A method for geological storage of carbon dioxide

Abstract

The present invention relates to the technical field of carbon dioxide storage and environmental safety monitoring and early warning, and specifically to a carbon dioxide geological storage method, including site selection, drilling and well construction, carbon dioxide capture and compression, carbon dioxide injection, storage monitoring, leakage risk assessment and early warning; real-time monitoring of the storage process includes: deploying monitoring equipment, collecting monitoring data; forming a time series curve of various types of data according to the acquired monitoring data in order of type and time point, traversing the time series curve data of various types of data for correlation analysis, and obtaining a correlation value; estimating the change trend of the time series curve according to the data difference between two adjacent data at each time point; evaluating the carbon dioxide geological storage process based on the correlation value and the change trend of the time series curve, quantifying the evaluation data, and obtaining a data analysis result; based on the data analysis result, evaluating the storage safety and leakage risk. The present invention improves the carbon dioxide leakage monitoring effect.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide storage and environmental safety monitoring and early warning, and in particular to a method for geological storage of carbon dioxide. Background Art

[0002] Carbon capture, storage and reuse technology CCUS (Carbon Capture, Utilization and Storage) is a large-scale greenhouse gas emission reduction technology and is considered to be an effective technical means to directly achieve carbon reduction. It provides important guarantees for reducing carbon dioxide emissions, ensuring energy and resource security, building ecological civilization and achieving sustainable development. Geological storage is one of the main ways to dispose of captured carbon dioxide to achieve permanent emission reduction. At present, the main places that can be used for carbon dioxide geological storage are deep saline aquifers in sedimentary basins, depleted or abandoned oil and gas fields, abandoned coal seams, goafs, etc. Among them, deep saline aquifers have the characteristics of wide distribution range, large thickness, good water-proof properties of top and bottom plates, and stable caprocks. They are the main space for large-scale carbon dioxide geological storage in the future and have great potential. During the underground storage process, carbon dioxide may leak into the surface or groundwater through faults, cracks or caprocks, causing environmental pollution and ecological damage, and carbon dioxide leakage needs to be monitored. However, the current carbon dioxide geological storage method has poor monitoring effect on carbon dioxide leakage and cannot detect leakage risks in time. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a method for geological storage of carbon dioxide, which can inject carbon dioxide into geological bodies such as depleted oil and gas fields or deep saline water layers to achieve the storage of carbon dioxide. At the same time, it also improves the monitoring effect of carbon dioxide leakage and timely discovers and judges the leakage risk.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A method for geological storage of carbon dioxide, comprising:

[0006] Site selection: Select a CO2 storage site, select a stratum with a depth greater than 800m, and determine the CO2 geological storage area;

[0007] Drilling and well construction: Drilling is carried out at selected locations to build injection wells and monitoring wells. Injection wells are used to inject carbon dioxide into the ground, while monitoring wells are used to monitor various parameters during the storage process in real time.

[0008] Carbon dioxide capture and compression: capture carbon dioxide and compress it;

[0009] Carbon dioxide injection: The compressed carbon dioxide is injected into the underground reservoir through an injection well;

[0010] Sealing monitoring: Real-time monitoring of the sealing process, analysis of monitoring data, evaluation of sealing effects, and timely detection and treatment of potential leakage risks, including:

[0011] Monitoring system deployment: deploy corresponding monitoring equipment at selected monitoring points;

[0012] Data collection and transmission: Collect monitoring data and use data transmission technology to transmit the data to the central processing system in real time;

[0013] Data analysis and processing: The acquired monitoring data is formed into time series curves of various types of data in order of type and time point, and the time series curve data of various types of data are traversed for correlation analysis to obtain correlation values; the trend of the time series curve is estimated based on the data difference between two adjacent data at each time point; the geological storage process of carbon dioxide is evaluated based on the correlation value and the trend of the time series curve, and the evaluation data is quantified to obtain data analysis results;

[0014] Leakage risk assessment and early warning: Based on data analysis results, evaluate CO 2 The safety and leakage risk of sealing. If a potential leakage risk is detected, an early warning will be issued immediately and appropriate emergency measures will be taken.

