CO2CRC Otway Project, Australia: Parameters Influencing Dynamic Modeling of CO2 Injection into a Depleted Gas Reservoir

Abstract The CO2CRC Otway Project, in Victoria, Australia, is one of the first projects of CO2 storage in a depleted gas reservoir. CO2 injection in the sandstone reservoir, at a depth of 2,000 mSS, started in March 2008 with the objective to inject up to 100,000 tonnes of CO2 over two years. This study compares the level of predictability obtained with different cases depending on the initial data, using the same numerical compositional simulation package. We use recorded data (production and injection) to build a new numerical reservoir model. A dynamic model had already been built before the injection well started (Xu et al., 2006) and was validated by history matching using the gas production data reported. In this paper, we used the same updated static model (Dance et al. 2007) as used for the pre-injection model, which is based on the production data and the data obtained from the injection well (CRC-1). With this updated static model, a different dynamic model is built using injection data and through a newly developed simulator option, which better simulates the CO2-water behavior. The injection rate and pressure data from CRC-1 are now available and the actual breakthrough time – at which the CO2 plume reached the monitoring well (Naylor-1) located 300 m away from CRC-1 – can be history matched. Various relative permeability curves including new laboratory measurements performed on a core taken from the reservoir formation (Waarre C) were used. The results from the updated dynamic modeling using this measured relative permeability data are compared to results using data from literature. In general, experimental measurements for drainage and imbibition processes are not available This study gives a better understanding of the parameters which strongly influence simulated CO2 behavior. It shows the relation between the data availability and prediction reliability.