Salt cavern gas storage direct well structure and construction method

Abstract

The present application relates to the technical field of salt cavern gas storage straight well structure, and provides a salt cavern gas storage straight well structure and a construction method, the straight well structure at least comprises: a well body, comprising a first open well and a second open well, a first open casing is arranged in the first open well, and a second open casing is arranged in the second open well; a support sleeve is arranged in a salt cavern solution cavity, one end of the support sleeve is in abutment with the bottom of the salt cavern solution cavity, the other end of the support sleeve is in abutment with the second open casing, and a plurality of hollow holes are arranged on the side wall of the support sleeve. The salt cavern gas storage straight well structure provided by the present application is a two-open well structure composed of a first open well and a second open well, so that the air flow area of the straight well is reduced only once, the along-the-way loss of high-pressure air is reduced, and the electric-to-electric conversion efficiency of the compressed air energy storage system is improved.

Description

Technical Field

[0001] This invention relates to the field of vertical well structure technology for salt cavern gas storage, specifically to a vertical well structure and construction method for salt cavern gas storage. Background Technology

[0002] Advanced compressed air energy storage systems (CAES) offer significant advantages such as large storage capacity, high efficiency, long lifespan, convenient dispatch, complete pollution-free operation, and low water consumption, making them the most promising energy storage technology today. The gas storage system within a CAES system is typically an underground salt cavern, artificial cavern, or artificial storage tank. Due to the extremely low permeability and good creep and damage recovery characteristics of salt rock, salt caverns offer high safety and airtightness as underground energy storage facilities, making them the ideal storage space for CAES systems. Salt caverns are usually located at depths of 1000 meters underground, requiring the drilling of vertical wells to transport large volumes of high-pressure air from the salt cavern to the energy storage system. However, considering the unknown height of the salt cavern top and the need for surface support during cementing, existing vertical wells employ a three-section well structure. This reduces the airflow cross-sectional area of ​​the vertical well twice, increasing the pressure loss along the high-pressure air path and reducing the electro-electric conversion efficiency of the CAES system. Summary of the Invention

[0003] Therefore, the technical problem to be solved by this invention is that existing vertical wells all adopt a three-section well structure, which reduces the air flow cross-sectional area of ​​the vertical well twice, increases the friction loss of high-pressure air, and reduces the electrical-to-electrical conversion efficiency of the compressed air energy storage system. Thus, this invention provides a vertical well structure and construction method for salt cavern gas storage.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0005] A vertical well structure for a salt cavern gas storage facility includes at least: a well body, comprising a first wellbore and a second wellbore, wherein a first wellbore casing is provided in the first wellbore and a second wellbore casing is provided in the second wellbore; and a support sleeve, disposed within the salt cavern cavity, one end of which abuts against the bottom of the salt cavern cavity and the other end of which abuts against the second wellbore casing, wherein a plurality of perforated holes are provided on the side wall of the support sleeve.

[0006] Furthermore, the vertical well structure of the salt cavern gas storage also includes a packer, which is disposed at one end of the support sleeve near the second-stage casing; the packer has a first state of sealing the support sleeve before the second-stage casing is lowered, and a second state of releasing the sealing of the support sleeve after the second-stage casing is lowered.

[0007] Furthermore, a sleeve shoe is provided at one end of the two-part sleeve near the packer, the sleeve shoe extending in a direction away from the center of the two-part sleeve and abutting against the packer.

[0008] Furthermore, the end of the support sleeve facing the two-section sleeve is provided with a reverse thread, which is suitable for separating from the drilling rig when the drilling rig rotates in the reverse direction.

[0009] Furthermore, the outer diameter of the support sleeve is equal to the inner diameter of the two-section well passage.

[0010] Furthermore, the length of the support sleeve is greater than the distance between the bottom and top of the salt cavern.

[0011] A construction method for a vertical well structure of a salt cavern gas storage facility, comprising the vertical well structure of the salt cavern gas storage facility described in any of the above claims, comprising the following specific steps: drilling a first wellbore and cementing the first wellbore by running a first casing; drilling a second wellbore until it connects to the salt cavern cavity; continuing to drill downwards and measuring the distance between the bottom and top of the salt cavern cavity; fabricating a support sleeve based on the distance between the bottom and top of the salt cavern cavity, placing the support sleeve into the salt cavern cavity, and ensuring that at least part of the top of the support sleeve extends into the second wellbore; and cementing the second wellbore by running a second casing.

