An evaluation method for improving the screening and storage safety of CO2 geological storage sites

Abstract

The application provides an evaluation method for improving CO2 geological storage site screening and storage safety, which comprises the following steps: obtaining the regional plane structure diagram of the target layer, the formation pore pressure gradient and the formation temperature gradient through geological data analysis, calculating the pore pressure plane diagram and the formation temperature plane diagram of different target layers, combining the formation fluid salinity diagram, and calculating the CO2 density plane diagram and the CO2 solubility plane diagram of different layers. On this basis, the CO2 geological storage capacity plane diagram and the CO2 geological storage solubility plane diagram can be calculated by combining the reservoir physical property plane diagram and the CO2 storage coefficient. Then, the CO2 reinjection formation pressure change diagram can be quickly calculated according to the CO2 density diagram combined with the reservoir physical property diagram. The regional CO2 geological storage site comprehensive sweet spot plane diagram can be obtained by using the element superposition method combined with the above calculated elements. The analysis method of the application ensures the rapidness, efficiency and quantification of CO2 site screening, and changes the limitations and subjectivity of the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of CO2 geological storage, in particular to a method for improving the evaluation of CO2 geological storage site screening and storage safety. BACKGROUND

[0002] At present, the screening of regional CO2 geological storage sites at home and abroad is basically based on qualitative evaluation of relevant geological parameters, including commonly used structural depth, reservoir quality, cap rock distribution, temperature and pressure system, fluid salinity, etc. By setting different thresholds for each parameter, different zones are divided, and then the element superposition method is used to obtain the storage site. The artificial, subjective and uncertain nature is relatively large. In order to improve the safety of CO2 geological storage, it is usually necessary to reduce the free state CO2 capacity, and to increase the bound state and dissolved state CO2 capacity, and to ensure that CO2 is stored in the form of supercritical state underground. The existing technical scheme only uses basic geological parameters and uses a simple element superposition method to describe the screening of CO2 geological storage sites, and lacks quantitative description of the properties of CO2 in the process of geological storage from basin to regional level. Therefore, it is impossible to accurately describe a reasonable and safe CO2 geological storage site.

[0003] In the process of CO2 geological storage, the phase state, density and solubility of CO2 in salt water will change with the change of formation pressure, temperature and formation water salinity. This change is usually a nonlinear change. For example, the solubility of CO2 in salt water will increase with the increase of pressure, and decrease with the increase of temperature and salinity. Therefore, it is impossible to simply determine the change of CO2 solubility by a single element. In addition, the existing technology assumes a constant CO2 density and solubility when evaluating the regional CO2 geological storage capacity, without considering the change of CO2 density caused by the change of regional temperature and pressure. Under the existing technical scheme, in order to accurately calculate the change of CO2 density and solubility in the process of CO2 geological storage, numerical simulation technology is needed. However, this technology is usually only used for simulation of target level storage sites, and numerical simulation technology requires a large amount of input data and calculation, which is relatively low in efficiency and cannot meet the rapid evaluation of regional CO2 geological storage site optimization and storage safety. SUMMARY

[0004] The purpose of the present application is to provide a method for improving the evaluation of CO2 geological storage site screening and storage safety, which combines digital technology to quickly calculate the planar graph of each element in the process of CO2 geological storage in different geological horizons at regional level, and realizes quantitative evaluation of CO2 geological storage site screening and safety through analytical calculation, to ensure the rapidity, efficiency and quantification of CO2 site screening, and to change the limitations and subjectivity of the existing technology.

[0005] To achieve the above object, the application provides an evaluation method for improving CO2 geological storage site screening and storage safety, which comprises the following steps:

[0006] S11, address data of a target site are acquired and analyzed to obtain a regional plane structure diagram of a target layer, a formation pore pressure gradient and a formation temperature gradient, so as to obtain a pore pressure plane diagram and a formation temperature plane diagram of different layers;

[0007] S12, a formation fluid salinity diagram of the target layer is obtained by analyzing the acquired geological data, and combined with the pore pressure plane diagram and the formation temperature plane diagram, CO2 solubility plane diagrams and CO2 density plane diagrams of different layers are obtained respectively;

[0008] S13, a reservoir porosity plane diagram, a reservoir permeability plane diagram and a reservoir thickness plane diagram of the target layer are obtained by analyzing the acquired geological data, combined with the CO2 density plane diagram and a CO2 storage coefficient, a CO2 geological storage capacity plane diagram of different layers is obtained, and combined with the CO2 geological storage capacity plane diagram and the CO2 solubility plane diagram, a CO2 geological storage dissolution amount plane diagram of different layers is obtained;

[0009] S14, a rock compressibility coefficient plane diagram of the target layer is obtained by the reservoir porosity plane diagram, combined with the CO2 density plane diagram, the reservoir porosity plane diagram, the reservoir permeability plane diagram and the reservoir thickness plane diagram, a CO2 reinjection formation pressure change diagram is obtained, and a minimum required caprock strength plane diagram of different layers is obtained by back calculation;

[0010] S15, a regional CO2 geological storage site comprehensive sweet spot plane diagram is obtained by combining the minimum required caprock strength plane diagram, the CO2 geological storage capacity plane diagram and the CO2 geological storage dissolution amount plane diagram by using the element superposition method, and CO2 geological storage site evaluation and development strategies are obtained by analysis.

[0011] Further, the geological data are analyzed, and specifically comprising:

[0012] S21, the collected geological data are integrated and analyzed by using geographic information system technology to construct a three-dimensional geological model of a research region;

[0013] S22, based on the three-dimensional geological model, relevant data required for CO2 geological storage are selected, drawing technology is used to draw required diagram data of the target layer, and required influence parameters are calculated by corresponding calculation methods.

[0014] Further, in step S11, the pore pressure plane diagram and the formation temperature plane diagram of different target layers are calculated, and specifically comprising:

[0015] S31, stratigraphic division and correlation are performed according to the drilling core data and the well logging curve in the geological data, the lithological characteristics and the electrical characteristics of the target layer and the adjacent layers above and below the target layer are identified, and a stratigraphic correlation marker layer is established;

[0016] S32, based on the three-dimensional geological model, the isopach map and the structural contour map of the target layer are extracted, and the regional plane structure map is drawn in combination with the stratigraphic correlation marker layer;

[0017] S33, a stratigraphic pressure prediction method is adopted, a function model is established according to the pore pressure data in the geological data, and the stratigraphic pore pressure gradient is calculated;

[0018] S34, a numerical simulation model of the stratigraphic temperature field is established by using the geothermal principle and combining the regional heat flow value and the stratigraphic thermal conductivity in the geological data, and the temperature gradient at different stratigraphic positions is obtained through simulation calculation;

[0019] S35, based on the regional plane structure map, the pore pressure gradient and the stratigraphic temperature gradient data are extended from the well point or the measuring point position to the plane range of the entire target layer by interpolation method, and the pore pressure plane map and the stratigraphic temperature plane map of different stratigraphic positions are drawn.

[0020] Further, in step S12, the calculation model of the CO2 solubility plane map is:

[0021]

[0022]

[0023] wherein,

[0024] ,

[0025]

[0026]

[0027]

[0028]

[0029]

[0030] is the solubility of CO2 in pure water, , , , is a fitting coefficient, is the critical pressure of CO2, is the formation pressure, is the solubility of CO2 in pure water, , is the first coefficient, is the second coefficient, is the formation temperature.

[0031] Further, in step S12, the calculation model of the CO2 density plane is:

[0032]

[0033] wherein, is the improved CO2 density considering the formation water, , is the formation water density, , is the CO2 component dissolved in the water considering the salinity of the formation water, is the apparent molar capacity of CO2, is the molar mass of CO2.

