Carbonate Reservoir Exploration Studies

Dravis Geological Services works with clients to develop improved strategies for exploring subsurface carbonate facies and sequences. An integrated approach is used to accomplish the following: (1) synthesize regional stratigraphic and structural information using client-based data and/or available literature; (2) evaluate nearby well or field data to establish the general environmental setting and resolve existing or potential play relationships; (3) generate regional stratigraphic cross sections when warranted; (4) develop guidelines from comparably-aged plays in the basin or elsewhere; (5) work with geophysicists to tie these guidelines into existing seismic data bases.

Remember, stratigraphy does not control facies, contrary to popular sequence stratigraphy dogma. Depositional setting dictates the types of facies developed and their distribution. To explore successfully, you must understand the environmental setting which can only come from “looking at the rocks.” Stratigraphy results from the accumulation of depositional facies, and is controlled by physiographic setting.

This regional stratigraphic cross-section of Devonian Sequences across Comet Platform, NW Alberta, Canada showing the results of an integrated core, thin section and log study (see Dravis, 1992). Comet Platform is over 25 miles across in places. Upper Keg River pools produce oil from dolomitized cycles of platform-interior cycles 7-12 meters thick. Reactivated basement faults dtic fluids which dissolved certain dolomitized facies in these cycles, creating the reservoir’s secondary porosity. These faults also created closure (15-25 meters) for hydrocarbon entrapment. This fault closure created a seismic expression misinterpreted for years as reflecting small-scale pinnacle reefs. However, looking at the rocks properly showed that these sequences were comprised of more restricted subtidal and peritidal facies.