Monitoring CO2 Plume Migration for a Carbon Storage-Enhanced Coalbed Methane Recovery Test in Central Appalachia

During the past decade, carbon capture, utilization, and storage (CCUS) has gained considerable recognition as a viable option to mitigate carbon dioxide (CO2) emissions. This process involves capturing CO2 at emission sources such as power plants, refineries, and processing plants, and safely and permanently storing it in underground geologic formations. Many CO2 injection tests have been successfully conducted to assess the storage potential of CO2 in saline formations, oil and natural gas reservoirs, organic-rich shales, and unmineable coal reservoirs. Coal seams are an attractive reservoir for CO2 storage due to coal's large capacity to store gas within its microporous structure, as well as its ability to preferentially adsorb CO2 over naturally occurring methane resulting in enhanced coalbed methane (ECBM) recovery.

A small-scale CO2 injection test was conducted in Southwest Virginia to assess the storage and ECBM recovery potential of CO2 in a coalbed methane reservoir. The goal of this test was to inject up to 20,000 tons of CO2 into a stacked coal reservoir of approximately 15-20 coal seams. Phase I of the injection test was conducted from July 2, 2015 to April 15, 2016 when a total of 10,601 tons of CO2 were injected. Phase II of the injection was conducted from December 14, 2016 to January 30, 2017 when an additional 2,662 tons of CO2 were injected, for a total of 13,263 total tons of CO2 injected. A customized monitoring, verification, and accounting (MVA) plan was created to monitor CO2 injection activities, including surface, near-surface, and subsurface technologies. As part of this MVA plan, chemical tracers were used as a tool to help track CO2 plume migration within the reservoir and determine interwell connectivity. The work presented in this dissertation will discuss the development and implementation of chemical tracers as a monitoring tool, detail wellbore-scale tests performed to characterize CO2 breakthrough and interwell connectivity, and present results from both phases of the CO2 injection test.