Linda G. Martin¹, Michael H. Gardner¹, Safian Atan¹, James M. Borer¹, Roger Wagerle¹

(1) Colorado School of Mines, Golden, CO

ABSTRACT: The Role of Digital Images in Outcrop Reservoir Analog Studies

Digital images are invaluable tools for quantifying outcrop information on the connectivity, continuity and distribution of sediment bodies forming subsurface hydrocarbon reservoirs. Photomosaics constructed by linking multiple overlapping digital images serve as field base maps that accurately capture high-resolution facies architecture. Complicated facies relationships and geometries depicted on a high-resolution photomosaics best capture the mesoscale architecture of sediment bodies that form the principle heterogeneity in subsurface reservoirs.

Outcrops photographed from either the ground or air must have a 30-50% overlap. More overlap is needed for high parallax situations such as deep cliff reentrants and corners. Photographic images are manipulated in Adobe Photoshop. These digital images can then be tied (rubberstamped) to digital elevation models. These large-format photomosaics are used to map facies, bedding contacts, bed thickness and length, sediment body geometry, and stratigraphic cycle boundaries. These data are converted to digital correlation panels for input into reservoir models.

The Popo Fault Block, exposing deep-water clastic deposits of the Permian middle Brushy Canyon Fm., Texas, illustrates this process. Fan 4 deposits were photographed from the ground, whereas overlying fan 5 deposits were photographed from a helicopter. Two correlation panels were generated that included all field data. The combined cross-section was corrected using section thickness and scales of the image measured directly in the field. This step removes photo parallax and distortion. The deterministic geologic model constructed from these data was converted into a two-million-cell reservior model.

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