Abstract: 3-D Fluid-Flow Model of the House Creekfield, Powder River Basin, Wyoming

Debra K. Higley

Core porosity, permeability, and bulk-density porosity for more than 120 wells were used with well-log, outcrop, and petrologic data to map the distribution of porosity in three dimensions for lithologic layers within the Upper Cretaceous Sussex Sandstone in the House Creek field. 3-D computer modeling techniques used interactive volumetric modeling on an IRIS workstation. The 3-D model illustrates zones of reservoir compartmentalization that result from complex interbedding of high- and low-depositional-energy facies, from laterally continuous permeability boundaries, and from early diagenetic cementation of some sandstone beds. Also shown on the computer model are (1) areas of potential bypass of production, (2) lateral and vertical distribution, and (3) connectivity of porous sands ones within the reservoir.

The four major reservoir sandstones step shoreward in an upward direction; this corresponds to transgressive deposition of the offshore marine Sussex sand-ridge system. Sand ridges consist of mainly tabular, massive to ripple-laminated, fine-grained sandstone; trough cross-bedded to planar-tabular bedded fine to medium-grained sandstone is concentrated near the top of the "B" sandstone and along the eastern field margin. Both upper and lower reservoir layers exhibit an upward increase in porosity and a corresponding increase in sandstone grain size; both reservoir intervals are perforated in most wells. Sandstones with the highest depositional energy exhibit the greatest porosity; these are largely the upper and ocean-facing trough cross-bedded units. Average porosity for reservoir sa dstones is about 13%; reservoir-grade porosity is greater than 8%.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994