Directional repair tubular column for partial solution cavity of salt-cavern gas storage and directional repair method of directional repair tubular column

Abstract

The invention discloses a directional repair tubular column for a partial solution cavity of a salt-cavern gas storage and a directional repair method of the directional repair tubular column, the lower end of a production sleeve is located above the partial solution cavity of the salt-cavern gas storage, a middle pipe is inserted into the production sleeve, the lower end of the middle pipe extends into the partial solution cavity of the salt-cavern gas storage, and the lower end opening of the middle pipe is located below an undissolved stratum to be repaired; a central pipe is inserted into the middle pipe, and the lower end of the central pipe extends to the bottom of the partial solution cavity of the salt cavern gas storage; a spraying hole facing an undissolved stratum to be repaired is formed in one side of the circumference of the lower portion of the middle pipe, a packer is connected into the center pipe in a screwed mode, and a rubber sleeve of the packer is arranged between a lower pipe opening of the middle pipe and the spraying hole in a setting mode. The packer is firstly set, then a dissolution inhibitor is injected from the annular space between the middle pipe and the center pipe to protect an upper salt layer, then clear water or light brine is injected from the annular space between the middle pipe and the center pipe, the dissolution stratum to be repaired is rapidly dissolved, and directional repairing of the deformed cavity is achieved. According to the method, the partial solution cavity repairing efficiency can be improved, and the cavity stability and the cavity forming rate are guaranteed.

Description

Technical Field

[0001] The present invention relates to a directional repair string, in particular to a directional repair string for a partially dissolved cavity in a salt cavern gas storage reservoir. The present invention also relates to a directional repair method for a partially dissolved cavity in a salt cavern gas storage reservoir, belonging to the technical field of repairing deformed cavities in salt cavern gas storage reservoirs, and is suitable for repairing and expanding cavities in a gas storage reservoir during a cavity-making period or a brine-expulsion period. Background Art

[0002] Salt cavern gas storage is an underground gas storage facility that uses artificial space formed by the dissolution of underground salt rocks to store natural gas or other gases and can carry out injection and production operations as needed. It has functions such as seasonal peak regulation, emergency supply and strategic reserves.

[0003] During the cavern formation process of the salt cavern gas storage, the salt layer is not dissolved uniformly in all directions due to the uneven distribution of insolubles in the underground salt layer in all directions on the plane and uneven thickness in the vertical direction. The dissolution rate is fast in the direction with high salt content and less insolubles, and slow in the direction with relatively low salt content and more insolubles, resulting in a "partial dissolution" phenomenon, which causes the cavity formed by the dissolution to present a deformed cavity with a large diameter on one side and a small diameter on the other side. This shape of cavity has poor stability, which will cause risks such as collapse in the later operation of the gas storage. Secondly, due to partial dissolution, no effective cavity is formed in the salt layer in the undissolved direction, resulting in a small cavity volume and a low cavity formation rate, wasting underground salt layer gas storage space resources.

[0004] At present, in the repair of deformed cavities caused by partial dissolution, the main method is to use the injected natural gas as a dissolution inhibitor during the gas injection and brine removal stage, and then use a reverse circulation method to inject brine or clean water into the cavity through the gas injection column to repair the cavity. When the clean water or brine injected in this way enters the cavity from the gas injection pipe, it diffuses and dissolves evenly in all directions. Although it can be repaired to a certain extent, it is easy to cause excessive dissolution of the fully dissolved area, and the undissolved direction cannot achieve the effect of enhanced dissolution, and the repair effect is poor.

[0005] A Chinese invention patent with the announcement number CN 108150220B discloses a salt cavern gas storage repair method. This method requires lowering a curved continuous tubing through a casing into a cavity. However, the casing has a small diameter, so it is difficult to lower the curved continuous tubing. On the other hand, this method proposes extending the continuous tubing radially along the cavity toward the undissolved stratum to be repaired. In practice, after the injection of clean water, the continuous tubing swings and is basically impossible to stably face the repair point, so it cannot play a repair role.

