Store building method for horizontal cavity building and gas injection cross operation of salt cavern gas storage

Abstract

The invention discloses a reservoir building method for horizontal cavity building and gas injection cross operation of a salt cavern gas storage, and relates to the field of underground cavern transformation. The reservoir building method for horizontal cavity building and gas injection cross operation of the salt cavern gas storage comprises the steps that a directional well A and a horizontal well B communicated with the well A are sequentially drilled to the bottom boundary of a target salt layer, and then a surface layer casing pipe, a production casing pipe and a cavity dissolving pipe column are put into the well A and the well B correspondingly; water is injected into a dissolving cavity pipe column of the well A, brine is discharged from an annular space between the dissolving cavity pipe column and the production sleeve, and a groove dissolving cavity is built; then gas is injected into the dissolving cavity from an annular space between the dissolving cavity pipe column of the well B and the production casing to adjust a gas-liquid interface in the dissolving cavity, and water is injected into the dissolving cavity from the dissolving cavity pipe column of the well B to discharge brine; and repeating the steps to enable the dissolving cavity to reach the final preset volume and to be filled with gas. According to the reservoir building method for horizontal cavity building and gas injection cross operation of the salt cavern gas storage, the investment cost can be reduced, tedious and complex construction operation procedures are avoided, the operation cost is reduced, and the reservoir building period is shortened.

Description

Technical Field

[0001] This application relates to the field of underground cave transformation. Specifically, it relates to a method for constructing a salt cavern gas storage reservoir with horizontal cavity formation and gas injection in cross - operation. Background Art

[0002] A salt cavern gas storage reservoir is formed by dissolving a thick underground salt layer or salt dome using the solution mining method to create an underground cave space. Storing natural gas or other media in it has the advantages of good safety, large injection - production throughput, and good sealing. Existing methods for constructing salt cavern gas storage reservoirs have reached a relatively mature level, but still face problems such as low cavity height, little effective utilization space, cumbersome construction steps of the cavity - building method, many engineering risks in downhole operation of pipe strings, long operation cycle, low cavity - building efficiency, long construction period, and high cost that need to be solved. Summary of the Invention

[0003] The purpose of this application is to provide a method for constructing a salt cavern gas storage reservoir with horizontal cavity formation and gas injection in cross - operation, which can reduce investment costs, avoid cumbersome and complex construction operation processes, reduce operation costs, and shorten the construction period of the gas storage reservoir.

[0004] This application is implemented as follows:

[0005] This application provides a method for constructing a salt cavern gas storage reservoir with horizontal cavity formation and gas injection in cross - operation, including the following steps:

[0006] S1. Drill the directional well A to the bottom boundary of the target salt layer. After cementing the first surface casing in well A, lower the first production casing to the top boundary of the target salt layer to complete the well;

[0007] S2. Lower the first cavity - building pipe string into well A, inject water through the first cavity - building pipe string, and discharge the brine from the annulus between the first cavity - building pipe string and the first production casing to build a groove and form a cavity until the cavity reaches a preset volume, then seal the first cavity - building pipe string;

[0008] S3. Drill the horizontal well B to the bottom boundary of the target salt layer and connect well B to the cavity. After cementing the second surface casing in well B, lower the second production casing to the top boundary of the target salt layer to complete the well. Lower the second cavity - building pipe string into well B and seal the annulus between the first cavity - building pipe string and the first production casing;

[0009] S4. Seal the second cavity - building pipe string, inject gas into the cavity from the annulus between the second cavity - building pipe string and the second production casing in well B to make the gas - liquid interface in the cavity reach the designed depth, and then seal the annulus between the second cavity - building pipe string and the second production casing in well B to keep the air pressure stable;

[0010] S5. Use the second cavity - building pipe string to inject water into the cavity so that the brine in the cavity is discharged from the first cavity - building pipe string in well A;

[0011] S6. When the solution cavity reaches the preliminary preset volume, repeat Step S4 and Step S5 to deepen the depth of the gas-liquid interface, so that the solution cavity reaches the final preset volume and is filled with gas.

[0012] In some alternative embodiments, Well A is a vertical well.

[0013] In some alternative embodiments, when the solution cavity reaches the preset volume in Step S2, it means the volume is above 2000 m 3 above.

