Log Imagery Data and Outcrop Analyses as Improvement Tools for Alpha Field (Devonian, Timan Pechora, CIS) Complex Karst Geological and Reservoir Modeling

Lapointe, Philippe; Neumann, Catherine

The carbonate platform suffered sub-aerial exposure that participated in reservoir characteristic improvements. Combined repetitive small and large-scale events lead to probable pellicular karst formation and development of plateau-type karst as well as coastal mixing water karst. Anomalous minerals related to fault and fracture enlargements characterize the latest hydrothermal karstic phases.

Porosity in non-karstic rocks ranges from 2 to 4%, while rocks exposed to karstic dissolution exhibit porosity up to 16%. Permeability varies accordingly, up to 1D.

The distribution of the karstic zones through the reservoir is based on all collected data (seismic, mud-logging, electrical-logging including imagery, cores, and production data) and calibrated through outcrop studies of such complex karst located in Spain (Mallorca island and Basque Province) and Kazakhstan.

Imagery logs provides valuable information with the proper core and outcrop features calibration and allows the propagation of the karsted zones throughout the platform both vertically and laterally with a high resolution compared to the seismic. With the outcrop guidelines, identification of the karst types and zonation as well as the successive phases can be performed at the field scale.

Thus, the modeling of the karstic reservoir remains critical in the forecast of the best reservoir-zone distribution and the prognosis for future production well location.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013