Eric Mackay

Heriot-Watt University

Is pressure space the most important resource for CO2 storage?

When CO₂ is injected into subsurface formations, native fluids must be displaced. Beyond CO₂ supply, two primary limitations affect storage capacity. First, CO₂ may bypass native fluids and escape the storage complex through operational or abandoned wells, spill points, permeable cap rocks, faults, outcrops, or other geological features. Second, native fluids—particularly brine—may remain trapped, causing pressure to increase beyond the capacity of compression equipment or, more importantly, damaging trapping-rock integrity or reactivating faults.

A third limitation arises when native fluids escape to locations where they cause environmental harm, such as brine migrating into potable aquifers. These risks highlight the need for effective pressure management. We discuss pressure-management strategies and their benefits for CO₂ injection into both saline aquifers and hydrocarbon-bearing formations.