Classification evaluation of the suitability of CO2 storage in Saline Aquifers

Abstract

It is crucial to evaluate the suitability of storing CO₂ in saline aquifers before determining storage locations and implementing efficient CO₂ storage plan. To assess the suitability of CO₂ storage in saline aquifers more quickly and accurately, this study established an evaluation system based on four aspects: salt solution properties, reservoir conditions, cap characteristics, and fault sealing. Grey correlation analysis and the numerical simulation approach were used to identify the primary governing parameters influencing storage effectiveness. Additionally, a categorization system and appropriateness evaluation model for CO₂ storage in saline aquifers were developed. The grading criteria for each influencing factor were defined. The results reveal that: (1) The suitability evaluation index system comprises 9 evaluation factors and 2 evaluation objectives. (2) Reservoir conditions, fault characteristics and saline salinity most significantly influence CO₂ dissolution and sealing capacity. Meanwhile, reservoir permeability, reservoir pressure, cap sealing, and fault characteristics have the greatest impact on CO₂ storage security. (3) By analyzing the relationship between the two evaluation objectives and each index, a comprehensive suitability evaluation factor F was established through weighted summation of the reciprocal of the dissolution storage evaluation factor (R) and storage safety evaluation factor (S) after standardization. (4) Based on F, the suitability of CO₂ storage in saline aquifers can be categorized into three groups: I (0.61–1), II (0.50–0.61), and III (0∼0.50).