ABSTRACT: A Fault-Controlled Gas-Water Boundary Near the Elmworth Field, Alberta: A Mundane Solution to a Previously Anomalous Situation

MASON, EDWARD, and CHRISTOPHER MURRAY, University of South Carolina, Columbia, SC, JANELLE DAVIDSON, Canadian Hunter Exploration Ltd., Calgary, Alberta, Canada, and ROBERT EHRLICH, University of South Carolina, Columbia, SC

Cretaceous sandstones in the Deep basin of Alberta contain normally pressured water updip and underpressured gas with little producible water downdip. A variety of explanations, mostly involving changes in sandstone microstructure, have been proposed to explain this anomalous situation. Trend surface residual mapping of Cretaceous tops from several thousand wells in and around the Elmworth field in Alberta shows a relationship between the location of the gas-water contact and a series of high angle faults; few have displacements exceeding 150 m. Many of these faults affected sedimentation patterns, causing thickening on the downthrown sides. In comparing the gas-water contacts for the Bluesky, Falher, Cadotte, and Cardium formations, the contact moves progressively downdip to the sout as younger formations are encountered. These abrupt changes in location of the gas-water contact are controlled by the discrete locations of major structures. Areas where the gas-water contact is geometrically complex generally coincide with structurally complex areas.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)