Numerical simulation of enhancement in CO2 sequestration with various water production schemes under multiple well scenarios

To determine the best CO2 injection and brine production strategy for achieving both the optimal water production and the optimal CO2 storage capacity while maintaining operational safety in CO2 enhanced brine production, three injection scenarios based on the typical geological parameters of the Junggar Basin in China are compared. They are the sole CO2 injection, sole water production and combined CO2 enhanced water recovery, and for the combined CO2 enhanced water recovery scenario, both the co-production of brine and pre-production of brine are considered. It is found that compared to the pre-production of brine, the combination of pre- and co-production of brine can be more effective in controlling the pressure perturbation and in increasing the CO2 storage capacity. However the volume of co-produced brine plays a smaller role in the pressure build-up. The influence of number of pumping wells is also analyzed. Although increasing the number of wells can enhance the CO2 storage, the economic analysis reveals that the revenue in water production and CO2 storage cannot compensate the expensive investment required in well drilling. The injection strategy is essential to the efficiency of CO2 enhanced water recovery; this paper compares the strategies for pre-production and co-production of brine on CO2 enhanced shale gas recovery. The conclusions given in this paper can serve as a reference for the design engineers interested in CO2 storage with co-production of brine.