Calculation method for maximum safety injection pressure of geological storage of carbon dioxide in deep saline water layer

Abstract

The invention discloses a method for calculating the maximum safe injection pressure of geological storage of carbon dioxide in a deep saline water layer, which comprises the following steps of: establishing a three-dimensional geomechanical model; the output parameters are overlying stress distribution and maximum horizontal principal stress distribution of a three-dimensional stress field under the initial formation fluid pressure field and minimum horizontal principal stress distribution under the initial formation fluid pressure field; gradually increasing the initial formation fluid pressure field to pressure fields of a plurality of simulation working conditions, and respectively obtaining minimum horizontal principal stress distribution and overburden stress distribution under the pressure fields of the plurality of simulation working conditions; determining the fracturing critical pressure of the cap layer; determining the activation pressure of a target fault at the cover layer; and determining the maximum safe injection pressure of the geological storage of the carbon dioxide in the deep saline water layer according to the critical pressure of fracture of the cover layer and the activation pressure of the target fault at the cover layer.

Description

Technical Field

[0001] This invention relates to the field of carbon capture, utilization and storage technology, and specifically to a method for calculating the maximum safe injection pressure for geological carbon dioxide storage in deep saline aquifers. Background Technology

[0002] Geological carbon dioxide (CCS) storage is a recognized key technology supporting the achievement of global "dual carbon" goals. Globally, deep saline aquifers in sedimentary basins account for 96% of total geological CCS resources, making them the main body for CCS geological storage. Currently, numerous deep saline aquifer CCS projects are operational globally, and an increasing number of CCS cluster projects centered on deep saline aquifer CCS are being planned and implemented. When designing CCS project schemes, the maximum safe injection pressure is a crucial parameter for dynamically simulating and evaluating the maximum safe storage capacity of the saline aquifer, and it is also an important parameter for designing injection schemes, determining wellhead injection pressure, and pipeline delivery pressure. Therefore, determining the maximum safe injection pressure is essential for CCS project scheme design.

[0003] High-pressure injection can lead to formation fracturing or activation of pre-existing faults, thereby causing abnormal underground seismic activity. Therefore, determining the maximum safe injection pressure is fundamental to ensuring the safety of carbon dioxide geological storage. The maximum safe injection pressure is mainly determined by evaluating the fracturing or activation pressure of the caprock and pre-existing faults, which depends primarily on in-situ stress, formation fluid pressure, and judgment criteria. Caprock fracturing caused by carbon dioxide injection is mainly due to hydraulic fracturing, which can be determined using the Griffith criterion; while activation of pre-existing faults caused by injection is mainly due to shear slip, which can be determined using the Mohr-Coulomb criterion. Currently, the evaluation of caprock fracturing pressure and pre-existing fault activation pressure is mainly based on the above criteria, calculated by determining the vertical and horizontal principal stresses and formation fluid pressure before injection, which is a static evaluation method. However, this method does not consider the differences in the vertical and horizontal principal stress path coefficients caused by the stress arching effect and porosity elasticity effect during actual carbon dioxide injection, and cannot reflect the differences in principal stress in various directions during injection, thus leading to inaccurate calculation results for the maximum safe injection pressure. Currently, none of the published patents address a method for determining the maximum safe injection pressure in deep saline water layers of CCS projects. Chinese patent CN106150463B proposes a method for determining the injection pressure increase of polymer flooding in conglomerate reservoirs. This method utilizes parameters such as reservoir properties, reservoir thickness, breakthrough coefficient, injection-production well spacing, and polymer viscosity to determine the maximum injection pressure increase. This falls under the field of enhanced oil recovery and cannot be applied to this work. Chinese patent CN114034622B proposes a method for determining the sealing performance of gas storage traps. This method is based on simulated samples of fault structures, determining the maximum injection pressure by simulating fault shear failure, permeability changes, and fault activation. Its fault shear failure analysis criterion is the Mohr-Coulomb criterion. However, this method cannot address the issue of anisotropic stress differences caused by stress arching effects and pore elasticity effects during carbon dioxide injection.

