Project assessment and evaluation of the area of review (AoR) at the citronelle secarb Phase III Site, Alabama USA

Abstract

The Southeast Regional Carbon Sequestration Partnership (SECARB) Anthropogenic Test is a demonstration of the deployment of CO2 capture, transport, geologic storage and monitoring technologies. This project is the first and the largest fully integrated commercial prototype coal-fired carbon capture and storage projects in the USA. The demonstration has reached the 100,000 metric ton (tonnes) injection milestone and is in the second year of injection operations. Two Class V Experimental Injection Well underground injection control (UIC) permits were issued in November 2011 and the project's injection wells were installed shortly thereafter. This paper provides an assessment of the CO2 injection program at the SECARB site after the first full year of injection and prior to reaching the milestone of 100,000 tonnes of CO2 injected. The purpose of the project assessment is to re-evaluate the Area of Review (AoR) for the injection well. The AoR is defined as the region surrounding the geological sequestration project that may be impacted by the injection activity. The AoR is further defined as the farthest reach of the tangible CO2 plume and/or the region of 'significant' reservoir pressure increase. An updated geologic model of the injection zones and storage reservoir sandstones incorporates geologic data obtained from the injection well and characterization wells drilled at the Phase III Anthropogenic Test site. The numerical modeling of the injection was conducted using the updated geologic model, plus the monitoring results obtained to August 31, 2013. The simulation demonstrates effective containment of CO2 by the reservoir architecture of the upper Paluxy Formation, consisting of multiple, stacked, highly porous and permeable sandstones, separated by low permeability flow barriers. This CO2 containment, demonstrated in this paper, estimates a CO2 plume radius of 440 feet from the injection well. This value is substantially less than the radius of the AoR from the pre-injection determination of 1,700 feet, which was based on a full three year injection program operating at peak rate (500 tonnes per day). Within this plume radius, the only wells within the AoR are the injection well, the D 9-7 #2, and its permanently abandoned twin, the D 9-7 #2. The nearest well to the injector is the D 9-8 #2. The surface location for this well is 870 feet away from the D 9-7 #2, placing the D 9-8 #2 outside the plume extent. Other key observations from the reservoir simulation of CO2 injection for the period August 23, 2012 to August 31, 2013 include the following. The dip of the Paluxy Formation influences the migration of mobile CO2 to a small degree after injection operations cease. The shallow angle of dip of approximately 1.25 degrees to the northwest limits the post-injection up dip migration. The maximum movement of CO2 is less than 720 ft (220 m) in any direction. The high transmissivity of the Paluxy results in a maximum CO2 extent that is greater than the extent of significant pressure build up. Consequently, the AoR determination is based on the extent of the CO2 movement.