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Mitch D. Pavlovic1
(1) Baker Atlas Geoscience, Houston, TX
Abstract: Integration of borehole image and conventional log data for improved petrophysical evaluation of thinly laminated, deep water turbidite reservoirs in the Gulf of Mexico
Thinly bedded sand-shale geological sequences are encountered throughout the world, particularly as low-contrast, low-resistivity pay intervals in the Northern Gulf of Mexico. The thickness of many individual layers is below the resolution capability of conventional logs and create a challenge in reservoir description and log analysis for both geological and petrophysical interpreters. Despite apparent water saturation values ranging from 55% to 85%, as derived by traditional conventional log interpretation techniques, significant discoveries in deep water Gulf of Mexico dramatically increase need for integration of borehole image log data and traditional open-hole log data for improved petrophysical evaluation of laminated shaly sands.
With the proposed new advanced technique much more complete log-based reservoir description is possible, including the determination of several important reservoirs properties that were previously quite elusive in the absence of core measurements. The success of this model is build on high resolution details seen in borehole image logs, that provides unique ability to calculate net reservoir volume more accurately. Through highly sophisticated process, high-resolution borehole images are integrated with conventional log data to derive enhanced porosity, laminar shale volume, and improved water saturation calculation that can predict effective hydrocarbon volumes in thinly bedded geological sequences. Productive zones that previously might have been otherwise overlooked are now located precisely. The overall result of an integrated thin-bed analysis is volumetrically balanced system that is believed to more accurately describe reservoir properties that leads ultimately to economic benefits.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana