SECARB Field Test for CO₂ Sequestration in Coalbed Methane Reservoirs of the Black Warrior Basin, Alabama

Pashin, Jack¹, Peter Clark², Richard Esposito³ (1) Geological Survey of Alabama, Tuscaloosa, AL (2) University of Alabama, Tuscaloosa, AL (3) Southern Company, Birmingham, AL

Assessment of the CO₂ sequestration and enhanced recovery potential of coalbed methane reservoirs in the Black Warrior basin of Alabama indicates that more than 5.9 Tcf of CO₂ can be sequestered while increasing coalbed methane reserves by more than 20 percent. The Black Warrior coalbed methane fields are approaching maturity, and CO₂-enhanced coalbed methane recovery has potential to add decades of life to these fields.

The Southeastern Regional Carbon Sequestration Partnership (SECARB) will be conducting a field test in the Black Warrior basin, where multiple coal seams are dispersed through a thick stratigraphic section. The permeability of coal decreases exponentially with depth, thus strategies need to be developed to manage injection into multiple coal seams with a broad range of reservoir properties. Reservoir testing will consist of a series of production and injection-falloff tests in three coal zones, and deep monitoring of pressure will be conducted through packer and interference tests in three observation wells. Baseline reservoir simulations will aid in the design of the testing program, and follow-up simulations will be performed for history matching of the results.

Soil-gas composition will be monitored to determine if seepage of injected gas occurs and to facilitate the identification of monitoring protocols that can be applied effectively to commercial injection and enhanced recovery operations. In addition, stochastic reservoir modeling software is being developed to characterize multi-phase flow in fracture networks and to assess environmental risks associated with CO₂ injection and enhanced coalbed methane recovery.