Analysis of Open Hole Logs in the Miocene Stevens Sands

MORROW, JEFF, No affiliation given

The analysis of open-hole logs in the Stevens Sands is difficult because of the mineralogical composition of the sands and the corresponding effects on the logging tools. Logging parameters presumed in other sandstone reservoirs may not be appropriate to the Stevens and may cause the log analysis to underestimate productive zones. Without the integration of full core data and knowledge of the mineralogy of the Stevens Sands, the results of log analysis can be very misleading. As shown in the example used in this paper, the net pay footage calculated using conventional cut offs can be improved from 10 to 45 ft by using the core measured rather than the commonly assumed valued for logging parameters. The increased pay footage is achieved by changing the mean water saturation from 70%, c lculated using commonly assumed parameters, to a mean value of 48%, calculated using core measured parameters.

AAPG Search and Discovery Article #91009©1991 AAPG-SEPM-SEG-SPWLA Pacific Section Annual Meeting, Bakersfield, California, March 6-8, 1991 (2009)