A brine removal device and method suitable for high-impurity salt mine sediment

Abstract

The present invention provides a brine drainage device and method suitable for high-impurity salt mine sediment, comprising an assembly pipe string, a brine drainage pipe, and a production casing. The assembly pipe string is installed in the production casing, and the brine drainage pipe is installed in the assembly pipe string. A gap is formed between the brine drainage pipe and the pipe wall of the assembly pipe string. The assembly pipe string includes a tunneling drill bit, a screen pipe section, and a pipe string. The tunneling drill bit is installed at the front end of the screen pipe section, and the rear end of the screen pipe section is connected to the pipe string to form a detachable structure. The gap serves as a gas injection channel, and the inner cavity of the brine drainage pipe serves as a brine drainage channel. After the cavity is constructed, the present invention uses the tunneling drill bit and the screen pipe section to reach the bottom of the sediment to drain as much brine as possible from the sediment gap, retaining the sediment gap for gas storage, thereby realizing the utilization of the sediment gap space and improving the gas storage economy in high-impurity salt mine areas.

Description

Technical Field

[0001] The invention relates to the technical field of salt cavern sediment gas storage, and mainly relates to a brine discharge device and method suitable for high-impurity salt mine sediment. Background Art

[0002] my country's salt deposits are layered, lacustrine sedimentary deposits characterized by thin salt layers, numerous non-salt interlayers, and high levels of insoluble impurities. During solution mining, these insoluble impurities accumulate to form a large amount of sediment, which occupies a significant amount of space within the salt cavity. Consequently, the available space for gas storage in the salt cavity is divided into the clear space above the sediment and the void space within the sediment.

[0003] Traditional brine drainage methods are limited to draining the brine above the sediment interface, leaving the sediment submerged in the brine. This method only utilizes the small amount of free space above the sediment. The void space filled with brine remains unused, resulting in a significant waste of space resources and significantly reducing the value of the cavity.

[0004] How to discharge the brine in the sediment and make full use of the sediment gaps to store gas is the key to breaking through the high-impurity salt mine and building salt cavern storage. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a brine discharge device and method suitable for high-impurity salt mine sediment. After the cavity is built, the excavation drill bit and the leakage screen pipe section are used to reach the bottom of the sediment to discharge as much brine as possible in the sediment gaps, thereby realizing the utilization of the sediment gap space and improving the gas storage economy in high-impurity salt mine areas.

[0006] The objective of the present invention is achieved through the following technical solution: A brine drainage device suitable for high-impurity salt mine sediments, comprising an assembly pipe string, a brine drainage pipe, and a production casing, wherein the assembly pipe string is installed in the production casing, the brine drainage pipe is installed in the assembly pipe string, and a gap is formed between the brine drainage pipe and the pipe wall of the assembly pipe string; the assembly pipe string comprises a tunneling drill bit, a screen pipe section, and a pipe string, wherein the tunneling drill bit is installed at the front end of the screen pipe section, and the rear end of the screen pipe section is connected to the pipe string to form a detachable structure; the gap serves as a gas injection channel, and the inner cavity of the brine drainage pipe serves as a brine drainage channel.

[0007] Furthermore, the leaky screen pipe section is provided with a plurality of air holes along the circumference and length directions.

[0008] Furthermore, the diameter of the assembly pipe string is smaller than that of the production casing, and the brine drainage pipe is a hollow pipe string, and its diameter is smaller than that of the assembly pipe string.

[0009] The present invention also provides a brine discharge method using the brine discharge device suitable for high-impurity salt mine sediment, comprising the following steps:

[0010] 1. Carry out sonar cavity measurement on the salt cavity, determine the shape and thickness of the sediment based on the cavity measurement results, and determine the length of the leakage screen tube section based on the thickness of the sediment;

[0011] 2. Assemble the tunneling drill bit, screen pipe section and pipe string to form an assembled pipe string. Lower the assembled pipe string into the production casing to the sediment. Start the tunneling drilling mode and insert the screen pipe section into the sediment.