[0034] Further, in step S13, the CO2 geological storage capacity plane is calculated, specifically including:

[0035] S41, the thickness, porosity value and permeability of the target layer are calculated respectively, and the thickness data, porosity value and permeability data obtained by calculation are interpolated into the entire study area by interpolation method to generate a reservoir porosity plane, a reservoir permeability plane and a reservoir thickness plane;

[0036] S42, the reservoir pore volume of different layers is calculated according to the reservoir thickness and porosity, and the pore volume distribution of the target site is obtained;

[0037] S43, the effective pore volume is determined in combination with the reservoir permeability, and the effective pore volume is converted into CO2 geological storage capacity by using the density value of each point in the CO2 density and the pore volume distribution of the target site;

[0038] S44, based on the CO2 storage coefficient, the CO2 geological storage capacity is interpolated into the entire target site by interpolation method to obtain a CO2 geological storage capacity plane.

[0039] Further, in step S13, the CO2 geological storage dissolution capacity plane is calculated, specifically including:

[0040] S51, based on the CO2 solubility plane, the dissolution capacity of CO2 in the formation water is calculated in combination with the pore volume of the formation water;

[0041] S52, the CO2 geological storage capacity of each position in the CO2 geological storage capacity plane is integrated with the corresponding CO2 dissolution capacity to calculate the dissolution capacity of each position in the CO2 geological storage dissolution capacity plane;

[0042] S53, interpolate the calculated CO2 geological storage dissolution amount data to the entire target site by interpolation method to obtain a CO2 geological storage dissolution amount plan.

[0043] Further, in step S14, a rock compression coefficient plan is obtained from the reservoir porosity plan, specifically comprising:

[0044] S61, calculate the rock skeleton compression coefficient according to the mineral composition data of the rock;

[0045] S62, calculate the volume change rate of the pore fluid under pressure change based on the reservoir porosity plan to obtain the fluid compression coefficient;

[0046] S63, calculate the rock compression coefficient by combining the rock skeleton compression coefficient and the fluid compression coefficient;

[0047] S64, interpolate the calculated rock compression coefficient data to generate a rock compression coefficient plan.

[0048] Further, in step S14, a CO2 reinjection formation pressure change map is generated, specifically comprising:

[0049] S71, calculate the initial formation pressure according to the reservoir porosity, permeability, thickness and rock compression coefficient, and calculate the CO2 injection amount according to the given CO2 reinjection rate and CO2 density;

[0050] S72, based on the initial formation pressure and the CO2 injection amount, calculate the change of the target layer pressure with time by numerical simulation to generate a CO2 reinjection formation pressure change map.

[0051] Further, in step S15, a regional level CO2 geological storage site comprehensive sweet spot plan is calculated, specifically comprising:

[0052] S81, spatially superimpose the minimum required caprock strength plan, the CO2 geological storage capacity plan and the CO2 geological storage dissolution amount plan, so that each grid point or position has caprock strength score, storage capacity score and dissolution amount score at the same time;

[0053] S82, preset the weight of each element in the CO2 geological storage site evaluation, multiply the score of each grid point by the corresponding weight, and then add to obtain a comprehensive sweetness value;

[0054] S83, based on the size of the comprehensive sweetness value, divide each grid point or position into different sweetness levels to generate a regional level CO2 geological storage site comprehensive sweet spot plan.

[0055] Compared with the prior art, the beneficial effects of the present application are:

[0056] The application provides an evaluation method for improving CO2 geological storage site screening and storage safety, which is based on the existing scheme and data, and quickly calculates the capacity and safety related planar graph, including CO2 storage capacity and CO2 dissolution amount, by using the analysis method of the application, and then obtains the optimized regional CO2 geological storage site comprehensive sweet spot planar graph by using the element superposition method based on the quantitative planar graph obtained by analysis and calculation. The subjective consideration and uncertainty of the CO2 geological storage site selection in the prior art are reduced, the purpose of maximizing the CO2 storage capacity and safety is considered, the potential risk of the project is reduced, and the economic efficiency and safety of the project are improved. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by the provided drawings without creative labor for those skilled in the art.

[0058] Figure 1 A flowchart of an evaluation method for improving CO2 geological storage site screening and storage safety is provided for the embodiments of the present application.

[0059] Figure 2 A technical guidance route diagram of an evaluation method for improving CO2 geological storage site screening and storage safety is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0060] The present application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, and not to limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, not all the structures.

