Site selection method for geological storage of carbon dioxide in saline water layer of land sedimentary basin

Abstract

The invention discloses a land sedimentary basin salt water layer carbon dioxide geological storage site selection method comprising the following steps: carrying out geological exploration in a to-be-stored area, and delineating a storage prospective area; geological exploration is carried out in the sequestration distant view area, a trap structure and geological conditions beneficial to carbon dioxide sequestration are found, and a sequestration target area is delineated through pre-exploration well drilling in combination with important mineral resource exploration development conditions and carbon dioxide sequestration and mineral resource development configuration; geological exploration is carried out in a storage target area, supplementary drilling is carried out under the conditions of shaft corrosion prevention and leakage, carbon dioxide storage and mineral resource development are configured to avoid the risk of carbon dioxide leakage caused by mineral resource development and abandoned drilling by combining important mineral resource exploration and development conditions, and a storage site is delineated; determining a carbon dioxide injection layer; and sealing site selection is completed. According to the method, a proper sealing site can be screened for large-scale safe carbon dioxide sealing for the salt water layer of the sedimentary basin, and the sealing effect is ensured.

Description

Technical Field

[0001] The present invention relates to a method for selecting sites for geological sequestration of carbon dioxide in saline aquifers of land-based sedimentary basins, belonging to the technical field of geological sequestration of carbon dioxide. Background Art

[0002] At present, deep saline aquifer sequestration is considered to be one of the most effective ways to reduce carbon emissions. Deep saline aquifers are widely distributed in China and have great carbon dioxide 2 sequestration potential. In this field, the theoretical injection depth of carbon dioxide is at least below 800 m underground. For the sake of improving safety, the general depth requirement is below 1000 m. Most of the groundwater at this depth has relatively high salinity and is often saline water. Implementing large-scale sequestration of carbon dioxide in deep saline aquifers will cause the pressure borne by the geological structure to accumulate sharply, and there is a great risk of 2 carbon dioxide leakage. Therefore, in order to ensure the sequestration effect and safety, selecting deep saline aquifers suitable for sequestering carbon dioxide gas, especially for sedimentary basins, is the first and important step for effectively and safely implementing carbon dioxide sequestration. 2 2 2 Summary of the Invention

[0003] The purpose of the present invention is to provide a method for selecting sites for geological sequestration of carbon dioxide in saline aquifers of land-based sedimentary basins, which can screen out suitable sequestration sites for large-scale and safe sequestration of carbon dioxide in saline aquifers of sedimentary basins and ensure the sequestration effect.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions: A method for selecting sites for geological sequestration of carbon dioxide in saline aquifers of land-based sedimentary basins includes the following steps: Step 1: General survey stage: Conduct geological exploration in the area to be sequestered, and delineate a sequestration prospective area that meets the potential requirements of the prediction level. Among them, the area to be sequestered is a sedimentary basin or a geological structure unit within a sedimentary basin, and a sedimentary basin is composed of multiple geological structure units; Step 2: Detailed survey stage: Conduct geological exploration in the sequestration prospective area, find trap structures and geological conditions conducive to carbon dioxide sequestration, drill exploration wells, and configure carbon dioxide sequestration and mineral resource development in combination with the exploration and development of important mineral resources, and delineate a sequestration target area that meets the potential requirements of the control level; ​​​Step 3: Exploration stage: Conduct geological exploration within the storage target area, carry out supplementary drilling under the conditions of wellbore anti-corrosion and leakage, and configure carbon dioxide storage and mineral resource development in combination with the exploration and development of important mineral resources to avoid the risk of carbon dioxide leakage caused by mineral resource development and abandoned wells, delineate the storage site, and determine the carbon dioxide injection layer. The storage site meets the potential requirements of the proven level; Step 4: Complete the storage site selection.

[0005] The advantages of the present invention are: The present invention provides a method for screening a suitable storage site for carbon dioxide in the deep saline aquifer of a land sedimentary basin. The storage site selected by the present invention can implement large-scale and safe storage of carbon dioxide, with good storage effect and is suitable for popularization. The present invention is applicable to the selection of sites for geological storage of carbon dioxide in the deep saline aquifer within a land sedimentary basin. Description of the Drawings

[0006] Figure 1 It is a flow chart of the method for selecting a site for geological storage of carbon dioxide in the saline aquifer of a land sedimentary basin of the present invention. Detailed Embodiments

[0007] As Figure 1 , the present invention proposes a method for selecting a site for geological storage of carbon dioxide in the saline aquifer of a land sedimentary basin, including the following steps: Step 1: General survey stage: Conduct geological exploration within the area to be stored, delineate the storage prospective area. The storage prospective area meets the potential requirements of the predicted level. Among them, the area to be stored is a sedimentary basin or a geological structure unit within a sedimentary basin, and the sedimentary basin is composed of multiple geological structure units; Step 2: Detailed survey stage: Conduct geological exploration within the storage prospective area, find trap structures and geological conditions conducive to carbon dioxide storage, through pre-exploration well drilling, and configure carbon dioxide storage and mineral resource development in combination with the exploration and development of important mineral resources, delineate the storage target area. The storage target area meets the potential requirements of the controlled level; Step 3: Exploration stage: Conduct geological exploration within the storage target area, carry out supplementary drilling under the conditions of wellbore anti-corrosion, leakage, etc., and configure carbon dioxide storage and mineral resource development in combination with the exploration and development of important mineral resources to avoid the risk of carbon dioxide leakage caused by mineral resource development and abandoned wells, delineate the storage site, and determine the carbon dioxide injection layer. The storage site meets the potential requirements of the proven level; Step 4: Complete the storage site selection.

[0008] During the general survey stage, geological exploration is mainly carried out by widely collecting various survey and exploration information and research results on geology, geophysical exploration, remote sensing, hydrology, minerals, etc., and conducting surface geological surveys. The surface geological surveys include measuring geological profiles, collecting and testing outcrop rocks and important water body samples, and carrying out two-dimensional seismic general surveys, and supplementing non-seismic geophysical exploration means as appropriate.

[0009] Specifically, during the general survey stage, geological exploration is carried out on the following contents: the basement characteristics of the area to be sealed and the contact relationship with the basin and mountains, the division of secondary tectonic units and their basic forms; the stratigraphic sequence of sedimentary rocks, including the lithology, sedimentary environment and sedimentary facies of sedimentary rock strata below 800 m in depth; formation pressure and geothermal field characteristics; hydrogeological conditions, including the physical and chemical properties of aquifers below 800 m in depth; crustal stability and historical earthquake information, including the development and activity of faults; the occurrence and development characteristics of deep energy minerals such as coal, oil, and natural gas, as well as the exploration and development situation. Of course, in actual implementation, it is not limited to the above contents.

[0010] The geological exploration carried out during the general survey stage should meet the following requirements: complete two-dimensional seismic general surveys, and the main survey line spacing should be less than 4 km; refer to the deep drilling data of other mineral resources within a range of 100 km × 100 km, and take cores or sidewall cores from the target layers of the wells; conduct core and water chemical analyses.

[0011] During the detailed survey stage, mainly based on the results of the general survey stage, two-dimensional seismic detailed surveys are carried out, non-seismic geophysical exploration means are supplemented as appropriate, and pre-exploration well drilling (logging) is implemented, and rock and water body samples of the target reservoir-cap rock are collected, etc., while obtaining data such as fluid properties, temperature, and pressure.

[0012] Specifically, during the detailed survey stage, geological exploration is carried out on the following contents: the distribution, types and characteristics of saline aquifer seals in the seal prospective area; the lithology, thickness, physical properties and distribution continuity of saline aquifer reservoirs, as well as the physical and chemical properties of groundwater; the lithology, thickness, physical properties and distribution continuity of cap rocks; formation pressure and geothermal field characteristics; the development and activity of faults; the occurrence and development characteristics of deep energy minerals such as coal, oil, and natural gas, as well as the exploration and development situation. Of course, in actual implementation, it is not limited to the above contents.

[0013] The geological exploration carried out during the detailed survey stage should meet the following requirements: complete two-dimensional seismic detailed surveys, and the main survey line spacing should be less than 2 km; there are representative cores in the saline aquifer sections of pre-exploration wells within a range of 20 km × 20 km; obtain fluid properties, temperature and pressure data through well testing.

[0014] The exploration phase is mainly based on the results of the survey phase and detailed investigation phase. It implements high-precision two-dimensional seismic detailed investigation or three-dimensional seismic exploration, completes drilling (well logging), collects complete coring sections of the target reservoir caprock for analysis and testing, and deploys annual storage capacity of 100,000 tons or more to implement carbon dioxide injection tests.

[0015] Specifically, geological surveys are conducted during the exploration phase on the following: reservoir conditions, including the detailed characterization of the physical and chemical properties and heterogeneity of the target saline layer, the formation temperature, formation pressure and hydrodynamic characteristics of the saline layer; geological stability conditions of the storage body, including the detailed characterization of the physical and chemical properties of the cap layer, the development of cracks and the continuity of distribution, and the development and properties of faults; environmental risks, including the tightness of abandoned drilling and wellbore, the development and properties of faults, and the conditions of environmentally sensitive areas such as densely populated areas; resource development feedback conditions, including shallow groundwater, coal resources, oil and gas resources, geothermal resources and brine resources and other mineral resources for which prospecting rights or mining rights have been approved; ground technical and economic conditions, including the development of geological disasters, the development of tectonic fissures, urban development boundaries, permanent basic farmland, ecological protection red lines and carbon dioxide transport conditions. Of course, in actual implementation, it is not limited to the above contents.

