Identification of Reservoir Geometry: Recent and Ancient Examples

Jacques Durand, Jean-Michel Champanhet, Raymond Cussey

Finite geometry of sandstone reservoirs results from the superposition of several phases. Two important stages independent of diagenesis for prediction in petroleum sedimentology are primary geometry and structure generally provided by recent bed forms (original forms of the reservoirs) and fossilized geometry and structure provided by ancient bed forms (preserved forms of the reservoirs).

Recent bed forms give useful comparative data for understanding the theoretical extension of sandstone reservoirs. New resolution seismic techniques associated with a cores approach improve quantification of internal structure and bed-form geometry. This core study is based upon longitudinal-scanner radiographs for reconstructing true dip and azimuth of bedding and bounding surfaces. The stick-plot pattern following the core profiles is used for reconstructing vertical bedding evolution and between correlated cores for bounding laterally extended surfaces. A precise calculation of bed-form volume is obtained from seismic and sidescan sonar data after reconstituting the external geometry of bed forms in 3-D.

For ancient bed forms, preserved shapes have been reconstructed from exposures and drilled cores. Topographic measurements on each bounding surface of bed forms have been plotted in space volume to obtain a realistic model. Narrow vertical sections provided dipmeter simulation of internal structures. Geometric and spatial distribution of carbonate tidal sand shoals in the Dogger of Burgundy (France) have been so characterized.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.