Biogenic Gas Generation from Organic Rich Shales of Southeastern Brazil: A Potential Contributor to Greenhouse Gas Emissions?

Studies regarding the biogeochemistry and internal structure of organic rich shales may assist the understanding of these as geological sources of greenhouse gases. The present work aims to evaluate the potential production and factors controlling the biogenic methane generation from Brazilian shales. Multiple anoxic incubations were prepared in order to quantify methane and dioxide carbon generation under wet and dry conditions. Experiments utilized samples collected from Devonian, Permian and Paleogene organic rich shales of Paraná and Taubaté basins, Southeastern Brazil. Production rates of 24 shale samples representing a wide range of total organic carbon and porosity were measured along several months. Carbon isotope values of carbon dioxide and methane enabled further investigation of biogenic gas generation and emission. A discussion regarding biogenic gas production and gas microseepage will be presented.