[0016] The geological surveys conducted during the exploration phase should meet the following requirements: except for complex geology, a two-dimensional seismic network or three-dimensional seismic survey of an area no larger than 1km×1km has been completed; drilling (well logging) evaluation has been completed within a range of 5km×5km, and the target reservoir caprock has at least one complete coring profile; the fluid properties, temperature and pressure data of the quasi-injection layer have been obtained; and carbon dioxide injection tests with an annual storage scale of 100,000 tons or more have been completed.

[0017] In actual implementation, the geological conditions of the designated storage prospective areas shall at least meet the following requirements: The exploration accuracy of the target saline reservoir and cap rock structure is 1:100000-1:250000; The saline water reservoir is refined into rock stratigraphic unit groups, which can clarify the lithology of the target saline water reservoir; Understand the regional faults that control basin sedimentation and the boundaries between primary and secondary structural units, identify the geological stability conditions of the storage body, and follow GB / T 16792 for the division of sedimentary basins and secondary structural units; Predicting effective volume of saline aquifer reservoirs.

[0018] In actual implementation, the geological conditions of the designated storage target area must at least meet the following requirements: The exploration accuracy of reservoir caprock structure reaches 1:50000-1:100000; The saline water reservoir is refined into rock stratigraphic unit sections to identify the lithology and physical properties of the saline water reservoir, and the fracture system is identified when fractures are developed in the reservoir; Identify the fluid properties, temperature, and pressure system of the brine aquifer reservoir; Identify the lithology and physical properties of the caprock, as well as the dissolution characteristics of the CO 2 -water-rock reaction; Understand the local faults that control the boundaries of the third-level tectonic units of the sedimentary basin, and identify the geological stability conditions of the storage body; Understand the exploration and development of important mineral resources for the configuration of carbon dioxide storage and mineral resource development.

[0019] In actual implementation, the geological conditions of the identified storage site should at least meet the following requirements: The exploration accuracy of the structural morphology of the reservoir and caprock reaches 1:5000 - 1:10000; Refine the rock-stratigraphic units of the brine aquifer reservoir to sand member or sand bed, and understand their petrophysical and chemical properties; Identify the fluid properties, temperature, and pressure system of the brine aquifer reservoir, as well as the dissolution and mineralization characteristics of carbon dioxide; Identify the petrophysical and chemical properties of the caprock, as well as the dissolution characteristics of the CO 2 -water-rock reaction; Understand the characteristics of the faults controlling the local structure and associated and minor faults, and identify the geological stability conditions of the storage body; Understand the exploration and development of important mineral resources for the configuration of carbon dioxide storage and mineral resource development, and avoid the risk of carbon dioxide leakage caused by mineral resource development and abandoned wells.

[0020] In the present invention, the storage site should meet the following site selection requirements: The geological conditions should meet the following reservoir conditions, caprock conditions, and geological stability conditions of the storage body, where: The reservoir conditions include: the depth of the brine aquifer reservoir is greater than 800 m, or the actual formation pressure and temperature measured by drilling can meet the requirements for carbon dioxide to reach the supercritical state after injection; when statistically analyzed in units of formation, section, or sand member according to the stratigraphic sequence, the single-layer thickness of the brine aquifer reservoir is greater than 1 m, and the superimposed thickness is greater than 5 m; the average effective porosity of the brine aquifer reservoir is higher than 5%, and the average permeability is higher than 1×10 -3 μm 2 ; according to the relevant regulations of GB / T14157 on the total salinity of underground brine and underground salt water, from the perspective of protecting underground water resources, the total salinity of the groundwater in the brine aquifer reservoir is greater than 8 g / L; the brine aquifer reservoir has a semi-closed or closed hydrogeological structure, and the groundwater alternation is slow; The caprock conditions include: the clay mineral content of the caprock is higher than 30% and does not contain minerals such as feldspar and carbonate rock, in order to reduce the CO 2- Water-rock reaction corrosion; in addition to a relatively good direct caprock, there is a secondary caprock with a certain thickness developed above the direct caprock in the saline aquifer reservoir. The geological stability conditions of the storage body include: the factor of active faults needs to be considered. According to the regulation in GB17741 that the near-field range of the seismic safety evaluation work for Class I sites should extend to a radius of 25 km, and the seismic tectonic classification principle in the "China Seismic Tectonic Environment Exploration Plan", there are no primary fault zones (fault zones active at the boundaries of Class I and Class II blocks) and secondary faults (faults active within Class II blocks, generally controlling tectonic units) within 25 km of the vertical projection distribution of the saline aquifer reservoir on the surface, and no tertiary faults (small-scale active faults and Quaternary faults of a certain scale within Class I and Class II blocks) within 5 km; the factor of the peak ground acceleration of regional seismic motion needs to be considered. The peak ground acceleration of regional seismic motion within the vertical projection distribution range of the saline aquifer reservoir on the surface is less than or equal to 0.15 g, and it is specifically implemented in accordance with the provisions of GB18306.

