Deepwater-Reservoir Elements: Channels and Their Sedimentary Fill
Published:January 01, 2006
2006. "Deepwater-Reservoir Elements: Channels and Their Sedimentary Fill", 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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Deepwater channels have received considerable attention in the petroleum industry during the past decade, because of (1) the important discoveries that have been made in several deepwater basins in which reservoir performance was critical to development decisions and strategies (e.g., Campos Basin, Brazil, offshore Angola, Nile, Mahakam Delta, northern Gulf of Mexico, West of Shetland Islands, and offshore mid-Norway); (2) the ability of 3D seismic to increasingly image the complex internal geometries of channel systems (especially those that are sinuous); and (3) the need to avoid shallow flow problems while drilling channel-fill sediments.
Many slope systems in passive margins are extremely muddy. The importance of channels as sand conduits for bypass to the basin floor probably was not fully appreciated until about 15 years ago, when large volumes of sand were recognized to occur downdip of muddy slope systems (e.g., Angola and the northern Gulf of Mexico). Many slope channels are marked by evidence of sediment bypass (coarse-grained lags, traction deposits, heterolithic deposits of fine-grained tails, and fine-grained levees, in some instances).
Channels and their fills have been studied for many years, from different perspectives, and using multiple data sets, including data from the modern seafloor, from the shallow subsurface (shallow seismic for shallow-hazards drilling surveys), from deeper-exploration seismic, from reservoirs, and from outcrops. In this introductory section, we present a few general, qualitative concepts that are widely accepted concerning channels and their fills.
Because of the large number of published studies, and because most channel fills have at least
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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.