--> Abstract: Geological and Petrophysical Properties of Thinly-Bedded Turbidite Deposits, Eastern Gulf of Mexico, by D. R. Rollins and R. D. Shew; #90987 (1993).

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ROLLINS, D.R. (DALE), Shell Offshore, Inc., New Orleans, LA; and ROGER D. SHEW, Shell Development Company, Houston, TX

ABSTRACT: Geological and Petrophysical Properties of Thinly-Bedded Turbidite Deposits, Eastern Gulf of Mexico

Numerous laminated to thick-bedded Miocene turbidite deposits have been encountered by deep-water exploratory drilling in Viosca Knoll blocks 780, 783, and 952. The intervals are dominated by laminated to thinly-bedded reservoir quality sands and silts, non-reservoir cemented sands, and mudrocks. Evaluation and prediction of thin-bed properties are necessary for (1) estimation of net pay, porosity, and kh, (2) modeling seismic response, (3) estimating compaction, (4) designing gravel packs and completion procedures, (5) understanding cross-fluid flow and sealing potential, and (6) input to reservoir modeling and simulations.

The sediments are interpreted as levee and interchannel deposits. As the thickness of many of the individual layers are below the resolution of conventional logs, whole core, sidewall core, and high resolution logging tools (FMS, SHDT, BHTV) are critical to the interpretation of reservoir and non-reservoir properties. Detailed geological and petrophysical summaries of samples spanning the reservoir quality spectrum from massive (Ta) to rippled (Tc) facies and the non-reservoir mudstone (Tet) facies are presented foreach area. The sediments are slightly consolidated, very fine-grained, clay-rich, moderately compacted, and feldspathic. Porosities and permeabilities are quite variable (24-30 percent and 10-800 millidarcies, respectively) but there are positive correlations with facies an bed thickness.

A rock catalog format is presented to provide a reference for interpreting lithotypes from this geographic and depositional setting. The data include CT scans, high pressure capillary pressure curves, grain size, petrographic interpretations, XRD, core and thin section photos, and associated wireline log responses.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.