[0006] The Chinese invention patent with announcement number CN 218598242U discloses a cavity repair simulation device for salt cavern gas storage. Salt bricks are used to simulate underground salt layers. The outer pipe and inner pipe are placed in the salt brick cavity. Fresh water enters the cavity through the annulus to dissolve the target layer below the gas-liquid interface layer by layer to achieve cavity repair simulation. This method is not targeted and cannot achieve directional repair of the repair layer. The repair distance is short and the effect is poor. In addition, it will over-dissolve the fully dissolved area, causing over-dissolution on the side with a larger cavity diameter, making the cavity more irregular and less stable.

[0007] The Chinese invention patent with the announcement number CN 219084341U discloses a simulated repair experimental device for deformed salt chambers, which uses a container to simulate an underground cavity, and is equipped with a gas pipe column and a water pipe column, and a shooting device is installed on the outer rail of the container. The device is mainly used to experimentally observe the changes in the brine flow field in the container, and to study the development and change laws of the brine flow field in the deformed salt cavity during the repair process. The repair method for the cavity is all-round dissolution, and directional repair is not achieved.

[0008] In summary, there is an urgent need for a directional repair technology for the partial dissolution cavity that can force dissolution in the undissolved direction and dissolve as little as possible in the fully dissolved area, so as to achieve the purpose of effectively repairing the partial dissolution deformity cavity. Summary of the invention

[0009] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0010] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0011] The primary purpose of the present invention is to overcome the problems of low efficiency and poor effect in the repair of the partial dissolution deformed cavity of the salt cavern gas storage in the prior art, and to provide a directional repair column for the partial dissolution cavity of the salt cavern gas storage, which can forcibly dissolve the salt layer in the undissolved direction, improve the repair efficiency of the partial dissolution cavity, improve the repair effect, and ensure the stability of the cavity and the cavity creation rate.

[0012] In order to solve the above technical problems, a directional repair string for a partially dissolved cavity of a salt cavern gas storage reservoir of the present invention comprises a production casing, the lower end of the production casing is located above the partially dissolved cavity of the salt cavern gas storage reservoir, an intermediate pipe is inserted into the production casing, the lower end of the intermediate pipe extends into the partially dissolved cavity of the salt cavern gas storage reservoir and the lower port is located below the undissolved formation to be repaired, a center pipe is inserted into the intermediate pipe, the lower end of the center pipe extends to the bottom of the partially dissolved cavity of the salt cavern gas storage reservoir; a spray hole facing the undissolved formation to be repaired is provided on one side of the lower circumference of the intermediate pipe, a packer is screwed into the center pipe, and the rubber cylinder of the packer is sealed between the lower pipe port of the intermediate pipe and the spray hole.

[0013] Furthermore, a centralizer is screwed into the intermediate pipe, and the slips of the centralizer are supported on the lower inner wall of the production casing.

[0014] Furthermore, an anti-dissolving agent is injected into the upper part of the partial dissolution cavity of the salt cavern gas storage reservoir, and the interface between the anti-dissolving agent and the brine is located above the undissolved stratum to be repaired.

[0015] Furthermore, during the cavity forming process, the solvent inhibitor is nitrogen.

[0016] Furthermore, during the gas injection and brine removal process, the dissolution inhibitor is natural gas.

[0017] Furthermore, during the gas injection and brine removal process, the intermediate pipe is the brine removal pipe, and the center pipe is the gas injection pipe; the distance between the lower edge of the spray hole of the intermediate pipe and the lower pipe mouth of the intermediate pipe is 3 meters, the distance between the centralizer and the pipe shoe of the production casing is 3-5 meters, and the sealing position of the packer is 1-2 meters away from the lower pipe mouth of the intermediate pipe.

[0018] Another object of the present invention is to overcome the problems of low efficiency and poor effect in the repair of the partial dissolution deformed cavity of the salt cavern gas storage in the prior art, and to provide a directional repair method for the partial dissolution cavity of the salt cavern gas storage, which can forcibly dissolve the salt layer in the undissolved direction, improve the repair efficiency of the partial dissolution cavity, improve the repair effect, and ensure the stability of the cavity and the cavity creation rate.

