Regional screening of saline aquifers in the Malay Basin for CO2 storage

• Identifies best areas of Malay Basin for saline aquifer CO 2 storage. • Pliocene aquifers too shallow, upper Miocene aquifers optimal in centre of basin. • Lower and middle Miocene aquifers optimal at basin margins. • Mostly low net-to-gross formations favouring stacked storage development. • Study advances screening methods for CO 2 storage in geological basins worldwide. The Malay Basin has received significant attention for geological carbon dioxide storage (GCS), but there are no published studies addressing the selection of appropriate deep saline aquifers. This study closes this gap. We process spatial data and use geological modelling and cluster analysis to identify optimal areas for GCS, considering various subsurface characteristics such as temperature, pressure, porosity and thermophysical CO 2 properties. It is found that the basin contains numerous Cenozoic aquifers suitable for GCS including locally thick, but low net-to-gross (NTG), stacked formations. Pliocene aquifers are too shallow to offer storage for CO 2 in large quantities, but upper Miocene aquifers located in the northwest of the basin contain promising intervals with significant porosities and conditions favouring denser CO 2 . Middle Miocene aquifers, while low NTG, are thick, and optimally located around the margins of the basin. They also have significant storage capacity and could be developed as a stacked GCS site. Lower Miocene aquifers are higher NTG, but deeply buried across many areas of the basin, yet the oldest aquifer evaluated still holds substantial storage capacity, where subject to minor burial at the margins of the basin. Overall, this study provides a novel first assessment of aquifer GCS potential in the Malay Basin, while also contributing to wider efforts to evolve screening workflows for other geological basins.