Basin‐scale CO 2 storage capacity assessment of deep saline aquifers in the Songliao Basin, northeast China

Geological storage of CO 2 in deep saline aquifers has become one of the most important methods of reducing the emission of anthropogenic greenhouse gas into the atmosphere. The assessment of potential CO 2 storage capacity is an important part of geological storage design. In this study, the potential CO 2 storage capacity in the deep saline aquifers of the Songliao Basin – a large sedimentary basin in northeastern China – was assessed on a basin scale. The study results showed that: (1) deep saline aquifers suitable for geological CO 2 storage occur mainly in the Cretaceous layers. Six deep saline aquifers were identified as potential storage formations, all with good reservoir‐caprock properties. (2) The residual gas trapping storage capacity and solubility trapping storage capacity of CO 2 were considered for theoretical storage capacity estimation and the total CO 2 storage capacity is 160030.00 × 10-super-6 t in the deep saline aquifers. The effective storage capacity was 19983.89 × 10-super-6 t, 78368.16 × 10-super-6 t and 215512.40 × 10-super-6 t with the storage efficiency factors of 0.0051, 0.02 and 0.055, respectively, and the average value is 104621.50 × 10-super-6 t. Storage intensity is defined as the effectiveness of unit area storage capability and the value of each tectonic unit ranges from 0.21 to 1.10 × 10-super-6 t/km-super-2, with an average storage intensity for the whole Songliao Basin of 0.63 × 10-super-6 t/km-super-2. The saline formations could be used to store CO 2 for at least 55 years with a great CO 2 emission annual growth rate of 10%, and for about 980 years with the CO 2 emission annual growth rate of 1%. (3) Comparative analysis of the deep saline storage capacities in the basin showed that the Northern Plunge area and Central Downwarp area have the highest potential for CO 2 storage in saline aquifer. These results could be used as important guidelines for the selection and design of CO 2 storage fields in the Songliao Basin, China.