[0019] In order to solve the above technical problems, a directional repair method of a partial dissolution cavity of a salt cavern gas storage reservoir of the present invention comprises the following steps in sequence: Step 1: determine the area to be repaired of the partial dissolved cavity of the salt cavern gas storage reservoir, and determine the position and depth of the undissolved stratum to be repaired by using the cavity measurement results of the cavity measurement instrument; Step 2: Directly punch a spray hole within a certain angle range on the wall of the middle tube near the nozzle; Step 3: Run the intermediate pipe with the centralizer in the directional hole. After the centralizer is run, the depth is 3-5 meters from the pipe shoe of the production casing. The depth of the directional hole is equivalent to the depth of the undissolved formation to be repaired. Step 4: After lowering a gyroscope into the middle pipe with a cable to measure the orientation, the pipe string is rotated and adjusted to ensure that the directional hole on the middle pipe faces the undissolved formation to be repaired; Step 5: Lower the central pipe from the middle pipe, on which a packer is screwed; lower the pipe string to a predetermined depth, and ensure that the packer is located 1-2 meters away from the pipe opening in the middle pipe; pressurize the wellhead to seal the packer, and block the downward passage at the pipe opening of the middle pipe; Step 6: During the cavity making process, the anti-solvent is injected from the annulus between the intermediate pipe and the central pipe to ensure that the interface between the anti-solvent and the brine is at the designed depth to protect the upper salt layer; Step 7: Inject clean water or brine from the annulus between the intermediate pipe and the center pipe. The clean water or brine is sprayed out from the spray holes to quickly dissolve the dissolved formation to be repaired and reduce the dissolution of the fully dissolved area, thereby achieving directional repair of the deformed cavity.

[0020] Furthermore, in step 2, the size and number of the blowholes are determined by the injection displacement, the injection pressure and the distance between the undissolved formation to be repaired and the wellbore.

[0021] Furthermore, in step 2, the central angle between the spray hole and the center of the intermediate tube is 15°-30°.

[0022] Furthermore, in step 7, the effective repair distance after the water is ejected from the directional hole is optimized based on the injection displacement of the clean water or brine, the injection pressure, and the flow area of ​​the directional hole, to ensure that the dissolved stratum to be repaired can be dissolved quickly and efficiently.

[0023] Furthermore, in the dissolution and cavity forming stage, the dissolution inhibitor is nitrogen.

[0024] Furthermore, in the process of gas injection and brine removal, the intermediate tube is a brine removal tube, the central tube is a gas injection tube, and the dissolving agent is natural gas.

[0025] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. The present invention performs directional drilling on the wall of the intermediate pipe (or gas injection pipe), and the injected water flows out through the directional holes on the pipe wall. The directional holes face the undissolved formation to be repaired, thereby achieving the goal of targeted repair.

[0026] 2. The direction of the injected water flow is determined, the flow rate is controllable, the repair speed is fast, the efficiency is high, the effect is good, and the impact on the fully dissolved area is greatly reduced, and the over-dissolution of the fully dissolved area is reduced; the formation in the undissolved area is quickly dissolved, the repair direction is controllable, and the repair distance is adjustable, which can achieve the goal of expanding the radius of the irregular side. At the same time, on the basis of directional repair, factors such as the stability of the pipe column are considered, and it has strong on-site operability.

[0027] 3. It can quickly and effectively repair the partial dissolution deformed cavity of the salt cavern gas storage reservoir. For the partial dissolution of the cavity caused by formation heterogeneity and other reasons, it can dissolve as little as possible in the fully dissolved area of ​​the partial dissolution deformed cavity, force the dissolution in the undissolved direction, and dissolve as little as possible in the fully dissolved area, so as to make the cavity more regular, thereby achieving effective repair of the partial dissolution deformed cavity, better stability and high salt layer utilization. Compared with the commonly used repair methods, the present invention has a relatively short repair time and high repair efficiency, ensuring that the gas storage reservoir is put into operation as soon as possible.

