Method for determining minimum depth of compressed air energy storage underground gas storage

Abstract

The application discloses a method for determining the minimum buried depth of a compressed energy storage underground gas storage, comprising the following steps: setting basic parameters of the compressed energy storage underground gas storage according to geological data of rock and volume requirements of the gas storage; considering factors of gas storage pressure, rock gravity, shear strength of surrounding rock and broken surface of the surrounding rock under pressure, establishing a vertical mechanical equation of the gas storage by adopting a conical body model, and obtaining a vertical buried depth capable of meeting maximum gas storage pressure requirements; and establishing a horizontal mechanical equation of the gas storage according to the basic parameters and the vertical buried depth of the gas storage, and obtaining a horizontal buried depth capable of meeting the maximum gas storage pressure requirements. Whether the vertical buried depth of the gas storage meets the limit inflation pressure is determined first, and then the horizontal broken surface mechanical equation is substituted into the horizontal buried depth on the basis of the vertical buried depth, so as to determine whether the horizontal buried depth meets the limit inflation pressure. The calculation method is simple, fast, accurate, and has good economic applicability.

Description

Technical Field

[0001] This invention belongs to the technical field of gas storage design methods, and relates to a method for determining the minimum burial depth of compressed gas storage underground gas storage. Background Technology

[0002] Compressed air energy storage technology is considered a highly promising large-scale energy storage technology due to its large storage capacity, long lifespan, high efficiency, and safety and reliability. Among its applications, the excavation of new hard rock caverns as compressed air storage facilities is a growing trend. A key advantage is that areas with storage needs generally possess various hard rock strata that meet the construction requirements, making site selection for hard rock cavern gas storage facilities relatively easy.

[0003] The first step in designing an underground compressed gas storage facility (CGS) is determining the storage pressure and the burial depth. Referring to relevant design specifications for hydraulic tunnels, there are three main uplift criteria for determining the overburden thickness: the vertical criterion, the snow mountain criterion, and the Norway criterion. These criteria only consider the uplift caused by the weight of the surrounding rock suppressing the gas pressure, without taking into account the shear strength of the rock mass itself. The ultimate pressure of CGS often reaches over 10 MPa, which leads to extremely deep underground storage facilities and increases construction costs. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the minimum burial depth of compressed gas storage underground gas storage, which solves the problem of large burial depth of underground gas storage in the prior art.

[0005] The technical solution adopted in this invention is a method for determining the minimum burial depth of compressed gas storage underground gas storage facilities, comprising the following steps:

[0006] Step 1: Based on the geological data of the rock and the required volume of the gas storage, set the basic parameters of the compressed gas storage underground gas storage.

[0007] Step 2: Based on the basic parameters of the gas storage facility, considering factors such as gas storage pressure, rock mass, surrounding rock shear strength, and surrounding rock fracture surface under pressure, a conical model is used to establish the vertical mechanical equation of the gas storage facility, and the vertical burial depth that can meet the maximum gas storage pressure requirement is obtained.

[0008] Step 3: Based on the basic parameters of the gas storage facility and the vertical burial depth obtained in Step 2, establish the horizontal mechanical equation of the gas storage facility to obtain the horizontal burial depth that can meet the maximum gas storage pressure requirements.

[0009] The invention is further characterized by:

[0010] The basic parameters include tunnel diameter, length, vertical burial depth, and horizontal burial depth.

[0011] The vertical mechanical equations for the gas storage tank in step 2 include:

[0012] Gravitational component: W = γhDl;

[0013] Shear strength component:

[0014]

[0015] Gas storage pressure P = pDl;

[0016] The rock mass, shear strength and gas storage pressure should satisfy KP≤(W+F), otherwise the vertical burial depth h should be adjusted;

[0017] In the above formula, p is the gas storage pressure, γ is the rock mass density, D is the tunnel diameter, l is the tunnel length, and c is the cohesion. α is the friction angle, K is the safety factor, α is the fracture angle, and k0 is the lateral pressure coefficient.

[0018] The horizontal mechanical equations for the gas storage tank in step 3 include:

[0019] Horizontal force component: W = k0γhDl;

[0020] Shear strength component:

[0021] Gas storage pressure P = pDl;

[0022] The rock mass, shear strength and gas storage pressure should satisfy KP≤(W+F), otherwise the horizontal burial depth s should be adjusted.

[0023] If the rock mass is a layered surrounding rock, the cohesion and friction angle of the rock mass are calculated using the following formula:

[0024] c = (c1h1 + c2h2 + ... + c) n h n ) / h;

[0025]

[0026] In the above formula, c n h represents the cohesion of each rock layer. n denoted as the thickness of each rock layer, and h represents the total thickness of the rock mass.

[0027] The beneficial effects of this invention are as follows: The method for determining the minimum burial depth of compressed air energy storage underground gas storage in this invention, in addition to considering the self-weight of the rock mass according to traditional methods, also considers the shear strength of the surrounding rock. The determination method conforms to the actual shear failure situation of the rock mass, and the results are more realistic and reliable, thereby reducing the construction cost of the gas storage. Considering the influence of the fracture angle of the rock and soil, a conical model is used instead of the simplified cubic model of the traditional method, which is more consistent with the failure mode of the rock mass under high internal pressure. The conical calculation model can more accurately calculate the minimum burial depth of the gas storage. When calculating the horizontal pressure, the lateral pressure coefficient is considered, which can more realistically calculate the friction force of the failure surface and improve the accuracy of the results. First, it is determined whether the vertical burial depth of the gas storage meets the ultimate inflation pressure. Based on the determination of the vertical burial depth, the mechanical equation of the horizontal fracture surface is substituted to determine whether the horizontal burial depth meets the ultimate inflation pressure. The calculation method is simple, fast, and accurate, and also has good economic applicability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the gas storage structure in the method for determining the minimum burial depth of the underground gas storage facility for compressed gas energy storage according to the present invention.

[0029] Figure 2 The method for determining the minimum burial depth of the compressed gas storage underground gas storage facility in this invention is a horizontally fractured cone-shaped structure of the gas storage facility;

[0030] Figure 3 The vertical fracture cone shape of the gas storage tank is used in the method for determining the minimum burial depth of the compressed gas storage underground gas storage tank in this invention. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0032] The method for determining the minimum burial depth of compressed gas storage underground gas storage facilities includes the following steps:

[0033] Step 1: Based on the geological data of the rock (including rock type, grade, strength, groundwater, topography, etc.) and the required gas storage volume, the gas storage facility... Figure 1 As shown, the basic parameters for setting up a compressed air storage underground gas storage facility are specified; the basic parameters include the tunnel diameter, length, vertical burial depth, and horizontal burial depth.

[0034] Step 2: Based on the basic parameters of the gas storage facility, consider factors such as the gas storage pressure, rock gravity, shear strength of the surrounding rock, and the fracture surface of the surrounding rock under pressure. Figure 2-3 As shown, a conical model is used to establish the vertical mechanical equations of the gas storage tank, and the vertical burial depth that can meet the maximum gas storage pressure requirements is obtained.

[0035] The vertical mechanical equations of the gas storage facility include:

[0036] Gravitational component: W = γhDl

[0037] Shear strength component:

[0038]

[0039] Gas storage pressure P = pDl

[0040] The rock mass, shear strength and gas storage pressure should satisfy KP≤(W+F), otherwise the vertical burial depth h should be adjusted;

[0041] If the rock mass is a layered surrounding rock, the cohesion and friction angle of the rock mass are calculated using the following formula:

[0042] c = (c1h1 + c2h2 + ... + c) n h n ) / h;

[0043]

[0044] In the above formula, c n h represents the cohesion of each rock layer. n denoted as the thickness of each rock layer, and h represents the total thickness of the rock mass.

[0045] In the above formula, p is the gas storage pressure, γ is the rock mass density, h is the vertical burial depth, D is the tunnel diameter, l is the tunnel length, and c is the cohesion. α is the friction angle, K is the safety factor, α is the fracture angle, and k0 is the lateral pressure coefficient.

[0046] Step 3: Based on the basic parameters of the gas storage facility and the vertical burial depth obtained in Step 2, establish the horizontal mechanical equation of the gas storage facility to obtain the horizontal burial depth that can meet the maximum gas storage pressure requirements.

[0047] The horizontal mechanical equations of the gas storage facility include:

[0048] Horizontal force component: W=k0γhDl

[0049] Shear strength component:

[0050] Gas storage pressure P = pDl

[0051] The rock mass, shear strength and gas storage pressure should satisfy KP≤(W+F), otherwise the horizontal burial depth s should be adjusted.

[0052] Through the above methods, the method for determining the minimum burial depth of the compressed gas storage underground gas storage facility of this invention, in addition to considering the self-weight of the rock mass according to traditional methods, also considers the shear strength of the surrounding rock, making the determination method more realistic and reliable, and the obtained vertical and horizontal burial depths more accurate. Considering the influence of the fracture angle of the rock and soil, a conical model is used instead of the simplified cubic model of the traditional method, which is more consistent with the failure mode of the rock mass under internal pressure, further improving the accuracy of the burial depth determination. When calculating the horizontal pressure, the lateral pressure coefficient is considered, which more accurately calculates the friction force of the failure surface. First, it is determined whether the vertical burial depth of the gas storage facility meets the ultimate inflation pressure. Based on the determination of the vertical burial depth, the mechanical equation of the horizontal failure surface is substituted to determine whether the horizontal burial depth meets the ultimate inflation pressure. The calculation method is simple and fast, and also has good economic applicability.

