The CO2CRC Otway Shallow CO2 Controlled Release Experiment: Geological Model and CO2 Migration Simulations

Abstract

CO2CRC is undertaking a feasibility study for a planned CO2 controlled release and monitoring experiment on a shallow fault at the CO2CRC Otway Research Facility. In the first phase of the project, a series of geophysical surveys and groundwater permeability assessments were conducted at the Otway Research Facility to characterise the prospective experimental site and confirm the presence of a shallow fault. The data from the surveys have been integrated into a 3D model of the upper faulted shallow geology of the CO2CRC Otway site. Five properties (hydrostratigraphic unit, horizontal permeability, vertical permeability, fault permeability and P-velocity from refraction tomography) were populated in the 3D grid to produce the final static model. The model has been developed to assist with designing the experiment and conceptualising the shallow stratigraphy and fault structure at the Otway site. Dynamic modelling simulations based on the static model suggest that under certain scenarios it is possible that CO2 could migrate up the fault to the base of the Hanson Plain Sand if injected at approximately 30 m depth. This suggests that the planned fault injection experiment is feasible but additional data is required to validate the geological model and better constrain the modelling simulations.

Keywords: Geological storage; geosequestration; fault; monitoring; fracture