Assessing a basin's potential for geological sequestration of carbon dioxide: an example from the Mesozoic of the Petrel Sub-basin, NW Australia

Abstract

Assessing the suitability of a sedimentary basin for CO2 sequestration requires detailed geological and geophysical studies. An example is presented from the Mesozoic succession of the Petrel Sub-basin. Two stratigraphic intervals were investigated as potential Environmentally Sustainable Sites for CO2 Injection (ESSCI): the Plover ESSCI (Plover and Elang formations, sealed by the Frigate Formation) and the Sandpiper ESSCI (Sandpiper Sandstone, sealed by the Bathurst Island Group). The Plover ESSCI reservoirs are laterally extensive, fluvial to deltaic sand bodies that are likely to have an excellent degree of interconnectivity. The Sandpiper ESSCI reservoirs are predominantly shoreface sand bodies, in which the interconnectivity depends on the degree of shoreface attachment, but is thought to be moderate to excellent. Reservoir quality, as indicated by detailed petrology, is considered to be good. The Bathurst Island Group regional seal has good to excellent seal potential, with the capability to withhold an average CO2 column height of 400 m. A geomechanical assessment indicates that the orientation of W-WNW, NNW-NNE and NE- trending faults near the basin margin would permit their reactivation within the inferred stress regime. However, most of these faults occur outside the potential CO2 containment area. The potential CO2 storage capacity is vast, in the order of several thousand Megatonnes (100s of TCF) of CO2 . This study illustrates how basin-scale geological sequestration may provide a technical solution to the problem of reducing greenhouse gas emissions.