A study of the potential of field-scale of CO₂ geological storage and enhanced water recovery in the eastern Junggar area of Xinjiang

CO₂ geological storage combined with saline recovery (CO₂-EWR) is considered to be one of the effective storage methods. Taking the lead in carrying out CO₂-EWR technology in the eastern Junggar of Xinjiang can achieve CO₂ emission reduction and mean while produce saline water, which can alleviate the local water resources shortage problem to a certain extent, and obtain dual benefits of environment and economy. Previous research mainly focused on generalized models, and the support of engineering practices is lacking. Based on the evaluation results of the suitability of CO₂ source - sink matching in the eastern Junggar Basin and the geological data of the first CO₂-EWR field pilot test site in China, a 3D heterogeneous model of the Xishanyao Formation of the CO₂-EWR test site in the eastern Junggar Basin is constructed to study the potential of the CO₂-EWR technology. The results show that the the oretical storage capacity of CO₂ at the test site is 1.72 × 10⁶ (P₅₀) tons, and the dynamic storage capacity is 2.14 × 10⁶ tons. When the CO₂-EWR technology is adopted, the CO₂ dynamic storage capacity can reach 11.18 × 10⁶ tons, which is 5.22 times the CO₂ geological storage only, and may increase the production of the saline water resources by 10.17 × 10⁶ tons with a mass ratio of 1 to 0.91 of CO₂ sweeping out saline water. Meanwhile, the CO₂-EWR technology can effectively slow down the accumulation of reservoir pressure caused by the massive injection of CO₂, improve the efficiency of CO₂ storage, and increase the saline water production potential. This study can provide theoretical basis and technical support for the implementation of large-scale CO₂ geological storage combined with deep saline water production project in the eastern Junggar of Xinjiang.