[0028] 4. It is suitable for repairing deformed cavities in the process of cavern making (or gas injection and brine removal) of salt cavern gas storage. After application, it can effectively repair deformed cavities caused by partial dissolution and other reasons, thereby improving cavity stability and salt layer utilization, expanding cavity storage capacity, and greatly increasing the subsequent gas injection and production volume and the operating life of the cavity. After the present invention is used in the repair of deformed cavities in domestic salt cavern gas storages, it can produce very obvious economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. The drawings are only provided for reference and explanation, not for limiting the present invention. Among them: Figure 1 This is the plane view of the deformed cavity caused by partial dissolution; Figure 2 This is a structural diagram of a directional repair string for a partial solution cavity of a salt cavern gas storage reservoir according to the present invention; Figure 3 This is a cross-sectional view of the directional repair of the partial dissolution cavity; In the figure: 1. production casing; 2. centralizer; 3. dissolving agent; 4. interface between dissolving agent and brine; 5. intermediate pipe; 6. packer; 7. center pipe; A. undissolved formation to be repaired. DETAILED DESCRIPTION

[0030] In the following description of the present invention, the directions or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "inside" and "outside" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific direction.

[0031] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below in conjunction with specific diagrams. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0033] like Figure 2 As shown, the directional repair string of the present invention is used in the nitrogen resistance dissolution cavity making stage or the gas injection and brine removal stage of the partial dissolution cavity of the salt cavern gas storage reservoir. The packer 6 is screwed on the predetermined depth of the central pipe 7 or the brine removal pipe to seal the annulus between the central pipe 7 and the intermediate pipe 5. The side of the intermediate pipe 5 or the gas injection pipe is perforated to discharge clean water or brine during directional repair of the cavity. The centralizer 2 is installed at the predetermined depth of the intermediate pipe 5 or the gas injection pipe to ensure the stability of the string during the repair process. Clean water or brine is injected into the annulus between the central pipe 7 (or brine removal pipe) and the intermediate pipe 5 (or gas injection pipe), and the direction of the spray hole is toward the undissolved salt layer, and directional dissolution repair is performed in this direction.

[0034] In the stage of resisting dissolution and forming cavities, the directional repair method of the partial dissolution cavity of the salt cavern gas storage reservoir of the present invention comprises the following steps in sequence: Step 1: Figure 1 As shown, the area to be repaired of the partial dissolution cavity of the salt cavern gas storage is determined, and the position and depth of the undissolved stratum A to be repaired are determined by the cavity measurement results of the cavity measurement instrument; Step 2: Directional drilling is performed on the wall of the intermediate pipe 5 about 3 meters away from the pipe mouth within a certain angle range. The size and number of the holes drilled are determined by the injection displacement, injection pressure and the distance between the undissolved formation A to be repaired and the wellbore; Step 3: In the nitrogen dissolution cavity making stage, the intermediate pipe 5 with the directional hole drilled and equipped with the centralizer 2 is lowered. The centralizer 2 is lowered to a depth of 3-5 meters from the pipe shoe of the production casing 1. The function of the centralizer 2 is to reduce the impact of the recoil force generated by the water flow on the stability of the pipe string when fresh water or brine is injected later for cavity repair. The depth of the directional hole is equivalent to the depth of the undissolved formation A to be repaired. Step 4: After lowering a gyroscope into the middle pipe 5 with a cable to measure the orientation, the pipe string is rotated and adjusted to ensure that the directional hole on the middle pipe 5 faces the undissolved formation A to be repaired; Step 5: lower the central pipe 7 from the intermediate pipe 5, and the central pipe 7 is screwed with a packer 6. Lower the pipe string to a predetermined depth (generally inserted into the bottom of the cavity), and ensure that the packer 6 is located 1-2 meters away from the pipe opening in the intermediate pipe 5. Pressurize the wellhead to seal the packer 6, and block the downward passage at the pipe opening of the intermediate pipe 5; Step 6: During the cavity making process, nitrogen or other dissolving agent 3 is injected from the annulus between the intermediate tube 5 and the central tube 7 to ensure that the interface 4 between the dissolving agent and the brine is at the designed depth to protect the upper salt layer; Step 7: Figure 2 , Figure 3 As shown, clean water or brine is injected from the annulus between the intermediate pipe 5 and the central pipe 7, and the effective repair distance after the water is ejected from the directional hole is optimized by parameters such as injection displacement, injection pressure, and flow area of ​​the directional hole, ensuring that the dissolved stratum to be repaired can be dissolved quickly and efficiently, while reducing the dissolution of the fully dissolved area, thereby achieving the goal of directional repair of the deformed cavity.