[0061] Reference Figure 1 The embodiments provide an evaluation method for improving CO2 geological storage site screening and storage safety, which comprises:

[0062] S11, obtaining address data of a target site and analyzing to obtain a regional planar structure graph of a target layer, a formation pore pressure gradient and a formation temperature gradient, so as to obtain a pore pressure planar graph and a formation temperature planar graph of different layers;

[0063] S12. By analyzing the acquired geological data, a formation fluid mineralization map of the target layer is obtained. Combined with the pore pressure plane map and the formation temperature plane map, CO2 solubility plane map and CO2 density plane map of different layers are obtained respectively.

[0064] S13. By analyzing the acquired geological data, the reservoir porosity plan, reservoir permeability plan, and reservoir thickness plan of the target layer are obtained. Combined with the CO2 density plan and CO2 sequestration coefficient, the CO2 geological sequestration capacity plan of different layers is obtained. The CO2 geological sequestration capacity plan and the CO2 solubility plan are combined to obtain the CO2 geological sequestration dissolution plan of different layers.

[0065] S14. Obtain the rock compressibility plane map of the target layer through the reservoir porosity plane map. Combine it with the CO2 density plane map, reservoir porosity plane map, reservoir permeability plane map and reservoir thickness plane map to obtain the CO2 reinjection formation pressure variation map. Obtain the minimum required caprock strength plane map for different layers through back calculation.

[0066] S15. By overlaying elements and combining the minimum required caprock strength plan, the CO2 geological storage capacity plan, and the CO2 geological storage dissolution plan, a comprehensive sweet spot plan of the regional CO2 geological storage site is obtained. The evaluation and development strategy of the CO2 geological storage site are then derived from the analysis.

[0067] In this embodiment, by calculating the comprehensive sweet spot plan of CO2 geological sequestration sites at different geological strata in a regional area, the evaluation and development strategies for CO2 geological sequestration sites are obtained through analysis. Since the method of this invention includes all geological parameters found in existing technical solutions, it can achieve quantitative evaluation of CO2 geological sequestration site selection and safety. Analytical calculations ensure rapid, efficient, and quantitative site selection, overcoming the limitations and subjectivity of existing technologies.

[0068] As a preferred implementation method, geological data is analyzed, specifically including:

[0069] S21. Using geographic information system technology, the collected geological data are integrated and analyzed to construct a three-dimensional geological model of the study area;

[0070] S22. Based on the three-dimensional geological model, select the relevant data required for CO2 geological storage, use mapping technology to draw the map data required for the target layer, and calculate the required influence parameters through the corresponding calculation method.

[0071] In this embodiment, the geological body is modeled using collected geological data and geostatistical methods and numerical simulation techniques to determine the distribution characteristics of reservoirs and caprocks, providing a geological framework for CO2 site selection.

[0072] In a preferred embodiment, step S11 involves calculating pore pressure plane diagrams and formation temperature plane diagrams for different target layers, specifically including:

[0073] S31. Based on the drilling core data and logging curves in the geological data, perform stratigraphic division and correlation, identify the lithological and electrical characteristics of the target layer and its adjacent upper and lower layers, and establish stratigraphic correlation marker layers.

[0074] S32. Based on the three-dimensional geological model, extract the isopyres and structural contours of the target layer, and combine them with stratigraphic marker layers to draw a regional planar structural map.

[0075] S33. Using formation pressure prediction methods, establish a function model based on pore pressure data in geological data to calculate the formation pore pressure gradient.

[0076] S34. Using the principles of geothermal science, and combining the regional heat flow value and the thermal conductivity of the strata in the geological data, establish a numerical simulation model of the stratum temperature field, and obtain the temperature gradient at different stratum locations through simulation calculation.

[0077] S35. Based on the regional planar structural map, the pore pressure gradient and formation temperature gradient data are extended from the well point or measuring point to the entire plane range of the target layer by interpolation method, and pore pressure plane map and formation temperature plane map of different layers are drawn.