[0012] 3. Lower the brine drainage pipe into the assembled pipe column, and lower the end of the brine drainage pipe to a certain height from the bottom of the screen pipe section;

[0013] 4. Compressed air is injected through the gap and discharged into the sediment through the air holes of the screen tube section. Under the action of gas pressure, a connecting path is formed between the gaps in the sediment;

[0014] 5. Separate the assembled string from the screen tube section and remove the string;

[0015] 6. Inject compressed air into the annulus between the brine discharge pipe and the production casing, open the brine discharge pipe, and under the action of gas pressure, the brine will flow into the leaky screen pipe section along the connecting path formed between the sediment gaps and be discharged from the brine discharge pipe.

[0016] The beneficial effects of the present invention are as follows: This sediment degassing method eliminates the need for building a dedicated brine drainage well; existing wells can be used to drain brine from the sediment, preserving the sediment voids for gas storage. This effectively improves cavity space utilization and is expected to address the large-scale gas storage problem in low-grade, multi-layered salt cavities. The brine drainage device is simple, inexpensive, and the brine drainage method is highly scalable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the brine discharge device for high-impurity salt chambers in the present invention.

[0018] Figure 2 Schematic diagram of the assembly column in the present invention.

[0019] Figure 3 Schematic diagram of the gas injection and brine removal process of the present invention Figure 1 .

[0020] Figure 4 Schematic diagram of the gas injection and brine removal process of the present invention Figure 2 .

[0021] Figure 5 Schematic diagram of the gas injection and brine removal process of the present invention Figure 3 .

[0022] Explanation of the reference numerals: assembly pipe string 1, drilling bit 1-1, screen pipe section 1-2, connection 1-3, pipe string 1-4, brine drainage pipe 2, production casing 3, salt cavity net space 4, brine 5, sediment 6, sediment gap 7, sediment interface 8, sediment bottom 9. DETAILED DESCRIPTION

[0023] To help those skilled in the art better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with the accompanying drawings and specific examples. However, it should be understood that the drawings are for illustrative purposes only and are not to be construed as limiting the present invention. To better illustrate the present embodiments, certain components in the drawings may be omitted, enlarged, or reduced, and do not represent the dimensions of actual products. It is understandable that certain well-known structures and their descriptions may be omitted from the drawings. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present invention.

[0024] The salt mine in a certain area of ​​my country is buried 1000m deep. Considering that the insoluble matter including the interlayer accounts for 35%, the salt layer has formed a salt cavity of 300,000 cubic meters during the early salt mining process. The expansion coefficient of the interlayer is 2.0, the sediment space in the cavity accounts for 70%, and the sediment voids account for half of the sediment accumulation space. The salt cavity has completed the cavity creation and cavity measurement work, and now it is necessary to discharge the brine in the sediment for compressed air storage application.

[0025] like Figure 1-2 As shown, a brine drainage device suitable for high-impurity salt mine sediment includes an assembly pipe string 1, a brine drainage pipe 2, and a production casing 3. The assembly pipe string 1 is installed in the production casing 3, and the brine drainage pipe 2 is installed in the assembly pipe string 1. The diameter of the assembly pipe string 1 is smaller than that of the production casing 3. The brine drainage pipe 2 is a conventional hollow pipe string with a smaller diameter than the assembly pipe string 1. A gap is formed between the brine drainage pipe 2 and the pipe wall of the assembly pipe string 1. The assembly pipe string 1 includes a tunneling drill bit 1-1, a screen pipe segment 1-2, and a pipe string 1-4. The screen pipe segment 1-2 is provided with a plurality of circular air holes along the circumference and length directions. The tunneling drill bit 1-1 is installed at the front end of the screen pipe segment 1-2. The rear end of the screen pipe segment 1-2 is connected to the pipe string 1-4 via a connection 1-3 to form a detachable structure. The gap serves as an air injection channel, and the inner cavity of the brine drainage pipe 2 serves as a brine drainage channel.

