Deepwater-Reservoir Elements: Mass-Transport Deposits and Slides
Published:January 01, 2006
2006. "Deepwater-Reservoir Elements: Mass-Transport Deposits and Slides", Introduction to the Petroleum Geology of Deepwater Setting, Paul Weimer, Roger M. Slatt, Renaud Bouroullec, Richard Fillon, Henry Pettingill, Matthew Pranter, Gabor Tari
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Slides and mass-transport-related materials constitute large volumes of sediments in deepwater settings. During the past decade, extensive interpretations of 3D seismic data, conducted by many companies, have indicated that such deposits are quite common along most deepwater margins. In some basins, individual depositional sequences in the upper Quaternary may consist of more than 50% slides and/or deformed sediments. For example, in Basin 4 of the Brazos Trinity system in the northwestern Gulf of Mexico, 50–60% of the ponded sequence is composed of mass–transport deposits (Beaubouef et al., 2003); in deepwater Brunei, such elements comprise 50% of the depositional sequences (McGilvery and Cook, 2003); offshore the Nile they average 50% of the depositional sequences, and in some areas, they constitute as much as 90% of the sequences (Newton et al., 2004); and offshore eastern Trinidad they comprise 50% of the Quaternary depositional sequences (C. Shipp, personal communication, 2004).
Slides and mass-transport-related sediments are rarely primary reservoirs and are certainly not primary exploration targets in siliciclastic settings. However, we review these deposits here because (1) they constitute important aspects of deepwater sediment fill, (2) they can be important regional seals, and, most critically, (3) their distribution in the shallow subsurface is an important factor that should be identified in any assessment of drilling hazards and in geotechnical studies for exploration and development planning.
Specifically, the transportation and deformation of mass-transport deposits and slides appear to cause water expulsion. As a consequence, these features commonly are overcom-pacted
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Introduction to the Petroleum Geology of Deepwater Setting
This publication is intended to provide the working geologist, geophysicist, and petroleum engineer with a broad overview of the petroleum systems of deepwater settings. Deepwater depositional systems are the one type of reservoir system that cannot be easily reached, observed, and studied in the modern environment, in contrast to other siliciclastic and carbonate reservoir systems. The study of deepwater systems requires many different remote observation techniques, each of which can only provide information on one part of the entire depositional system. As a consequence, the study and understanding of deepwater depositional systems as reservoirs has lagged behind that of the other reservoir systems, whose modern processes are more easily observed and documented. For this reason, geoscientists use an integrated approach, working in interdisciplinary teams with multiple data types. The types of data used in the study of deepwater deposits include: outcrop studies, 2D and 3D seismic-reflection data (both for shallow and deep resolution), cores, conventional and specialized log suites, biostratigraphy, and well test and production information. These data sets are routinely incorporated into computer reservoir modeling programs for production performance simulation and forecasting. Technologies for deepwater exploration and development are improving rapidly. The intent of this publication is to provide information that will be usable even as the technologies advance beyond what we present here.