[0012] Furthermore, after the support sleeve is placed into the salt cavern cavity, the drilling rig is reversed to separate the support sleeve from the drilling rig.

[0013] Furthermore, after cementing the second wellbore is completed, the drilling rig continues drilling to open the packer at the end of the support sleeve so that the support sleeve can be connected to the second well casing.

[0014] Furthermore, when the wellbore is drilled to half the depth of the vertical well, a casing is run in to cement the wellbore.

[0015] The technical solution of this invention has the following advantages:

[0016] The salt cavern gas storage vertical well structure provided by this invention has a two-section well structure consisting of a single wellbore and a second wellbore. This reduces the air flow cross-sectional area of ​​the vertical well only once, thereby reducing the friction loss of high-pressure air and improving the electrical-to-electrical conversion efficiency of the compressed air energy storage system. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a salt cavern gas storage facility in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of an open well passage in the vertical well structure of the salt cavern gas storage facility in an embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the two-section wellhead in the vertical well structure of the salt cavern gas storage facility in an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the support sleeve in the vertical well structure of the salt cavern gas storage facility in an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of the vertical well structure of the salt cavern gas storage facility after the support sleeve has been placed in an embodiment of the present invention;

[0023] Figure 6 This is a schematic diagram of the vertical well structure of the salt cavern gas storage facility in an embodiment of the present invention;

[0024] Figure 7 for Figure 6 A magnified schematic diagram of a local structure.

[0025] 1. Salt cavern; 2. Opening of the wellbore; 3. Opening of the casing;

[0026] 4. Two-section shaft; 5. Two-section casing; 6. Support sleeve;

[0027] 7. Perforated hole; 8. Reverse thread; 9. Sealer;

[0028] 10. Sleeveless shoes. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] Figure 1 This is a schematic diagram of a salt cavern gas storage facility in an embodiment of the present invention; Figure 2 This is a schematic diagram of an open well passage in the vertical well structure of the salt cavern gas storage facility in an embodiment of the present invention; Figure 3 This is a schematic diagram of the two-section wellhead in the vertical well structure of the salt cavern gas storage facility in an embodiment of the present invention; Figure 4 This is a schematic diagram of the support sleeve in the vertical well structure of the salt cavern gas storage facility in an embodiment of the present invention; Figure 5 This is a schematic diagram of the vertical well structure of the salt cavern gas storage facility after the support sleeve has been placed in an embodiment of the present invention; Figure 6 This is a schematic diagram of the vertical well structure of the salt cavern gas storage facility in an embodiment of the present invention; Figure 7 for Figure 6 A magnified schematic diagram of a local structure; such as Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 as well as Figure 7 As shown, this embodiment provides a vertical well structure for a salt cavern gas storage facility, comprising at least: a well body, including a first wellbore 2 and a second wellbore 4, wherein a first casing 3 is installed in the first wellbore 2 for cementing, and a second casing 5 is installed in the second wellbore 4 for cementing, and the well body undergoes only one diameter reduction from the first wellbore 2 to the second wellbore 4; and a support sleeve 6, which is installed in the salt cavern cavity 1, with one end abutting against the bottom of the salt cavern cavity 1 and the other end abutting against the second casing 5, wherein the side wall of the support sleeve 6 is provided with a plurality of perforated holes 7, which allow liquid and gas in the salt cavern cavity 1 to pass through.

[0034] The outer diameter of the support sleeve 6 is equal to the inner diameter of the second-stage well 4. After the second-stage well 4 is drilled, it is placed in the salt cavern cavity 1 so that the support sleeve 6 can serve as the bottom support when cementing the second-stage casing 5. This arrangement allows the second-stage casing 5 to be directly connected to the salt cavern cavity 1. Compared with the vertical well structure of the three-stage well structure, the air flow cross-sectional area of ​​the vertical well structure of the two-stage well structure is reduced only once.

[0035] The salt cavern gas storage vertical well structure provided in this embodiment has a two-section well structure consisting of a single wellbore 2 and a second wellbore 4. This reduces the air flow cross-sectional area of ​​the vertical well only once, thereby reducing the friction loss of high-pressure air and improving the electrical-to-electrical conversion efficiency of the compressed air energy storage system.

[0036] The vertical well structure of the salt cavern gas storage facility also includes a packer 9. For example, the packer 9 can be an aluminum plate. The packer 9 can be welded into the inner cavity of the support sleeve 6 and is located at one end of the support sleeve 6 near the second-stage casing 5. The packer 9 has a first state of sealing the support sleeve 6 before the second-stage casing 5 is lowered, and a second state of releasing the seal on the support sleeve 6 after the second-stage casing 5 is lowered. In the initial state, the packer 9 seals the support sleeve 6. When it is necessary to change from the first state to the second state, the packer 9 can be drilled open using a drilling rig, so that the support sleeve 6 is connected to the second-stage casing 5.

[0037] Among them, a sleeve shoe 10 is provided at one end of the two-open sleeve 5 near the packer 9. The sleeve shoe 10 extends in a direction away from the center of the two-open sleeve 5 and abuts against the packer 9.

[0038] The support sleeve 6 has a reverse thread 8 at the end facing the split sleeve 5, which is suitable for separating from the drilling rig when the drilling rig rotates in the reverse direction. For example, the reverse thread 8 can be provided on the outer wall of the support sleeve 6.

[0039] The outer diameter of the support sleeve 6 is equal to the inner diameter of the second shaft 4.

[0040] The length of the support sleeve 6 is greater than the distance between the bottom and top of the salt cavern 1, so that a suitable position can be selected according to the characteristics of the rock and soil inside the stratum to complete the docking of the second-opening sleeve 5 and the support sleeve 6.

[0041] Another embodiment provides a construction method for a vertical well structure of a salt cavern gas storage facility, including the vertical well structure of any of the above-mentioned salt cavern gas storage facilities. The specific steps are as follows: a first wellbore 2 is drilled using a drilling rig, and a first casing 3 is run in to cement the first wellbore 2; after the drilling rig changes the drill rod, a second wellbore 4 is drilled until it connects to the salt cavern cavity 1; drilling continues downward and the distance between the bottom and top of the salt cavern cavity 1 is measured; a support sleeve 6 is made according to the distance between the bottom and top of the salt cavern cavity 1, and the support sleeve 6 is placed into the salt cavern cavity 1 using the drill rod, with at least part of the top of the support sleeve 6 extending into the second wellbore 4. At this time, the drilling rig can be reversed to separate the support sleeve 6 from the drill rod of the drilling rig; then, a second casing 5 is run in using the drilling rig to cement the second wellbore 4.

[0042] After cementing of the second wellbore 4 is completed, the drilling rig continues to drill and drills open the packer 9 at the end of the support sleeve 6 so that the support sleeve 6 can be connected to the second wellbore 5.

[0043] When the first wellbore 2 is drilled to half the depth of the vertical well, the first casing 3 is run in to cement the first wellbore 2.

[0044] The specific construction method is as follows:

[0045] The morphology of the original strata and the bottom salt cavern cavity 1 is as follows Figure 1 As shown.

[0046] like Figure 2 As shown, firstly, the first wellbore 2 of the gas storage vertical well is drilled, with a drilling distance of half the designed well depth. Then, the first casing 3 is run in and cementing is completed.

[0047] like Figure 3 As shown, after cementing the first wellbore 2, a new drill bit is used to drill the second wellbore 4 until the borehole of the second wellbore 4 connects with the internal salt cavern cavity 1. Drilling continues, and the distance between the bottom and top of the salt cavern cavity 1 corresponding to this vertical well location is measured.

[0048] like Figure 4 and Figure 5 As shown, a support sleeve 6 is machined according to the distance between the top and bottom of the cavity. The top of the support sleeve 6 is designed with a reverse thread 8 for connection with the drill pipe. The support sleeve 6 has a hollowed-out design on its wall, with an outer diameter equal to the diameter of the second-stage borehole, and a length that can be equal to or greater than the distance between the top and bottom of the cavity. The support sleeve 6 is lowered to the bottom of the cavity using the drill pipe, ensuring it is at least partially located within the second-stage wellbore 4. Then, the drilling rig is reversed to disassemble the drill pipe from the support sleeve 6.

