Lesley W. Evans¹, Barbara F. Keusch¹, Stephen D. Sturm¹, William J. Clark¹

(1) Schlumberger Holditch-Reservoir Technologies, Denver, CO

ABSTRACT: Tight Gas Sand Exploitation: Linking Geosciences to Enhance Operations, Siberia Ridge Field, Wyoming

This Gas Research Institute study provides insight into mechanisms controlling gas production in Siberia Ridge Field, southwestern Wyoming. The purpose of the study was to characterize the Almond Formation (Cretaceous) to better understand controls on productivity and to compile this information for analogous tight-gas sandstone reservoirs. The Siberia Ridge Field Reservoir Characterization study is comprised of full-field geoscience, petrophpsyical and engineering analyses including the results of a cooperative research well.

Geological facies analysis, petrophysical data, and seismic attribute data were mapped with production data to determine productive trends. Coherency analysis was used to determine the location of significant linear features. The combination of depositional, petrophysical, and structural data revealed areas of better petrophysical properties generally indicated better production, even with a small range in reservoir quality.

With average reservoir porosity ranging from eight to ten percent, and matrix permeability in the micro-darcy range, the role of natural fractures to productivity was of particular interest. FMI and core data were used to characterize the natural fracture system. Natural fracture density was more greatly influenced by lithology than wellbore deviation and lineament proximity. Rather than providing increased conductivity to natural gas, natural fractures were found to provide increased relative permeability to deep Almond water.

Specific completion practices were evaluated with geological and petrophysical data to determine relationships to gas production. Results indicated that completion practices were critical to well performance.

Enhanced reservoir understanding can improve drilling, completion and production practices, ultimately impacting well economics by decreasing risk and increasing recoverable reserves.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado