Petroleum System Attributes of Bossier and Barnett Shale of East Texas: Evolving Ideas and Their Impact on Shale and Tight Sand Gas Resource Assessment

Ahmed Chaouche
Anadako Petroleum Corporation, Houston, TX

Conventional versus unconventional gas resources: What's the difference? The obvious response lies more likely in the trapping mechanisms and the unusual low permeability and microporosity of sand and sand shale holding significant resources at a basin scale in unconventional traps when compared to the finite and discontinuous high porosity permeability reservoirs in conventional ones. Insights from Bossier shale compared to Barnett shale reveals some fundamental aspects of the petroleum system that lead to revisit the recently challenged idea of “Basin-Center Gas Accumulation” and shed some light on the specifics that induce such accumulations. Far beyond any other considerations, the geological history of basin together with the source rock quality and richness have been found determinant in the occurrence and distribution of the fluid in the unroofed versus sealed system offered by these two examples of East Texas.