From the Pore Scale to Reservoir Scale: Lithohydraulic Flow Unit Characterization of a Shallow Shelf Carbonate Reservoir, North Robertson Unit, West Texas

Richard K. Vessell and David K. Davies

This paper presents the results of integrated geological-petrophysical reservoir characterization performed as part of the US Department of Energy Class II reservoir program. Petrographic image analysis, using a specially equipped SEM, allowed for the identification of 8 petrophysical rock types at the North Robertson Unit. Detailed log analysis resulted in the development of algorithms for the log-based identification of these rock types in 109 wells. Porosity was related to permeability for each Rock Type: thus permeability is determined from well log data. Evaluation of porosity, permeability, Sw and HPV distribution has allowed for the identification of 12 lithohydraulic flow units. These flow units have been mapped across the unit.

The technique allows for the development of log-based reservoir models that are simulator-ready. The results of this study have application to all heterogeneous, shallow shelf carbonate reservoirs, they demonstrate that large fields can be successfully characterized using few cores and emphasize the importance of integrated geological-engineering analysis in reservoir characterization.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California