DANG, THU-THUY, ARCO E&P Technology, Plano, TX, and TODD A. BUIKEMA, ALBI, Long Beach, CA

ABSTRACT: A Systematic Approach to Analyzing Well Logs for the Long Beach Unit

A comprehensive and systematic approach has been developed to analyze well logs from more than 1200 wells in the Long Beach Unit. This field is primarily produced from formations comprised of highly unconsolidated turbidite deposits. Hence, acquiring competent cores and reliable core measurements is difficult. Well log information has become a crucial source of information about the reservoir. Log types vary from uncompensated density logs to phasor induction logs. The varied log types and vintages present in this field represent a challenge to evaluation and complete description of the reservoir.

To analyze the variety of log types, a simple and consistent procedure for computing shale volume, porosity, and water saturation has been developed and implemented. Rigorous data quality control and log normalization were performed. Electrical properties measured from recent core samples also aided in the selection and application of a shaly-sand water saturation model. Maximum entropy inversion was applied to improve thin bed detection.

The procedure has been successfully applied to a pilot set of cored wells in the Long Beach Unit. Comparison of results to recent reliable core data suggests that the log model accurately predicts reservoir properties. Computed shale-volume curves were used with a unique reservoir zonation workstation system to help understand reservoir architecture. Processing more than 1200 wells in the field will be significantly facilitated by the application of these algorithms. This log model provides the basic framework for generating critical petrophysical properties for future mapping, volumetrics, and reservoir simulation.

AAPG Search and Discovery Article #90992©1993 AAPG Pacific Section Meeting, Long Beach, California, May 5-7, 1993.