[0078] In this embodiment, high pore pressure zones may induce fault slippage or rock fracturing, affecting the safety of CO2 storage. A pore pressure plane map visually represents the formation pressure distribution. In lower pressure areas, CO2 injection requires less pressure to overcome, resulting in smoother injection, while higher pressure areas may require more energy to maintain injection. A formation temperature plane map helps understand the formation's thermal state. CO2 injection in high-temperature zones may cause thermal disturbances, affecting the properties of surrounding rocks and fluids, thus impacting storage stability. Combined with the formation temperature plane map, temperature affects the phase and density of CO2. In low-temperature zones, CO2 tends to exist in a liquid or supercritical state, with a high density, which is beneficial for increasing storage capacity. Understanding the pore pressure and temperature distribution provides a data foundation for comprehensively delineating suitable areas for CO2 storage. Simultaneously, by adjusting injection parameters and implementing temperature and pressure control measures, CO2 can be kept in a more stable state within the formation, reducing its migration and escape possibilities, and enhancing the long-term stability of CO2 storage.

[0079] In a preferred embodiment, the calculation model for the CO2 solubility plane diagram in step S12 is as follows:

[0080]

[0081]

[0082] in,

[0083] ,

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] This represents the solubility of CO2 in pure water. , , , These are the fitting coefficients. This is the critical pressure of CO2. For formation pressure, This represents the solubility of CO2 in pure water. , For the first One coefficient, This refers to the formation temperature.

[0090] In this embodiment, since the solubility of CO2 varies with formation temperature, pressure and fluid salinity, it is necessary to establish a regional calculation model of CO2 solubility in relation to temperature, pressure and solubility, so as to study the variation law of CO2 solubility in regional saline aquifers.

[0091] In a preferred embodiment, the calculation model for the CO2 density plane diagram in step S12 is as follows:

[0092]

[0093] in, To account for the improved CO2 density after formation water, , The density of the formation water. , To account for the dissolved CO2 content in the formation water after considering its salinity, For the apparent molar capacity of CO2, This represents the molar mass of CO2.

[0094] In a preferred embodiment, step S13 involves calculating a CO2 geological sequestration capacity plan, specifically including:

[0095] S41. Calculate the thickness, porosity, and permeability of the target layer respectively. Interpolate the calculated thickness, porosity, and permeability data to the entire study area using the interpolation method to generate reservoir porosity planar map, reservoir permeability planar map, and reservoir thickness planar map.

[0096] S42. Based on the reservoir thickness and porosity, calculate the reservoir pore volume at different strata to obtain the pore volume distribution at the target site.

[0097] S43. Combine reservoir permeability to determine effective pore volume, and use CO2 density and density values ​​at each point in the pore volume distribution of the target site to convert the effective pore volume into CO2 geological storage capacity.

[0098] S44. Based on the CO2 sequestration coefficient, the CO2 geological sequestration capacity is interpolated to the entire target site using an interpolation method to obtain a CO2 geological sequestration capacity plan.

[0099] In this embodiment, the CO2 geological storage capacity plan of different layers is calculated, which can intuitively present the CO2 storage capacity of each layer, help to accurately locate areas with outstanding storage capacity, improve site screening efficiency, and reduce invalid exploration.

[0100] In a preferred embodiment, step S13 involves calculating a CO2 geological sequestration dissolution plan, specifically including:

[0101] S51. Based on the CO2 solubility plane diagram and the pore volume of formation water, calculate the amount of CO2 dissolved in formation water.

[0102] S52. Integrate the CO2 geological sequestration capacity at each location on the CO2 geological sequestration capacity plan with the corresponding CO2 dissolution amount, and calculate the dissolution amount at each location on the CO2 geological sequestration dissolution amount plan.

[0103] S53. The calculated CO2 geological sequestration dissolution data is interpolated to the entire target site using the interpolation method to obtain a CO2 geological sequestration dissolution plan map.

[0104] In this embodiment, CO2 dissolution is a long-term process. The dissolution amount planar diagram can intuitively show the distribution of CO2 dissolution amount in different layers. After clarifying the differences in dissolution amount in each layer, the long-term CO2 dissolution amount in different layers can be predicted, the sealing effect can be evaluated, and the sealing stability can be understood in advance.

[0105] In a preferred embodiment, step S14 involves obtaining a rock compressibility plane map from a reservoir porosity plane map, specifically including:

[0106] S61. Calculate the rock skeleton compression coefficient based on the mineral composition data of the rock;

[0107] S62. Based on the reservoir porosity plan, calculate the volume change rate of pore fluid under pressure changes to obtain the fluid compressibility coefficient.

[0108] S63. The rock compressibility coefficient is calculated by combining the rock skeleton compressibility coefficient and the fluid compressibility coefficient.

[0109] S64. Interpolate the calculated rock compression coefficient data to generate a rock compression coefficient plane map.

[0110] In this embodiment, the porosity planar diagram mainly reflects the pore structure characteristics of the reservoir, while the rock compressibility coefficient planar diagram further reflects the volume change characteristics of the reservoir rock under pressure changes, reflecting the degree of change in rock volume under pressure changes. In CO2 geological storage, considering the rock compressibility coefficient can more accurately estimate the elastic storage capacity of the reservoir, avoiding formation fracturing or inducing geological disasters due to excessively high injection pressure.

[0111] In a preferred embodiment, step S14 involves generating a CO2 reinjection formation pressure variation map, specifically including:

[0112] S71. Calculate the initial formation pressure based on reservoir porosity, permeability, thickness and rock compressibility coefficient; calculate the CO2 injection rate based on the given CO2 reinjection rate and CO2 density.

[0113] S72. Based on the initial formation pressure and CO2 injection rate, the change of target formation pressure over time is calculated through numerical simulation, and a CO2 reinjection formation pressure change map is generated.

[0114] In this embodiment, based on the CO2 density planar diagram obtained above, combined with the reservoir porosity planar diagram, reservoir permeability planar diagram, and reservoir thickness planar diagram, the formation pressure variation with reinjection time at a given reinjection rate can be quickly calculated. Typically, this pressure variation reaches its maximum when reinjection stops. To ensure that the formation pressure does not break through the overburden, the minimum required caprock strength to support the pressure variation caused by reinjection can be calculated. Since the caprock strength varies at different depths and at different strata, a relatively safe storage site can be obtained using this method.

[0115] As a preferred implementation, step S15 involves calculating a comprehensive sweet spot plan of a regional-level CO2 geological sequestration site, specifically including:

[0116] S81. Spatially overlay the minimum required caprock strength plan, the CO2 geological sequestration capacity plan, and the CO2 geological sequestration dissolution plan so that each grid point or location simultaneously has caprock strength score, sequestration capacity score, and dissolution score.

[0117] S82. Preset the weight of each element in the evaluation of CO2 geological storage sites, multiply the score of each grid point by the corresponding weight, and then add them together to obtain the comprehensive sweetness value.

[0118] S83. Based on the magnitude of the comprehensive sweetness value, each grid point or location is divided into different sweetness levels to generate a comprehensive sweetness plan of the regional CO2 geological storage site.

[0119] In this embodiment, a single geological factor cannot comprehensively measure the quality of a CO2 geological sequestration site. For example, considering only areas with large sequestration capacity may result in insufficient caprock strength, making safe CO2 sequestration impossible; focusing only on areas with high caprock strength may limit their sequestration capacity or dissolution rate, hindering large-scale and efficient sequestration. By using an element overlay method, key element maps are integrated. Based on the overall sweetness value, the natural discontinuity method or equal-interval method is used to determine the sweetness level classification threshold. Each grid point or location is divided into different sweetness levels, such as "high sweetness," "medium sweetness," and "low sweetness," or a continuous color gradient is used to represent sweetness changes, thereby generating a regional-level comprehensive sweetness map of CO2 geological sequestration sites.