[0053] Example

[0054] The relevant parameters of a certain compressed gas storage underground gas storage facility are as follows: rock density 0.026MN / m 3 The cohesion is 0.5 MPa, the friction angle is 45°, the cavern diameter is 10 m, the length is 1000 m, the vertical burial depth is 100 m, the horizontal burial depth is 100 m, the maximum gas storage pressure is 10 MPa, and the safety factor is 1.5.

[0055] ① First, calculate the fracture angle and lateral pressure coefficient:

[0056]

[0057]

[0058] ②Then calculate the relevant parameters for vertical burial depth:

[0059] Gravitational component: W = γhDl = 26000MN

[0060] Shear strength component: Gas storage pressure P = pDl = 100000MN

[0061] KP≤(W+F): 150000MN<218573MN The vertical burial depth meets the requirements, so the vertical burial depth is 100m.

[0062] ③ Calculate the relevant parameters of horizontal burial depth:

[0063] Horizontal force component: W = k0γhDl = 7615MN

[0064] Shear strength component:

[0065]

[0066] Gas storage pressure P = pDl = 100000MN

[0067] KP≤(W+F):150000MN>119759MN

[0068] According to the above formula, the horizontal burial depth does not meet the requirements. Therefore, to meet the horizontal burial depth requirements, the horizontal burial depth is increased from 100m to 130m, and the calculation is repeated:

[0069] Horizontal force component: W = k0γhDl = 7615MN

[0070] Shear strength component:

[0071]

[0072] Gas storage pressure P = pDl = 100000MN

[0073] KP≤(W+F): 150000MN<152556MN The horizontal burial depth meets the requirements, so the horizontal burial depth is 130m.

[0074] Under the surrounding rock conditions and design parameters of this compressed air energy storage underground gas storage facility, the minimum vertical burial depth of the cavern is 100m and the minimum horizontal burial depth is 130m.

Claims

1. A method for determining the minimum burial depth of an underground compressed gas storage facility, characterized in that, Includes the following steps: Step 1: Based on the geological data of the rock and the volume requirements of the gas storage facility, set the basic parameters of the compressed gas storage underground gas storage facility; the basic parameters include the tunnel diameter, length, vertical burial depth, and horizontal burial depth; Step 2: Based on the basic parameters of the gas storage tank, considering factors such as gas storage pressure, rock mass, surrounding rock shear strength, and surrounding rock fracture surface under pressure, a conical model is used to establish the vertical mechanical equation of the gas storage tank, and the vertical burial depth that can meet the maximum gas storage pressure requirement is obtained. The vertical mechanical equations for the gas storage tank in step 2 include: Gravity component: W = γhDl ; Shear strength component: F =( ch / cosα (2) l+2D ) + ( k 0 γh 2 tanφ / cosα ()( l+D) ; α =45°- φ / 2， k 0=1 -sinφ ； Gas storage pressure P = pDl ; The rock mass, shear strength, and gas storage pressure should meet the following requirements. KP≤(W+F) Otherwise, it will affect the vertical burial depth. h Make adjustments; In the above formula, p For gas storage pressure, γ The rock mass is of high density. D The diameter of the tunnel. l The length of the tunnel. c For cohesion, φ Let be the friction angle. K For safety reasons, α For the breakage angle, k 0 represents the lateral pressure coefficient; Step 3: Based on the basic parameters of the gas storage facility and the vertical burial depth obtained in Step 2, establish the horizontal mechanical equation of the gas storage facility to obtain the horizontal burial depth that can meet the maximum gas storage pressure requirements. The horizontal mechanical equations for the gas storage tank in step 3 include: Horizontal force component: W = k 0 γhDl ; Shear strength component: F =( cs / cosα (2) l+2D ) + ( γhstanφ / cosα ) l+ ( k 0 γhstanφ / cosα ) D ; Gas storage pressure P = pDl ; The rock mass, shear strength, and gas storage pressure should meet the following requirements. KP≤(W+F) Otherwise, it will affect the horizontal burial depth. s Adjustments will be made.

2. The method for determining the minimum burial depth of the compressed gas storage underground gas storage facility according to claim 1, characterized in that, If the rock mass is a layered surrounding rock, the cohesion and friction angle of the rock mass are calculated using the following formula: c=(c 1 h 1 +c 2 h 2 +…+c n h n ) / h ； φ=(φ 1 h 1 +φ 2 h 2 +…+φ n h n ) / h ； In the above formula, c n The cohesion of each rock layer, h n The thickness of each rock layer, h Indicates the vertical burial depth.

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