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CN-121976774-A - Wellhead device suitable for air salt cavern gas storage and method for protecting air salt cavern gas storage sleeve

CN121976774ACN 121976774 ACN121976774 ACN 121976774ACN-121976774-A

Abstract

The invention relates to the technical field of compressed air energy storage and underground gas storage, in particular to a wellhead device suitable for an air salt cavern gas storage and a method for protecting an air salt cavern gas storage sleeve. The problem that the inner wall of the sleeve is easy to corrode and the safety and the service life of the gas storage are influenced is solved. The gas storage device comprises a main channel, a first valve, a gas storage device, a first branch, a second valve and a third valve, wherein the first valve is arranged on the main channel, and the first branch and the second branch are respectively communicated with pipe sections on two sides of the main channel and the gas storage device. And after the energy release process is finished, the air in the air storage device is injected into the salt cavern air storage sleeve through the second branch to form an air isolation section in the sleeve, so that the direct contact between the high-humidity and high-salt air rising in the salt cavern and the inner wall of the sleeve is isolated. The invention can reduce the risk of casing corrosion, reduce hidden danger of air leakage and prolong the service life of the air salt cavern gas storage.

Inventors

  • CHEN SHIQING
  • ZHOU XUEZHI
  • LI WEN
  • ZHANG XINJING
  • ZHAO MINGZHI
  • XU YUJIE
  • CHEN HAISHENG

Assignees

  • 中国科学院工程热物理研究所

Dates

Publication Date
20260505
Application Date
20260325

Claims (10)

  1. 1. The wellhead device suitable for the air salt cavern gas storage is characterized by comprising a main channel (1), a first valve (2), a gas storage device (3), a first branch (4), a second branch (5), a second valve (6) and a third valve (7); one end of the main channel (1) is used for being connected with a ground energy storage and release system (8), and the other end of the main channel is used for being connected with a wellhead main body of the salt cavern gas storage; The first valve (2) is arranged on the main channel (1) and divides the main channel (1) into a first pipe section (11) positioned between the first valve (2) and the surface energy storage and release system (8) and a second pipe section (12) positioned between the first valve (2) and the wellhead main body; the first branch (4) is communicated with the first pipe section (11) and the gas storage device (3), and the second valve (6) is arranged on the first branch (4); The second branch (5) is communicated with the second pipe section (12) and the gas storage device (3), and the third valve (7) is arranged on the second branch (5); the air storage device (3) is used for storing air from the ground energy storage and release system (8) at the end of the energy storage process, and injecting air into the sleeve of the salt cavern air storage after the energy release process is finished.
  2. 2. Wellhead device according to claim 1, characterised in that the gas storage means (3) are a group of high-pressure gas cylinders.
  3. 3. Wellhead device according to claim 1, characterised in that the wellhead body comprises a wellhead four-way (9) and a casing head (10), the main channel (1) being connected to the wellhead four-way (9).
  4. 4. A wellhead device according to claim 3, characterised in that a first gate valve (13) and a second gate valve (14) are arranged in sequence between the wellhead four-way (9) and the casing head (10).
  5. 5. Wellhead device according to claim 4, characterised in that one end of the first gate valve (13) is connected to the wellhead four-way (9) and the other end is connected to the second gate valve (14), one end of the second gate valve (14) being connected to the first gate valve (13) and the other end being connected to the casing head (10).
  6. 6. A method of protecting an air salt cavern gas storage well casing using the wellhead device of any one of claims 1 to 5, comprising: In the beginning stage of the energy storage process, the second valve (6) and the third valve (7) are closed, and the first valve (2) is opened, so that the ground energy storage and release system (8) injects air into the salt cavern gas storage; At the end of the energy storage process, a second valve (6) is opened, and the first valve (2) is closed, so that the ground energy storage and release system (8) charges air into the air storage device (3); Closing the first valve (2) and the second valve (6) at the end of the energy storage process; In the energy release process, the second valve (6) and the third valve (7) are closed, and the first valve (2) is opened, so that the salt cavern gas storage outputs air to the ground energy storage and release system (8); After the energy release process is finished, the first valve (2) and the second valve (6) are closed, and the third valve (7) is opened, so that the air in the air storage device (3) is injected into the sleeve of the salt cavern air storage.
  7. 7. Method according to claim 6, characterized in that after the end of the energy release process the air in the air reservoir (3) is injected into the sleeve by means of the pressure difference between the air reservoir (3) and the salt cavern air reservoir.
  8. 8. Method according to claim 7, characterized in that the third valve (7) is closed when a pressure equilibrium is reached between the gas storage device (3) and the salt cavern gas storage.
  9. 9. Method according to claim 6, wherein the gas storage volume of the gas storage device (3) is arranged such that, when air is injected into the casing via the third valve (7) after the end of the energy release process, an air barrier is formed in the casing from the wellhead to a predetermined depth.
  10. 10. The method of claim 9, wherein the air isolation section is configured to isolate the direct contact of the elevated, humid, high salt air returning in the salt cavern with the interior wall of the cannula during the shutdown phase after the end of the energy release process.