[0035] In the process of gas injection and brine removal, the directional repair method of the partial solution cavity of the salt cavern gas storage reservoir of the present invention comprises the following steps in sequence: Step 1: Figure 1 As shown, the area to be repaired of the partial dissolution cavity of the salt cavern gas storage is determined, and the position and depth of the undissolved stratum A to be repaired are determined by the cavity measurement results of the cavity measurement instrument; Step 2: Directional drilling is performed within a certain angle range on the wall of the gas injection pipe about 3 meters away from the pipe mouth. The size and number of the holes drilled are determined by the injection displacement, injection pressure and the distance between the undissolved formation A to be repaired and the wellbore; Step 3: During the gas injection and brine removal stage, a gas injection pipe with a directional hole drilled and equipped with a centralizer 2 is lowered. After lowering, the centralizer 2 is 3-5 meters away from the pipe shoe of the production casing 1; the depth of the directional hole is equivalent to the depth of the undissolved formation A to be repaired; Step 4: After the gyroscope is lowered into the gas injection pipe with a cable to measure the direction, the pipe string is rotated and adjusted to ensure that the directional hole on the gas injection pipe faces the undissolved formation A to be repaired; Step 5: Lower the brine discharge pipe from the gas injection pipe, and the brine discharge pipe is screwed with a packer 6. Lower the pipe string to a predetermined depth (usually into the bottom of the cavity), and ensure that the packer 6 is located 1-2 meters away from the pipe opening in the gas injection pipe. Pressurize the wellhead to seal the packer 6, and block the downward passage at the pipe opening of the gas injection pipe. Step 6: During the cavity making process, natural gas is injected from the annulus between the gas injection pipe and the brine discharge pipe as a dissolving agent 3 to ensure that the interface 4 between the dissolving agent and the brine is at a designed depth to protect the upper salt layer; Step 7: Figure 2 , Figure 3 As shown, clean water or fresh brine is injected from the annulus between the gas injection pipe and the brine discharge pipe. The effective repair distance after the water is ejected from the directional hole is optimized based on the injection displacement, injection pressure, flow area of ​​the directional hole and other parameters to ensure that the dissolved formation to be repaired can be dissolved quickly and efficiently, while reducing the dissolution of the fully dissolved area, thereby achieving the goal of directional repair of the deformed cavity.

[0036] The above is only a preferred embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation modes without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. The technical features not described in the present invention can be realized by or using existing technologies, which will not be repeated here.

Claims

1. A directional repair string for a partial dissolution cavity of a salt cavern gas storage reservoir, comprising a production casing, wherein the lower end of the production casing is located above the partial dissolution cavity of the salt cavern gas storage reservoir, and characterized in that: An intermediate pipe is inserted into the production casing, the lower end of the intermediate pipe extends into the partially dissolved cavity of the salt cavern gas storage reservoir and the lower port is located below the undissolved formation to be repaired, a central pipe is inserted into the intermediate pipe, the lower end of the central pipe extends to the bottom of the partially dissolved cavity of the salt cavern gas storage reservoir; a spray hole facing the undissolved formation to be repaired is provided on one side of the lower circumference of the intermediate pipe, a packer is screwed into the central pipe, and the rubber cylinder of the packer is seated between the lower pipe port of the intermediate pipe and the spray hole.

2. The directional repair string for the partial solution cavity of the salt cavern gas storage according to claim 1 is characterized by: A centralizer is screwed into the intermediate pipe, and the slips of the centralizer are supported on the lower inner wall of the production casing.

3. The directional repair string for the partial solution cavity of the salt cavern gas storage according to claim 1 is characterized by: The upper part of the partial dissolution cavity of the salt cavern gas storage reservoir is filled with an anti-solvent, and the interface between the anti-solvent and the brine is located above the undissolved stratum to be repaired.

