Assessment of the Geological Storage Potential and Suitability of CO2 in the Deep Saline Aquifers in the Northwest Plain of Shandong Province, China

Carbon capture and storage (CCS) technology is a crucial and effective tool to achieve China's dual carbon goals. The primary locations suitable for underground CO2 storage include depleted oil and gas reservoirs, deep saline aquifers, and deep unmineable coal seams. Among these, deep saline aquifers are widely distributed in most of the world's sedimentary basins, and they offer significant advantages-such as substantial storage capacity, well-established technology, high safety standards, and cost effectiveness-making them crucial geological reservoirs for carbon dioxide storage. In comparison to foreign countries' projects on CO2 capture, utilization, and storage (CCUS) technology, China's initiatives have been implemented more recently, and no research has been conducted on the geological storage of CO2 in the deep saline aquifers within the study area. In this study, we systematically analyzed the key factors for the geological storage of CO2 in saline reservoirs within the northwest plain of Shandong Province: the Paleogene Shahejie Formation saline aquifer, and the lower reservoir of the Minghuazhen Formation saline aquifer located east of the Zhanhua-Lijin-Dongying line. The CO2 geological storage potential of these aquifers was assessed using the evaluation methodology of the United States Department of Energy, yielding a result of 30.355 billion tons. An evaluation index system of CO2 geological storage suitability was established. Evaluation indices for regions in the study area were assigned according to this evaluation index, and the score and grade of each unit were obtained. The results indicated that the Huimin latent fault depression, Dongying latent fault depression, Dezhou latent fault depression, and Dongming-Shenxian latent fault depression are suitable prospective areas for CO2 geological storage in the saline aquifers of Shandong Province's northwest plain.