Quantification of Thermal Maturity Indicies with Relationships to Predicted Shale Gas Producibility:Gate-Way Visualization and Attribute Technique
Michael S. Cameron1, Frank E. Walles2, and Daniel M. Jarvie3
1Corporate Unconventional Resources, Devon Energy Corporation, Oklahoma City, OK
2Corporate Unconventional Resources, Devon Energy Corporation, Houston, TX
3Humble Geochemical-Weatherford Core Evaluation Services, Humble, TX
A critical component for economic shale gas producibility involves accurately quantifying the geochemical maturity attributes of the hydrocarbon system. Identifying the key parameters and measuring these maturity indicies with accuracy and repeatability has been an area of concern in comparing and contrasting shale gas reservoirs. The evaluation process requires an accurate estimate of thermal maturity as a function of the geologic thermal history in the interval of interest. Commonly, vitrinite reflectance (%Ro) alone is used to characterize thermal maturity. Inherent small populations of vitrinite material, small intervals of sampling, kerogen type and distribution differences, methods of sample preparation, and differences in standards of visual description lead to a large variance in data reporting and precision.
Geochemical Attribute Technology Evaluation and Visualization (Gate-Way), is an interpretive methodology and visualization technique for improvement in the analysis of thermal maturity indicies utilizing a combination of geochemical attributes inclusive of %Ro, methane/ethane/propane isotopes, gas measured BTU, fluid analysis, whole rock pyrolysis data, and Tmax. Residual liquids that correspond to lower levels of thermal maturation are modeled to be limitations in expected gas producibility. This combination approach in quantifying the uncertainties in thermal maturity is a key parameter in the economic prediction of reserves as it relates to producibility in shale gas resources. The purpose is to advance the understanding and improve the standardization in defining a concise thermal maturity measurement. This visualization of geochemical parameters with dynamic attribute measurement data has allowed more precise quantification of the variations compared with the stand alone vitrinite analysis and interpretation.
AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas