable design. The natural gas pipeline can be opened and closed through the valve 4, which facilitates the injection of natural gas into the cavity.

[0027] The present invention also relates to a method for detecting a gas-water interface in a sediment-type salt-cavern gas storage, which is implemented using the above-mentioned gas-water interface detection device in a sediment-type salt-cavern gas storage, and includes the following specific steps:

[0028] S1: natural gas is injected into the cavity through the natural gas pipeline, and brine is discharged to the ground through the brine discharge pipe;

[0029] S2: connecting the mold cavity with the annular cavity between the brine discharge pipe and the brine discharge sleeve until the pressure is balanced, and detecting the interface depth of the brine in the brine discharge sleeve, that is, the depth of the gas-liquid interface in the mold cavity, by an interface detector.

[0030] The beneficial effect of adopting the above-mentioned further scheme is that the present invention provides a method for detecting the gas-water interface in a sediment-type salt cavern gas storage. This detection method can conveniently and effectively detect the depth of the gas-water interface in the sediment, thereby avoiding the gas from entering the brine drainage well during the subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure when the cavity is a single cavity in the present invention;

[0032] Figure 2 This is a structural schematic diagram of a first embodiment of the present invention when the cavity is a U-shaped cavity;

[0033] Figure 3 This is a structural diagram of a second embodiment of the present invention when the cavity is a U-shaped cavity.

[0034] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0035] 1. Cavity; 2. Ground manifold; 3. Fiber optic interface meter; 4. Acoustic gas-water interface meter; 5. Natural gas pipeline; 6. Brine drainage casing; 7. Branch casing; 8. Brine drainage pipe; 9. Fiber optic; 10. Valve three; 11. Valve five; 12. Pressure gauge; 13. Valve one; 14. Valve two; 15. Valve four. DETAILED DESCRIPTION

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0040] Example 1

[0041] like Figures 1 to 3 As shown, this embodiment provides a gas-water interface detection device for a sediment-type salt cavern gas storage, comprising a cavity 1, an underground brine drainage well, a surface manifold 2 and an interface detector, wherein the bottom of the underground brine drainage well is connected to the bottom of the cavity 1; the surface manifold 2 is horizontally fixedly installed above the cavity 1 and the underground brine drainage well, and is connected to one end of a natural gas pipeline 5; a brine drainage casing 6 is vertically fixedly installed in the underground brine drainage well, the upper end of the brine drainage casing 6 extends to the outside of the underground brine drainage well and is connected to the surface manifold 2, and the top of the cavity 1 is connected to the surface manifold 2 through a branch casing 7; a brine drainage pipe 8 is vertically fixedly installed in the brine drainage casing 6, the lower end of the brine drainage pipe 8 extends to the bottom of the underground brine drainage well, and the upper end thereof extends to the outside of the brine drainage casing 6; the interface detector is used to detect the interface depth of brine in the brine drainage casing 6.

[0042] During the detection process, first, natural gas is injected into the mold cavity 1 through the natural gas pipeline 5, and the brine is discharged to the ground through the brine discharge pipe 8; then, the mold cavity 1 and the annular cavity between the brine discharge pipe 8 and the brine discharge sleeve 6 are connected to the pressure balance, and the interface depth in the brine discharge sleeve 6, that is, the gas-liquid interface in the mold cavity 1, is measured by the interface detector.

[0043] Preferably, in this embodiment, the interface detector includes an acoustic wave gas-water interface meter 4 , which is installed at the upper end of the brine discharge sleeve 6 to detect the interface of brine in the brine discharge sleeve 6 .

[0044] In addition, the above-mentioned interface detector also includes an optical fiber interface instrument 3, which is located outside the brine drainage sleeve 6 and is fixedly connected to one end of the optical fiber 9. The other end of the optical fiber 9 extends to the bottom of the brine drainage sleeve 6.

[0045] When the acoustic wave air-water interface meter 4 and the optical fiber interface meter 3 are provided at the same time, the accuracy of detection can be further improved.