[0120] Analysis of the comprehensive sweet spot plan identified high-sweetness areas, which typically possess good caprock strength, large storage capacity, and high solubility, making them priority candidate sites for CO2 geological sequestration. Simultaneously, medium-sweetness and low-sweetness areas were analyzed to identify their advantages and disadvantages, providing a basis for subsequent development strategy formulation. A detailed analysis was conducted on the distribution range, continuity, and relationship with other geological structures and engineering facilities of areas with different sweetness levels to assess their feasibility and potential in practical engineering. For example, whether high-sweetness areas have sufficient area and connectivity to meet the needs of large-scale CO2 sequestration, and whether they are compatible with the location of CO2 emission sources, etc. This process accurately identifies high-quality sites that demonstrate good performance in terms of safety, storage capacity, and efficiency, while screening out unsuitable sites with significant defects.

[0121] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the selection and evaluation of CO2 geological sequestration sites and the safety of CO2 sequestration, characterized in that, The method includes: S11. Obtain the address data of the target site and analyze it to obtain the regional planar structural map of the target layer, the formation pore pressure gradient and the formation temperature gradient, thereby obtaining the pore pressure planar map and formation temperature planar map of different layers. S12. By analyzing the acquired geological data, a formation fluid mineralization map of the target layer is obtained. Combined with the pore pressure plane map and the formation temperature plane map, CO2 solubility plane map and CO2 density plane map of different layers are obtained respectively. S13. By analyzing the acquired geological data, the reservoir porosity plan, reservoir permeability plan, and reservoir thickness plan of the target layer are obtained. Combined with the CO2 density plan and CO2 sequestration coefficient, the CO2 geological sequestration capacity plan of different layers is obtained. The CO2 geological sequestration capacity plan and the CO2 solubility plan are combined to obtain the CO2 geological sequestration dissolution plan of different layers. S14. Obtain the rock compressibility plane map of the target layer through the reservoir porosity plane map. Combine it with the CO2 density plane map, reservoir porosity plane map, reservoir permeability plane map and reservoir thickness plane map to obtain the CO2 reinjection formation pressure variation map. Obtain the minimum required caprock strength plane map for different layers through back calculation. S15. By overlaying elements and combining the minimum required caprock strength plan, the CO2 geological storage capacity plan, and the CO2 geological storage dissolution plan, a comprehensive sweet spot plan of the regional CO2 geological storage site is obtained. The evaluation and development strategy of the CO2 geological storage site are then derived from the analysis.

2. The method for improving the selection and evaluation of CO2 geological storage site safety according to claim 1, characterized in that, Geological data analysis specifically includes: S21. Using geographic information system technology, the collected geological data are integrated and analyzed to construct a three-dimensional geological model of the study area; S22. Based on the three-dimensional geological model, select the relevant data required for CO2 geological storage, use mapping technology to draw the map data required for the target layer, and calculate the required influence parameters through the corresponding calculation method.

3. The method for improving the selection and evaluation of CO2 geological storage site safety according to claim 2, characterized in that, In step S11, the pore pressure planar diagrams and formation temperature planar diagrams for different target layers are calculated, specifically including: S31. Based on the drilling core data and logging curves in the geological data, perform stratigraphic division and correlation, identify the lithological and electrical characteristics of the target layer and its adjacent upper and lower layers, and establish stratigraphic correlation marker layers. S32. Based on the three-dimensional geological model, extract the isopyres and structural contours of the target layer, and combine them with stratigraphic correlation marker layers to draw a regional planar structural map. S33. Using formation pressure prediction methods, establish a function model based on pore pressure data in geological data to calculate the formation pore pressure gradient. S34. Using the principles of geothermal science, and combining the regional heat flow value and the thermal conductivity of the strata in the geological data, establish a numerical simulation model of the stratum temperature field, and obtain the temperature gradient at different stratum locations through simulation calculation. S35. Based on the regional planar structural map, the pore pressure gradient and formation temperature gradient data are extended from the well point or measuring point to the entire plane range of the target layer by interpolation method, and pore pressure plane map and formation temperature plane map of different layers are drawn.

4. The method for improving the selection and evaluation of CO2 geological storage site safety according to claim 1, characterized in that, In step S12, the calculation model for the CO2 solubility plane diagram is as follows: in, ， This represents the solubility of CO2 in pure water. , , , These are the fitting coefficients. This is the critical pressure of CO2. For formation pressure, This represents the solubility of CO2 in pure water. , For the first One coefficient, This refers to the formation temperature.

5. The method for improving the selection and evaluation of CO2 geological storage site safety according to claim 4, characterized in that, In step S12, the calculation model for the CO2 density plane diagram is as follows: in, To account for the improved CO2 density after formation water, , The density of the formation water. , To account for the dissolved CO2 content in the formation water after considering its salinity, For the apparent molar capacity of CO2, This represents the molar mass of CO2.

6. The method for improving the selection and evaluation of CO2 geological storage site safety according to claim 1, characterized in that, In step S13, the CO2 geological sequestration capacity plan is calculated, specifically including: S41. Calculate the thickness, porosity, and permeability of the target layer respectively. Interpolate the calculated thickness, porosity, and permeability data to the entire study area using the interpolation method to generate reservoir porosity planar map, reservoir permeability planar map, and reservoir thickness planar map. S42. Based on the reservoir thickness and porosity, calculate the reservoir pore volume at different strata to obtain the pore volume distribution at the target site. S43. Combine reservoir permeability to determine effective pore volume, and use CO2 density and density values ​​at each point in the pore volume distribution of the target site to convert the effective pore volume into CO2 geological storage capacity. S44. Based on the CO2 sequestration coefficient, the CO2 geological sequestration capacity is interpolated to the entire target site using an interpolation method to obtain a CO2 geological sequestration capacity plan.

7. The method for improving the selection and evaluation of CO2 geological storage site safety according to claim 1, characterized in that, In step S13, the CO2 geological sequestration dissolution plan is calculated, specifically including: S51. Based on the CO2 solubility plane diagram and the pore volume of formation water, calculate the amount of CO2 dissolved in formation water. S52. Integrate the CO2 geological sequestration capacity at each location on the CO2 geological sequestration capacity plan with the corresponding CO2 dissolution amount, and calculate the dissolution amount at each location on the CO2 geological sequestration dissolution amount plan. S53. The calculated CO2 geological sequestration dissolution data is interpolated to the entire target site using the interpolation method to obtain a CO2 geological sequestration dissolution plan map.

8. The method for improving the selection and evaluation of CO2 geological storage site safety according to claim 1, characterized in that, In step S14, a rock compressibility plane map is obtained through the reservoir porosity plane map, specifically including: S61. Calculate the rock skeleton compression coefficient based on the mineral composition data of the rock; S62. Based on the reservoir porosity plan, calculate the volume change rate of pore fluid under pressure changes to obtain the fluid compressibility coefficient. S63. The rock compressibility coefficient is calculated by combining the rock skeleton compressibility coefficient and the fluid compressibility coefficient. S64. Interpolate the calculated rock compression coefficient data to generate a rock compression coefficient plane map.

9. The method for improving the selection and evaluation of CO2 geological storage site safety according to claim 1, characterized in that, In step S14, a CO2 reinjection formation pressure change map is generated, specifically including: S71. Calculate the initial formation pressure based on reservoir porosity, permeability, thickness and rock compressibility coefficient; calculate the CO2 injection rate based on the given CO2 reinjection rate and CO2 density. S72. Based on the initial formation pressure and CO2 injection rate, the change of target formation pressure over time is calculated through numerical simulation, and a CO2 reinjection formation pressure change map is generated.

10. The method for improving the selection and evaluation of CO2 geological storage site safety according to claim 1, characterized in that, In step S15, a comprehensive sweet spot plan of the regional-level CO2 geological sequestration site is calculated, specifically including: S81. Spatially overlay the minimum required caprock strength plan, the CO2 geological sequestration capacity plan, and the CO2 geological sequestration dissolution plan so that each grid point or location simultaneously has caprock strength score, sequestration capacity score, and dissolution score. S82. Preset the weight of each element in the evaluation of CO2 geological storage sites, multiply the score of each grid point by the corresponding weight, and then add them together to obtain the comprehensive sweetness value. S83. Based on the magnitude of the comprehensive sweetness value, each grid point or location is divided into different sweetness levels to generate a comprehensive sweetness plan of the regional CO2 geological storage site.

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