Paper No. 7
Presentation Time: 9:00 AM-6:30 PM
USING CARBON ISOTOPES TO MONITOR CO2 AT THE CONSOL ENERGY INC. COAL SEQUESTRATION PILOT TEST SITE IN WEST VIRGINIA, USA
The use of carbon isotopes is one of the most effective ways for monitoring, verification and accounting (MVA) of injected CO2 as carbon forms part of the CO2 molecule itself. The study focuses on using carbon isotopes to understand CO2 dissolution, monitoring CO2 plume migration, and identifying the presence/absence of CO2 leakage into overlying formations and shallow subsurface at the CONSOL Energy Inc. sequestration test site located in Marshall County, West Virginia along the Pennsylvania Fork of Fish Creek. The CO2 gas is being injected, for testing both coal bed methane recovery and carbon sequestration, into the Upper Freeport coal bed at ~1200 feet depth. Ongoing CO2 injection began in 2009, and ongoing geochemical environmental monitoring of shallow ground water, Fish Creek, and vadose zone gas began in 2008. In summer 2012, water and gas sampling began for carbon isotopic analysis at or near the test site; water is being sampled and tested from three groundwater monitoring wells, a few domestic groundwater supplies, and Fish Creek, and gas is being sampled and tested from the CO2 injection source gas tank, two deep coal bed methane producing wells, one deep monitoring well, and eight shallow vadose zone monitoring wells. The preliminary data indicate that the CO2 gas used in this sequestration operation has a different isotopic value compared to naturally occurring CO2 in the geological formations. Initial data indicate that carbon isotopes can be used as an effective “natural built-in tracer” for monitoring the CO2 plume and/or its leakage into overlying shallow aquifers and upper subsurface.