[0049] like Figure 6 As shown, based on the drilling conditions, a preferred formation location is selected, and a second casing 5 is run in. The cementing of the second wellbore 4 is achieved by utilizing the blocking effect of the casing shoe 10 and the packer 9.

[0050] like Figure 7 As shown, after the second cementing is completed, drilling continues, and the packer 9 is drilled open. The second casing 5 is connected to the salt cavern cavity 1 through the perforated hole 7 on the support sleeve 6. At this time, the support sleeve 6 placed in the salt cavern cavity 1 can be used to protect the neutron source, sonar, or underwater probe for testing.

[0051] In summary, the vertical well structure and construction method for salt cavern gas storage in this application features a large-diameter well, avoiding throttling and friction losses caused by gas flow during energy release in salt cavern gas storage, thus improving the operating efficiency of the energy storage system. Furthermore, the cementing location for the second wellbore can be optimized, and the cementing quality is controllable.

[0052] The vertical well structure and construction method of the salt cavern gas storage in this application, and the hollow design of the support sleeve, can serve as a protective string for subsequent detection instruments and be used for safe operation monitoring of the gas storage.

[0053] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A vertical well structure for a salt cavern gas storage facility, characterized in that, At least including: The well body includes a first well passage and a second well passage. A first-opening sleeve is installed in the first well passage, and a second-opening sleeve is installed in the second well passage. A support sleeve is set inside the salt cavern cavity, with one end abutting against the bottom of the salt cavern cavity and the other end abutting against the two-opening sleeve. Several hollow holes are provided on the side wall of the support sleeve. It also includes a packer, which is disposed at one end of the support sleeve near the two-section sleeve; The packer has a first state of sealing the support sleeve before the two-sleeve is inserted, and a second state of releasing the sealing of the support sleeve after the two-sleeve is inserted. A sleeve shoe is provided at one end of the two-piece sleeve near the packer. The sleeve shoe extends in a direction away from the center of the two-piece sleeve and abuts against the packer.

2. The vertical well structure of the salt cavern gas storage facility according to claim 1, characterized in that, The support sleeve is provided with a reverse thread at one end facing the two-section sleeve, which is suitable for separating from the drilling rig when the drilling rig rotates in the reverse direction.

3. The vertical well structure of the salt cavern gas storage facility according to claim 1, characterized in that, The outer diameter of the support sleeve is equal to the inner diameter of the two-section shaft.

4. The vertical well structure of the salt cavern gas storage facility according to claim 1, characterized in that, The length of the support sleeve is greater than the distance between the bottom and top of the salt cavern.

5. A construction method for a vertical well structure of a salt cavern gas storage facility, characterized in that, The salt cavern gas storage vertical well structure according to any one of claims 1-4 includes the following specific steps: Drill a shaft and run a casing into the shaft for cementing. Drill two wells until they connect to the salt cavern cavity; Continue drilling downwards and measure the distance between the bottom and top of the salt cavern. A support sleeve is made according to the distance between the bottom and top of the salt cavern cavity. The support sleeve is placed into the salt cavern cavity, and the top of the support sleeve extends at least partially into the second-stage wellbore. The second casing is lowered in for cementing of the second wellbore.

6. The construction method for the vertical well structure of the salt cavern gas storage facility according to claim 5, characterized in that, After the support sleeve is placed into the salt cavern, the drilling rig is reversed to separate the support sleeve from the drilling rig.

7. The construction method for the vertical well structure of the salt cavern gas storage facility according to claim 5, characterized in that, After cementing is completed in the second wellbore, the drilling rig continues drilling to open the packer at the end of the support sleeve so that the support sleeve can be connected to the second well casing.

8. The construction method for the vertical well structure of the salt cavern gas storage facility according to claim 5, characterized in that, When the first wellbore is drilled to half the depth of the vertical well, the first casing is run in to cement the first wellbore.

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