<p>CO<sub>2</sub> geological storage (CGS) proved to be an enormously significant mid-to-long-term solution for mitigating and even nullifying the net greenhouse gas emissions, and CO<sub>2</sub>-enhanced water recovery (CO<sub>2</sub>-EWR) technology may improve the efficiency of CO<sub>2</sub> injection and saline water production with potential economic value as a means of storing CO<sub>2</sub> and supplying cooling water to power plants. The strata with dip-angle are common in nature, because of the effects of geological structure and diagenesis. It is of great significance to study the influence of the dip-angle on the efficiency and safety of CO<sub>2</sub>-EWR. Based upon the typical formation parameters of the China Geological Survey CO<sub>2</sub>-EWR test site in the eastern Junggar Basin, a series of three-dimensional (3D) injection-extraction models with fully coupled wellbores and reservoirs were established to evaluate the effect of dip-angle on the enhanced efficiency of CO<sub>2</sub> storage and saline production, considering geochemical reactions. Numerical simulation results show that the dip-angle has a regular influence on the formation pressure field, the CO<sub>2</sub> transport distance in the reservoir and the CO<sub>2</sub> sealing capacity, and the influence of dip-angle strata on the total storage amount of CO<sub>2</sub> changed in a non-monotone mode compared with the CO<sub>2</sub> geological storage in horizontal strata at the same injection condition. The effect of water chemical characteristics on the migration of CO<sub>2</sub> in different phases and the transformations of major sequestered carbon minerals were determined from the resulting mechanism. Because non-horizontal strata are predominant in deep saline aquifers in nature, regardless of the influence of formation dip, CO<sub>2</sub> leakage risks in geological storage will be greatly underestimated, and the stratum dip angle must be considered in research related to CO<sub>2</sub> geological storage. Overall, the results of analysis provide a guide and reference for the CO<sub>2</sub>-EWR site selection.</p>
Study on Field-scale of CO2 Geological Storage Combined with Saline Water Recovery: A Case Study of East Junggar Basin of Xinjiang