[0004] In summary, there is currently a lack of methods to determine the maximum safe injection pressure for geological sequestration of carbon dioxide in deep saline aquifers. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a method for calculating the maximum safe injection pressure for deep saline aquifer carbon dioxide geological storage, thereby solving the current problem of lacking a method for determining the maximum safe injection pressure for deep saline aquifer carbon dioxide geological storage.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a method for calculating the maximum safe injection pressure for carbon dioxide geological sequestration in deep saline aquifers, characterized by comprising: Step A: Establish a one-dimensional geomechanical model, where the input parameters are P-wave and S-wave logging data, density logging data, rock mechanics experimental data, and pressure measurement data, and the output parameters are the single-well static elastic parameter curve, the single-well formation fluid pressure curve, and the overburden stress, maximum horizontal principal stress, and minimum horizontal principal stress of the one-dimensional geomechanical model. Step B: Establish a three-dimensional geomechanical model, and use the output parameters of the one-dimensional geomechanical model as the initial conditions for the three-dimensional geomechanical model. The output parameters of the three-dimensional geomechanical model are the initial formation fluid pressure field. Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and initial formation fluid pressure field Minimum horizontal principal stress distribution ; Step C: Based on the initial formation fluid pressure field Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and minimum horizontal principal stress distribution Gradually increase the initial formation fluid pressure field The minimum horizontal principal stress distribution under the pressure fields of multiple simulated working conditions was obtained. and overlying stress distribution ; Step D: Based on the initial formation fluid pressure field Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Determine the critical pressure for caprock rupture; Step E: Based on the initial formation fluid pressure field Minimum horizontal principal stress distribution and the overlying stress distribution under pressure fields of multiple simulated working conditions. and minimum horizontal principal stress distribution Determine the activation pressure of the target fault at the caprock; Step F: Determine the maximum safe injection pressure for deep saline aquifer carbon dioxide geological sequestration based on the critical pressure for caprock rupture and the activation pressure of the target fault at the caprock.

[0007] Step A includes the following steps: Step A1: Calculate the dynamic elastic parameter curves of a single well based on the P-wave and S-wave logging data and density logging data, including the dynamic Young's modulus curve and the dynamic Poisson's ratio curve; Step A2: Establish the dynamic-static elastic parameter conversion relationship based on rock mechanics experimental data, and calculate the static elastic parameter curve of a single well through the dynamic-static elastic parameter conversion relationship, including the static Young's modulus curve and the static Poisson's ratio curve; Step A3: Calculate the formation fluid pressure curve for a single well based on the pressure measurement data; Step A4: Calculate the overburden stress of the one-dimensional geomechanical model based on density logging data; Step A5: Based on the single-well static elastic parameter curve, the single-well formation fluid pressure curve, and the overlying stress of the one-dimensional geomechanical model, obtain the maximum and minimum horizontal principal stresses of the one-dimensional geomechanical model.

[0008] Step B includes the following specific steps: Step B1: Based on the static elastic parameter curve of a single well, a three-dimensional elastic parameter is established using the method of phase-controlled attribute modeling and seismic attribute constraint, including the three-dimensional static Young's modulus and the three-dimensional static Poisson's ratio; Step B2: Based on the single-well formation fluid pressure curve, establish the initial formation fluid pressure field using phase-controlled attribute modeling and seismic attribute constraints. ; Step B3: Based on the three-dimensional static Young's modulus, the three-dimensional static Poisson's ratio, and the initial formation fluid pressure field... The three-dimensional stress field under initial conditions was established using the finite element method. Its output parameters are the initial formation fluid pressure field. Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and minimum horizontal principal stress distribution .

[0009] Step D includes the following specific steps; Step D1: Calculate the initial formation fluid pressure field Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. The corresponding caprock rupture pressure; Step D2: Initial formation fluid pressure field The pressure field values ​​under multiple simulated operating conditions are used as the x-axis to represent the initial formation fluid pressure field. Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Corresponding caprock fracture pressure Using the vertical axis as the ordinate, a cross-plot of reservoir fluid pressure and corresponding caprock fracture pressure is plotted, and the correlation is fitted to obtain the critical caprock fracture pressure.

[0010] In step D2, the formula for calculating the caprock rupture pressure is:

[0011] In the formula, This refers to the caprock rupture pressure. The minimum horizontal principal stress in the three-dimensional stress field; This represents the tensile strength of the capping layer.

[0012] Step E includes the following specific steps; Step E1: Based on the overlying stress distribution under pressure fields of multiple simulated working conditions and minimum horizontal principal stress distribution Calculate the effective normal stress at the fault plane and shear stress at the fracture surface ; Step E2: Then, based on the effective normal stress at the fault plane... and shear stress at the fracture surface and the initial formation fluid pressure field Minimum horizontal principal stress distribution Calculate the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. The corresponding fault activation pressure; Step E3: Initial formation fluid pressure field The pressure field values ​​under multiple simulated operating conditions are used as the x-axis to represent the initial formation fluid pressure field. Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Overburden stress distribution Corresponding fault activation pressure Using the vertical axis as the ordinate, a cross-plot of reservoir fluid pressure and corresponding caprock fracture pressure is plotted, and the correlation is fitted to obtain the critical activation pressure of the target fault at the caprock.

[0013] In step E1, the effective normal stress of the fault The calculation formula is:

[0014] The overlying stress is the stress within the three-dimensional stress field. This represents the minimum horizontal principal stress in the three-dimensional stress field. The angle between the fault plane normal and the overlying stress; This represents the reservoir fluid pressure.

[0015] In step E1, the shear stress of the fracture surface The calculation formula is as follows:

[0016] In the formula, The overlying stress is the stress within the three-dimensional stress field. This represents the minimum horizontal principal stress in the three-dimensional stress field. It is the angle between the fault plane normal and the overlying stress.

[0017] In step E2, the formula for calculating the fault activation pressure is:

[0018] In the formula, Fault activation pressure; Reservoir fluid pressure; The effective normal stress at the fault plane; For shear stress at the fracture surface; This is the cohesive force within the fault; is the friction coefficient within the fault.

[0019] Step E includes the following specific steps; Step F1: Take 90% of the critical pressure for caprock rupture as the maximum safe injection pressure for caprock; Step F2: Compare the maximum safe injection pressure of the caprock with the critical activation pressure of the target fault, and take the minimum of the two as the maximum safe injection pressure of the target reservoir.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention discloses a method for calculating the maximum safe injection pressure for carbon dioxide geological sequestration in deep saline aquifers, comprising the following steps: Step A: Establish a one-dimensional geomechanical model, where the input parameters are P-wave and S-wave logging data, density logging data, rock mechanics experimental data, and pressure measurement data, and the output parameters are the single-well static elastic parameter curve, the single-well formation fluid pressure curve, and the overburden stress, maximum horizontal principal stress, and minimum horizontal principal stress of the one-dimensional geomechanical model. Step B: Establish a three-dimensional geomechanical model, and use the output parameters of the one-dimensional geomechanical model as the initial conditions for the three-dimensional geomechanical model. The output parameters of the three-dimensional geomechanical model are the initial formation fluid pressure field. Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and initial formation fluid pressure field Minimum horizontal principal stress distribution ; Step C: Based on the initial formation fluid pressure field Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and minimum horizontal principal stress distribution Gradually increase the initial formation fluid pressure field The minimum horizontal principal stress distribution under the pressure fields of multiple simulated working conditions was obtained. and overlying stress distribution ; Step D: Based on the initial formation fluid pressure field Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Determine the critical pressure for caprock rupture; Step E: Based on the initial formation fluid pressure field Minimum horizontal principal stress distribution and the overlying stress distribution under pressure fields of multiple simulated working conditions. and minimum horizontal principal stress distribution Determine the activation pressure of the target fault at the caprock; Step F: Determine the maximum safe injection pressure for deep saline aquifer carbon dioxide geological sequestration based on the critical pressure for caprock rupture and the activation pressure of the target fault at the caprock.

[0021] This invention discloses a method for calculating the maximum safe injection pressure of carbon dioxide in deep saline aquifers. Addressing the lack or inadequacy of current methods for evaluating the maximum safe injection pressure of carbon dioxide in deep saline aquifers, this method considers the impact of stress path coefficient differences during carbon dioxide injection on the evaluation of caprock fracturing pressure and fault activation pressure, as well as the changes in vertical and horizontal principal stress differences caused by stress arching effect and porosity elasticity effect. By dynamically analyzing the impact of stress field changes on caprock fracturing and fault activation, the critical pressures for caprock fracturing and fault activation can be effectively evaluated, thereby determining the maximum safe injection pressure of the target reservoir to meet the pressure design requirements of the CCS project's injection and delivery schemes. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the determination of the critical pressure for caprock rupture provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of determining the critical activation pressure of the target fault at the caprock, provided in an embodiment of the present invention. Detailed Implementation

