Active pressure management through brine production for basin-wide deployment of geologic carbon sequestration

In order for carbon capture and storage (CCS) to have a significant impact on anthropogenic carbon emissions, large volumes of carbon dioxide (CO₂) will need to be captured and stored in the subsurface. It is therefore likely that multiple storage operations will access the same storage reservoir, leading to the potential for overlapping pressure responses. Pressure management through brine production is an approach to reduce the pressure response of injection operations, concomitantly reducing the potential for overlap. In this study numerical modeling is used to simulate the basin-wide deployment of CCS in the Illinois Basin, USA to determine the potential impact of brine production on pressure increase at the injection wells and the Areas of Review (the area that the US Environmental Protection agency deems at risk for CO₂ and brine leakage; AoR) of the injection operations. The results show that brine production can reduce the combined size of AoRs by about one order of magnitude, if a volume of brine equivalent to the volume of injected CO₂ is produced. Sites with low injection rates and/or favorable storage properties (i.e., high permeability and porosity, large thickness and depth) may not need pressure management, if the critical pressure is only exceeded within the CO₂ plume. Injection of CO₂ at locations with favorable storage properties leads to a combined AoR 30% smaller than if the injection sites are co-located with large stationary sources. However, pipeline networks would need to be developed to transport CO₂ from the sources to the injection sites. If the produced brine is to be disposed through reinjection into the subsurface, the reinjection formation needs to be hydraulically isolated from the storage formation, as to not negate the effect of pressure management. The results also show that injectivity does not seem to be a major issue in the Illinois Basin, with only four out of 54 hypothetical CCS sites exceeding the allowable pressure increase set to prevent injection-induced seismicity. Unfortunately, brine production is not an effective strategy to control the maximum pressure increase at the four sites, so that a reduction in injection rates is necessary. If the injections occur at locations more favorable for injection, pressures are well below the maximum allowable levels, while maintaining the same basin-wide injection rates.