The SECARB Cranfield project has produced information relevant to long-term storage in saline aquifers, as well as storage incidental to CO2 enhanced oil recovery (EOR). The SECARB project added testing passive pressure in the above-zone monitoring interval (AZMI), supported injection at high rates, and assessed capacity of the downdip brine-bearing part of the system to accept additional CO2 through a ¡ªstacked storage concept.
Capacity-assessment results include a multiphysics assessment of distribution of the CO2 plume in time and space in heterogeneous lithologies. The 20-m-thick sandstones and conglomerates of the lower Tuscaloosa injection zone are predominantly highly permeable strata, but as flow evolved under a changing injection rate, CO2 accessed only preferred paths. Dissolution of CO2 into brine caused methane to come out of solution, which can have a significant impact on capacity where this process is important.
The monitoring program in the reservoir included fieldwide injection and production data, 4-D seismic, downhole pressure and temperature, geochemical sampling, and microseismic monitoring. Focused studies tested real-time pressure and temperature in an AZMI as a tool for detecting nonconformance. At the detailed area of study (DAS) in the downdip water leg, processes at the well- and interwell- scale were measured using electrical, acoustic, geochemical, pressure, pulsed-neutron, and thermal tools. Near-surface deployments included groundwater monitoring and a soil-gas study area. Data collected are still in assessment via numerous collaborations. Modeling by numerous teams is under way so that maximum information can be extracted from observations.