[0014] In some alternative embodiments, when repeating Step S4 and Step S5 to deepen the depth of the gas-liquid interface, keep the second solution cavity string below the depth of the gas-liquid interface.

[0015] In some alternative embodiments, when the solution cavity reaches the final preset volume, it is a horizontal cavity.

[0016] In some alternative embodiments, when injecting gas into the solution cavity, inject air.

[0017] In some alternative embodiments, when injecting gas into the solution cavity, inject inert gas.

[0018] In some alternative embodiments, when the solution cavity reaches the final preset volume, the solution cavity is filled with gas.

[0019] The beneficial effects of the present application are as follows: The method for constructing a salt cavern gas storage reservoir with horizontal cavity formation and gas injection in cross - operation provided by the present application includes the following steps: Drill the directional well A to the bottom boundary of the target salt layer. After cementing the first surface casing in well A, lower the first production casing to the top boundary of the target salt layer to complete the well; Lower the first cavity - forming string in well A, inject water through the first cavity - forming string, and discharge the brine from the annulus between the first cavity - forming string and the first production casing to form a cavity until the cavity reaches a preset volume, and then seal the first cavity - forming string; Drill the horizontal well B to the bottom boundary of the target salt layer and connect well B to the cavity. After cementing the second surface casing in well B, lower the second production casing to the top boundary of the target salt layer to complete the well. Lower the second cavity - forming string in well B and seal the annulus between the first cavity - forming string and the first production casing; Seal the second cavity - forming string, inject gas into the cavity from the annulus between the second cavity - forming string and the second production casing in well B to make the gas - liquid interface in the cavity reach the designed depth, and then seal the annulus between the second cavity - forming string and the second production casing in well B to keep the gas pressure stable; Use the second cavity - forming string to inject water into the cavity to discharge the brine in the cavity from the first cavity - forming string in well A; When the cavity reaches the preliminary preset cavity volume, repeat step S4 and step S5 to deepen the depth of the gas - liquid interface until the cavity reaches the final preset volume and is filled with gas. The method for constructing a salt cavern gas storage reservoir with horizontal cavity formation and gas injection in cross - operation provided by the present application can reduce the investment costs of cavity - forming engineering and related surface supporting facilities for gas injection and production, avoid complicated construction operation procedures, reduce operation costs, shorten the construction period of the reservoir, and effectively improve the economic benefits of reservoir construction. Detailed implementation manners

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. Therefore, the detailed description of the embodiments of the present application below is not intended to limit the scope of the present application that is claimed, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0021] The features and performance of the method for constructing a salt cavern gas storage reservoir with horizontal cavity formation and gas injection in cross - operation of the present application will be further described in detail below in combination with embodiments.

[0022] The embodiments of the present application provide a method for constructing a salt cavern gas storage reservoir with horizontal cavity formation and gas injection in cross - operation, including the following steps:

[0023] S1. Drill the vertical well A to the bottom boundary of the target salt layer. After cementing the first surface casing in well A, lower the first production casing to the top boundary of the target salt layer to complete the well;

[0024] S2. Lower the first cavity pipe string into Well A, inject water into the target salt layer through the first cavity pipe string, and discharge the brine from the annulus between the first cavity pipe string and the first production casing to build a cavity until the cavity reaches a preset volume of more than 2000 m, and then seal the first cavity pipe string. 3 When it reaches the above preset volume, seal the first cavity pipe string.

[0025] S3. Drill the horizontal Well B to the bottom boundary of the target salt layer, connect Well B to the cavity, after cementing the second surface casing in Well B, lower the second production casing to the top boundary of the target salt layer to complete the well, and then lower the second cavity pipe string into Well B and seal the annulus between the first cavity pipe string and the first production casing.

[0026] S4. Seal the second cavity pipe string, inject gas into the cavity from the annulus between the second cavity pipe string and the second production casing of Well B to make the gas-liquid interface in the cavity reach the designed depth, then seal the annulus between the second cavity pipe string and the second production casing of Well B to stop injecting gas and keep the air pressure in the cavity stable; wherein the gas is air or inert gas.

[0027] S5. Use the second cavity pipe string of Well B to inject water into the cavity so that the brine in the cavity is discharged from the first cavity pipe string of Well A.