[0026] It should be noted that:

[0027] Creating and measuring salt cavities are common technologies. After the creation of the cavities is completed, a production casing 3 is formed.

[0028] The tunneling drill bit 1-1 mainly realizes the effect of tunneling in sediments. It is for short-term use, does not require special materials, has low cost, and has no effect on the subsequent salt cavity gas storage operation when it is drilled into the sediments, and does not need to be recovered.

[0029] The material of the leaky screen segment 1-2 is the same as that of conventional salt cavern production casing. The rear end of the leaky screen segment 1-2 is connected to the pipe string 1-4 via a connection 1-3. The connection can be separated by moving the clip up and down. Since the lower leaky screen segment 1-2 is embedded in the sediment 6, it can be separated by pulling the normal pipe string 1-4.

[0030] The present invention also provides a brine removal method, the gas injection brine removal process is as follows Figure 3-5 As shown, the steps for tunneling and injecting gas to remove brine using the above device are as follows:

[0031] 1. Carry out sonar cavity measurement on the salt cavity, determine the shape and thickness of the sediment 6 based on the cavity measurement results, and determine the length of the leakage screen tube section 1-2 based on the thickness of the sediment 6; the length of the leakage screen tube section 1-2 should not be shorter than the sediment thickness and generally not longer than the height of the salt cavity.

[0032] 2. Assemble the tunneling drill bit 1-1, the screen pipe section 1-2, and the pipe string 1-4 to form the assembly pipe string 1. Lower the assembly pipe string 1 into the production casing 3 to the sediment interface 8. Start the tunneling drilling mode. The tunneling drill bit 1-1 is driven by the power device. The screen pipe section 1-2 is firmly inserted into the sediment 6 along with the tunneling drill bit 1-1 during the tunneling process until it reaches the sediment bottom 9, so that the screen pipe section 1-2 can form a columnar clean brine space in the sediment 6.

[0033] 3. Lower the brine drainage pipe 2 into the assembled pipe string 1, and lower the end of the brine drainage pipe 2 to a certain height from the bottom of the leakage screen pipe section 1-2, that is, lower the brine drainage pipe 2 to a position close to the bottom of the leakage screen pipe section 1-2;

[0034] 4. Compressed air or other gas is injected through the gap and discharged into the sediment 6 through the air holes of the leakage screen tube section 1-2. Under the action of gas pressure, blockage around the leakage screen tube section 1-2 is avoided, so that a communication path is formed between the sediment gaps 7;

[0035] 5. Separate the pipe string 1-4 from the screened pipe section 1-2 of the assembly string 1 and remove the upper, functioning pipe string 1-4. Removing the upper, functioning pipe string prevents it from creating a flow path with the lower, screened pipe string. After separation, only one annulus and one brine drain pipe remain. When gas is injected into the annulus, brine can only be discharged from the lowest brine drain pipe, effectively pressing out the brine from the bottom of the salt cavity. If gas is not injected into both annuli, there will likely be two annuluses and one internal pipe string space. If both annuli are gassed, a sediment screen and an external cavity will likely form. After the brine in the screen is drained, a large amount of brine will remain outside. If gas is injected into the outer annulus, and both the inner annulus and the brine drain pipe are used for brine removal, brine can only be discharged to the first screen compartment. Otherwise, continued gas injection will cause gas to escape from the annulus, preventing pressure buildup and preventing brine discharge.

[0036] 6. Compressed air is injected into the annulus between the brine discharge pipe 2 and the production casing 3 (the gap between the pipe walls of the brine discharge pipe 2 and the production casing 3), and the brine discharge pipe 2 is opened. Under the action of gas pressure, the brine 5 flows into the leakage screen pipe section 1-2 along the connecting path formed between the sediment gaps 7, and is discharged from bottom to top through the brine discharge pipe 2 at the bottom of the leakage screen pipe section 1-2, thereby realizing the discharge of brine deep in the sediment and protecting the brine discharge pipe 2 from being blocked by the sediment 6.

