(736c) Post Injection Site Care (PISC) at the Secarb Anthropogenic Test

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 was the largest fully integrated commercial prototype coal-fired carbon capture and storage project in the USA. The demonstration reached the 100,000 metric ton (tonnes) injection milestone and injection operations were terminated in September 2014 after reaching this goal. This paper provides an assessment of the CO₂ injection program and the strategy for site closure. 

Two Underground Injection Control (UIC) Class V Experimental Injection Well permits were issued in November 2011 and the project’s injection wells were installed soon thereafter. Surface and subsurface monitoring was initiated prior to start of injection to establish background conditions and trends and continued throughout the injection period.  The injection target was the lower Cretaceous Paluxy formation that occurs at a depth of 9,400 feet below ground surface. Post injection monitoring will be conducted into 2018 to track in-situ CO₂ movement. 

Per the UIC permit requirements, the Area of Review (AoR) for the injection well was re-evaluated annually since the onset of injection operations via monitoring results and reservoir simulation. The AoR is defined as the region surrounding the geological storage 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.    

The monitoring program was developed and implemented to track the CO₂ plume and the associated pressure field. Methods used to do so include downhole pressure/temperature measurements, surface CO₂ flux, shallow and deep fluid geochemistry, tracers, cross-well seismic, vertical seismic profiling (VSP) and cased-hole geophysical well logs. The results from these monitoring tools were used to inform the reservoir simulation, which is used to render three dimensional assessments of CO₂ position versus time. The simulation results demonstrate effective containment of CO₂ by the reservoir architecture of the formation, consisting of multiple, stacked, highly porous and permeable sandstones, separated by low permeability flow barriers.

Other observations from the reservoir simulation include the following: 1) the dip of the Paluxy Formation influences the migration of mobile CO₂ to a small degree after injection operations cease, 2) the high transmissivity of the Paluxy results in a maximum CO₂ extent that is greater than the extent of significant pressure build up, and 3) consequently, the AoR determination is based on the extent of the CO₂ movement.

Permit closure is contingent on using the monitoring data and modelling assessments to demonstrate that the CO₂ is safely confined within the injection zone and that underground sources of drinking water (USDWs) are not endangered by the fugitive movement of the in-situ CO₂. This presentation will focus on the strategy to acquire PISC data and the model updates to build the case for permit closure.