Numerical study of CO2 geological storage combined with saline water recovery and optimization of injection-production schemes in eastern Junggar Basin of China

The industrial development of Xinjiang is facing serious carbon emissions and water shortage problems in this region. It is urgent to find a sustainable development way. CO2 geological storage combined with enhanced water recovery (CO2-EWR) is a win-win technology that can increase CO2 geological storage potential and obtain abundant groundwater resources meanwhile. A 3D heterogeneous geologic model was built to estimate the potential of field-scale CO2 geological storage combined with enhanced water recovery according to the seismic, well logging data and well testing data of the Cretaceous Donggou Formation in the eastern Junggar Basin of China. Twelve injection-production scenarios were designed. The results show that CO2-EWR technology can greatly reduce the pressure buildup with the minimum pressure increase of 1.3 MPa and thus increase CO2 injection with a maximum cumulative amount of 100 Mt, three times more than that for sole CO2 injection. Also, it can enhance total production of deep saline water by a factor of similar to 100 compared to that for sole water production. Formation parameters such as permeability, porosity and slope of the reservoir primarily control the migration and dissolution of CO2. The heterogeneity of the reservoir plays an important role in the CO2 spatial distribution and even saline water production. One injection well with constant rate injection of CO2 and one production well with constant pressure production of saline water scenario is the preferred option in engineering practice of eastern Junggar Basin, which can obtain the maximum amount of CO2 injection and saline water resources. This study provides a technical reference for implementation of CO2-EWR at the field-scale or industrial-scale to solve CO2 emission reduction and water shortage problems.