Numerical Simulation of CO<sub>2</sub> Storage in Subseabed Sediments in the Shenhu Area, South China Sea: The Effect of Reservoir Permeability Anisotropy
Yongqiang Xia, Peng Gao, Zhibo Jiang, Qi Hua Fan, Rupeng Wei, Qingping Li, Lunxiang Zhang, Tao Yu, Jiafei Zhao, Lei Yang, Yongchen Song
Abstract
CCUS has been an important technological approach to mitigate global warming, and CO 2 storage plays a key role in this process. The ocean is a huge potential carbon sink; therein, CO 2 injected into subseabed sediments will form relatively stable CO 2 hydrate under the appropriate conditions, which is expected to achieve long-term CO 2 storage. Of special interest is that marine sediments are generally anisotropic in permeability; this would significantly affect the resulting storage behavior of CO 2 . In this study, by constructing a large-scale numerical model of CO 2 storage in the South China Sea, we investigated the effect of permeability anisotropy on CO 2 transport and transformation. The results show that the mass of CO 2 stored in the free phase is higher than that in the hydrate phase during the CO 2 storage process; the CO 2 hydrate storage efficiency is larger in reservoirs with large permeability anisotropy values; the increase in R hv expands the horizontal extent of the hydrate cap but restricts the hydrate volume in the vertical zone. In addition, the study proposed a double-layer CO 2 injection method assisted by increasing the vertical pressure to improve the hydrate storage efficiency. These findings provide a scientific basis for CO 2 storage in subseabed reservoirs with permeability anisotropy.