THE ENVIRONMENTAL EFFECTS OF GEOLOGICALLY SEQUESTERED CARBON DIOXIDE GAS AND THE ENHANCED RECOVERY OF COAL BED METHANE FROM AN UNMINABLE COAL SEAM

The importance of greenhouse gas mitigation, especially anthropogenic carbon dioxide (CO₂) emissions in modern society is paramount to help offset any unnatural climate change that may occur. The feasibility of sequestering CO₂ in geologic formations is currently being explored. A carbon capture and storage (CCS)/enhanced coal bed methane (CBM) recovery test site located in Marshall County West Virginia uses an unminable coal seam to house CO₂. The study investigates the effects of sequestered CO₂ on shallow ground and surface waters, in addition to its effects on the vadose zone at various depths. No significant change in the dissolved cation concentrations of any waters has been observed through ICP-AES analysis, which also holds true for anions derived via titration. Dissolved sulfates can fluctuate in the ground water depending on sampling location as is shown by ion chromatography analysis; this may be directly related to methane (CH₄) reducing sulfate (SO₄^2-) to sulfide (S^2-). A GM series CO₂ probe demonstrates the shallow vadose zone shows a relative low-high-low trend across the test site with the highest values occurring in the middle near the injecting structure. The presence of vadose CH₄ has been detected in the water wells using a multi-gas detection meter. Shallow vadose CO₂ concentrations may be high due in part to the growing season and diurnal fluctuations. Although no significant changes in the water chemistry has been observed to date, the continued monitoring is necessary as CO₂ injection has been sporadic and well below the 27 tons per day permitted. The study will aid in determining the environmental impact of CCS/ enhanced CBM recovery in settings geologically similar to the Appalachian Plateau.