[0021] In addition, the mutual feedback conditions of resource development and the ground technical and economic conditions should also be considered, and they meet the following requirements, where: The mutual feedback conditions of resource development include: Site exploration and subsequent carbon dioxide injection should not violate China's existing legal system for mineral resource management and important policy regulations. The storage site should minimize the mutual feedback degree with deep resource development, or be able to propose scientific safeguard measures such as the priority order, monitoring and early warning, and emergency response.

[0022] The ground technical and economic conditions include: The site ground use does not conflict with the control requirements of the "Three Zones and Three Lines" of the national territorial space; the selection of the site ground use is implemented in accordance with GB18598 and is far from crowded places; on the premise of having a carbon source target, the source-sink distance should be shortened as much as possible, and the carbon dioxide transportation conditions are better.

[0023] In the present invention, the storage prospective area, the storage target area, and the storage site should respectively meet the potential requirements of the prediction level, the control level, and the proven level, where: The potential requirement of the prediction level means that the storage prospective area has a prediction technical capacity, and the prediction technical capacity is the storage technical capacity corresponding to the maximum degree of filling of the pore space in the reservoir of the storage prospective area by carbon dioxide. The potential requirement of the control level means that the storage target area has a control technical capacity, and the control technical capacity is the storage technical capacity corresponding to the maximum degree of filling of the pore space in the reservoir of the storage target area by carbon dioxide. The potential requirement of the proven level means that the storage site has a proven technical capacity, and the proven technical capacity is the storage technical capacity corresponding to the maximum degree of filling of the pore space in the reservoir of the storage site by carbon dioxide.

[0024] Assume that the deep saline aquifer has an open hydrogeological boundary and all pore spaces can be filled with carbon dioxide to the maximum extent. The predicted technical capacity and the controlled technical capacity are calculated by the volume method based on the following formula (1): 1) In formula (1): is the storage technical capacity, i.e., the predicted technical capacity or the controlled technical capacity, with the unit of kilogram (kg); is the reservoir area, with the unit of square meter (m 2 ); is the reservoir thickness, with the unit of meter (m); is the reservoir porosity, dimensionless; is the density of carbon dioxide in the reservoir, with the unit of kilogram per cubic meter (kg / m 3 ); is the geological coefficient, dimensionless; is the displacement coefficient, dimensionless.

[0025] The mechanism method takes into account the storage mechanism, and it is difficult to obtain parameters, requiring relatively rich geological data support. It is more suitable for evaluating the storage volume in a specific site or a specific time period.

[0026] The mechanism method includes the structural-stratigraphic trapping method, the bound trapping method, and the dissolution trapping method, among which: If the proven technical capacity is calculated by the mechanism method, the proven technical capacity is the sum of the storage technical capacities calculated by the structural-stratigraphic trapping method, the bound trapping method, and the dissolution trapping method; If the predicted technical capacity and the controlled technical capacity are calculated by the mechanism method, under the condition of an open hydrogeological boundary, the predicted technical capacity and the controlled technical capacity are the sum of the storage technical capacities calculated by the structural-stratigraphic trapping method and the bound trapping method, while under the condition of a closed hydrogeological boundary, the predicted technical capacity and the controlled technical capacity are the sum of the storage technical capacities calculated by the dissolution trapping method and the bound trapping method; Under the action of the structural-stratigraphic trap and the hydrodynamic trap, carbon dioxide is trapped and stored in the saline aquifer. Based on this mechanism, the structural-stratigraphic trapping method calculates the storage technical capacity through the following formula (2): 2) In formula (2): is the storage technical capacity of carbon dioxide trapped by the structural-stratigraphic trapping in the deep saline aquifer, with the unit of kilogram (kg); is the volume of the structural or stratigraphic trap, in cubic meters (m 3 ); is the reservoir porosity, dimensionless; is the irreducible water saturation, that is, the percentage of the volume of water in the rock pores after CO 2 drainage to the pore volume, dimensionless; is the density of carbon dioxide in the reservoir, in kilograms per cubic meter (kg / m 3 ); is the reservoir area, in square meters (m 2 ); is the reservoir thickness, in meters (m).

