Combining brine extraction, desalination, and residual-brine reinjection with CO2 storage in saline formations: Implications for pressure management, capacity, and risk mitigation

Abstract

For industrial-scale CO2 injection in saline formations, pressure increase can be a limiting factor in storage capacity. To address this concern, we introduce Active CO2 Reservoir Management (ACRM), which combines brine extraction and residual-brine reinjection with CO2 injection, contrasting it with the conventional approach, which we call Passive CO2 Reservoir Management. ACRM reduces pressure buildup and CO2 and brine migration, which increases storage capacity. Also, “push-pull” manipulation of the CO2 plume can counteract buoyancy, exposing less of the caprock seal to CO2 and more of the storage formation to CO2, with a greater fraction of the formation utilized for trapping mechanisms. If the net extracted volume of brine is equal to the injected CO2 volume, pressure buildup is minimized, greatly reducing the Area of Review, and the risk of seal degradation, fault activation, and induced seismicity. Moreover, CO2 and brine migration will be unaffected by neighboring CO2 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.