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

This is an abstract only. The complete paper is not available forpurchase. In this paper we discuss evaluating the geological and petrophysical characteristics of thinly bedded turbidite deposits. Shell Offshore Inc'sDeepwater Division has encountered numerous laminated to thick-bedded Mioceneturbidite deposits during exploratory drilling in Viosca Knoll blocks 780, 783, and 952. The intervals are dominated by laminated reservoir quality sands and silts, non-reservoir cemented sands, and mudrocks. The sediments are interpreted as levee and interchannel deposits which are slightly consolidated, very fine-grained, clay-rich, moderately compacted, and feldspathic. The thickness of many of the individual layers are below the resolution of conventional logs; therefore whole core, sidewall core, and high resolution logging tools are critical to the interpretation of reservoir and non-reservoir properties. We present 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 for each area. Evaluation and prediction of thinbed 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. Porosities and permeabilities are quite variable(24-30 percent and 10-800 millidarcies, respectively) in the reservoir sencountered, but there are positive correlations with bed thickness. Bed thicknesses are predominantly less than 10 centimeters and are mostly ripplebedded (Tc) and parallel-bedded (Td). Facies and established depositional stacking patterns have been successfully used to predict well test response and as input to reservoir simulators. We present a rock catalog format to provide a reference for interpreting lithotypes from this geographic and depositional setting as well as a methodology for evaluating these types of thinly-bedded deposits. P. 883^