Ultra-large-diameter well bore structure capable of storing energy through compressed air and construction method of ultra-large-diameter well bore structure

Abstract

The invention discloses a compressed air energy storage ultra-large-diameter well bore structure and a construction method thereof.The compressed air energy storage ultra-large-diameter well bore structure comprises a first well opening hole, a second well opening hole and a third well opening hole, the first well opening hole, the second well opening hole and the third well opening hole are formed in a rock salt deposition mining area and sequentially communicated, the hole diameters of the first well opening hole, the second well opening hole and the third well opening hole are sequentially decreased from top to bottom, the inner diameter of the first well opening hole is 760 mm to 764 mm, and the inner diameter of the second well opening hole is 570 mm to 572 mm; the inner diameter of the third well opening hole ranges from 406 mm to 408 mm. The diameter of the drill bit sequentially used from top to bottom is reduced through a three-time drilling well body structure, a surface casing pipe and shallow water are adopted for first drilling, a production casing pipe and a salt layer and cover layer section above a cavity top are adopted for second drilling, so that the integrity of a shaft is guaranteed, the drill bit reaches a salt cavity through drilling and barefoot well completion, a central pipe is adopted as an injection and production channel, and the drilling efficiency is improved. In addition, the combination mode of the surface casing and the production casing meets the requirements of safety and environment management, the number of wells deployed by salt cavern compressed air energy storage can be reduced, and the total project investment is reduced.

Description

Technical Field

[0001] The invention relates to the field of compressed air energy storage in salt caverns, and in particular to an ultra-large-caliber wellbore structure for compressed air energy storage and a construction method thereof. Background Art

[0002] Salt cavern compressed air energy storage is a large-capacity physical energy storage technology that uses underground salt caverns to store gas. During low-load periods of the power grid, air is compressed by a compressor and high-pressure air is stored in the gas storage reservoir. At the same time, the compression heat is recovered by the heat storage medium. During high-load periods of the power grid, the high-pressure gas in the gas storage reservoir is released to expand in the air turbine to do work, driving the generator to transmit electricity to the power grid. Compressed air energy storage technology is a clean, efficient, and flexible energy storage method with large scale, long life, and no pollution. It plays an important role in shaving peaks and filling valleys and enhancing the stability of the power grid. It is one of the important directions for achieving the "dual carbon" goal.

[0003] The wellbore structure refers to the level, depth and corresponding wellbore size of the special casing that must be inserted into the well section above the reservoir. The design method of the wellbore structure varies with factors such as the size of regional geostress, geostress direction, collapse pressure, fracture pressure, drilling fluid properties and drilling process methods. However, if the wellbore structure is not designed reasonably, it may cause a series of complex situations such as well leakage, drill stuck, and even blowout, which will seriously affect the drilling time and safety. In addition, the wellbore, casing and center pipe of the injection and production well are the connection channels between the energy storage reservoir and the ground equipment. However, due to the limitation of gas injection and production flow and the influence of erosion, the current small-diameter wellbore structure seriously limits the installed capacity of compressed air energy storage power stations. Therefore, an ultra-large-diameter wellbore structure suitable for salt cavern compressed air energy storage is urgently needed. Summary of the invention

[0004] The purpose of the present invention is to provide an ultra-large-diameter wellbore structure for compressed air energy storage and a construction method thereof, so as to solve the problems existing in the above-mentioned prior art, realize scientific, high-quality, economical and safe drilling operations, reduce the number of wells deployed in salt cavern compressed air power stations, reduce project investment, and bring significant economic benefits.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A super-large-diameter wellbore structure for compressed air energy storage, comprising a first wellbore, a second wellbore and a third wellbore which are opened in a rock salt deposition mining area and are connected in sequence and whose apertures decrease from top to bottom, a surface casing, a production casing and a central pipe respectively arranged in the first wellbore, the second wellbore and the third wellbore, the surface casing, the production casing and the central pipe have apertures that decrease from top to bottom and are connected in sequence, the inner diameter of the first wellbore is 760 mm to 764 mm, the inner diameter of the second wellbore is 570 mm to 572 mm, and the inner diameter of the third wellbore is 406 mm to 408 mm.

[0007] Preferably, the rock salt deposition mining area includes clay, mudstone, sandstone, limestone, gypsum and rock salt from top to bottom.

[0008] Preferably, the outer diameter of the surface casing is 609 mm to 610 mm, the outer diameter of the production casing is 473 mm to 474 mm, and the outer diameter of the central pipe is 339 mm to 340 mm.

[0009] Preferably, the surface casing and the production casing, and the production casing and the central pipe are connected by welding or by locking a male buckle and a female buckle.

[0010] Preferably, the adjacent surface casings are connected by BC buckles, and the adjacent production casings and the adjacent central pipes are connected by airtight buckles.

[0011] A method for constructing an ultra-large-caliber wellbore structure for compressed air energy storage comprises the following steps:

[0012] Using a first drill bit to drill and form the first wellbore, the first wellbore is drilled to bedrock, and the surface casing is placed in the first wellbore to isolate shallow water;

[0013] Continue drilling with a second drill bit to form the second wellbore, lower the production casing into the second wellbore, seal the surface casing and the production casing, and isolate the salt layer and cap rock above the cavity top;

[0014] A third drill bit is used to continue drilling and form the third wellbore, and the central pipe is lowered into the third wellbore. The central pipe is sealed and connected to the production casing.

[0015] Preferably, cement slurry is filled between the first wellbore and the surface casing and between the second wellbore and the production casing to complete cementing.

[0016] Preferably, the surface casing cementing cement slurry formula and performance requirements are as follows: The surface casing requires cement slurry to return to the ground, the design adopts single-stage cementing, and adopts a conventional density cement slurry system with a density requirement of 1.85-1.90 g / cm 3 The cement slurry has a ratio of G-grade oil well cement, 1.0% dispersant, 2.0% early strength agent, 0.1% defoamer and 40% water.

[0017] Preferably, the production casing cementing slurry formula and performance requirements: the production casing requires the cement slurry to return to the ground, using a conventional density salt-resistant elastic toughness cement slurry system, the density requirement is 1.85-1.90g / cm 3 ; The elastic modulus of cement stone is ≤6GPa; the formula of cement slurry is G-grade cement, 5-10% elastic particles, 4% expansion agent, 3% salt-resistant fluid loss reducer, 2% early strength agent, 1% dispersant, 2% stabilizer, 0.5% defoamer, retarder and semi-saturated brine.

[0018] Preferably, the surface casing, production casing and central pipe are hoisted by a drilling rig during the hoisting process.

[0019] Compared with the prior art, the present invention has achieved the following technical effects:

[0020] The present invention adopts a three-opening large-diameter wellbore structure for rock salt deposition mining areas, and the diameter of the drill bits used in sequence from top to bottom decreases, wherein the first opening adopts a surface casing to isolate shallow water, the second opening adopts a production casing to isolate the salt layer and the cap layer section above the cavity top to ensure the integrity of the wellbore, the third opening drill bit drills to the salt cavity, the open hole is completed, and the center pipe is used as the injection and production channel, which can greatly increase the injection and production flow rate. In addition, the combination of the large-diameter surface casing and the production casing meets the requirements of safety and environmental management, can reduce the number of wells deployed for salt cavern compressed air energy storage, reduce engineering investment, and bring significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a structural schematic diagram of the present invention;

[0023] Among them, 1. the first wellbore; 2. the second wellbore; 3. the third wellbore; 4. the surface casing; 5. the production casing; 6. the center pipe. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0025] The purpose of the present invention is to provide an ultra-large diameter wellbore structure for compressed air energy storage and a construction method thereof, so as to solve the problems existing in the above-mentioned prior art, realize scientific, high-quality, economical and safe drilling operations, improve drilling efficiency, reduce the number of deployed wells, reduce project investment, and bring significant economic benefits.

[0026] 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.

[0027] refer to Figure 1 , an ultra-large-diameter wellbore structure for compressed air energy storage, comprising a first wellbore, a second wellbore and a third wellbore which are connected in sequence and whose apertures decrease from top to bottom in a rock salt deposition mining area, a surface casing, a production casing and a central pipe which are respectively arranged in the first wellbore, the second wellbore and the third wellbore, wherein the apertures of the surface casing, the production casing and the central pipe decrease from top to bottom and are connected in sequence, the inner diameter of the first wellbore is 760 mm to 764 mm, the inner diameter of the second wellbore is 570 mm to 572 mm, the inner diameter of the third wellbore is 406mm to 408mm; the present invention adopts a three-opening wellbore structure, and the diameter of the drill bit used in sequence from top to bottom decreases, wherein the first opening adopts surface casing to isolate shallow water, the second opening adopts production casing to isolate the salt layer and cap layer section above the cavity top to ensure the integrity of the wellbore, the third opening drill bit drills to the salt cavity, the open hole is completed, and the center pipe is used as the injection and production channel, which can greatly increase the injection and production flow rate. In addition, this combination of surface casing and production casing meets the requirements of health, safety, and environmental management, can improve drilling efficiency, reduce the number of deployed wells, reduce engineering investment, and bring significant economic benefits.

[0028] Furthermore, the rock salt deposition mining area includes clay, mudstone, sandstone, limestone, gypsum, and rock salt from top to bottom.

[0029] Furthermore, the outer diameter of the surface casing is 609 mm to 610 mm, the outer diameter of the production casing is 473 mm to 474 mm, and the outer diameter of the central pipe is 339 mm to 340 mm.

[0030] Furthermore, the surface casing and the production casing, as well as the production casing and the central pipe are connected by welding or by locking male and female buckles.

[0031] Furthermore, the adjacent surface casings are connected by BC buckles, and the adjacent production casings and the adjacent central pipes are connected by airtight buckles.

[0032] Furthermore, the bottom elevation of the production casing is lower than the bottom elevation of the central casing, and the bottom elevation of the production casing is 3 to 5 meters lower than the bottom elevation of the central casing.

[0033] A method for constructing an ultra-large-caliber wellbore structure for compressed air energy storage comprises the following steps:

[0034] For the rock salt deposit mining area, a first wellbore with an outer diameter of 762mm is used to drill and form the first wellbore, and a surface casing with an outer diameter of 609.6mm is lowered into the first wellbore to isolate the shallow water;

[0035] A second drill bit with an outer diameter of 571.5 mm was used to continue drilling and form a second wellbore. A production casing with an outer diameter of 473.1 mm was lowered into the second wellbore. The surface casing and the production casing were sealed and connected to isolate the salt layer and cap rock above the cavity top to ensure the integrity of the wellbore.

[0036] A third drill bit with an outer diameter of 406.4 mm is used to continue drilling to form a third wellbore and reach the salt cavity. A central pipe with an outer diameter of 339.7 mm is lowered into the third wellbore, and the central pipe is sealed and connected to the production casing.

[0037] In the present invention, in view of the characteristics of frequent injection and production cycles, gas erosion, and limited injection and production flow of the pipe column in the salt cavern compressed air energy storage, a Φ339.7 mm central pipe is used as the injection and production channel, which can greatly increase the injection and production flow.

[0038] In the present invention, the borehole size is matched as 762.0mm for the first opening + Φ571.5mm for the second opening + Φ406.4mm for the third opening, and the tubing size is matched as Φ609.6mm surface casing + Φ473.1mm production casing. This structure meets the requirements of health, safety and environmental management, can improve drilling efficiency, reduce the number of deployed wells, reduce project investment, and bring significant economic benefits.

[0039] Furthermore, the outer diameter of the first drill bit is the same as the inner diameter of the first wellbore, the outer diameter of the second drill bit is the same as the inner diameter of the second wellbore, and the outer diameter of the third drill bit is the same as the inner diameter of the third wellbore.

[0040] Furthermore, cement slurry is filled between the first wellbore and the surface casing and between the second wellbore and the production casing to complete cementing.

[0041] Furthermore, the surface casing cementing slurry formula and performance requirements: The surface casing requires cement slurry to return to the surface, and the design adopts single-stage cementing to ensure that there is no pressure leakage and use a conventional density cement slurry system, with a density requirement of 1.85-1.90g / cm 3 The cement slurry system performance requires high early strength; the recommended formula of cement slurry: G-grade oil well cement + 1.0% dispersant + 2.0% early strength agent + 0.1% defoaming agent + 40% water.

[0042] Furthermore, the production casing cementing slurry formula and performance requirements: the production casing requires the cement slurry to return to the ground, using a conventional density salt-resistant elastic toughness cement slurry system, the density requirement is 1.85 ~ 1.90g / cm 3 ; Performance requirements: zero water precipitation, low water loss, right-angle thickening, cement stone elastic modulus ≤6GPa; Recommended cement slurry formula: G-grade cement + 5-10% elastic particles + 4% expansion agent + 3% salt-resistant water loss reducer + 2% early strength agent + 1% dispersant + 2% stabilizer + 0.5% defoamer + retarder + semi-saturated brine.

[0043] Furthermore, the surface casing, production casing and central pipe are hoisted by a drilling rig during the hoisting process.

[0044] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An ultra-large-caliber wellbore structure for compressed air energy storage, characterized in that: It includes a first wellbore, a second wellbore and a third wellbore which are opened in a rock salt deposition mining area and are connected in sequence and whose apertures decrease from top to bottom, and a surface casing, a production casing and a central pipe are respectively arranged in the first wellbore, the second wellbore and the third wellbore. The apertures of the surface casing, the production casing and the central pipe decrease from top to bottom and are connected in sequence. The inner diameter of the first wellbore is 760mm to 764mm, the inner diameter of the second wellbore is 570mm to 572mm, and the inner diameter of the third wellbore is 406mm to 408mm.

2. The ultra-large-caliber wellbore structure for compressed air energy storage according to claim 1, characterized in that: The rock salt deposition mining area includes clay, mudstone, sandstone, limestone, gypsum and rock salt from top to bottom.

3. The ultra-large-caliber wellbore structure for compressed air energy storage according to claim 1, characterized in that: The outer diameter of the surface casing is 609 mm to 610 mm, the outer diameter of the production casing is 473 mm to 474 mm, and the outer diameter of the central pipe is 339 mm to 340 mm.

4. The ultra-large-caliber wellbore structure for compressed air energy storage according to claim 1, characterized in that: The surface casing and the production casing, as well as the production casing and the central pipe are connected by welding or by locking male and female buckles.

5. The ultra-large-caliber wellbore structure for compressed air energy storage according to claim 1, characterized in that: The adjacent surface casings are connected by BC buckles, and the adjacent production casings and the adjacent central pipes are connected by airtight buckles.

6. A method for constructing an ultra-large-caliber wellbore structure for compressed air energy storage, characterized in that: The ultra-large-caliber wellbore structure for compressed air energy storage according to any one of claims 1 to 5 comprises the following steps: Drilling with a first drill bit in a rock salt deposit mining area to form the first wellbore, the first wellbore being drilled to bedrock, and lowering the surface casing into the first wellbore to seal shallow water; Continue drilling with a second drill bit to form the second wellbore, lower the production casing into the second wellbore, seal the surface casing and the production casing, and isolate the salt layer and cap rock above the cavity top; A third drill bit is used to continue drilling and form the third wellbore, and the central pipe is lowered into the third wellbore. The central pipe is sealed and connected to the production casing.

7. The construction method of a super-large-caliber wellbore structure for compressed air energy storage according to claim 6, characterized in that: Cement slurry is filled between the first wellbore and the surface casing and between the second wellbore and the production casing to complete cementing.

8. The method for constructing a super-large-caliber wellbore structure for compressed air energy storage according to claim 7, characterized in that: The surface casing cementing cement slurry formula and performance requirements are as follows: The surface casing requires cement slurry to return to the ground, the design adopts single-stage cementing, and adopts a conventional density cement slurry system with a density requirement of 1.85-1.90 g / cm 3 The cement slurry has a ratio of G-grade oil well cement, 1.0% dispersant, 2.0% early strength agent, 0.1% defoamer and 40% water.

9. The method for constructing an ultra-large-caliber wellbore structure for compressed air energy storage according to claim 7, characterized in that: Production casing cementing cement slurry formula and performance requirements: Production casing requires cement slurry to return to the ground, using conventional density salt-resistant elastic toughness cement slurry system, density requirements 1.85 ~ 1.90g / cm 3 ; The elastic modulus of cement stone is ≤6GPa; the formula of cement slurry is G-grade cement, 5-10% elastic particles, 4% expansion agent, 3% salt-resistant fluid loss reducer, 2% early strength agent, 1% dispersant, 2% stabilizer, 0.5% defoamer, retarder and semi-saturated brine.

10. The method for constructing an ultra-large-caliber wellbore structure for compressed air energy storage according to claim 7, characterized in that: The surface casing, production casing and central pipe are hoisted by a drilling rig during the hoisting process.

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