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.