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Abstract: Multi-Well Petrophysical Processing Using Symbiolog: An Example Using Both Old and New Well Logs from the Monterey Formation; San Joaquin Valley


As part of a DOE-funded demonstration reservoir characterization project, a petrophysical field study project was undertaken in the Monterey Formation in the vicinity of the Pioneer and Los Lobos Fields, T11N/R23W, Kern County, California. The dataset consisted of about 45 wells including old E-logs (1930s through 1950s), IES logs (1960s), and modern logging suites (1980s to present). A conventional analysis was performed on the 12 modern wells to derive values for lithology and porosity, and the results were used to calibrate an empirical model to obtain the same parameters from the old E-log wells. The analysis on the wells with porosity logs was calibrated to core data using a geologically-based analytical approach to parameter selection, and a close match was obtained. The extension of the model to the E-log only wells required careful interpretation by a geologist/petrophysicist, but with close attention to parameter selection quite meaningful results were obtained on the old wells through the Monterey interval. The work required a complex processing sequence involving several custom programs to calculate input curves for the main petrophysical model, which was made possible using the tools available in Symbiolog. Symbiolog is an advanced log analysis program that functions as an add-on to many other petrophysical systems, providing enhanced processing features, a user programming module, and multi-well capability even to systems that are single-well oriented. For this project, Symbiolog was used in conjunction with the Petrolog log analysis system from Crocker Data Processing, which was used for all log input/output, graphics, database, and log curve manipulation. The results of this project has significance for many fields in California, since it shows that petrophysical analysis of both new and old wells can be done efficiently and with a high degree of accuracy. This will greatly enhance the accuracy and efficiency of reservoir characterization and reservoir modeling work in the typical field that has many wells with old or limited log suites.

Search and Discovery Article #90945©1997 AAPG Pacific Section Meeting, Bakersfield, California