--> Abstract: A Petrophysical Study of Reservoir Quality and Flow Unit Continuity in a Lower Clearfork Oil Field, Lower Permian Dolostones, West Texas, Using Ten Wells of Variable Age and Data Quality, by Eric Eslinger and R. V. Everett; #90039 (2005)

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A Petrophysical Study of Reservoir Quality and Flow Unit Continuity in a Lower Clearfork Oil Field, Lower Permian Dolostones, West Texas, Using Ten Wells of Variable Age and Data Quality

Eric Eslinger1 and R. V. Everett2
1 Eric Geoscience, Inc. and The College of Saint Rose, Glenmont, NY
2 Consultant, Victoria, BC

A petrophysical study was made on ten wells from an oil field in dolostones of the Lower Clearfork (Lower Permian, Ector County, West Texas) with the goals of identifying the best horizons to perforate and of evaluating continuity between injector and producer wells for infill drilling planning. A major challenge was how to integrate sparse "older" (1950s-60s) well logs with only gamma ray and neutron curves with "newer" (1980s) more complete well logs into a coherent model for generating credible porosity and permeability profiles. A 10-well model was developed that included three non-cored wells which had only gamma ray and neutron logs. Three of the wells contained useable core plug data. A unique clustering procedure estimated missing data and lithology. Well samples with valid core data for porosity, permeability, and grain density were used to calibrate a mineralogy-based forward modeling procedure resulting in profiles for porosity, permeability, and water saturation for all ten wells. Interwell comparison of permeability profiles indicated generally poor horizontal flow continuity. Porosity-ft and permeability-ft were computed for all ten wells. Although the percentage of total porosity-feet (all wells total) attributed to each well varied within a small range (5 to 13% per well), the percentage of total permeability-feet (all wells total) attributed to each well varied widely (1 to 53% per well) with four wells containing less than 2% each of the total permeability-feet. The major challenge of integrating sparse well logs and useable core was successfully met.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005