[0015] Furthermore, the monitoring equipment includes seismic detectors, soil gas monitoring equipment, atmospheric monitoring equipment, various sensors, etc., which are used to monitor various monitoring data such as seismic activity, temperature, pressure, flow, gas concentration, etc.

[0016] Furthermore, the data difference between two adjacent data at each time point is used to estimate the change trend of the time series curve:

[0017] ;

[0018] in, W ij is the change trend difference of the i-th data time point of the j-th type of data, J ij represents the detection data of the i-th data time point of the j-th category data, J i-1j Represents the detection data of the i-1th data time point of the jth category data, J i+1j Represents the detection data of the i+1th data time point of the jth type of data.

[0019] Furthermore, the geological storage process of carbon dioxide is evaluated based on the correlation values ​​and the trend of the time series curve:

[0020] ;

[0021] Among them, P is the evaluation value, R is the correlation value, and m is the number of data time points. l is the number of data types, d ij is the weight of the i-th data time point of the j-th category data, W ij is the change trend difference of the i-th data time point of the j-th category data.

[0022] Furthermore, based on the data analysis results, the CO 2 The safety and leakage risks of sealing, the specific process is:

[0023] Determine the interval to which the assessment value P belongs: [P1, P2), [P2, P3), [P3, P4); if P is less than P1 or falls within the interval [P1, P2), it is determined to be safe and there is no leakage risk; if P falls within the interval [P2, P3), it is determined to be a Level I leakage risk; if P falls within the interval [P3, P4), it is determined to be a Level II leakage risk; if P is greater than P4, it is determined to be a Level III or above leakage risk. If a potential leakage risk is detected, an early warning will be issued immediately, and corresponding emergency measures will be taken according to the risk level.

[0024] Furthermore, the carbon dioxide geological storage method also includes a carbon dioxide geological storage potential evaluation, which includes establishing a carbon dioxide geological storage monitoring technology method system, establishing a carbon dioxide geological storage suitability evaluation system, and establishing a carbon dioxide geological storage potential evaluation system.

[0025] Furthermore, a technical method system for monitoring CO2 geological storage is established: ① monitoring of CO2 injection rate, injection pressure and formation pressure; ② monitoring of wellbore integrity; ③ monitoring of reservoir geochemistry; ④ monitoring of deep CO2 migration; ⑤ monitoring of shallow aquifers; ⑥ monitoring of aeration zones and surface;

[0026] Furthermore, a CO2 geological storage suitability evaluation system should be established:

[0027] Selection of evaluation indicators: cap rock, storage structure, surface characteristics, hydrogeological characteristics, etc.;

[0028] Determination of evaluation index weights: Use the 1-9 scale method to quantify the judgment, give weights based on the evaluation, and then construct a judgment matrix based on the hierarchical structure and the index affiliation between the upper and lower layers:

[0029] ;

[0030] Among them, R is the judgment matrix, satisfying b ij =1 / bji ; b ij For the indicator, b i For b j The relative importance of , i,j=1,2,...,n;

[0031] Calculate the indicator weight: Use the sum-product method to calculate the composite weight of each layer of indicators to the system goal, and perform a total ranking to determine the importance of the lowest layer element; the sum-product method uses the arithmetic mean of n column vectors as the weight vector:

[0032] ;

[0033] Where i,j,k=1,2,...,n, represents the sum of the elements in the jth column;

[0034] Graphic space processing: Use the spatial analysis function of GIS to process spatial data to form a suitability evaluation map of a single evaluation index, and then use spatial overlay analysis and buffer analysis to overlay the layers of two geographic objects;

[0035] Geological storage suitability evaluation zoning: Based on the determination of evaluation index weights and graphic space processing, each index is identified and extracted, and then the spatial superposition of information is performed using the comprehensive index method to obtain the suitability evaluation results. Finally, the carbon dioxide geological storage suitability evaluation zoning is carried out according to the classification standards:

[0036] ;

[0037] in, x is a comprehensive index; x i Take values ​​for indicator traits; a i is the indicator weight; s is the number of evaluation indicators.

[0038] Furthermore, a system for evaluating the geological storage potential of carbon dioxide should be established:

[0039] The carbon dioxide storage potential evaluation formula is expressed as:

[0040] ;

[0041] in, is the mass of stored carbon dioxide; E is the carbon dioxide storage efficiency; is the density of carbon dioxide; A av is the average reservoir area; H av is the average reservoir thickness; is the average reservoir porosity; S wirris the residual water saturation of the reservoir.

[0042] Technical effects of the present invention:

[0043] Compared with the prior art, the carbon dioxide geological storage method of the present invention can achieve safe and efficient storage of carbon dioxide, and can enhance the stability and safety of energy supply. Through effective data analysis and processing, the carbon dioxide leakage monitoring effect is improved, and high-precision monitoring results can be provided, which is helpful to accurately assess the leakage risk. The carbon dioxide geological storage potential evaluation is not only highly popular, but also can improve the storage potential evaluation accuracy, and can meet the needs of various types of storage potential evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a flow chart of the carbon dioxide geological storage method of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention is clearly and completely described below in conjunction with the accompanying drawings.

[0046] Embodiment 1:

[0047] like Figure 1 As shown, this embodiment involves a method for geological storage of carbon dioxide, including site selection, drilling and well construction, carbon dioxide capture and compression, carbon dioxide injection, storage monitoring, leakage risk assessment and early warning.

[0048] Site selection: Select a carbon dioxide storage site, select a stratum with a depth greater than 800m, and determine the carbon dioxide geological storage area. At this time, the temperature of the stratum is greater than 31.1℃ and the pressure is greater than 7.38MPa, both above the critical point of carbon dioxide, which can ensure that the carbon dioxide is in a supercritical state with a larger density and better fluidity.

[0049] Drilling and well construction: Drilling is carried out at selected locations to build injection wells and monitoring wells. Injection wells are used to inject carbon dioxide into the ground, while monitoring wells are used to monitor various parameters during the storage process in real time.

[0050] Carbon dioxide capture and compression: Capturing carbon dioxide from industrial emissions and compressing it to increase its density for injection underground.

[0051] Carbon dioxide injection: The compressed carbon dioxide is injected into the underground reservoir through an injection well. The injection pressure and speed must be strictly controlled during the injection process to ensure that the carbon dioxide can be fully dissolved or adsorbed in the rock.

[0052] Sealing monitoring: Real-time monitoring of the sealing process, analysis of monitoring data, evaluation of sealing effects, and timely detection and treatment of potential leakage risks, including:

[0053] Monitoring system deployment: Deploy corresponding monitoring equipment at selected monitoring points. The monitoring equipment includes seismic detectors, soil gas monitoring equipment, atmospheric monitoring equipment, and various sensors, etc., to monitor various monitoring data such as seismic activity, temperature, pressure, flow, and gas concentration, ensuring that the equipment can collect data in real time and has sufficient sensitivity to capture small changes;

[0054] Data collection and transmission: Collect monitoring data regularly or continuously through automated or semi-automated methods, and use data transmission technology to transmit the data to the central processing system in real time;

[0055] Data analysis and processing: The acquired monitoring data is formed into time series curves of various types of data in order of type and time point, and the time series curve data of various types of data are traversed for correlation analysis to obtain correlation values; according to the data difference between two adjacent data at each time point, the change trend of the time series curve is estimated:

[0056] ;

[0057] in, W ij is the change trend difference of the i-th data time point of the j-th type of data, J ij represents the detection data of the i-th data time point of the j-th category data, J i-1j Represents the detection data of the i-1th data time point of the jth category data, J i+1j Represents the detection data of the i+1th data time point of the jth category data;

[0058] Based on the correlation values ​​and the trend of the time series curve, the geological storage process of carbon dioxide is evaluated, the evaluation data is quantified, and the data analysis results are obtained:

[0059] ;

[0060] Among them, P is the evaluation value, R is the correlation value, and m is the number of data time points. l is the number of data types, d ij is the weight of the i-th data time point of the j-th category data.