4. The directional repair string for the partial solution cavity of the salt cavern gas storage according to claim 3 is characterized by: During the cavity making process, the solvent inhibitor is nitrogen.

5. The directional repair string for the partial solution cavity of the salt cavern gas storage according to claim 3 is characterized by: During the gas injection and brine removal process, the solvent inhibitor is natural gas.

6. The directional repair string for the partial solution cavity of the salt cavern gas storage according to claim 1, characterized in that: During the gas injection and brine removal process, the intermediate pipe is the brine removal pipe, and the central pipe is the gas injection pipe; the distance between the lower edge of the spray hole of the intermediate pipe and the lower pipe mouth of the intermediate pipe is 3 meters, the distance between the centralizer and the pipe shoe of the production casing is 3-5 meters, and the sealing position of the packer is 1-2 meters away from the lower pipe mouth of the intermediate pipe.

7. A method for directional repair of a partial dissolution cavity in a salt cavern gas storage reservoir, characterized in that: The steps are as follows: Step 1: determine the area to be repaired of the partial dissolved cavity of the salt cavern gas storage reservoir, and determine the position and depth of the undissolved stratum to be repaired by using the cavity measurement results of the cavity measurement instrument; Step 2: Directly punch a spray hole within a certain angle range on the wall of the middle tube near the nozzle; Step 3: Run the intermediate pipe with the centralizer in the directional hole. After the centralizer is run, the depth is 3-5 meters from the pipe shoe of the production casing. The depth of the directional hole is equivalent to the depth of the undissolved formation to be repaired. Step 4: After lowering a gyroscope into the middle pipe with a cable to measure the orientation, the pipe string is rotated and adjusted to ensure that the directional hole on the middle pipe faces the undissolved formation to be repaired; Step 5: Lower the central pipe from the middle pipe, on which a packer is screwed; lower the pipe string to a predetermined depth, and ensure that the packer is located 1-2 meters away from the pipe opening in the middle pipe; pressurize the wellhead to seal the packer, and block the downward passage at the pipe opening of the middle pipe; Step 6: During the cavity making process, the anti-solvent is injected from the annulus between the intermediate pipe and the central pipe to ensure that the interface between the anti-solvent and the brine is at the designed depth to protect the upper salt layer; Step 7: Inject clean water or brine from the annulus between the intermediate pipe and the center pipe. The clean water or brine is sprayed out from the spray holes to quickly dissolve the dissolved formation to be repaired and reduce the dissolution of the fully dissolved area, thereby achieving directional repair of the deformed cavity.

8. The directional repair method of the partial dissolution cavity of the salt cavern gas storage according to claim 7 is characterized by: In step 2, the size and number of the blowholes are determined by the injection displacement, injection pressure and the distance between the undissolved formation to be repaired and the wellbore.

9. The method for directional repair of the partial dissolution cavity of the salt cavern gas storage according to claim 7, characterized in that: In step 2, the central angle between the spray hole and the center of the intermediate tube is 15°-30°.

10. The directional repair method of the partial solution cavity of the salt cavern gas storage according to claim 7, characterized in that: In step 7, the effective repair distance after the water is ejected from the directional hole is optimized based on the injection displacement of clean water or brine, the injection pressure, and the flow area of ​​the directional hole, ensuring that the dissolved stratum to be repaired can be dissolved quickly and efficiently.

11. The directional repair method of the partial solution cavity of the salt cavern gas storage according to claim 7, characterized in that: In the stage of dissolution resistance and cavity formation, the dissolution resistance is nitrogen.

12. The method for directional repair of the partial solution cavity of the salt cavern gas storage according to claim 7, characterized in that: During the gas injection and brine removal process, the intermediate tube is a brine removal tube, the central tube is a gas injection tube, and the dissolving agent is natural gas.

13. The directional repair method of the partial solution cavity of the salt cavern gas storage according to claim 7, characterized in that: The size of the horizontal area covered by the spray holes is determined by the horizontal projection area of ​​the undissolved strata, and the size of the vertical area covered by the spray holes is determined by the thickness of the undissolved strata.

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