A CO2-high salt water co-sequestration device and method

Abstract

The application discloses a CO2-high-salt water cooperative storage device and a storage method, relates to the cross technical field of unconventional oil and gas reservoir development and carbon storage technology, and is characterized in that a drilling structure is extended in a vertical direction from the ground to a fluid storage layer, a part of the drilling structure located in the fluid storage layer is gradually inclined in a horizontal direction from top to bottom, and the bottom end of the part is extended in the horizontal direction; a casing structure is arranged in the drilling structure and is synchronously extended with the drilling structure, a cementing structure is arranged between the part of the casing structure located above the fluid storage layer and the drilling structure; the part of the casing structure located in the fluid storage layer and extended horizontally is provided with a liquid outlet; an inner tube structure is arranged in the casing structure and has a spacing between the casing structure and the inner tube structure, and the bottom end of the inner tube structure is arranged in the part of the casing structure extended horizontally and is provided with a gas outlet, so that the problem that absorption efficiency is low in the gas-liquid fluid mixing process in the prior art and fluid efficient mixing cannot be realized is solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of unconventional oil and gas reservoir development and carbon sequestration technology, in particular to a CO2-high-salinity-water collaborative sequestration device and method. BACKGROUND

[0002] The coal mine high-salinity-water and CO2 collaborative geological sequestration is an innovative method for synchronously solving the problems of waste gas and waste water. The current CO2 geological sequestration technology generally adopts a vertical well layered injection mode, and problems such as the mixing of CO2 and salt water layer being uncontrollable, the sequestration potential being insufficient due to less water in the target layer in some areas, and the economic cost being too high exist. Specifically, in the prior art, fluid injection is difficult, which leads to insufficient injectability of the sequestration formation in the process of the collaborative geological sequestration of carbon dioxide and mine water; and in the process of gas-liquid fluid mixing, the absorption efficiency is low, which leads to the failure to realize efficient mixing of the fluid.

[0003] In addition, the dynamic stress adaptability of the drilling cement ring is weak: the conventional cement ring generates radial cracks (width >=100 mu m) when the shear stress >=35 MPa, which leads to the escape of CO2 along the cracks, the corrosion leakage of the wellbore, the collaborative corrosion of high-salinity-water Cl⁻ (>=15,000 mg / L) and supercritical CO2 (pH<3), and the annual wall thickness loss of the casing >=1.2 mm. SUMMARY

[0004] The purpose of the application is to provide a CO2-high-salinity-water collaborative sequestration device and method to solve the problems existing in the prior art, and to solve the problem of low absorption efficiency in the process of gas-liquid fluid mixing in the prior art, which leads to the failure to realize efficient mixing of the fluid.

[0005] To achieve the above-mentioned purpose, the application provides the following scheme: the application provides a CO2-high-salinity-water collaborative sequestration device, which comprises a drilling structure, a casing structure and an inner tube structure; the drilling structure extends from the ground to a fluid sequestration reservoir in the vertical direction, a part of the drilling structure above the fluid sequestration reservoir gradually inclines along the horizontal direction from top to bottom, and the bottom end of the drilling structure extends along the horizontal direction; the casing structure is arranged in the drilling structure and extends synchronously with the drilling structure, a solid well structure is arranged between the casing structure and the drilling structure above the fluid sequestration reservoir; a liquid outlet is arranged in the part of the casing structure extending horizontally in the fluid sequestration reservoir; the inner tube structure is arranged in the casing structure and has a space for the flow of coal mine high-salinity-water between the casing structure and the inner tube structure, and the bottom end of the inner tube structure is arranged in the part of the casing structure extending horizontally and is provided with a gas outlet for discharging CO2.

[0006] Preferably, a gas-liquid mixing area for mixing coal mine high-salinity-water and CO2 is arranged between the bottom end of the inner tube structure and the liquid outlet.

[0007] Preferably, the portion of the drilling structure located in the fluid-sealing storage layer includes at least two drilling branches arranged in parallel, each of the drilling branches gradually inclines in the horizontal direction from top to bottom, and its bottom end extends in the horizontal direction; each of the drilling branches is provided with the casing structure extending synchronously therewith, and the top of the casing structure in each of the drilling branches is sealed and connected with the bottom end of the casing structure located above the fluid-sealing storage layer; the bottom end of the casing structure in each of the drilling branches is provided with the liquid outlet; the inner tube structure includes a plurality of inner tube branch pipelines, each of the inner tube branch pipelines extends into the casing structure in each of the drilling branches, extends to the horizontal extension part of the casing structure in the drilling branch, and is provided with the air outlet.

[0008] Preferably, the end of the horizontally extending portion of the casing structure is a sieve tube-like structure.

[0009] Preferably, the drilling structure is a multi-stage stepped structure, the various levels of the drilling structure are coaxially arranged and arranged in sequence along the vertical direction, and their diameters gradually decrease from top to bottom; the casing structure is a multi-stage stepped structure, and the various levels of the casing structure are correspondingly arranged in the various levels of the drilling structure.

[0010] Preferably, the drilling structure includes a first wellbore, a second wellbore and a third wellbore distributed in sequence along the vertical direction; the casing structure includes a primary casing, a secondary casing and a tertiary casing distributed in sequence along the vertical direction; the first wellbore extends vertically and extends to the bottom of the upper aquifer after passing through the surface; the first casing is arranged in the first wellbore, and the cementing structure is arranged between the first wellbore and the first casing; the second wellbore extends vertically, and the top end of the second wellbore is coaxially connected to the bottom end of the first casing, and its diameter is smaller than that of the second wellbore. The diameter of the first-level casing, the bottom end of the second-opening wellbore extends to the top position of the fluid-sealing storage layer; the second-level casing is arranged in the second-opening wellbore, and the cementing structure is arranged between the first-opening wellbore and the second-level casing; the top end of the third-opening wellbore is coaxially docked at the bottom end position of the second-level casing, and is located in the fluid-sealing storage layer as a whole, and its diameter is smaller than the diameter of the second-level casing, the overall structure of the third-opening wellbore gradually tilts horizontally from top to bottom, and its bottom end extends horizontally; the third-level casing is arranged in the third-opening wellbore.

[0011] Preferably, the cementing structure comprises a silicate cement matrix, latex and carbon nanotubes are added to the silicate cement matrix, and the cementing structure maintains an annular pressure of 15 MPa during the setting period.

[0012] Preferably, the monitoring system for monitoring the temperature and pressure changes in the wellbore is further included, the monitoring system comprises a monitoring optical fiber and a monitoring device, the monitoring optical fiber is arranged on the outer wall of the part of the casing structure located in the fluid storage reservoir, and the monitoring device is located on the ground and is electrically connected with the monitoring optical fiber through a cable.

[0013] Preferably, the end of the inner tube structure is in a spiral tube structure, and a plurality of gas outlets are uniformly distributed on the spiral tube structure.

[0014] A storage method is also provided, comprising the following steps:

[0015] S1, using the required drilling equipment, drilling downward from the ground to the bottom of the upper aquifer to complete the drilling work of a first wellbore, then placing a first casing in the first wellbore and fixing the first casing by cementing;

[0016] S2, using the required drilling equipment, drilling downward through the first wellbore to the top of the fluid storage reservoir to complete the drilling work of a second wellbore, then placing a second casing in the second wellbore and fixing the second casing by cementing;

[0017] S3, using the required drilling equipment and the required rotary steering equipment, drilling downward through the second wellbore to the bottom of the fluid storage reservoir to complete the drilling work of a third wellbore, and arranging a monitoring optical fiber on the outer wall of the third casing, then placing the third casing in the third wellbore;

[0018] S4, lowering the inner tube structure, and the bottom end of the inner tube structure is located in the horizontally extended part of the casing structure;

[0019] S5, passing the coal mine high-salinity water through the first casing, the second casing and the third casing, and passing the CO2 through the inner tube structure.

[0020] The present application has the following technical effects compared with the prior art:

[0021] The application discloses a CO2-high-salt water cooperative storage device, which is characterized in that a casing structure is arranged between a part above a fluid storage layer and a drilling structure, and a cementing structure is arranged between the casing structure and the drilling structure, so that the casing structure and the drilling structure are stably connected, and subsequent injection of coal mine high-salt water can be avoided to prevent leakage above the fluid storage layer; CO2 is injected into the casing structure through an inner pipe structure and a gas outlet of the inner pipe structure, and then is mixed with coal mine high-salt water entering through a space between the inner pipe structure and the casing structure, and finally is discharged into the fluid storage layer through a liquid outlet of the casing structure. Since the gas outlet and the liquid outlet are respectively arranged on horizontally extended parts of the inner pipe structure and the casing structure, after the coal mine high-salt water and the CO2 are fully mixed, the mixture directly enters the fluid storage layer, so that when the inner pipe structure and the casing structure are arranged as a whole in a horizontal structure, the CO2 is affected by the buoyancy and floats upwards in the coal mine high-salt water before being fully mixed with the coal mine high-salt water, thereby solving the problem of low absorption efficiency in the gas-liquid mixing process in the prior art, and realizing efficient mixing of the fluid. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0023] Figure 1 Example one of the overall structure schematic diagram of the present application;

[0024] Figure 2 The flow chart of the present application; wherein (a) is a drilling and opening wellbore schematic diagram, (b) is a next stage casing and cementing schematic diagram, (c) is a drilling and opening wellbore schematic diagram, (d) is a next stage casing and cementing schematic diagram, (e) is a drilling and opening wellbore schematic diagram, (f) is a next stage casing schematic diagram, and (g) is an inner pipe structure schematic diagram;

[0025] Figure 3 Example two of the overall structure schematic diagram of the present application;

[0026] Figure 4 Example three of the overall structure schematic diagram of the present application;

[0027] Figure 5 Schematic diagram of the end of the inner pipe structure of the present application being provided with a spiral pipe structure;

[0028] Among them, 1-primary casing, 2-first wellbore, 3-second wellbore, 4-secondary casing, 5-third wellbore, 6-third-stage casing, 7-tail pipe hanger, 8-inner pipe structure, 9-drilling branch, 10-casing structure, 11-inner pipe branch pipeline, 12-screen tube structure, 13-liquid outlet, 14-gas outlet, 15-gas-liquid mixing area, 16-spiral tubular structure, 17-cementing structure. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] The purpose of the present invention is to provide a CO2-high-salt water collaborative storage device and storage method to solve the problems existing in the above-mentioned prior art, and solve the problem that the absorption efficiency in the gas-liquid fluid mixing process in the prior art is low, resulting in the inability to achieve efficient fluid mixing.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] like Figures 1 to 5 As shown, the present invention provides a CO2-high-salt water collaborative storage device, including a drilling structure, a casing structure 10 and an inner tube structure 8; first of all, it should be noted that the entire formation structure is divided into the surface, the upper aquifer, the fluid-sealing storage layer and the basement rock layer from top to bottom. For the CO2-high-salt water collaborative storage, it is sealed in the fluid-sealing storage layer; the drilling structure extends vertically from the surface to the fluid-sealing storage layer, and the part of the drilling structure located in the fluid-sealing storage layer gradually tilts horizontally from top to bottom, and its bottom end extends horizontally, that is, a horizontal well structure; the casing Structure 10 is positioned within the drilling structure and extends synchronously with it. It is preferably constructed of oil casing. A cementing structure 17 is positioned between the portion of casing structure 10 above the fluid-tight reservoir and the drilling structure. A liquid outlet 13 is defined within the horizontally extending portion of casing structure 10 within the fluid-tight reservoir. An inner pipe structure 8 is positioned within casing structure 10, with a gap between it and casing structure 10 for the circulation of high-salt coal mine brine. The bottom end of inner pipe structure 8 is located within the horizontally extending portion of casing structure 10 and is provided with an outlet 14 for the discharge of CO2 (carbon dioxide). Inner pipe structure 8 is used to transport supercritical CO2, and the annular space between inner pipe structure 8 and casing structure 10 is used to transport high-salt coal mine brine, with a salinity of ≥15 g / L. Inner pipe structure 8 is constructed of corrosion-resistant seamless steel pipe.

[0033] The CO2-high-salinity water cooperative storage device discloses a casing structure 10 located above the fluid storage reservoir, and a cementing structure 17 is arranged between the casing structure 10 and the drilling structure to ensure the stable connection of the casing structure 10 and the drilling structure, and to avoid the leakage of the coal mine high-salinity water above the fluid storage reservoir after subsequent injection. CO2 is introduced into the casing structure 10 through the inner pipe structure 8 and the gas outlet 14 of the inner pipe structure 8, and then mixed with the coal mine high-salinity water entering through the interval between the inner pipe structure 8 and the casing structure 10, and then discharged into the fluid storage reservoir through the liquid outlet 13 of the casing structure 10. Since the gas outlet 14 and the liquid outlet 13 are respectively located on the horizontally extended parts of the inner pipe structure 8 and the casing structure 10, after the coal mine high-salinity water and CO2 are fully mixed, they directly enter the fluid storage reservoir, avoiding the situation that when the inner pipe structure 8 and the casing structure 10 are arranged as a whole in a horizontal structure, CO2 floats up in the coal mine high-salinity water under the influence of buoyancy before it is fully mixed with the coal mine high-salinity water, solving the problem of low absorption efficiency in the gas-liquid mixing process in the prior art, which leads to inefficient mixing of fluids.

[0034] In the embodiment, for the processing of the part of the drilling structure located in the fluid storage reservoir, a special drilling tool is selected, such as a sharp cone casing shoe or a special grinding shoe, and in the specific construction process, a straight well section of a certain distance is first drilled to establish a stable borehole; then the build-up angle starting depth is selected according to the design, the required rotary steering equipment is selected, the tool face is dynamically adjusted through the internal eccentric mechanism, and the required mud motor is selected to fix the bent housing motor, and the sliding drilling directional drilling is carried out. When the inclination reaches 80°~85°, the stable inclination section is entered, and the trajectory is adjusted to smoothly transition to horizontal (90°).

[0035] In the embodiment, the casing structure 10 is lowered by using floating casing, rotating casing, casing booster, and elastic / flexible casing design.

[0036] In a specific embodiment, a gas-liquid mixing area 15 for mixing coal mine high-salinity water and CO2 is arranged between the bottom end of the inner pipe structure 8 and the liquid outlet 13. By arranging the gas-liquid mixing area 15, the coal mine high-salinity water and CO2 are further mixed before being discharged from the casing structure 10, so as to prolong the mixing time of the coal mine high-salinity water and CO2 and ensure the sufficient mixing of the two.

[0037] In one embodiment, the drilling structure is located in the part of the fluid storage layer, which includes at least two parallel drilling branches 9, each of which is gradually inclined in the horizontal direction from top to bottom, and the bottom end of which extends horizontally, so that the bottom end of the drilling structure forms a multi-horizontal well structure; each of the drilling branches 9 is provided with a casing structure 10 extending synchronously therewith, the top end of the casing structure 10 in each of the drilling branches 9 is in sealed communication with the bottom end of the casing structure 10 above the fluid storage layer; the bottom end of the casing structure 10 in each of the drilling branches 9 is provided with a liquid outlet 13; the inner tube structure 8 includes a plurality of inner tube branch pipelines 11, each of which corresponds to the casing structure 10 in each of the drilling branches 9, and extends to the horizontally extending part of the casing structure 10 in each of the drilling branches 9, and is provided with a gas outlet 14 to increase the amount of CO2 gas and improve the injectability of CO2 and coal mine high-salinity water in the process of geological storage.

[0038] In this embodiment, after the drilling work of the drilling structure above the fluid storage layer is completed, the bottom end of the casing structure 10 lowered inside is provided with a prefabricated branch connector or a multi-way joint, which provides a plurality of outlets, each of which is used to guide the subsequent drilling work of each of the drilling branches 9. The branch connector or the multi-way joint is provided with a guide groove and a sealing interface, and each of the drilling branches 9 is drilled through the guide groove by using the existing directional drilling technology. The top end of the casing structure 10 in each of the drilling branches 9 is provided with a liner hanger 7, which is anchored at the inner wall of each of the outlets by hydraulic or mechanical means to provide mechanical support after being lowered into the drilling branch 9. An inflatable packer, such as a hydraulic or mechanical packer, is used above or at the connection of the liner hanger 7 to form a high-pressure seal.

[0039] In another embodiment, the horizontally extending part of the casing structure 10 is provided with a screen pipe structure 12 at the end thereof to increase the amount of CO2 gas.

[0040] In a specific embodiment, the drilling structure is in a multi-stage ladder structure, each stage of the drilling structure is coaxially arranged and sequentially arranged in the vertical direction, and the diameter gradually decreases from top to bottom; the casing structure 10 is in a multi-stage ladder structure, and each stage of the casing structure 10 is correspondingly arranged in each stage of the drilling structure. By arranging the drilling structure and the casing structure 10 in a multi-stage ladder structure, the construction process can be smoothly carried out, and the strength and stability of the entire drilling structure and the casing structure 10 are ensured. Specifically, a relatively thick first drilling tool structure is used at the beginning of drilling, the drilling work of the first stage of the drilling structure is completed, and the first stage of the casing structure 1 is lowered on the basis of the first stage of the drilling structure, and then a second drilling tool structure thinner than the first stage of the casing structure 1 is used, the drilling work of the second stage of the drilling structure is completed, the inner diameter of the second stage of the drilling structure is smaller than the inner diameter of the first stage of the casing structure 1, and so on until the drilling of the last stage of the drilling structure and the lowering of the last stage of the casing structure 1 are completed. The last stage of the drilling structure and the last stage of the casing structure 1 are horizontally extended at the end, and the coal mine high-salt water and CO2 pass through the last stage of the casing structure 1 and then enter the last stage of the drilling structure and then enter the fluid storage layer. The top end of the last stage of the casing structure 1 is provided with a liner hanger 7, which is anchored on the inner wall of each upper stage of the casing structure 1 by hydraulic or mechanical means after being lowered to the last stage of the drilling structure, thereby providing mechanical support. An inflatable packer, such as a hydraulic or mechanical packer, is used above or at the connection of the liner hanger 7 to form a high-pressure seal.

[0041] In the embodiment, the drilling structure includes a first open wellbore 2, a second open wellbore 3 and a third open wellbore 5 sequentially arranged in the vertical direction; the casing structure 10 includes a first casing 1, a second casing 4 and a third casing 6 sequentially arranged in the vertical direction; the first open wellbore 2 extends vertically and passes through the ground surface and extends to the bottom of the upper aquifer; the first open wellbore 2 is provided with the first casing 1, and the well cementing structure 17 is arranged between the first open wellbore 2 and the first casing 1; the second open wellbore 3 extends vertically, the top end of the second open wellbore 3 is coaxially connected to the bottom end of the first casing 1, and the diameter of the second open wellbore 3 is smaller than that of the first casing 1, and the bottom end of the second open wellbore 3 extends to the top of the fluid storage layer; the second open wellbore 3 is provided with the second casing 4, and the well cementing structure 17 is arranged between the first open wellbore 2 and the second casing 4; the top end of the third open wellbore 5 is coaxially connected to the bottom end of the second casing 4, and the diameter of the third open wellbore 5 is smaller than that of the second casing 4, the overall structure of the third open wellbore 5 gradually inclines in the horizontal direction from top to bottom, and the overall structure is located in the fluid storage layer, and the bottom end extends in the horizontal direction; the third open wellbore 5 is provided with the third casing 6, and the top end of the third casing 6 is provided with a liner hanger 7 for anchoring on the inner wall of the second casing 4.

[0042] In this embodiment, the first wellbore 2 has a diameter of 444.5 mm and is limited to a depth that completely penetrates the upper aquifer. A primary casing 1 with a diameter of 339.7 mm is lowered into it. The second wellbore 3 has a diameter of 311.1 mm and is limited to a depth that reaches the top of the fluid-sealed storage layer. A secondary casing 4 with a diameter of 244.5 mm is lowered into it. The third wellbore 5 has a diameter of 215.9 mm and is entirely located within the fluid-sealed storage layer. A tertiary casing 6 with a diameter of 168.3 mm is lowered into it. The horizontal extensions of the third wellbore 5 and tertiary casing 6 are approximately 700 m long. Furthermore, the inner pipe, a continuous pipe with a diameter of 88.9 mm, serves as a channel for CO2 injection. Supercritical CO2 is transported to the horizontal extension of the inner pipe structure 8 and discharged through the gas outlet 14 into the horizontal extension of the casing structure 10. Due to buoyancy, the supercritical CO2 mixes with the high-salt coal mine brine during its ascent and is then injected into the fluid-sealed storage layer through the liquid outlet 13. The specifications of the first wellbore 2, the second wellbore 3 and the third wellbore 5 are shown in Table 1:

[0043] Table 1

[0044]

[0045] In one specific embodiment, cementing structure 17 comprises a silicate cement matrix to which latex and carbon nanotubes are added, wherein the latex content is 10-15 wt% and the carbon nanotube content is 0.5-1.2 wt%. Cementing structure 17 maintains an annular pressure of 15 MPa during the curing period and is maintained for 72 hours. Cementing structure 17 is used to prevent high-salt coal mine brine and CO2 from seeping into the formation, thereby preventing formation collapse. Key performance characteristics of cementing structure 17 include compressive strength of 55-65 MPa (ASTM C39 standard), elastic modulus of 6-7 GPa (ISO 10406:2014), and self-healing capability: a repair rate of ≥85% for cracks ≤200 μm at a pressure differential of 1 MPa.

[0046] In a specific embodiment, a monitoring system for monitoring temperature and pressure changes within the wellbore is also included. The monitoring system includes a monitoring optical fiber and a monitoring device. The monitoring optical fiber is arranged on the outer peripheral wall of the portion of the casing structure 10 located in the fluid-sealed storage layer. The monitoring device is located on the ground and is electrically connected to the monitoring optical fiber via a cable. The monitoring device and the monitoring optical fiber are used to monitor temperature and pressure changes within the drilling structure in real time to prevent high-salt water and CO2 in the coal mine from breaking through the drilling structure and leaking. The monitoring optical fiber preferably adopts a distributed temperature / strain optical fiber with a sampling interval of 0.1m and a temperature accuracy of ±0.1°C. When a leak occurs in the drilling structure, the monitoring equipment displays temperature anomalies (gradient > 2°C / m) and strain mutations (> 300με).

[0047] In the present embodiment, before the last casing 1 structure is lowered into the well, the monitoring optical fiber is spirally wound or linearly laid along the outer wall of the last casing 1 structure, wrapped with a high-temperature and high-pressure resistant protective sleeve such as a stainless steel hose or a composite material layer, and fixed with a shear-resistant adhesive tape. At the position where the monitoring optical fiber passes through the hanger, a flexible metal sheath is additionally added to prevent mechanical damage during the setting process. The tailpipe hanger 7 is also modified to design a micro guide groove or a perforated channel (5-10 mm in diameter) in the hanger body, which is positioned away from the main sealing area and the key stress points to ensure that the structural strength is not affected. The channel is filled with a high-temperature silicone seal ring or uses a metal-ceramic composite seal to prevent the infiltration of well fluid while allowing the optical fiber to slide through.

[0048] In a specific embodiment, the end of the inner tube structure 8 is in the form of a spiral tube structure 16, and a plurality of gas outlets 14 are uniformly distributed on the spiral tube structure 16, so that the CO2 discharged from each gas outlet 14 flows in a spiral shape, thereby increasing the contact area with the coal mine high-salinity water and prolonging the mixing time with the coal mine high-salinity water. The spiral-flowing CO2 has the effect of stirring the coal mine high-salinity water, improving the solubility of CO2 in the coal mine high-salinity water, and fully mixing with the coal mine high-salinity water.

[0049] In a specific embodiment, a sealing method is also provided, comprising the following steps:

[0050] S1, using the required drilling equipment, drilling downward from the ground to the bottom of the upper aquifer, generally 400-700 m, in order to protect the upper aquifer from pollution caused by sealing, completing the drilling of the first wellbore 2, then placing the first casing 1 in the first wellbore 2, and fixing the first casing 1 by cementing;

[0051] S2, using the required drilling equipment, drilling downward through the first wellbore 2 to the top of the fluid sealing reservoir, completing the drilling of the second wellbore 3, then placing the second casing 4 in the second wellbore 3, and fixing the second casing 4 by cementing;

[0052] S3, using the required drilling equipment and the required rotary steering equipment, drilling downward through the second wellbore 3 to the bottom of the fluid sealing reservoir, completing the drilling of the third wellbore 5, and arranging the monitoring optical fiber on the outer wall of the third casing 6, then placing the third casing 6 in the third wellbore 5;

[0053] S4, lowering the inner tube structure 8, with the bottom end of the inner tube structure 8 located in the horizontally extended part of the casing structure 10;

[0054] S5, the coal mine high-salt water is introduced through the primary sleeve 1, the secondary sleeve 4 and the tertiary sleeve 6, and the CO2 is introduced through the inner tube structure 8. Specifically, the coal mine high-salt water is introduced in the annulus between the primary sleeve 1 and the inner tube structure 8, and then flows along the annulus between the secondary sleeve 4 and the inner tube structure 8 and the annulus between the tertiary sleeve 6 and the inner tube structure 8 to the gas-liquid mixing area 15. After the CO2 is discharged from the gas outlet 14 of the inner tube structure 8, the CO2 also enters the gas-liquid mixing area 15. The CO2 and the coal mine high-salt water are fully mixed in the gas-liquid mixing area 15, and then are discharged into the fluid storage layer through the liquid outlet 13.

[0055] The adaptive changes according to actual needs are within the protection scope of the present application.

[0056] It should be noted that, for those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0057] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above embodiment descriptions are only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will have changes. In conclusion, the content of the present description should not be understood as a limitation of the present application.

Claims

1. A CO2-salt water collaborative storage device, characterized in that: Including drilling structure, casing structure and inner pipe structure; The drilling structure extends vertically from the ground surface to the fluid-sealing storage layer, the portion of the drilling structure located in the fluid-sealing storage layer gradually tilts horizontally from top to bottom, and the bottom end thereof extends horizontally; The casing structure is arranged in the drilling structure and extends synchronously with the drilling structure. A cementing structure is provided between the portion of the casing structure located above the fluid-tight storage layer and the drilling structure. A liquid outlet is provided in the portion of the casing structure located in the fluid-tight storage layer and extending horizontally. The inner tube structure is located inside the casing structure, and there is a gap between the inner tube structure and the casing structure for the circulation of high-salt coal mine water. The bottom end of the inner tube structure is located inside the horizontally extending portion of the casing structure and is provided with an outlet for the discharge of CO2. A gas-liquid mixing zone for mixing coal mine high-salt water and CO2 is provided between the bottom end of the inner tube structure and the liquid outlet; The end of the horizontally extending portion of the casing structure is a sieve-tube structure; The end of the inner tube structure is a spiral tube structure, and a plurality of air outlets are evenly distributed on the spiral tube structure.

