Well completion method for injection and production well of salt cavern reservoir and injection and production well structure of salt cavern reservoir

Abstract

The invention relates to a salt cavern reservoir injection and production well completion method and a salt cavern reservoir injection and production well structure. The method comprises the steps that S1, a lower packer assembly is tripped into an injection and production well production casing through an operation oil pipe; s2, a ground pipeline is connected, and a lower packer is pressed and set; carrying out annulus seal examination; s3, the operation oil pipe is separated from the lower packer assembly, the operation oil pipe is lifted up, fresh water is injected into the operation oil pipe, brine in the shaft above the lower packer is circularly replaced, and water injection is stopped after sufficient circulation; s4, an upper packer is put down through the injection-production pipe column, and the upper packer is pressed and set at a wellhead; carrying out annulus seal examination; and S5, a plug at the bottom end of the injection and production pipe column and a plug at the bottom end of the lower packer assembly are opened, and a gas injection and production channel is formed. The risk of salt crystallization of the pipe wall of the production casing pipe can be reduced, the sealing effect of the packer is improved, and long-time safe operation of an injection and production well is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of salt cavern underground storage construction, and particularly relates to a salt cavern storage injection-production well completion method and a salt cavern storage injection-production well structure. BACKGROUND

[0002] Salt rock stratum is an excellent geological body for deep geothermal energy storage, which has the characteristics of low permeability (less than 10-20 m2) and small porosity (less than 1%). The existing research has demonstrated the technical feasibility of hydrogen / helium storage in the salt rock stratum.

[0003] For the construction of the salt cavern hydrogen / helium storage, it is a key to ensure the sealing of the injection-production well bore. The gas injection and brine discharge is a key process before the salt cavern gas storage enters the operation stage. In this process, the saturated brine will precipitate crystals, which will adhere to the inner wall of the brine discharge pipe string and grow rapidly. If not cleaned in time, the brine discharge pipe string may be blocked, and the gas injection and brine discharge construction work may be interrupted.

[0004] In view of the salt crystallization / scale particles existing on the production casing pipe wall during the completion of the salt cavern injection-production well, the existing technology usually uses well flushing and scraping to clean the pipe wall. However, the traditional well flushing and scraping cannot meet the needs of well bore cleaning, and there will be some salt crystallization / scale particles on the production casing pipe wall, which will cause micro gaps between the packer rubber and the production casing pipe wall during the sealing process, and easily cause the injection-production well annulus pressure and gas leakage.

[0005] Some studies propose to prevent brine crystallization by increasing the injection gas temperature, using high-temperature fresh water low-flow small-displacement backwashing, and coating paint on the inner wall of the brine discharge pipe. However, these methods have the problems of complex device, delay of construction process, and poor anti-crystallization effect.

[0006] Therefore, the present application is proposed by the present inventor based on years of experience and practice in the relevant industry to overcome the defects of the prior art. SUMMARY

[0007] The present application aims to provide a salt cavern storage injection-production well completion method and a salt cavern storage injection-production well structure, which can reduce the risk of salt crystallization on the production casing pipe wall, improve the sealing effect of the packer, and ensure the long-term safe operation of the injection-production well.

[0008] The purpose of the present application is achieved by a salt cavern storage injection-production well completion method, which comprises the following steps:

[0009] Step S1, connecting a bottom-end blocked lower packer assembly on the work string, lowering the lower packer assembly into the production casing of the injection-production well through the work string, and locating the lower packer assembly at the top end of the salt cavern reservoir; the lower packer assembly comprises a lower packer;

[0010] Step S2, connecting the surface pipeline, pressing and setting the lower packer; performing annulus sealing test;

[0011] Step S3, disconnecting the work string from the lower packer assembly, lifting the work string, injecting fresh water into the work string, and circulating to replace the brine in the wellbore above the lower packer; stopping water injection after sufficient circulation; and lifting the work string;

[0012] Step S4, sleeving an upper packer on the injection-production string, blocking the bottom end of the injection-production string; lowering the upper packer to a set position above the lower packer through the injection-production string, and pressing and setting the upper packer at the wellhead; and performing annulus sealing test;

[0013] Step S5, opening the blockage at the bottom end of the injection-production string and the blockage at the bottom end of the lower packer assembly, and forming an injection-production gas channel by guiding the salt cavern reservoir through the annulus between the upper packer and the lower packer and the lower pipe string.

[0014] In a preferred embodiment of the present application, the lower packer assembly comprises a bottom-end blocked lower pipe string, a lower packer is sleeved on the lower pipe string, and the top end of the lower pipe string is connected to the work string through a releasing tool.

[0015] In a preferred embodiment of the present application, the bottom end of the lower pipe string is connected to a first landing sub, and a first plug is arranged on the first landing sub.

[0016] In a preferred embodiment of the present application, the bottom end of the injection-production string is connected to a second landing sub, and a second plug is arranged on the second landing sub.

[0017] In a preferred embodiment of the present application, in step S5, a wireline operation is performed into the injection-production string, the second plug on the second landing sub and the first plug on the first landing sub are recovered, and the injection-production string guides the salt cavern reservoir through the annulus between the upper packer and the lower packer and the lower pipe string.

[0018] In a preferred embodiment of the present application, the sealing rating of the lower packer is V3 or V4.

[0019] In a preferred embodiment of the present application, the sealing rating of the upper packer is V0.

[0020] In a preferred embodiment of the present application, a safety valve is arranged above the upper packer on the injection-production string.

[0021] The object of the present application can also be achieved by a salt cavern storage injection-production well structure formed by the foregoing salt cavern storage injection-production well completion method; the salt cavern storage injection-production well structure comprises an injection-production pipe string, an upper packer and a lower packer assembly.

[0022] In a preferred embodiment of the present application, the lower packer assembly comprises a lower pipe string, a lower packer sleeved on the lower pipe string, the lower packer being located at the top end of the salt cavern storage, and the bottom end of the lower pipe string being communicated with the salt cavern storage; the upper packer is arranged at an interval above the lower packer assembly, the upper packer being sleeved on the injection-production pipe string, and a safety valve being arranged on the injection-production pipe string.

[0023] According to the foregoing, the salt cavern storage injection-production well completion method and the salt cavern storage injection-production well structure of the present application have the following beneficial effects:

[0024] The present application can greatly reduce the risk of salt crystallization on the wall of the production casing, ensure complete sealing of the packer and the injection-production well production casing, improve the sealing effect and service life of the packer, and ensure long-term safe operation of the injection-production well; and the process adopted by the present application is simple and has strong operability in the field.

[0025] The salt cavern storage injection-production well structure of the present application has a simple structure, good sealing effect, and effectively ensures the subsequent mining efficiency and safety. BRIEF DESCRIPTION OF DRAWINGS

[0026] The following drawings are only intended to schematically illustrate and explain the present application, and do not limit the scope of the present application.

[0027] Wherein:

[0028] Figure 1 It is a schematic diagram of step S2 of the salt cavern storage injection-production well completion method of the present application.

[0029] Figure 2 It is a schematic diagram of step S3 of the salt cavern storage injection-production well completion method of the present application.

[0030] Figure 3 It is a schematic diagram of step S4 of the salt cavern storage injection-production well completion method of the present application.

[0031] Figure 4 It is a schematic diagram of the salt cavern storage injection-production well structure of the present application.

[0032] In the drawings:

[0033] 1, injection-production well production casing;

[0034] 2, salt cavern storage;

[0035] 3. First location joint;

[0036] 4. Lower packer;

[0037] 5. Disposal tools;

[0038] 6. Working oil pipe;

[0039] 7. Lower pipe string;

[0040] 8. Safety valve;

[0041] 9. Injection and production tubing;

[0042] 10. Upper packer;

[0043] 11. Second location joint;

[0044] 12. Fresh water. Detailed Implementation

[0045] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0046] The specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art can conceive of any possible modifications based on the invention, all of which should be considered within the scope of the invention. It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "mounted," "connected," and "linked" should be interpreted broadly; for example, they can refer to mechanical or electrical connections, or internal communication between two elements, and can be direct or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] Example 1

[0049] The application provides a method for completing a salt cavern storage injection-production well, comprising the following steps:

[0050] Step S1, connecting a bottom-end blocked lower packer assembly on a work string, lowering the lower packer assembly into the injection-production well production casing 1 through the work string, and locating the lower packer assembly at the top end of the salt cavern storage 2; the lower packer assembly comprises a lower packer 4;

[0051] Specifically, the salt cavern storage 2 is a hydrogen storage or helium storage.

