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ABSTRACT: Computerized Old E-Log Analysis in Central and North Texas

ASQUITH, G. B.

The presence of old E-logs (Pre-1958) in North America as a percentage of the available log suites is not uniform. Due to drilling activities some areas like Central and North Texas have a high percentage of old log suites.

These old E-Log suites commonly consisted of a Spontaneous Potential log (SP), a Short Normal log (SN), a Long Normal log (LN) and a Lateral log (LAT). After 1948 a Microlog (ML) was sometimes run with this old E-Log suite. Because the SN, LN and LAT logs were non-focused logs both borehole and thin bed corrections are often very important. Further, the lateral log is most often the best Rt device but the rules of how determine Rt form the lateral log are complex and time consuming to apply. Therefore, what is needed is a fast interactive computer program to aid the geologist/engineer in the analysis of old E-Logs.

Such a program exists and it is called "Old E-Log Advisor" (OEA). The software allows the user to determine Rt in both fresh- and saltwater- based muds, porosity from the SN, ML, Microlaterolog (MLL), Limestone Lateral logs or old neutron logs. In addition, there are a series of cross plots to help the user determine if the zone is hydrocarbon productive, and finally there is a final analysis that displays porosity, water saturation and net pay. In order to illustrate the software, an example will be presented from the Atoka Bend Conglomerate.

AAPG Search and Discovery Article #90947©1997 AAPG Southwest Section Meeting, San Angelo, Texas