Linking Formation Water and Host Rock Geochemistry in the Antrim Shale Biogenic Gas Reservoir

Claire Astore
The University of Tulsa, Geosciences Tulsa, Oklahoma U.S.A
[email protected]

The Upper Devonian Antrim Formation, Michigan Basin, U.S.A., is one of North America’s most productive biogenic gas reservoirs. The majority of recoverable gas occurs along the northern margin of the basin in a region referred to as the Northern Producing Trend (NPT). Multiple scientific studies and 20+ years of production from the NPT have resulted in an extensive database of subsurface geology, formation water and gas chemistry. This historical data is integrated with new production and water chemistry in this study. Data was imported into ArcMap in order to compare production rates with metal, dissolved organic carbon (DOC) concentrations and historic hydrogeochemical data. The Antrim acts as a natural bioreactor and allows us to observe relationships between geochemical variables and biogenic production. Formation water chemistry, and production techniques, may be the major controls on gas production in the biogenic fairway of the NPT. Of particular interest is how the presence of micronutrients, for example iron, can be linked to gas production rates. Antrim fluids from five biogenic-gas producing wells were analyzed for total metal concentrations and DOC. There proved to be a positive correlation between a selection of transition metals and gas production. GIS maps of the NPT also illustrate regional stratigraphic variations that will be integrated with production rates. Integrating this historical record in GIS maps with modern measurements provide the necessary framework to understand the relationships between subsurface geochemistry, specifically trace metal variations, and biogenic gas production.

AAPG Search and Discovery Article #90157©2012 AAPG Foundation 2012 Grants-in-Aid Projects