[0023] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0024] This invention provides a method for calculating the maximum safe injection pressure for carbon dioxide geological storage in deep saline aquifers. This method requires prior data collection, including P-wave and S-wave logging data (if S-wave logging is unavailable, the S-wave transit time can be calculated by establishing a P-wave / S-wave transit time relationship), density logging data, rock mechanics experimental data (including dynamic and static Young's modulus, dynamic and static Poisson's ratio, compressive strength, etc.), pressure measurement data, and leakage test data. The method includes the following steps: Step A: Establish a one-dimensional geomechanical model, where the input parameters are P-wave and S-wave logging data, density logging data, rock mechanics experimental data, and pressure measurement data; the output parameters are the single-well static elastic parameter curve, the single-well formation fluid pressure curve, and the overburden stress, maximum horizontal principal stress, and minimum horizontal principal stress of the one-dimensional geomechanical model, including the following steps: Step A1: Calculate the dynamic elastic parameter curves of a single well based on the P-wave and S-wave logging data and density logging data, including the dynamic Young's modulus curve and the dynamic Poisson's ratio curve; Step A2: Establish the dynamic-static elastic parameter conversion relationship based on rock mechanics experimental data, and calculate the static elastic parameter curve of a single well through the dynamic-static elastic parameter conversion relationship, including the static Young's modulus curve and the static Poisson's ratio curve; Step A3: Calculate the formation fluid pressure curve for a single well based on the pressure measurement data; Step A4: Calculate the overburden stress of the one-dimensional geomechanical model based on density logging data; Step A5: Based on the single-well static elastic parameter curve, the single-well formation fluid pressure curve, and the overlying stress of the one-dimensional geomechanical model, obtain the maximum and minimum horizontal principal stresses of the one-dimensional geomechanical model.

[0025] Based on the overlying stress, maximum horizontal principal stress, and minimum horizontal principal stress of the one-dimensional geomechanical model, the stress field type of the study area is determined to be tensile, i.e., the overlying stress of the one-dimensional geomechanical model > the maximum horizontal principal stress > the minimum horizontal principal stress.

[0026] Step B: Establish a three-dimensional geomechanical model, using the output parameters of the one-dimensional geomechanical model as the initial conditions for the three-dimensional model. The output parameters of the three-dimensional geomechanical model are the initial formation fluid pressure field. Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and initial formation fluid pressure field Minimum horizontal principal stress distribution This includes the following specific steps: Step B1: Based on the static elastic parameter curve of a single well, a three-dimensional elastic parameter is established using the method of phase-controlled attribute modeling and seismic attribute constraint, including the three-dimensional static Young's modulus and the three-dimensional static Poisson's ratio; Step B2: Based on the single-well formation fluid pressure curve, establish the initial formation fluid pressure field using phase-controlled attribute modeling and seismic attribute constraints. ; Step B3: Based on the three-dimensional static Young's modulus, the three-dimensional static Poisson's ratio, and the initial formation fluid pressure field... The three-dimensional stress field under initial conditions was established using the finite element method. Its output parameters are the initial formation fluid pressure field. Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and minimum horizontal principal stress distribution .

[0027] The output parameters of the one-dimensional geomechanical model are the static elastic parameters of a single well, formation fluid pressure and overlying stress, maximum horizontal principal stress and minimum horizontal principal stress; the initial condition of the three-dimensional geomechanical model is the initial formation fluid pressure field. The corresponding condition is that the output parameters of the one-dimensional geomechanical model are used as the input parameters of the three-dimensional geomechanical model, and these input parameters are the initial formation fluid pressure field. The corresponding conditions are as follows.

[0028] Step C: Based on the initial formation fluid pressure field Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and minimum horizontal principal stress distribution Gradually increase the initial formation fluid pressure field The minimum horizontal principal stress distribution under the pressure fields of multiple simulated working conditions was obtained. and overlying stress distribution .

[0029] Specifically, the initial formation fluid pressure field is gradually increased. The pressure fields of the three simulated operating conditions, including the pressure field of the first simulated operating condition. Pressure field of the second simulated working condition and the pressure field of the third simulation condition .

[0030] Specifically, the initial formation fluid pressure field ; Pressure field under the first simulated working condition ; Pressure field under the second simulated working condition ; Pressure field under the third simulated working condition .

