CO₂ storage capacity estimation for a deep saline formation by static reservoir modelling: the Cretaceous Paaratte Formation, offshore Otway Basin, Victoria

Abstract

This study used stochastic simulation to estimate the CO₂ storage capacity of the Cretaceous Paaratte Formation within the Casino 3D seismic survey area of the offshore Otway Basin, Victoria. Besides interpretation results from primary hard data (well data), relative acoustic impedance was used as secondary soft (proxy) data to model the distribution of the volume fraction of shale (V-Shale). The V-Shale model provided an equivalent model of lithofacies for the clastic reservoir. V-Shale correlated well with the net-to-gross and effective porosity parameters in well log interpretation results. Collocated co-kriging was then used to model the distributions of net-to-gross and effective porosity from well profiles by stochastic co-simulation processes. Using the total pore volume (TPV) obtained from this 3D modelling and storage efficiency factors defined by US DOE-NETL (2012), the potential CO2 storage capacity of the Paaratte reservoir is estimated to be between 11.94 million tonnes (P90) and 128.75 million tonnes (P10) within the geographic footprint of the Casino 3D seismic survey area. The expected TPV storage capacity (P50 confidence interval) is 46.82 million tonnes.