[0046] It should be noted that the above-mentioned optical fiber interface meter 3 and acoustic wave air-water interface meter 4 are both based on existing technologies, and their specific structures and principles are not described in detail here.

[0047] This embodiment can conveniently and effectively detect the depth of the gas-water interface in the sediment, thereby preventing gas from entering the brine drainage well during the subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage.

[0048] Example 2

[0049] On the basis of Example 1, in this embodiment, the cavity 1 is a single cavity, and the underground brine drainage well is located on one side of the single cavity.

[0050] This solution can conveniently and effectively detect the depth of the gas-water interface in the sediment in a single cavity, avoiding the risk of gas entering the brine drainage well during subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage.

[0051] Example 3

[0052] On the basis of Example 1, in this embodiment, the cavity 1 is a U-shaped cavity, the underground brine drainage well is located on one side of the U-shaped cavity, and both sides of the top of the U-shaped cavity are connected to the ground manifold 2 through the branch casing 7 respectively.

[0053] This solution can conveniently and effectively detect the depth of the gas-water interface in the sediment in the U-shaped cavity, avoiding the risk of gas entering the brine drainage well during the subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage.

[0054] Example 4

[0055] On the basis of Example 1, in this embodiment, the cavity 1 is a U-shaped cavity, the underground brine drainage well is located between the two sides of the U-shaped cavity, and the two sides of the top of the U-shaped cavity are connected to the ground manifold 2 through the branch casing 7 respectively.

[0056] This solution can conveniently and effectively detect the depth of the gas-water interface in the sediment in the U-shaped cavity, avoiding the risk of gas entering the brine drainage well during the subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage.

[0057] The above-mentioned embodiments 2 to 4 are parallel solutions, and different cavities 1 are distributed in different ways with underground brine drainage wells.

[0058] Based on the above solution, there is sediment at the bottom of the cavity 1.

[0059] Example 5

[0060] On the basis of Example 3 or Example 4, in this embodiment, a valve 3 10 and a valve 5 11 are fixedly installed on the two branch sleeves 7 respectively.

[0061] This solution has a simple structure and a reasonable design. The two branch sleeves 7 can be connected and disconnected respectively through the valve three 10 and the valve five 11, which makes detection more convenient.

[0062] Example 6

[0063] On the basis of Example 3 or Example 4, in this embodiment, a pressure gauge 12 is fixedly installed on the upper end of the brine discharge sleeve 6 and / or the two branch sleeves 7 respectively.

[0064] This solution has a simple structure and a reasonable design. The pressure gauge 12 can be used to monitor the pressure at the wellhead of the underground brine drainage well and the pressure in the two branch casings 7 in real time. It is safe and reliable.

[0065] Example 7

[0066] On the basis of the above embodiments, in this embodiment, a valve 13 is fixedly installed on the upper end of the brine exhaust pipe 8.

[0067] This solution has a simple structure and a reasonable design. The brine discharge pipe 8 can be opened and closed by a valve 13, making brine discharge convenient.

[0068] Example 8

[0069] On the basis of the above embodiments, in this embodiment, a second valve 14 is fixedly installed at one end of the surface manifold 2 close to the underground brine drainage well.

[0070] This solution has a simple structure and a reasonable design. The ground manifold 2 can be opened or closed by the second valve 14, thereby achieving the connection or disconnection of the annular cavity between the cavity 1 and the brine discharge pipe 8 and the brine discharge sleeve 6, which is convenient for interface detection.

[0071] Example 9

[0072] On the basis of the above embodiments, in this embodiment, a valve 4 15 is fixedly installed on the natural gas pipeline 5.

[0073] This solution has a simple structure and a reasonable design. The valve 4 15 can be used to open and close the natural gas pipeline 5, making it convenient to inject natural gas into the cavity 1.

[0074] Based on the above solution, when the cavity 1 is a single cavity, one end of the ground manifold 2 is connected to the upper end of the brine discharge casing 6, and the other end is open and used to pass natural gas. In this case, the ground manifold 2 directly serves as the natural gas pipeline 5. During the detection, the interface detector detects the interface depth of the gas-liquid interface 1, that is, the depth of the gas-liquid interface 2 (see Figure 1 ).

