Combining Brine Extraction, Desalination, and Residual-Brine Reinjection with CO_2 Storage in Saline Formations: Implications for Pressure Management, Capacity, and Risk Mitigation

摘要

For industrial-scale CO_2 injection in saline formations, pressure increase can be a limiting factor in storage capacity. To address this concern, we introduce Active CO_2 Reservoir Management (ACRM), which combines brine extraction and residual-brine reinjection with CO_2 injection, contrasting it with the conventional approach, which we call Passive CO_2 Reservoir Management. ACRM reduces pressure buildup and CO_2 and brine migration, which increases storage capacity. Also, "push-pull" manipulation of the CO_2 plume can counteract buoyancy, exposing less of the caprock seal to CO_2 and more of the storage formation to CO_2, with a greater fraction of the formation utilized for trapping mechanisms. If the net extracted volume of brine is equal to the injected CO_2 volume, pressure buildup is minimized, greatly reducing the Area of Review, and the risk of seal degradation, fault activation, and induced seismicity. Moreover, CO_2 and brine migration will be unaffected by neighboring CO_2 operations, which allows planning, assessing, and conducting of each operation to be carried out independently. In addition, ACRM creates a new product, as extracted brine is available as a feedstock for desalination technologies, such as Reverse Osmosis. These benefits can offset brine extraction and treatment costs, streamline permitting, and help gain public acceptance.