2. The CO2-salt water co-storage device according to claim 1, characterized in that: The portion of the drilling structure located in the fluid-sealing storage layer includes at least two drilling branches arranged in parallel, each of the drilling branches gradually tilts horizontally from top to bottom, and the bottom end thereof extends horizontally; Each of the drilling branches is provided with the casing structure extending synchronously therewith, the top end of the casing structure in each drilling branch is sealedly connected to the bottom end of the casing structure located above the fluid sealing storage layer; the bottom end of the casing structure in each drilling branch is provided with the liquid outlet; The inner tube structure includes a plurality of inner tube branch pipelines, each inner tube branch pipeline extends into the casing structure in each drilling branch, extends to the horizontal extension part of the casing structure in the drilling branch, and is provided with the air outlet.

3. The CO2-salt water co-storage device according to claim 1 or 2, characterized in that: The drilling structure is a multi-level stepped structure, and the various levels of the drilling structure are coaxially arranged and arranged in sequence along the vertical direction, and their diameters gradually decrease from top to bottom; the casing structure is a multi-level stepped structure, and the various levels of the casing structure are correspondingly arranged in the various levels of the drilling structure.

4. The CO2-salt water co-storage device according to claim 3, characterized in that: The drilling structure includes a first wellbore, a second wellbore and a third wellbore sequentially distributed in the vertical direction; the casing structure includes a first-level casing, a second-level casing and a third-level casing sequentially distributed in the vertical direction; The first wellbore extends vertically and extends to the bottom of the upper aquifer after passing through the ground surface; the first-level casing is arranged in the first wellbore, and the cementing structure is arranged between the first wellbore and the first-level casing; The secondary wellbore extends vertically, the top end of the secondary wellbore is coaxially connected to the bottom end of the primary casing, and its diameter is smaller than that of the primary casing. The bottom end of the secondary wellbore extends to the top of the fluid-sealing storage layer; the secondary casing is arranged in the secondary wellbore, and the cementing structure is arranged between the secondary wellbore and the secondary casing; The top end of the three-opening wellbore is coaxially docked with the bottom end of the secondary casing and is located as a whole in the fluid sealing storage layer. Its diameter is smaller than that of the secondary casing. The overall structure of the three-opening wellbore gradually tilts horizontally from top to bottom, and its bottom end extends horizontally. The three-level casing is arranged in the three-opening wellbore.

5. The CO2-salt water co-storage device according to claim 1 or 2, characterized in that: The cementing structure includes a silicate cement matrix, latex and carbon nanotubes are added to the silicate cement matrix, and the cementing structure maintains an annular pressure of 15 MPa during the waiting period.

6. The CO2-salt water co-storage device according to claim 1 or 2, characterized in that: It also includes a monitoring system for monitoring temperature and pressure changes in the wellbore, the monitoring system includes a monitoring optical fiber and a monitoring device, the monitoring optical fiber is arranged on the outer peripheral wall of the part of the casing structure located in the fluid sealing storage layer, and the monitoring device is located on the ground and is electrically connected to the monitoring optical fiber through a cable.

7. A storage method using the CO2-high-salt water collaborative storage device according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: S1, using required drilling equipment to drill from the ground to the bottom of the upper aquifer to complete drilling of a wellbore, then placing a primary casing in the wellbore, and fixing the primary casing by cementing; S2. Drilling the secondary wellbore downward through the primary wellbore to the top of the fluid-sealing storage layer using the required drilling equipment, then placing a secondary casing in the secondary wellbore and securing the secondary casing by cementing. S3. Using the required drilling equipment and the required rotary steering equipment, drill downward through the secondary wellbore to the bottom of the fluid-sealed storage layer to complete the drilling of the tertiary wellbore, and install a monitoring optical fiber on the outer wall of the tertiary casing. Then, place the tertiary casing in the tertiary wellbore; S4. The inner tube structure is lowered into the casing structure, with the bottom end of the inner tube structure located within the horizontally extending portion of the casing structure; S5. The high-salt coal mine water is introduced through the primary casing, the secondary casing and the tertiary casing, and CO2 is introduced through the inner pipe structure.

Images