[0075] When the cavity 1 is a U-shaped cavity and the brine discharge sleeve 6 is located on one side of the cavity 1, the natural gas pipeline 5 is set perpendicular to the ground manifold 2, and the valve 2 14 is fixedly installed on the ground manifold 2, which is located on the same side of the two branch sleeves 7. During the detection, the interface detector detects the interface depth of the gas-liquid interface 1, that is, the depth of the gas-liquid interface 2 and the gas-liquid interface 3 (see Figure 2 ).

[0076] When the cavity 1 is a U-shaped cavity and the brine discharge sleeve 6 is located between the two sides of the cavity 1, the natural gas pipeline 5 is arranged perpendicular to the ground manifold 2, and the valve 2 14 is fixedly installed on the upper end of the brine discharge sleeve 6. During the detection, the interface detector detects the interface depth of the gas-liquid interface 1, that is, the depth of the gas-liquid interface 2 and the gas-liquid interface 3 (see Figure 3 ).

[0077] Example 10

[0078] Based on the above embodiments, this embodiment further provides a method for detecting the gas-water interface in a sediment-type salt cavern gas storage, which is implemented using the above-mentioned gas-water interface detection device in a sediment-type salt cavern gas storage, and includes the following specific steps:

[0079] S1: natural gas is injected into the cavity 1 through the natural gas pipeline 5, and the brine is discharged to the ground through the brine discharge pipe 8;

[0080] S2: The mold cavity 1 is connected to the annular cavity between the brine discharge pipe 8 and the brine discharge sleeve 6 until the pressure is balanced, and the interface depth of the brine in the brine discharge sleeve 6, that is, the depth of the gas-liquid interface in the mold cavity 1, is detected by an interface detector.

[0081] This embodiment provides a method for detecting the gas-water interface in a sediment-type salt cavern gas storage. This method can conveniently and effectively detect the depth of the gas-water interface in the sediment, thereby preventing gas from entering the brine drainage well during subsequent gas injection and brine drainage, causing damage to the wellhead and even the risk of flammable gas leakage.

[0082] The working principle of the present invention is as follows:

[0083] (1) Gas injection and brine removal: Open valves 4, 3, 2, and 1, close valve 2, and inject natural gas simultaneously through two branch casings into both sides of the top of the U-shaped cavity (i.e., U-shaped cavity 1 and U-shaped cavity 2). Brine is discharged to the surface through the brine discharge pipe. Due to the principle of communicating vessels, the gas-water interface 2 in U-shaped cavity 1 and the gas-water interface 3 in U-shaped cavity 2 drop synchronously until the gas-water interface sinks into the sediment. At this point, the gas-water interface cannot be detected using conventional neutron logging methods.

[0084] (2) Check the interface position: Close valve 4 and valve 1 to stop the gas injection and brine removal operation. Open valve 2 to connect the gas in the U-shaped cavity with the annulus of the brine discharge pipe and the brine discharge casing. Let it stand for a while to allow the fluid in the U-shaped cavity and the fluid in the annulus of the brine discharge pipe and the brine discharge casing to fully flow and eventually achieve pressure balance.

[0085] During this period, the fluid pressure balance can be determined by observing the consistency of the pressure gauge readings in the three wells. Because the U-shaped cavity forms a connecting vessel with the annulus of the brine drainage pipe and casing, after sufficient quiescence, the depths of gas-liquid interface 1, gas-liquid interface 2, and gas-liquid interface 3 should be exactly the same. At this time, the depths of gas-liquid interface 1 within the sediment can be determined by measuring the wellhead fiber optic interface meter and the acoustic gas-water interface meter.

[0086] In order to solve the problem that the gas-water interface in the sediment cannot be detected by neutron logging during gas injection and brine removal in sediment-type gas storage, the present invention provides a gas-water interface detection method for sediment-type salt cavern gas storage. This method can detect the position of the gas-water interface in the sediment, which is beneficial to improving the efficiency of gas injection and brine removal and preventing the risk of gas being discharged from the brine discharge pipe outlet.