[0052] The lower packer assembly comprises a bottom-end blocked lower string 7, the lower packer 4 is sleeved on the lower string 7, and the top end of the lower string 7 is communicated with the work string 6 through a releasing tool 5. Specifically, a ball seat can be arranged in the lower string 7, and the lower string 7 is blocked by ball dropping.

[0053] Alternatively, the bottom end of the lower string 7 is connected with a first landing sub 3, and a first plug is arranged on the first landing sub 3 to block the bottom end of the lower string 7. The first plug can be recycled, so that the lower string 7 can be communicated with the salt cavern storage 2.

[0054] The lower packer 4 is a hydraulic setting packer, which is made of conventional carbon steel; and the sealing grade of the lower packer 4 is V3 or V4.

[0055] Step S2, connecting the work string 6 with a ground pipeline, pressing and setting the lower packer 4, as shown in Figure 1 , performing annulus sealing test, and performing the next operation after the sealing test is qualified.

[0056] Step S3, as shown in Figure 2 , disconnecting the work string 6 from the lower packer assembly, lifting the work string 6, injecting fresh water 12 into the work string 6, circulating and replacing the brine in the wellbore above the lower packer 4 (the inner cavity of the injection-production well production casing 1), stopping water injection after sufficient circulation, and lifting the work string 6.

[0057] Specifically, the releasing tool 5 is started, the work string 6 is disconnected from the lower packer 4, the work string 6 is lifted, and fresh water is injected.

[0058] Step S4, as shown in Figure 3 , sleeving an upper packer 10 on an injection-production string 9, blocking the bottom end of the injection-production string 9; lowering the upper packer 10 to a set position above the lower packer 4 through the injection-production string 9, and pressing and setting the upper packer 10 at the wellhead; performing annulus sealing test, and performing the next operation after the sealing test is qualified.

[0059] Specifically, the bottom end of the injection-production pipe string 9 is connected with the second landing joint 11, and the second landing joint 11 is provided with a second plug. The second plug can be recovered, so that the bottom end of the injection-production pipe string 9 is connected with the annulus between the upper packer 10 and the lower packer 4.

[0060] The upper packer 10 is a hydraulic setting packer, which is made of hydrogen embrittlement resistant material or special material (80S or 110S material); and the sealing level of the upper packer 10 is V0.

[0061] The safety valve 8 is arranged above the upper packer 10 on the injection-production pipe string 9.

[0062] In step S5, the blockage at the bottom end of the injection-production pipe string 9 and the blockage at the bottom end of the lower packer assembly are opened, the injection-production pipe string 9 is connected with the salt cavern storage 2 through the annulus between the upper packer 10 and the lower packer 4 and the lower packer assembly (the lower pipe string 7), and the injection-production channel is formed.

[0063] Specifically, the wireline operation is performed in the injection-production pipe string 9, the second plug on the second landing joint 11 and the first plug on the first landing joint 3 are recovered, the injection-production pipe string 9 is connected with the salt cavern storage 2 through the annulus between the upper packer 10 and the lower packer 4 and the lower pipe string 7, and the injection-production channel is formed. Finally, the salt cavern injection-production well structure (as shown in Figure 4 ) is formed.

[0064] The salt cavern injection-production well completion method provided by the present application can greatly reduce the risk of salt crystallization on the wall of the production casing, ensure that the rubber sleeve of the upper packer 10 (the completion packer) is completely sealed with the production casing of the injection-production well, improve the sealing effect of the packer and the service life of the packer, and ensure the safe operation of the injection-production well for a long time. The process adopted by the present application is simple, and the on-site implementation is easy to operate.

[0065] Example 2

[0066] As shown in Figure 4 , the present application provides a salt cavern injection-production well structure, which is formed by the foregoing salt cavern injection-production well completion method; the salt cavern injection-production well structure comprises an injection-production pipe string 9, an upper packer 10 and a lower packer assembly.

[0067] Further, the lower packer assembly comprises a lower pipe string 7, the lower pipe string 7 is sleeved with a lower packer 4, the lower packer 4 is located at the top end of the salt cavern storage 2, and the bottom end of the lower pipe string 7 is connected with the salt cavern storage 2; the upper packer 10 is arranged above the lower packer assembly, the upper packer 10 is sleeved on the injection-production pipe string 9, and the safety valve 8 is arranged on the injection-production pipe string 9.

[0068] The salt cavern storage injection-production well structure has simple structure and good sealing effect, and effectively guarantees subsequent mining efficiency and safety.

[0069] As described above, the salt cavern storage injection-production well completion method and the salt cavern storage injection-production well structure have the following beneficial effects:

[0070] The application can greatly reduce the risk of salt crystallization on the wall of the production casing, ensure complete sealing between the packer and the production casing of the injection-production well, improve the sealing effect and service life of the packer, and ensure long-term safe operation of the injection-production well.

[0071] The salt cavern storage injection-production well structure has simple structure and good sealing effect, and effectively guarantees subsequent mining efficiency and safety.

[0072] The above description is only a specific embodiment of the application, and is not intended to limit the scope of the application. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the application shall fall within the scope of the application.

Claims

1. A method of completing a salt cavern storage and recovery well, characterized by, The method comprises the following steps: Step S1, connecting a bottom-end blocked lower packer assembly on a work string, lowering the lower packer assembly into a production casing of the injection-production well through the work string, and locating the lower packer assembly at a top end of the salt cavern reservoir; the lower packer assembly comprises a lower packer; Step S2, connecting a surface pipeline, pressing and setting the lower packer, and performing annular sealing inspection; Step S3, disconnecting the work string from the lower packer assembly, lifting the work string, injecting fresh water into the work string, and replacing brine in a wellbore above the lower packer by circulation, and stopping water injection after sufficient circulation; and lifting the work string; Step S4, sleeving an upper packer on an injection-production string, blocking a bottom end of the injection-production string, lowering the upper packer to a set position above the lower packer through the injection-production string, and pressing and setting the upper packer at the wellhead; and performing annular sealing inspection; Step S5, opening the blockage at the bottom end of the injection-production string and the blockage at the bottom end of the lower packer assembly, and forming an injection-production gas channel by guiding the salt cavern reservoir through the annulus between the upper packer and the lower packer and the lower pipe string.

2. The salt cavern storage well completion method of claim 1, wherein, The lower packer assembly comprises a bottom-end blocked lower pipe string, the lower pipe string is sleeved with a lower packer, and a top end of the lower pipe string is connected to the work string through a releasing tool.

3. The salt cavern storage well completion method of claim 2, wherein, A first setting sub is connected to a bottom end of the lower pipe string, and a first plug is arranged on the first setting sub.

4. The salt cavern storage well completion method of claim 3, wherein, A second setting sub is connected to a bottom end of the injection-production string, and a second plug is arranged on the second setting sub.

5. The salt cavern storage well completion method of claim 4, wherein, In step S5, a wireline operation is performed in the injection-production string, the second plug on the second setting sub and the first plug on the first setting sub are recovered, and the salt cavern reservoir is guided through the annulus between the upper packer and the lower packer and the lower pipe string.

6. The salt cavern storage well completion method of claim 2, wherein, The sealing level of the lower packer is V3 or V4.

7. The salt cavern storage well completion method of claim 1, wherein, The sealing level of the upper packer is V0.

8. The salt cavern storage well completion method of claim 1, wherein, A safety valve is arranged above the upper packer on the injection-production string.

9. A salt cavern storage and retrieval well structure characterized by, The method is implemented by the method for completing the salt cavern reservoir injection-production well according to any one of claims 1 to 8, and the structure of the salt cavern reservoir injection-production well comprises an injection-production string, an upper packer, and a lower packer assembly.

10. The salt cavern storage and retrieval well structure of claim 9, wherein, The lower packer assembly comprises a lower pipe string, the lower pipe string is sleeved with a lower packer, the lower packer is located at a top end of the salt cavern reservoir, and a bottom end of the lower pipe string guides the salt cavern reservoir; the upper packer is arranged above the lower packer assembly, the upper packer is sleeved on the injection-production string, and a safety valve is arranged on the injection-production string.

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