Optimizing recovery from fractured and faulted petroleum reservoirs requires improved methods for incorporating the influence of faults and fractures in predictive reservoir simulations. We are building a synthetic fractured and faulted reservoir that: 1) includes the most significant structural features, 2) is based on geologically reasonable methods for extrapolating fracture/fault systems from sparse wellbore and seismic data, and 3) allows us to test the ability of different upscaling methods to preserve the influence of fractures and faults on production. The synthetic reservoir is based on data collected from a fractured/faulted petroleum reservoir exhumed in open pit gold mines at Alligator Ridge, Nevada. Detailed mapping suggests that locally concentrated petroleum inclusions along with gold and arsenic mineralization reflect the focusing of fluid flow within highly-fractured regions. Fracture and fault geometries have been mapped in detail using scanlines along the mine walls. These data are used to build a synthetic model of the reservoir at three different scales. Faults are incorporated at the oilfield(10⁷ to 10⁹ m³) scale by `growing' fault networks according to the rules inferred from their geological evolution and constrained by ground- and satellite-based fault mapping. At the interwell (10³ to 10⁶ m³) scale, 3-D networks of large fractures are reconstructed using data from each mine and conditioned by our understanding of the structural history. At the wellbore (1 to 100 m³) scale, 3-D discrete fracture models are constructed using the detailed fracture networks mapped within faults.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah