This paper describes methods and results of integrating modern openhole well logs and core data with old electric survey logs (ES) to determine porosity, water saturation, and net pay thickness for more than 240 wells in the San Andres Field, Veracruz, Mexico. A majority of the wells were logged with the old ES logs. As field development continued, modern resistivity logs and porosity logs were run. Several relationships were developed which allowed the old ES logs to be analyzed and the results incorporated into the reservoir description. Specifically, relationships were developed to determine porosity from the old neutron logs (GNT - both count rate and API scales), and to determine true formation resistivity (Rt) using the 64" normal logs. Log calculated porosity and water saturation were verified with available core results.
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