RETRACTED: Impact of CO2 injection in deep saline aquifers: study on pressure response in stratified formation of Qianjiang depression area, China (Retracted Article)

In order to mitigate the adverse impacts of climate change, CO2 captured from carbon emitters like coal-fired power plants may be stored in deep saline aquifers. This action may cause pressure changes, which affect subsurface volumes. The main purpose of this study is to evaluate the pressure changes during CO2 sequestration in CO2 storage formation embedded in a sequence of aquifers and aquitard of Qianjiang depression area in China. In order to demonstrate the transient pressure, we have conducted TOUGH2 modeling of CO2 injection into closed formations of different thicknesses assuming impermeable boundaries. A 2-D radially symmetric model was developed to represent a CO2 storage site in the Qianjiang depression area. The storage formation into which CO2 was injected is 120 m thick and located at a depth of about 1380m below the ground surface. The CO2 injection thickness was 15m from the bottom of the storage formation. Carbon dioxide was injected into a zone of 77 m radial extent representing a few distributed wells. Injection occurs at an annual rate of 2.488 * 10 (7) tonnes of CO2 representing 16 times the CO2 rate captured from a medium-size-coal-fired power plant. The simulation runs cover a time period of 100 years altogether, comprising the 30-year injection period and a 70-year post-injection period. The pressure buildup results after one year never attains 50% of initial pressure (maximum tolerable pressure buildup). Our simulation results indicate that interlayer pressure propagation through a sequence of aquitard/aquifer will not affect the top aquifer. Moderate pressure increases occur in top aquifer only in case when pore compressibility was reduced by one order of magnitude.