[0027] During the migration of carbon dioxide in the saline aquifer, part of the carbon dioxide is permanently retained on the mineral surface or remains in the rock pores in a discontinuous state due to the interfacial tension between the gas and liquid phases. Based on this mechanism, the bound trapping method calculates the sequestration technology capacity through Equation (3) below: The calculation formula is as follows: (3) In Equation (3): is the sequestration technology capacity of bound trapping in the saline aquifer, in kilograms (kg); is the volume of the rock that was originally saturated with carbon dioxide and then invaded by water, in cubic meters (m 3 ); is the saturation of residual carbon dioxide after the liquid flow countercurrent, dimensionless; is the reservoir porosity, dimensionless; is the density of carbon dioxide in the reservoir, in kilograms per cubic meter (kg / m 3 ); The sequestration amount of carbon dioxide dissolved in the formation water of the deep saline aquifer can be regarded as the amount of carbon dioxide that can be dissolved when the original formation water reaches carbon dioxide saturation. Based on this mechanism, the dissolution trapping method calculates the sequestration technology capacity through Equation (4) below: (4) In Equation (4): is the sequestration technology capacity of dissolution trapping of carbon dioxide in the deep saline aquifer, in kilograms (kg)); is the reservoir area, in square meters (m 2 ); is the reservoir thickness, in meters (m); is the reservoir porosity, dimensionless; is the average density of formation water saturated with carbon dioxide, in kilograms per cubic meter (kg / m 3 ); is the density of the initial formation water, in kilograms per cubic meter (kg / m 3 ); is the average mass fraction of carbon dioxide in formation water when the formation water dissolves carbon dioxide and reaches saturation, dimensionless; is the average mass fraction of the original carbon dioxide in formation water, dimensionless; is the solubility of carbon dioxide in formation water, in moles per kilogram (mol / kg); is the molar mass of carbon dioxide, 0.044 kilograms per mole (kg / mol).

[0028] In actual implementation, when the geological parameter uncertainties are large or the geological parameters cannot be accurately obtained, the predicted technical capacity, controlled technical capacity, and proven technical capacity are calculated by the analogy method or the probability method.

[0029] The analogy method refers to using the geological parameters of adjacent areas to calculate the storage technical capacity, or in other words, the storage technical capacity of adjacent areas can be borrowed by analogy. In addition, average values can also be used for calculation.

[0030] The probability method determines the variation range of the effective reservoir area based on structures, reservoirs, formation and lithology boundaries, sedimentary facies, etc. It can also determine the variation ranges of the effective thickness and effective porosity based on geological conditions, lower limit standards, well logging interpretations, etc. Of course, it can also obtain the cumulative probability curve of the storage technical capacity based on the variation range of calculation parameters, and estimate the storage technical capacity according to the required probability value.

[0031] The analogy method and the probability method are common methods in this field.

[0032] In addition, the calculation of the predicted technical capacity, controlled technical capacity, and proven technical capacity should follow the following principles: When evaluating the technical capacity of a sedimentary basin or geological structure unit, the calculation area of the predicted and controlled technical capacity shall not be greater than 5 km × 5 km; The calculated area for exploring the technical capacity shall not be greater than 1 km × 1 km. Among them, when the area is relatively small, the calculation accuracy should be appropriately improved; Calculation shall be carried out vertically upward, and separate calculation units shall be divided for saline aquifer reservoirs with different lithologies and reservoir characteristics; The technical capacity evaluation shall be carried out in sequence from low to high levels. If the potential level of a higher level is calculated, the calculation of lower levels shall no longer be carried out. However, when there are significant differences between the understanding obtained from new exploration or engineering injection practices and the original evaluation results, or even when the project fails, the technical capacity evaluation work shall be carried out again.

[0033] In actual implementation, the following acquisition methods are given for some of the above key parameters.

[0034] Geological coefficient E geol , which is the reservoir area for effectively sequestering carbon dioxide A , thickness h and porosity φ, reflects the spatial heterogeneity characteristics of the reservoir and is calculated based on the following formula (5): E geol =E An / At •E hn / hg •E φe / φtot 5) In formula (5): E An / At is the effective coefficient of the reservoir area, which is the ratio of the reservoir area that can effectively and appropriately sequester carbon dioxide to the total reservoir area; E hn / hg is the effective coefficient of the reservoir thickness, which is the ratio of the reservoir thickness that can effectively and appropriately sequester carbon dioxide to the total reservoir thickness; E φe / φtot is the effective coefficient of the reservoir porosity, which is the ratio of the porosity that can effectively and appropriately sequester carbon dioxide and is interconnected to the total porosity.

[0035] When the reservoir is an ideal homogeneous reservoir, the geological coefficient = 1. With the continuous improvement of the geological understanding degree in the reservoir exploration stage, E An / At , E hn / hg , E φe / φtot and E geol gradually increase and get closer to 1.