[0061] Leakage risk assessment and early warning: Based on data analysis results, evaluate CO 2 Safety and leakage risks of storage:

[0062] Determine whether the evaluation value P belongs to the following intervals: [P1, P2), [P2, P3), [P3, P4); if P is less than P1 or falls within the interval [P1, P2), it is determined to be safe and there is no leakage risk; if P falls within the interval [P2, P3), it is determined to be a Level I leakage risk; if P falls within the interval [P3, P4), it is determined to be a Level II leakage risk; if P is greater than P4, it is determined to be a Level III or above leakage risk. If a potential leakage risk is detected, an early warning will be issued immediately, and corresponding emergency measures will be taken according to the risk level.

[0063] The carbon dioxide geological storage method also includes a carbon dioxide geological storage potential evaluation, which includes establishing a carbon dioxide geological storage monitoring technology method system, establishing a carbon dioxide geological storage suitability evaluation system, and establishing a carbon dioxide geological storage potential evaluation system.

[0064] Establish a technical method system for monitoring geological storage of carbon dioxide: ① Monitoring of carbon dioxide injection rate, injection pressure and formation pressure. The monitoring data can also be used to invert hydrogeological parameters and multiphase flow parameters at the field scale, detect reservoir blockage or increased permeability, etc.; ② Wellbore integrity monitoring. The integrity of the injection part and water stop of the well can be monitored by continuously monitoring the pressure and gas composition in the annulus. The changes in pressure and composition can be quickly measured by pressure sensors or infrared analyzers. The bonding state between the casing and the rock can be determined through periodic measurements of cement bonding logging. Passive acoustic wave and other means can be used for monitoring through casing leakage or direct leakage of the wellbore; ③ Reservoir geochemical monitoring. Geochemical methods can be used to directly monitor the migration of underground carbon dioxide and understand the reaction between carbon dioxide and reservoir fluids and minerals. The main ions of fluid samples (such as Na + , K + , Ca 2+ Mg 2+ 、Mn、Cl - 、Si、HCO 3 - 、SO 4 2- ), pH, alkalinity, stable isotopes, gases (such as hydrocarbons, carbon dioxide and its isotopes); conduct tracer studies using natural tracers (C, O, H isotopes and noble gases associated with injected carbon dioxide) or artificial tracers (noble gases, SF 6, perfluorocarbons, etc.), draw tracer response curves, analyze the direction and rate of carbon dioxide migration, and study the permeability mechanical properties (saturation, permeability, etc.) of multiphase flow and their changes; ④ Monitoring of deep carbon dioxide migration. Through 4-D seismic, the spatiotemporal evolution of carbon dioxide halo can be investigated, or before and after carbon dioxide injection, the vertical seismic profile (VSP) method can be applied to the injection well to monitor the migration and spatial distribution of carbon dioxide halo. The inter-well geomorphology method can be applied to the injection well and the monitoring well to monitor the spatial distribution of carbon dioxide halo between wells, and the spatial distribution of carbon dioxide saturation can be obtained based on the monitoring results. The migration of deep underground carbon dioxide can also be directly determined by measuring the changes in pore fluids in monitoring wells. By analyzing the changes in fluid chemical composition (such as pH, Alk, HCO 3 - or EC, etc.), to determine whether CO2 has reached the monitoring well; ⑤ Shallow aquifer monitoring: due to capillary breakthrough, mechanical breakthrough and CO2-rich fluids reacting with cap layers and cement, cap layer and abandoned well breakthrough, fluids and CO2 in the reservoir will leak into the shallow aquifer. Geochemical indicators and tracer gas shallow aquifers can be used; ⑥ Vadose zone and surface monitoring: through soil gas monitoring and surface CO2 flux monitoring, determine whether CO2 enters the vadose zone from the reservoir and then reaches the surface or only the surface environment;

[0065] Establishment of a CO2 geological storage suitability assessment system:

[0066] Selection of evaluation indicators: cap rock, storage structure, surface characteristics, hydrogeological characteristics, etc.;

[0067] Determination of evaluation index weights: Use the 1-9 scale method to quantify the judgment, give weights based on the evaluation, and then construct a judgment matrix based on the hierarchical structure and the index affiliation between the upper and lower layers:

[0068] ;

[0069] Among them, R is the judgment matrix, satisfying b ij =1 / b ji ; b ij For the indicator, b i For b j The relative importance of , i,j=1,2,...,n;

[0070] Calculate the indicator weight: Use the sum-product method to calculate the composite weight of each layer of indicators to the system goal, and perform a total ranking to determine the importance of the lowest layer element; the sum-product method uses the arithmetic mean of n column vectors as the weight vector:

[0071] ;

[0072] Where i,j,k=1,2,...,n, represents the sum of the elements in the jth column;

[0073] Spatial processing of graphics: Use the spatial analysis function of GIS to deeply process or analyze spatial data to form a suitability evaluation map of a single evaluation index, and then use spatial overlay analysis and buffer analysis to overlay the layers of two geographic objects to generate multiple attribute characteristics of spatial regions, or establish spatial correspondence between geographic objects. According to the different object characteristics, it can be divided into three types: point-polygon overlay, line-polygon overlay, and polygon-polygon overlay;

[0074] Geological storage suitability evaluation zoning: Based on the determination of evaluation index weights and graphic space processing, each index is identified and extracted, and then the spatial superposition of information is performed using the comprehensive index method to obtain the suitability evaluation results. Finally, the carbon dioxide geological storage suitability evaluation zoning is carried out according to the classification standards:

[0075] ;

[0076] in, x is a comprehensive index; x i Take values ​​for indicator traits; a i is the indicator weight; s is the number of evaluation indicators.

[0077] Establishment of a system for evaluating the geological storage potential of carbon dioxide:

[0078] The carbon dioxide storage potential evaluation formula is expressed as:

[0079] ;

[0080] in, is the mass of stored carbon dioxide (kg), E is the carbon dioxide storage efficiency (the proportion of the reservoir pore volume occupied by carbon dioxide, (dimensionless), is the density of carbon dioxide (kg / m 3 ), A av is the average reservoir area (m 2 ), H av is the average reservoir thickness (m), is the average reservoir porosity, S wirr is the residual water saturation of the reservoir (i.e., the water saturation that cannot be reduced any further).

[0081] The carbon dioxide geological storage potential evaluation method of the present invention has good popularity and is not only applicable to geological types with large sedimentary basins as units, but its working accuracy can also support the needs of other types of storage potential evaluation and has wide applications.

Claims

1. A method for geological storage of carbon dioxide, characterized in that: include: Site selection: Select a CO2 storage site, select a stratum with a depth greater than 800m, and determine the CO2 geological storage area; Drilling and well construction: Drilling is carried out at selected locations to build injection wells and monitoring wells. Injection wells are used to inject carbon dioxide into the ground, while monitoring wells are used to monitor various parameters during the storage process in real time. Carbon dioxide capture and compression: capture carbon dioxide and compress it; Carbon dioxide injection: The compressed carbon dioxide is injected into the underground reservoir through an injection well; Sealing monitoring: Real-time monitoring of the sealing process, analysis of monitoring data, evaluation of sealing effects, and timely detection and treatment of potential leakage risks, including: Monitoring system deployment: Deploy monitoring equipment at selected monitoring points; Data collection and transmission: Collect monitoring data and use data transmission technology to transmit the data to the central processing system in real time; Data analysis and processing: The acquired monitoring data is formed into time series curves of various types of data in order of type and time point, and the time series curve data of various types of data are traversed for correlation analysis to obtain correlation values; the trend of the time series curve is estimated based on the data difference between two adjacent data at each time point; the geological storage process of carbon dioxide is evaluated based on the correlation value and the trend of the time series curve, and the evaluation data is quantified to obtain data analysis results; Leakage risk assessment and early warning: Based on data analysis results, evaluate the safety and leakage risk of CO2 storage; The data difference between two adjacent data at each time point estimates the trend of the time series curve: ； in, W ij is the change trend difference of the i-th data time point of the j-th type of data, J ij represents the detection data of the i-th data time point of the j-th category data, J i-1j Represents the detection data of the i-1th data time point of the jth category data, J i+1j Represents the detection data of the i+1th data time point of the jth category data; Evaluate the CO2 geological storage process based on correlation values ​​and time series curve trends: ； Among them, P is the evaluation value, R is the correlation value, and m is the number of data time points. l is the number of data types, d ij is the weight of the i-th data time point of the j-th category data, W ij is the change trend difference of the i-th data time point of the j-th category data; Based on the data analysis results, the safety and leakage risk of CO2 storage are evaluated. The specific process is as follows: Determine the interval to which the evaluation value P belongs: [P1, P2), [P2, P3), [P3, P4); if P is less than P1 or falls within the interval [P1, P2), it is determined to be safe and has no leakage risk; if P falls within the interval [P2, P3), it is determined to be a Level I leakage risk; if P falls within the interval [P3, P4), it is determined to be a Level II leakage risk; if P is greater than P4, it is determined to be a Level III or above leakage risk.

2. The method for geological storage of carbon dioxide according to claim 1, characterized in that: The monitoring equipment includes seismic detectors, soil gas monitoring equipment, atmosphere monitoring equipment and sensors.

3. The method for geological storage of carbon dioxide according to claim 1 or 2, characterized in that: The carbon dioxide geological storage method also includes a carbon dioxide geological storage potential evaluation, which includes establishing a carbon dioxide geological storage monitoring technology method system, establishing a carbon dioxide geological storage suitability evaluation system, and establishing a carbon dioxide geological storage potential evaluation system.

4. The method for geological storage of carbon dioxide according to claim 3, characterized in that: Establish a technical method system for monitoring carbon dioxide geological storage: ① monitoring of carbon dioxide injection rate, injection pressure and formation pressure; ② monitoring of wellbore integrity; ③ monitoring of reservoir geochemistry; ④ monitoring of deep carbon dioxide migration; ⑤ monitoring of shallow aquifers; ⑥ monitoring of aeration zones and surface.

5. The method for geological storage of carbon dioxide according to claim 4, characterized in that: Establishment of a CO2 geological storage suitability assessment system: Selection of evaluation indicators: cap rock, storage structure, surface characteristics, hydrogeological characteristics; Determination of evaluation index weights: Use the 1-9 scale method to quantify the judgment, give weights based on the evaluation, and then construct a judgment matrix based on the hierarchical structure and the index affiliation between the upper and lower layers: ； Among them, R is the judgment matrix, satisfying b ij =1 / b ji ; b ij For the indicator, b i For b j The relative importance of , i,j=1,2,...,n; Calculate the indicator weight: Use the sum-product method to calculate the composite weight of each layer indicator to the system goal and perform a total ranking; the sum-product method uses the arithmetic mean of n column vectors as the weight vector: ； Where i,j,k=1,2,...,n, represents the sum of the elements in the jth column; Graphic space processing: Use the spatial analysis function of GIS to process spatial data to form a suitability evaluation map of a single evaluation index, and then use spatial overlay analysis and buffer analysis to overlay the layers of two geographic objects; Geological storage suitability evaluation zoning: Based on the determination of evaluation index weights and graphic space processing, each index is identified and extracted, and then the spatial superposition of information is performed using the comprehensive index method to obtain the suitability evaluation results. Finally, the carbon dioxide geological storage suitability evaluation zoning is carried out according to the classification standards: ； in, x is a comprehensive index; x i Take values ​​for indicator traits; a i is the indicator weight; s is the number of evaluation indicators.

6. The method for geological storage of carbon dioxide according to claim 4, characterized in that: Establishment of a system for evaluating the geological storage potential of carbon dioxide: The carbon dioxide storage potential evaluation formula is expressed as: ； in, is the mass of stored carbon dioxide; E is the carbon dioxide storage efficiency; is the density of carbon dioxide; A av is the average reservoir area; H av is the average reservoir thickness; is the average reservoir porosity; S wirr is the residual water saturation of the reservoir.

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