Reservoir-Engineering Aspects and Resource-Assessment Methodology of Eastern Devonian Gas Shales

摘要

The US Department of Energy's Morgantown Energy Technology Center (METC) and Science Applications, Inc., are cooperating in the characterization of the Eastern Devonian Shale gas resource. This study, focusing on the Lincoln County, WV, area, characterizes the resource and shows that conventional volumetric techniques cannot be used to determine the amount of gas in place. Previous studies, using calculations based on limited offgassing measurements and volumetric information, have indicated that the resource ranges from 500 TCF to 2400 TCF of gas in place. Previous studies, using calculations based on limited offgassing measurements and volumetric information, have indicated that the resource ranges from 500 TCF to 2400 TCF of gas in place. The volumetric method based on fracture porosity data yields low values; offgassing measurements can be used to determine gas in place if sufficient time is allowed for gas to sorb from the shale matrix. Production-pressure decline curves are presented for several wells to show the effect of sorption on cumulative production. A mathematical model for describing the behavior of a dual-porosity gas reservoir is presented. It shows the effect of sorption on the production behavior of the gas reservoir. It is concluded that the early part of production behavior is controlled by free gas in the fractures, while long-time behavior is controlled by sorption-diffusion mechanisms. 16 figures, 5 tables. (ERA citation 08:023052)