Coal Seams: Things You''ve Always Wanted to Know - FossilFuel.…Coal Seams: Things You''ve Always Wanted to Know2020-2-5 · Coal seam gas content ranges from a few ft3/t to 800 ft3/t for depths of up to 3000 ft. Coal seams are the origin of all gases, and also the reservoir. Methane accounts for 80%-95% of the full gas content, while the balance consists of butane, ethane, propane, hydrogen, argon, carbon dioxide, and oxygen. Coal Seam DegasificationCoal Seam - an overview | ScienceDirect TopicsCoal seams originate and are formed by the consolidation of biota, minerals, and natural chemicals through geologic time. Compression, heat, sedimentation, erosion, and chemical energy are agents of the coal formation process. Multiple coal seams can exist in a reserve, with each coal seam separated by sedimentary rock interburden.