[0037] It should be noted that when there is gas pressure both inside and outside the pore, it proves that the brine interface has dropped below the pore. If the gas is injected slowly and continuously to increase the pressure, the pressure difference will force the brine out from the lowest brine discharge pipe outlet.

[0038] During the brine discharge process, in order to discharge the brine in the sediment voids as much as possible, a slow air injection method is adopted until the brine 5 in the sediment 6 is discharged to the sediment bottom 9. Compressed air enters the sediment voids 7 and discharges the brine 5 in the sediment voids 7 through the connecting path, the leakage screen pipe section 1-2 and the brine discharge pipe 2. At this time, the gas storage operation mode is turned on, and gas enters the sediment voids 7, achieving the purpose of utilizing the sediment voids to store gas and forming a salt cavity clear space 4 at the upper part.

[0039] It is understandable that for those skilled in the art, any equivalent replacement or change to the technical solution and inventive concept of the present invention should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A brine removal method using a brine removal device suitable for high-impurity salt mine sediment, characterized by: The steps are as follows: (1) Conduct sonar cavity measurement on the salt cavity, determine the shape and thickness of the sediment (6) based on the cavity measurement results, and determine the length of the leakage screen tube section (1-2) based on the thickness of the sediment (6); (2) Assembling the excavation drill bit (1-1), the screen pipe section (1-2) and the pipe string (1-4) to form an assembly pipe string (1), lowering the assembly pipe string (1) into the production casing (3) to the sediment (6), starting the excavation drilling mode, and driving the screen pipe section (1-2) into the sediment (6); (3) Lower the brine discharge pipe (2) into the assembled pipe column (1), and lower the end of the brine discharge pipe (2) to a certain height from the bottom of the leakage screen pipe section (1-2); (4) Compressed air is injected through the gap and discharged into the sediment (6) through the air holes of the sieve tube section (1-2). Under the action of the gas pressure, a connecting path is formed between the sediment gaps (7); (5) Separate the tubing string (1-4) of the assembled tubing string (1) from the leaky screen tube section (1-2), and remove the tubing string (1-4); (6) Compressed air is injected into the annulus between the brine discharge pipe (2) and the production casing (3), and the brine discharge pipe (2) is opened. Under the action of the gas pressure, the brine (5) flows into the leakage screen pipe section (1-2) along the communication path formed between the sediment gaps (7) and is discharged from the brine discharge pipe (2); The brine discharge device suitable for high-impurity salt mine sediment comprises an assembly pipe string (1), a brine discharge pipe (2) and a production casing (3); the assembly pipe string (1) is installed in the production casing (3), the brine discharge pipe (2) is installed in the assembly pipe string (1), and a gap is formed between the pipe walls of the brine discharge pipe (2) and the assembly pipe string (1); the assembly pipe string (1) comprises a tunneling drill bit (1-1), a screen pipe section (1-2) and a pipe string (1-4); the tunneling drill bit (1-1) is installed at the front end of the screen pipe section (1-2), and the rear end of the screen pipe section (1-2) is connected to the pipe string (1-4) to form a detachable structure; the gap serves as a gas injection channel, and the inner cavity of the brine discharge pipe (2) serves as a brine discharge channel.

2. The brine removal method according to claim 1, wherein: The brine is discharged by slow gas injection until the brine (5) in the sediment (6) is discharged to the bottom of the sediment (9). At this time, the gas storage operation mode is turned on, and the gas enters the sediment gap (7) and forms a salt cavity net space (4) at the upper part.

3. The brine removal method according to claim 1, wherein: The leaky screen tube section (1-2) is provided with a plurality of air holes along the circumference and length direction.

4. The brine removal method according to claim 1, wherein: The diameter of the assembly pipe string (1) is smaller than that of the production casing (3); the brine drainage pipe (2) is a hollow pipe string, and its diameter is smaller than that of the assembly pipe string (1).

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