[0031] Accordingly, the minimum horizontal principal stress distribution under multiple simulated working conditions was obtained. The pressure fields for the first simulated working condition are respectively Minimum horizontal principal stress distribution Pressure field of the second simulated working condition Minimum horizontal principal stress distribution and the pressure field of the third simulation condition Minimum horizontal principal stress distribution Similarly, the overlying stress distribution under pressure fields in multiple simulated working conditions... The pressure fields for the first simulated working condition are respectively Underlying stress distribution Pressure field of the second simulated working condition Overlying stress distribution and the pressure field of the third simulation condition Underlying stress distribution .

[0032] Step D: Based on the initial formation fluid pressure field Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Determining the critical pressure for caprock rupture includes the following specific steps; Step D1: Calculate the initial formation fluid pressure field Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. The corresponding caprock rupture pressure; Specifically, the formula for calculating the caprock rupture pressure is as follows: (Equation 1) In the formula, This refers to the caprock rupture pressure. The minimum horizontal principal stress in the three-dimensional stress field has a value of [value missing]. ; This represents the tensile strength of the capping layer.

[0033] The formula for calculating the caprock rupture pressure is based on the Griffith criterion.

[0034] Step D2: Initial formation fluid pressure field The pressure field values ​​under multiple simulated operating conditions are used as the x-axis to represent the initial formation fluid pressure field. Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Corresponding caprock fracture pressure Using the vertical axis as the ordinate, a cross-plot of reservoir fluid pressure and corresponding caprock fracture pressure is plotted, and the correlation is fitted to obtain the critical caprock fracture pressure.

[0035] Specifically, the initial formation fluid pressure field is expressed in terms of equivalent density. The pressure fields under multiple simulated working conditions are expressed in terms of equivalent density, representing the critical pressure for caprock rupture. Figure 1 As shown.

[0036] Expressed as equivalent density, when the initial formation fluid pressure field Pressure field of the first simulated working condition Pressure field of the second simulated working condition Pressure field of the third simulated working condition Calculate the initial formation fluid pressure field Pressure field of the first simulated working condition Pressure field of the second simulated working condition Pressure field of the third simulated working condition Calculate the pressure field for the first simulated working condition. Pressure field of the second simulated working condition and the pressure field of the third simulation condition The corresponding caprock rupture pressure , , and ,Depend on Figure 1 It can be seen that the critical pressure for caprock rupture can ultimately be obtained as follows: .

[0037] Step E: Based on the initial formation fluid pressure field Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Determining the activation pressure of the target fault at the caprock involves the following specific steps; Step E1: Based on the overlying stress distribution under pressure fields of multiple simulated working conditions and minimum horizontal principal stress distribution Calculate the effective normal stress at each fault plane. and shear stress at the fracture surface ; Among them, the effective normal stress of the fault plane and shear stress at the fracture surface Based on the minimum horizontal principal stress distribution of the three-dimensional stress field Overlying stress distribution in a three-dimensional stress field The angle between the fault plane normal and the overlying stress and reservoir fluid pressure calculate.

[0038] Specifically, the effective normal stress of the fault The calculation formula is: (Equation 2) The overlying stress is the stress in the three-dimensional stress field, and its value is... ; The minimum horizontal principal stress in the three-dimensional stress field has a value of [value missing]. ; The angle between the fault plane normal and the overlying stress; This represents the reservoir fluid pressure.

[0039] Specifically, the shear stress at the fracture surface The calculation formula is as follows: (Equation 3) In the formula, The overlying stress is the stress in the three-dimensional stress field, and its value is... ; The minimum horizontal principal stress in the three-dimensional stress field has a value of [value missing]. ; It is the angle between the fault plane normal and the overlying stress.

[0040] Step E2: Then, based on the initial formation fluid pressure field Minimum horizontal principal stress distribution Effective normal stress at the fault plane and shear stress at the fracture surface Calculate the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. The corresponding fault activation pressure; Specifically, the formula for calculating the fault activation pressure is as follows: (Equation 4) In the formula, Fault activation pressure; Reservoir fluid pressure; The effective normal stress at the fault plane; For shear stress at the fracture surface; This is the cohesive force within the fault; is the friction coefficient within the fault.

[0041] Specifically, the fault cohesion C=0, and the fault internal friction coefficient... =0.62.

