Source-rock Analysis of the Lower Member of the Lewis Shale, Washakie Basin, Wyoming
Adriana V. Rigoris
Department of Geology and Geological Engineering, Colorado School of Mines
Golden, CO
[email protected]
Turbidite Sandstones within the Lewis Shale (upper Cretaceous) comprise an emerging tight-gas resource in the eastern Green River Basin, Wyoming. The purpose of this research is to provide a complete Lewis Shale source-rock characterization using organic geochemistry techniques. This study will help clarify the relationship between the potential source-rocks and the gas-oil production and rock properties from the lower 600 ft (200 m) of the Lewis Shale.
The Lewis Shale contains several marine condensed sections with sufficient organic content (TOC between 0.45-2.5%) to be effective source-rocks. The condensed intervals have not been clearly established as the source for gas and oil produced from Lewis Shale reservoirs.
Representative shale samples were collected; 3-ft composite samples were taken from nine cores of the Lewis Shale to perform TOC and Rock-Eval pyrolysis to determine source-rock richness, quality and maturity. The laboratory analyses help define source-rock quality within the Lewis Shale.
Artificial neural networks will be used to predict the nature of the dependency between TOC values and Gamma Ray, resistivity, and porosity logs. The goal is create a tool to analyze source-rock richness for the hundreds of wells within the Lewis Shale that have no core.
AAPG Search and Discovery Article #90033©2004 AAPG Foundation Grants-in-Aid