[0087] It should be noted that all electronic components involved in the present invention adopt existing technologies, and the above components are electrically connected to the controller, and the control circuits between the controller and the components are existing technologies.

[0088] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0089] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gas-water interface detection device for a sediment-type salt cavern gas storage, characterized in that: The invention comprises a mold cavity (1), an underground brine drainage well, a surface manifold (2) and an interface detector, wherein the bottom of the underground brine drainage well is connected to the bottom of the mold cavity (1); the surface manifold (2) is horizontally fixedly installed above the mold cavity (1) and the underground brine drainage well, and is connected to one end of a natural gas pipeline (5); a brine drainage casing (6) is vertically fixedly installed in the underground brine drainage well, the upper end of the brine drainage casing (6) extends to the outside of the underground brine drainage well and is connected to the surface manifold (2), and the top of the mold cavity (1) is connected to the surface manifold (2) through a branch casing (7); a brine drainage pipe (8) is vertically fixedly installed in the brine drainage casing (6), the lower end of the brine drainage pipe (8) extends to the bottom of the underground brine drainage well, and the upper end of the brine drainage pipe (8) extends to the outside of the brine drainage casing (6); the interface detector is used to detect the interface depth of brine in the brine drainage casing (6).

2. The gas-water interface detection device for a sediment-type salt cavern gas storage according to claim 1 is characterized in that: The cavity (1) is a single cavity, and the underground brine drainage well is located on one side of the single cavity.

3. The gas-water interface detection device for a sediment-type salt cavern gas storage according to claim 1 is characterized in that: The cavity (1) is a U-shaped cavity, the underground brine drainage well is located on one side of the U-shaped cavity, and both sides of the top of the U-shaped cavity are connected to the surface manifold (2) through the branch casing (7) respectively.

4. The gas-water interface detection device for a sediment-type salt cavern gas storage according to claim 1 is characterized in that: The cavity (1) is a U-shaped cavity, the underground brine drainage well is located between two sides of the U-shaped cavity, and the two sides of the top of the U-shaped cavity are respectively connected to the ground manifold (2) through the branch casing (7).

5. The gas-water interface detection device for a sediment-type salt cavern gas storage according to claim 3 or 4, characterized in that: A valve three (10) and a valve five (11) are respectively fixedly mounted on the two branch sleeves (7).

6. The gas-water interface detection device for a sediment-type salt cavern gas storage according to claim 3 or 4, characterized in that: A pressure gauge (12) is fixedly mounted on the upper end of the brine discharge sleeve (6) and / or the two branch sleeves (7).

7. The gas-water interface detection device for a sediment-type salt cavern gas storage according to any one of claims 1 to 4, characterized in that: A valve 1 (13) is fixedly mounted on the upper end of the brine exhaust pipe (8).

8. The gas-water interface detection device for a sediment-type salt cavern gas storage according to any one of claims 1 to 4, characterized in that: A second valve (14) is fixedly installed at one end of the surface manifold (2) close to the underground brine drainage well.

9. The gas-water interface detection device for a sediment-type salt cavern gas storage according to any one of claims 1 to 4, characterized in that: A valve four (15) is fixedly installed on the natural gas pipeline (5).

10. A method for detecting the gas-water interface of a sediment-type salt cavern gas storage, characterized in that: The method is implemented by using the sludge type salt cavern gas storage gas-water interface detection device as described in any one of claims 1 to 9, comprising the following specific steps: S1: natural gas is injected into the mold cavity (1) through the natural gas pipeline (5), and brine is discharged to the ground through the brine discharge pipe (8); S2: The mold cavity (1) is connected to the annular cavity between the brine discharge pipe (8) and the brine discharge sleeve (6) until the pressure is balanced, and the interface depth of the brine in the brine discharge sleeve (6), that is, the depth of the gas-liquid interface in the mold cavity (1), is detected by an interface detector.

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