[0042] Step E3: Initial formation fluid pressure field The pressure field values ​​under multiple simulated operating conditions are used as the x-axis to represent the initial formation fluid pressure field. Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Overburden stress distribution Corresponding fault activation pressure Using the vertical axis as the ordinate, a cross-plot of reservoir fluid pressure and corresponding caprock fracture pressure is plotted, and the correlation is fitted to obtain the critical activation pressure of the target fault at the caprock.

[0043] Specifically, the initial formation fluid pressure field is expressed in terms of equivalent density. Pressure fields under multiple simulated operating conditions, with reservoir fluid pressure and corresponding caprock fracture pressure expressed in equivalent density, are shown as follows: Figure 2 As shown.

[0044] Expressed as equivalent density, when the initial formation fluid pressure field Pressure field of the first simulated working condition Pressure field of the second simulated working condition Pressure field of the third simulated working condition Calculate the initial formation fluid pressure field Pressure field of the first simulated working condition Pressure field of the second simulated working condition Pressure field of the third simulated working condition Calculate the pressure field for the first simulated working condition. Pressure field of the second simulated working condition and the pressure field of the third simulation condition The corresponding caprock rupture pressure , , and The fluid pressure at which the two are equal is the critical activation pressure of the target fault at the caprock, considering the stress arching effect and the pore elasticity effect. Figure 2 It can be seen that the activation pressure of the target fault at the caprock can ultimately be obtained as follows: .

[0045] Step F: Based on the critical pressure for caprock fracturing and the critical pressure for target fault activation at the caprock, determine the maximum safe injection pressure for deep saline aquifer carbon dioxide geological sequestration, including the following specific steps: Step F1: Take 90% of the critical pressure for caprock rupture, i.e., 1.27 g / cm³. 3 As the maximum safe injection pressure for the cap layer; Step F2: Compare the maximum safe injection pressure of the caprock with the critical activation pressure of the target fault (1.17 g / cm3), and take the minimum of the two as the maximum safe injection pressure of the target reservoir (expressed as equivalent density), i.e., 1.17 g / cm3.

[0046] The target reservoir is the geological structure of a deep saline aquifer that has been injected with carbon dioxide and sealed.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the maximum safe injection pressure for carbon dioxide geological sequestration in deep saline aquifers, characterized in that, include: Step A: Establish a one-dimensional geomechanical model, where the input parameters are P-wave and S-wave logging data, density logging data, rock mechanics experimental data, and pressure measurement data, and the output parameters are the single-well static elastic parameter curve, the single-well formation fluid pressure curve, and the overburden stress, maximum horizontal principal stress, and minimum horizontal principal stress of the one-dimensional geomechanical model. Step B: Establish a three-dimensional geomechanical model, and use the output parameters of the one-dimensional geomechanical model as the initial conditions for the three-dimensional geomechanical model. The output parameters of the three-dimensional geomechanical model are the initial formation fluid pressure field. Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and initial formation fluid pressure field Minimum horizontal principal stress distribution ; Step C: Based on the initial formation fluid pressure field Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and minimum horizontal principal stress distribution Gradually increase the initial formation fluid pressure field The minimum horizontal principal stress distribution under the pressure fields of multiple simulated working conditions was obtained. and overlying stress distribution ; Step D: Based on the initial formation fluid pressure field Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Determine the critical pressure for caprock rupture; Step E: Based on the initial formation fluid pressure field Minimum horizontal principal stress distribution and the overlying stress distribution under pressure fields of multiple simulated working conditions. and minimum horizontal principal stress distribution Determine the activation pressure of the target fault at the caprock; Step F: Determine the maximum safe injection pressure for deep saline aquifer carbon dioxide geological sequestration based on the critical pressure for caprock rupture and the activation pressure of the target fault at the caprock.

2. The method according to claim 1, characterized in that, Step A includes the following steps: Step A1: Calculate the dynamic elastic parameter curves of a single well based on the P-wave and S-wave logging data and density logging data, including the dynamic Young's modulus curve and the dynamic Poisson's ratio curve; Step A2: Establish the dynamic-static elastic parameter conversion relationship based on rock mechanics experimental data, and calculate the static elastic parameter curve of a single well through the dynamic-static elastic parameter conversion relationship, including the static Young's modulus curve and the static Poisson's ratio curve; Step A3: Calculate the formation fluid pressure curve for a single well based on the pressure measurement data; Step A4: Calculate the overburden stress of the one-dimensional geomechanical model based on density logging data; Step A5: Based on the single-well static elastic parameter curve, the single-well formation fluid pressure curve, and the overlying stress of the one-dimensional geomechanical model, obtain the maximum and minimum horizontal principal stresses of the one-dimensional geomechanical model.

3. The method according to claim 1, characterized in that, Step B includes the following specific steps: Step B1: Based on the static elastic parameter curve of a single well, a three-dimensional elastic parameter is established using the method of phase-controlled attribute modeling and seismic attribute constraint, including the three-dimensional static Young's modulus and the three-dimensional static Poisson's ratio; Step B2: Based on the single-well formation fluid pressure curve, establish the initial formation fluid pressure field using phase-controlled attribute modeling and seismic attribute constraints. ; Step B3: Based on the three-dimensional static Young's modulus, the three-dimensional static Poisson's ratio, and the initial formation fluid pressure field... The three-dimensional stress field under initial conditions was established using the finite element method. Its output parameters are the initial formation fluid pressure field. Overlying stress distribution in the lower three-dimensional stress field Maximum horizontal principal stress distribution and minimum horizontal principal stress distribution .

4. The method according to claim 1, characterized in that, Step D includes the following specific steps; Step D1: Calculate the initial formation fluid pressure field Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. The corresponding caprock rupture pressure; Step D2: Initial formation fluid pressure field The pressure field values ​​under multiple simulated operating conditions are used as the x-axis to represent the initial formation fluid pressure field. Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Corresponding caprock fracture pressure Using the vertical axis as the ordinate, a cross-plot of reservoir fluid pressure and corresponding caprock fracture pressure is plotted, and the correlation is fitted to obtain the critical caprock fracture pressure.

5. The method according to claim 4, characterized in that, In step D2, the formula for calculating the caprock rupture pressure is: In the formula, This refers to the caprock rupture pressure. The minimum horizontal principal stress in the three-dimensional stress field; This represents the tensile strength of the capping layer.

6. The method according to claim 1, characterized in that, Step E includes the following specific steps; Step E1: Based on the overlying stress distribution under pressure fields of multiple simulated working conditions and minimum horizontal principal stress distribution Calculate the effective normal stress at the fault plane and shear stress at the fracture surface ; Step E2: Then, based on the effective normal stress at the fault plane... and shear stress at the fracture surface and the initial formation fluid pressure field Minimum horizontal principal stress distribution Calculate the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. The corresponding fault activation pressure; Step E3: Initial formation fluid pressure field The pressure field values ​​under multiple simulated operating conditions are used as the x-axis to represent the initial formation fluid pressure field. Minimum horizontal principal stress distribution and the minimum horizontal principal stress distribution under pressure fields of multiple simulated working conditions. Overburden stress distribution Corresponding fault activation pressure Using the vertical axis as the ordinate, a cross-plot of reservoir fluid pressure and corresponding caprock fracture pressure is plotted, and the correlation is fitted to obtain the critical activation pressure of the target fault at the caprock.

7. The method according to claim 6, characterized in that, In step E1, the effective normal stress of the fault The calculation formula is: The overlying stress is the stress within the three-dimensional stress field. The minimum horizontal principal stress in the three-dimensional stress field; The angle between the fault plane normal and the overlying stress; This represents the reservoir fluid pressure.

8. The method according to claim 6, characterized in that, In step E1, the shear stress of the fracture surface The calculation formula is as follows: In the formula, The overlying stress is the stress within the three-dimensional stress field. The minimum horizontal principal stress in the three-dimensional stress field; It is the angle between the fault plane normal and the overlying stress.

9. The method according to claim 6, characterized in that, In step E2, the formula for calculating the fault activation pressure is: In the formula, Fault activation pressure; For reservoir fluid pressure; The effective normal stress at the fault plane; For shear stress at the fracture surface; This is the cohesive force within the fault; is the friction coefficient within the fault.

10. The method according to claim 1, characterized in that, Step E includes the following specific steps; Step F1: Take 90% of the critical pressure for caprock rupture as the maximum safe injection pressure for caprock; Step F2: Compare the maximum safe injection pressure of the caprock with the critical activation pressure of the target fault, and take the minimum of the two as the maximum safe injection pressure of the target reservoir.

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