[0036] Displacement coefficient E sweep , which is the volume displacement coefficientE V and the microscopic displacement coefficient E d The product of reservoir physical properties, water chemistry, pressure, temperature, relative permeability, etc. will all affect the value of the displacement coefficient. E sweep The displacement coefficient E sweep is calculated based on Equation (6) below: 6) In Equation (6): is the volumetric displacement coefficient, which is the ratio of the reservoir volume with carbon dioxide distributed within the effective thickness to the total reservoir volume due to the density difference between carbon dioxide and formation water; is the microscopic displacement coefficient, which is the proportion of the pore space in the reservoir where carbon dioxide cannot be sequestered due to the immobility of in-situ fluids.

[0037] CO 2 density. The density of carbon dioxide in the brine reservoir is a function of temperature and pressure, and can be obtained by looking up the table.

[0038] Example: If the temperature of the brine reservoir is 90 °C and the pressure is 25 MPa, then by looking up the table, the density of carbon dioxide in the brine reservoir is approximately 645 kg / m 3 .

[0039] CO 2 solubility R CO2 , the solubility of carbon dioxide in pure water decreases with increasing temperature and increases with increasing pressure. The solubility of carbon dioxide in brine decreases with increasing salinity, and can be calculated by referring to the solubility diagram of carbon dioxide in pure water (IPCC 2005) and using Equation (7) below: 7) In Equation (7): is the solubility of carbon dioxide in pure water, with the unit of kg / 100 kg of water.

[0040] is the salinity of the initial brine, with the unit of %.

[0041] Example: If the reservoir temperature of the saline aquifer is 90 °C, the pressure is 25 MPa, and the initial salinity of the saline water is 5%, first, the solubility of carbon dioxide in pure water at a temperature of 90 °C and a pressure of 25 MPa can be obtained by referring to the solubility diagram of carbon dioxide in pure water (IPCC 2005). The solubility of carbon dioxide in pure water is approximately 5.40 kg / 100 kg of water. Then, the solubility of carbon dioxide in saline water can be calculated by Equation (7) to be approximately 4.24 kg / 100 kg of water.

[0042] CO 2 Saturation, after the liquid countercurrent in the mechanism of trapped gas in the deep saline aquifer, the trapped CO 2 Estimation of saturation (residual gas saturation). Generally speaking, the residual gas saturation in sandstone reservoirs will increase with the following conditions: decrease in porosity; reduction in sorting and particle size; increase in viscosity; increase in clay content.

[0043] If there is no core, the residual gas saturation is a variable that is difficult to estimate. For regional work, the calculation method seems to be limited. Usually, its value is limited within the range of 0.05 - 0.95. In addition, it can be obtained according to the empirical method included in Holtz (2003).

[0044] The advantages of the present invention are: The present invention provides a method for screening suitable storage sites for carbon dioxide sequestration in the deep saline aquifers of terrestrial sedimentary basins. The storage sites selected by the present invention can implement large-scale and safe carbon dioxide sequestration, with good sequestration effects and being suitable for popularization. The present invention is applicable to the site selection of carbon dioxide geological sequestration in deep saline aquifers within terrestrial sedimentary basins.

[0045] The above is the preferred embodiment of the present invention and the technical principles applied. For those skilled in the art, any obvious changes such as equivalent transformations and simple substitutions based on the technical solution of the present invention without departing from the spirit and scope of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin, characterized in that: Includes steps: Step 1: Survey stage: Conduct geological surveys in the area to be sealed and identify storage prospective areas, which meet the potential requirements of the prediction level. The area to be sealed is a sedimentary basin or a geological structural unit in a sedimentary basin, and the sedimentary basin is composed of multiple geological structural units. Step 2: Detailed investigation stage: Conduct geological surveys in the storage prospective area to find the trap structures and geological conditions that are conducive to CO2 storage. Through the drilling of pilot wells, combined with the exploration and development of important mineral resources, configure CO2 storage and mineral resource development, and delineate the storage target area, which meets the potential requirements of the control level; Step 3: Exploration stage: Conduct geological surveys in the storage target area, conduct supplementary drilling under the conditions of wellbore anti-corrosion and leakage, combine the exploration and development of important mineral resources, configure carbon dioxide storage and mineral resource development to avoid the risk of carbon dioxide leakage caused by mineral resource development and abandoned drilling, delineate the storage site, and determine the carbon dioxide injection layer. The storage site meets the potential requirements of the proven level; Step 4: Complete the storage site selection.