[0028] S6. When the cavity reaches the preliminary preset cavity volume, repeat Step S4 and Step S5 to deepen the depth of the gas-liquid interface in the cavity, and keep the second cavity pipe string below the depth of the gas-liquid interface, and leach the salt layer from top to bottom until the cavity reaches the final preset volume and the cavity is filled with gas. When the cavity reaches the final preset volume, it is a horizontal cavity.

[0029] The reservoir construction method for horizontal cavity building and gas injection cross-operation of a salt cavern gas storage provided by the embodiment of the present application drills the vertical Well A and the horizontal Well B to the bottom boundary of the target salt layer respectively, injects water into the target salt layer through Well A to discharge the brine to build a cavity, connects the horizontal Well B to the cavity, and then injects gas into the cavity through Well B to discharge the brine in the cavity from Well A, so as to leach the salt layer from top to bottom until the cavity reaches the final preset volume and the cavity is filled with gas and can be directly put into operation for gas injection and production.

[0030] The reservoir construction method for horizontal cavity building and gas injection cross-operation of a salt cavern gas storage provided by the embodiment of the present application can increase the gas storage volume, reduce the investment cost of cavity engineering and ground supporting related to gas injection and production, avoid complicated construction operation procedures, reduce the operation cost, effectively shorten the reservoir construction period and improve the economic benefit of gas storage construction.

[0031] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of this application that is claimed, but merely represents selected embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without making creative efforts fall within the scope of protection of this application.

Claims

1. A method for constructing a salt cavern gas storage reservoir with horizontal cavity formation and gas injection in cross - operation, characterized in that, The method includes the following steps: S1. Drill the directional well A to the bottom boundary of the target salt layer. After setting the first surface casing in the well A and cementing it, set the first production casing to the top boundary of the target salt layer to complete the well; S2. Set the first cavity pipe string in the well A. Inject water through the first cavity pipe string, and discharge the brine from the annulus between the first cavity pipe string and the first production casing to build a cavity until the cavity reaches a preset volume, and then seal the first cavity pipe string; S3. Drill the horizontal well B to the bottom boundary of the target salt layer and connect the well B to the cavity. After setting the second surface casing in the well B and cementing it, set the second production casing to the top boundary of the target salt layer to complete the well. Set the second cavity pipe string in the well B and seal the annulus between the first cavity pipe string and the first production casing; S4. Seal the second cavity pipe string. Inject gas into the cavity from the annulus between the second cavity pipe string and the second production casing of the well B to make the gas-liquid interface in the cavity reach the designed depth. Then seal the annulus between the second cavity pipe string and the second production casing of the well B to keep the air pressure stable; S5. Use the second cavity pipe string to inject water into the cavity to discharge the brine in the cavity from the first cavity pipe string of the well A; S6. When the cavity reaches the preliminary preset cavity volume, repeat steps S4 and S5 to deepen the depth of the gas-liquid interface so that the cavity reaches the final preset volume.

2. The method for constructing a salt cavern gas storage reservoir for horizontal cavity formation and gas injection cross - operation according to claim 1, characterized in that, The well A is a vertical well.

3. The method for constructing a salt cavern gas storage reservoir for horizontal cavity formation and gas injection cross - operation according to claim 1, characterized in that, The dissolution cavity described in step S2 reaching the preset volume means that the volume is above 2000 m 3 or more.

4. The method for constructing a salt cavern gas storage reservoir for horizontal cavity formation and gas injection cross - operation according to claim 1, characterized in that, When repeating steps S4 and S5 to deepen the depth of the gas-liquid interface, keep the second cavity pipe string below the depth of the gas-liquid interface.

5. The method for constructing a salt cavern gas storage reservoir for horizontal cavity formation and gas injection cross-operation according to claim 1, wherein When the cavity reaches the final preset volume, it is a horizontal cavity.

6. The method for constructing a salt cavern gas storage reservoir for horizontal cavity formation and gas injection cross - operation according to claim 1, characterized in that, When injecting gas into the cavity, inject air.

7. The method for building a salt cavern gas storage reservoir for horizontal cavity building and gas injection cross - operation according to claim 1, characterized in that, When injecting gas into the cavity, inject inert gas.

8. The method for building a salt cavern gas storage reservoir for horizontal cavity formation and gas injection cross - operation according to claim 1, characterized in that, When the cavity reaches the final preset volume, the cavity is filled with gas.