Description

Wellhead device suitable for air salt cavern gas storage and method for protecting air salt cavern gas storage sleeve Technical Field The invention relates to the technical field of compressed air energy storage and underground gas storage, in particular to a wellhead device suitable for an air salt cavern gas storage and a method for protecting an air salt cavern gas storage sleeve. Background The advanced compressed air energy storage system has the advantages of large energy storage scale, high efficiency, long service life, flexible scheduling, small pollution, low water resource consumption and the like, and has good application prospect in the field of large-scale energy storage. In the existing compressed air energy storage system, an underground salt cavern is often used as a gas storage space. The salt rock has the characteristics of low permeability, good creep property, strong damage self-healing capacity and the like, so that the salt cavern gas storage has higher tightness and safety, and is suitable for being used as an underground storage place of high-pressure air. However, during the operation of the air salt cavern gas storage, the well casing is in a high-pressure, high-humidity and high-salt environment for a long time, particularly during the gas injection, gas production and shutdown conversion process, the air state in the well is continuously changed, and the high-humidity and high-salt gas in the salt cavern is easy to directly contact with the inner wall of the casing, so that chemical corrosion is generated on the casing. As the run time increases, casing corrosion may lead to reduced wellbore sealing performance and even risk of gas leakage, thereby affecting the safety, reliability and service life of the gas reservoir. In the prior art, long-term protection measures for the air salt cavern gas storage sleeve in a high-humidity and high-salt environment are still limited, and a wellhead device which has a simple structure and is convenient to control and can effectively reduce the corrosion risk of the inner wall of the sleeve in the energy storage and release operation process and a control method thereof are not provided. Therefore, it is necessary to provide a wellhead device suitable for an air salt cavern gas storage, and by arranging a gas storage device and a corresponding valve control structure, air is supplemented into a sleeve in a specific operation stage, so that the direct action of high-humidity and high-salt gas in the sleeve on the inner wall of the sleeve is reduced, and the service life of the gas storage is prolonged. Disclosure of Invention In order to solve the problems in the prior art, namely the problems that the sleeve is in a high-pressure, high-humidity and high-salt environment for a long time in the energy storage and release operation process of the air salt cavern gas storage, the inner wall corrosion is easy to occur, and the safety and the service life of the gas storage are influenced, the invention provides a wellhead device suitable for the air salt cavern gas storage and a method for protecting the sleeve of the air salt cavern gas storage. The first aspect of the invention provides a wellhead device suitable for an air salt cavern gas storage, which comprises a main channel, a first valve, a gas storage device, a first branch, a second valve and a third valve; One end of the main channel is used for being connected with a ground energy storage and release system, and the other end of the main channel is used for being connected with a wellhead main body of the salt cavern gas storage; The first valve is arranged on the main channel and divides the main channel into a first pipe section positioned between the first valve and the surface energy storage and release system and a second pipe section positioned between the first valve and the wellhead main body; the first branch is communicated with the first pipe section and the gas storage device, and the second valve is arranged on the first branch; The second branch is communicated with the second pipe section and the gas storage device, and the third valve is arranged on the second branch; The air storage device is used for storing air from the ground energy storage and release system at the end section of the energy storage process, and injecting air into the sleeve of the salt cavern air storage after the energy release process is finished. Further, the gas storage device is a high-pressure gas storage cylinder group. Further, the wellhead main body comprises a wellhead four-way and a casing head, and the main channel is connected with the wellhead four-way. Further, a first gate valve and a second gate valve are sequentially arranged between the wellhead four-way valve and the casing head. Further, one end of the first gate valve is connected with the wellhead four-way joint, the other end of the first gate valve is connected with the second gate valve, and one end of the second gate valv