Abstract: Petrophysical Properties and OOIP from a Predominantly Old E-log Suite, Huntington Beach Field, California

BEDARD, ROBERT, EarthQuest Technology, Inc, Bakersfield, CA; DEBORAH OLSON, Digital Petrophysics, Inc., Bakersfield, CA 

Quantitative values for reservoir properties are an essential part of a reservoir characterization. However, obtaining this information is a challenge in many older fields that lack modern logs. Reliable data for reservoir properties were obtained for the Upper Main Zone at Huntington Beach through the development of an empirical model for clay and shale volume, porosity, and permeability calibrated to core data and to the modern log suites that were present. Water saturation for OOIP calculations was derived from a capillary pressure-based model referenced to the rock properties calculated from the empirical model. First, the modern logs were analyzed using the clay volume and Dual Water saturation models incorporated in the Symbiolog log analysis system. Parameters were verified and calibrated to core data where available. Clay volume was derived only from SP supplemented by GR, curves which were available in the predominating E-log and IES log suites. Then, effective porosity was derived from clay volume. Silt index was calculated from the shallow resistivity, and a permeability curve was developed from the silt index, calibrated to laboratory air permeability from core. Available laboratory capillary pressure curves were analyzed and incorporated into a model that assigned a value of Swi to each level in the reservoir based on its computed properties. The entire E-log only model was constructed within the user-programming module of Symbiolog. The reservoir properties were summed and used to generate volumetrics, thus producing the first measure of OOIP in this reservoir based on quantitative well log data. This methodology is more interpretive than modern log analysis techniques and the best results are obtained by involving both geological and petrophysical expertise in the execution of the analysis.

AAPG Search and Discovery Article #90911©2000 AAPG Pacific Section and Western Region Society of Petroleum Engineers, Long Beach, California