In the pursuit of global carbon neutrality, the energy sector is grappling with the challenge of reducing greenhouse gas emissions, primarily CO₂. A recent study published in the journal *Oil and Gas Reservoir Evaluation and Development* offers a promising approach to evaluating the sealing performance of salt-gypsum caprocks in depleted gas reservoirs, a critical factor for secure and long-term CO₂ storage.
Led by Dr. Jiang Beibei from the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation at Southwest Petroleum University, the research team developed a comprehensive evaluation method tailored to salt-gypsum caprocks. These caprocks, known for their low porosity, low permeability, high structural stability, and high breakthrough pressure, are considered promising candidates for CO₂ storage. However, their unique physicochemical characteristics have posed challenges in evaluating their sealing performance.
The team employed the Analytic Hierarchy Process (AHP) to develop a comprehensive evaluation index system, considering key influencing factors such as macro indicators, micro indicators, and breakthrough pressure. They defined four grading levels for each index and determined the influence weight of each index on the sealing performance of salt-gypsum caprocks. By integrating the Fuzzy Comprehensive Evaluation Method, they calculated the total weight for evaluating the sealing performance of these caprocks for CO₂ storage.
Dr. Jiang Beibei explained, “Our method provides a more accurate and reliable way to evaluate the sealing performance of salt-gypsum caprocks, which is crucial for the safe and effective implementation of Carbon Capture and Storage (CCS) technology.”
The research team applied their method to the Gaoshiti-Moxi block in the Sichuan Basin, a region with significant potential for CO₂ storage. The results revealed that the total weight of the sealing performance evaluation of the caprocks in this area ranged from [2.5,3.0), corresponding to a grade of “relatively good.” This indicates a relatively strong capacity for CO₂ storage, suggesting that the site is suitable for future CCS technology application.
The implications of this research are significant for the energy sector. As Dr. Liu Jiabo from the Engineering Technology Research Institute at PetroChina Southwest Oil & Gasfield Company noted, “This study provides technical guidance for site selection and storage safety evaluation of CO₂ storage in depleted gas reservoirs with salt-gypsum caprocks. It can help energy companies make informed decisions about where to invest in CCS technology, ultimately contributing to the global effort to reduce greenhouse gas emissions.”
The research published in *Oil and Gas Reservoir Evaluation and Development* marks a significant step forward in the field of CO₂ storage. By providing a reliable method for evaluating the sealing performance of salt-gypsum caprocks, it opens up new possibilities for the safe and effective implementation of CCS technology, a crucial component in the global strategy to achieve carbon neutrality.