2. The method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin according to claim 1, characterized in that: During the survey stage, geological surveys are conducted on the following contents: basement characteristics of the area to be sealed and its contact relationship with the basin and mountain range, the division of secondary tectonic units and their basic forms; sedimentary rock stratigraphic sequence, including the lithology, sedimentary environment and sedimentary facies of sedimentary rock strata below 800m in depth; formation pressure and geothermal field characteristics; hydrogeological conditions, including the physical and chemical properties of aquifers below 800m in depth; crustal stability, historical earthquake information, including the development of faults and their activity; deep energy mineral deposits and development characteristics and exploration and development conditions; The geological survey conducted in the survey stage shall meet the following requirements: complete a 2D seismic survey with a main survey line distance of less than 4 km; refer to the existing deep drilling data of other mineral resources within a range of 100 km × 100 km, and core the target layer or the well wall; perform core and water chemical analysis; During the detailed investigation stage, geological surveys are conducted on the following contents: the distribution, type and characteristics of saline water layer sealing closures in the sealing prospective area; the lithology, thickness, physical properties and distribution continuity of the saline water layer reservoir, and the physical and chemical properties of groundwater; the lithology, thickness, physical properties and distribution continuity of the cap rock; the characteristics of the formation pressure and geothermal field; the development and activity of faults; the development characteristics of deep energy mineral deposits and the exploration and development status; The geological survey conducted in the detailed survey stage meets the following requirements: 2D seismic detailed survey has been completed, with the main survey line distance less than 2km; representative cores of the saline layer section of the pre-exploration well within the range of 20km×20km; fluid properties, temperature and pressure data have been obtained through well testing; During the exploration phase, geological surveys are conducted on the following: reservoir conditions, including detailed characterization of the physical and chemical properties and heterogeneity characteristics of the target saline aquifer, the formation temperature, formation pressure and hydrodynamic characteristics of the saline aquifer; geological stability conditions of the storage body, including detailed characterization of the physical and chemical properties of the caprock, the development of fractures and their distribution continuity, and the development and properties of faults; environmental risks, including the tightness of abandoned wells and wellbores, the development and properties of faults, and the conditions of environmentally sensitive areas; resource development feedback conditions, including shallow groundwater, coal resources, oil and gas resources, geothermal resources and brine resources; ground technical and economic conditions, including the development of geological disasters, the development of tectonic fissures, urban development boundaries, permanent basic farmland, ecological protection red lines and carbon dioxide transport conditions; The geological surveys conducted in the exploration phase meet the following requirements: a two-dimensional seismic network or three-dimensional seismic exploration within a range of no more than 1km×1km has been completed; drilling evaluation has been completed within a range of 5km×5km, and the target reservoir caprock has at least one complete coring profile; the fluid properties, temperature and pressure data of the quasi-injection layer have been obtained; and a carbon dioxide injection test with an annual storage scale of 100,000 tons or more has been completed.

3. The method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin according to claim 1, characterized in that: The geological conditions of the designated storage prospective area shall at least meet the following requirements: The exploration accuracy of the target saline reservoir and cap rock structure is 1:100000-1:250000; The saline water reservoir is refined into rock stratigraphic unit groups, which can clarify the lithology of the target saline water reservoir; Understand the regional faults that control basin sedimentation and the boundaries between primary and secondary structural units, and identify the geological stability conditions of the storage body; Predicting effective volume of saline aquifer reservoirs.

4. The method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin according to claim 1, characterized in that: The geological conditions of the designated storage target area shall at least meet the following requirements: The exploration accuracy of reservoir caprock structure reaches 1:50000-1:100000; The saline water reservoir is refined into rock stratigraphic unit sections to identify the lithology and physical properties of the saline water reservoir, and the fracture system is identified when fractures are developed in the reservoir; Identify the reservoir fluid properties, temperature and pressure system of saline aquifers; Identify the lithology and physical properties of the caprock, as well as the CO2-water-rock reaction dissolution characteristics; Understand the local faults that control the boundaries of the third-level structural units of the sedimentary basin and find out the geological stability conditions of the storage body; Understand the exploration and development status of important mineral resources for the purpose of allocating carbon dioxide storage and mineral resource development.

5. The method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin according to claim 1, characterized in that: The geological conditions of the designated storage site shall at least meet the following requirements: The exploration accuracy of reservoir caprock structure reaches 1:5000-1:10000; The rock stratigraphic units of saline reservoirs are refined to sand groups or sand layers to understand their rock physicochemical properties; Identify the reservoir fluid properties, temperature and pressure system, and CO2 dissolution and mineralization characteristics of saline aquifers; Identify the physical and chemical properties of the caprock and the CO2-water-rock reaction dissolution characteristics; Understand the characteristics of the faults and associated faults and small faults that control the local structure, and find out the geological stability conditions of the storage body; Understand the exploration and development status of important mineral resources to configure carbon dioxide storage and mineral resource development, and avoid the risk of carbon dioxide leakage caused by mineral resource development and abandoned drilling.

