David K. Larue¹, Francois Friedmann¹

(1) Chevron Petroleum Technology Company, San Ramon, CA

ABSTRACT: Deep-Water Reservoir Architecture and Waterflooding Recovery Efficiency

How much does the stratigraphic architecture of a deep-water reservoir influence the ultimate recovery from the reservoir? For example, how does the range in orientation of channels, whether all parallel or highly dispersed, affect potential for waterflooding in the cross-channel direction? How does the sinuosity of a deep-water channelized reservoir affect reservoir performance? To address these and other issues, we built and flow-simulated a suite of geologic models. Our goal is to quantify the total uncertainty in recovery as a function of stratigraphic and structural architecture, by permeability distribution, well spacing and orientation, and drive mechanism. The conceptual models we built have variable channel width to thickness ratios. Channel stacking patterns included bar stacking, random stacking, and clustered stacking. Variable channel sinuosities and deviations from the mean channel direction were modeled. Channel fills were characterized by a slight reduction in permeability vertically, and thief zones and impermeable barriers were modeled with different volumes and lengths. Constant pressure waterfloods were simulated for each suite of geologic models. Effects of pattern size were examined using 5-spot well configurations. We conclude that stratigraphic complexity has a greater effect on reservoir performance during later, rather than earlier, field development and at higher, rather than lower, mobility ratios. Permeability-related architecture and net-to-gross are clearly significant variables, whereas channel stacking, thickness and channel length to width ratios are only marginally significant variables. "Spread" of results is not as pronounced as anticipated. We conclude that uncertainty with regard to reservoir architecture may be defined within a global range.

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