Utilization of a high-temperature depleted gas condensate reservoir for CO2 storage and geothermal heat mining: A case study of the Arun gas reservoir in Indonesia

In this study, field scale reservoir simulations and production history matching are performed to investigate CO2 storage and CO2 heat mining potential in the high-temperature Arun gas condensate reservoir in Indonesia. Our study shows that CO2 injection into the depleted Arun reservoir can produce 51 MMbbl of condensate over 16 years. Afterwards, continuous CO2 injection without any production over 20 years can allow 1.2 Gt of CO2 to be stored by raising the reservoir pressure to the initial value. In addition, subsequent recycling of CO2 can produce substantial amount of geothermal energy for electricity production. Analyses show that at an oil price of $60/bbl, CO2 cost of $30/ton, and a discount rate of 7%, the produced condensate can generate a net present value (NPV) of $1,910 MM. This profit is enough to pay for storing 205 Mt CO2 in two years after condensate recovery. Alternatively, it can be also used to generate 1.1 × 1010 kWh of electricity in seven years through CO2 heat mining. Results, however, are even more encouraging if CO2 cost is zero or negative through CO2 pricing. Furthermore, by applying CO2-enhanced gas recovery (EGR) to all gas condensate reservoirs in Indonesia, we estimate that the low, mid and high values of condensate recovery is 2,100, 2,900 and 3,700 MMbbl, respectively. This, in turn, gives low, mid and high values of 6.6, 7.0 and 7.4 Gt of CO2 storage capacity, respectively. The gas condensate reservoirs have enough capacity to store 45 years of CO2 emission from power and industrial plants in Indonesia if one assumes 45% of the emission is capturable. Additionally, a significant portion of the geothermal resource of 2.06 × 1019 J in the gas condensate reservoirs in Indonesia may be developed by CO2 heat mining after CO2-EGR and CO2 storage.