6. The method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin according to claim 1, characterized in that: The storage site meets the following site selection requirements: The geological conditions meet the following reservoir conditions, cap rock conditions and geological stability conditions of the sealing body, among which: The reservoir conditions include: the depth of the saline water reservoir is greater than 800m, or the actual formation pressure and temperature measured by drilling can meet the supercritical state after carbon dioxide injection; when statistically analyzed in groups, sections or sand layers according to the stratigraphic sequence, the single layer thickness of the saline water reservoir is greater than 1m, and the stacked thickness is greater than 5m; the average effective porosity of the saline water reservoir is higher than 5%, and the average permeability is higher than 1×10 -3 μm 2 ; The total mineralization of groundwater in the saline aquifer reservoir is greater than 8g / L; The saline aquifer reservoir is a semi-closed or closed hydrogeological structure; Cap rock conditions include: the clay mineral content of the cap rock is higher than 30% and it cannot be rich in feldspar and carbonate minerals; in addition to the direct cap rock, the saline reservoir has a secondary cap rock developed above the direct cap rock; The geological stability conditions of the sealing body include: there are no primary fault zones and secondary faults within 25km of the vertical projection distribution of the saline water layer reservoir on the surface, and there are no tertiary faults within 5km; the regional seismic peak acceleration within the vertical projection distribution range of the saline water layer reservoir on the surface is less than or equal to 0.15g.

7. The method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin according to claim 1, characterized in that: The storage prospect area, the storage target area and the storage site meet the potential requirements of the prediction level, the control level and the proven level respectively, wherein: The potential requirement of the predicted level means that the storage prospect area has the predicted technical capacity, and the predicted technical capacity is the storage technical capacity corresponding to the maximum extent that the pore space in the reservoir of the storage prospect area can be filled with carbon dioxide; The potential requirement of the control level means that the storage target area has a control technology capacity, and the control technology capacity is the storage technology capacity corresponding to the maximum extent that the pore space in the reservoir of the storage target area can be filled with carbon dioxide; The proven potential requirement means that the storage site has a proven technical capacity, which is the storage technical capacity corresponding to the maximum extent to which the pore space in the reservoir of the storage site can be filled with carbon dioxide.

8. The method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin according to claim 7, characterized in that: The predicted technical capacity and the controlled technical capacity are calculated by the volumetric method based on the following formula 1): 1） In formula 1): To store technical capacity; is the reservoir area; is the reservoir thickness; is the reservoir porosity; is the density of carbon dioxide in the reservoir; is the geological coefficient; is the displacement coefficient.

9. The method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin according to claim 7, characterized in that: The mechanism method includes structural stratum capture method, restraint capture method and dissolution capture method, among which: If the proven technical capacity is calculated by the mechanism method, then the proven technical capacity is the sum of the storage technical capacities calculated by the tectonic formation capture method, the restraint capture method and the dissolution capture method; If the predicted technical capacity and the controlled technical capacity are calculated by the mechanism method, then under open hydrogeological boundary conditions, the predicted technical capacity and the controlled technical capacity are the sum of the storage technical capacities calculated by the structural stratum capture method and the restrained capture method, while under closed hydrogeological boundary conditions, the predicted technical capacity and the controlled technical capacity are the sum of the storage technical capacities calculated by the dissolution capture method and the restrained capture method; The structural formation capture method calculates the storage technical capacity by the following formula 2): 2） In formula 2): To store technical capacity; is the volume of structural or stratigraphic trap; is the reservoir porosity; is the residual water saturation; is the density of carbon dioxide in the reservoir; is the reservoir area; is the reservoir thickness; The tethered capture method calculates the storage technology capacity by the following formula 3): The calculation formula is as follows: 3） In formula 3): To store technical capacity; is the volume of rock that was originally saturated with carbon dioxide and then immersed in water; is the residual carbon dioxide saturation after the liquid flow is reversed; is the reservoir porosity; is the density of carbon dioxide in the reservoir; The dissolution capture method calculates the storage technology capacity by the following formula 4): 4） In formula 4): To store technical capacity; is the reservoir area; is the reservoir thickness; is the reservoir porosity; is the average density of formation water when it is saturated with carbon dioxide; is the initial formation water density; The average mass fraction of carbon dioxide in formation water when the formation water dissolves carbon dioxide and reaches saturation; is the average mass fraction of original carbon dioxide in formation water; is the solubility of carbon dioxide in formation water; is the molar mass of carbon dioxide.

10. The method for selecting a site for geological storage of carbon dioxide in a saline aquifer in a terrestrial sedimentary basin according to claim 7, characterized in that: When the geological parameters cannot be accurately obtained, the prediction technology capacity, the control technology capacity, and the exploration technology capacity are calculated by analogy or probability method.

Images