Petroleum Systems of Deepwater Settings
Published:January 01, 2006
2006. "Petroleum Systems of Deepwater Settings", 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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Understanding and predicting the petroleum systems of deepwater settings is one of the most challenging aspects of deepwater exploration and production. Unlike reservoirs and traps, deepwater system’s source, seal, generation, timing, and migration are the least constrained scientifically. Thus, deepwater interpretations must be imaged from seismic, wireline log, petroleum seeps, or modeling.
Petroleum-systems modeling is a topic of active research in many companies, yet few results have been published because of the data, representing a major competitive advantage. One significant challenge in the modeling is that the petroleum system in each sedimentary basin is unique. Subtle changes in source-rock richness and distribution, timing of structures, and/or different pressure regimes can contribute to vastly different prospectivity. In general, deepwater basins are unique compared with other petroleum basins because (1) their petroleum was generated and migrated fairly recently (during the last 5–10 million years), and (2) all elements of their petroleum systems are constantly changing (evolving structures, changing stratal architecture, migration paths, and seal capacity).
The first two elements of petroleum systems—reservoirs and traps—are described in Chapter 5 through Chapter 10, and Chapter 15, respectively. In this chapter, we address the five remaining aspects of petroleum systems in deepwater settings: source rocks, seals, petroleum generation, migration, and timing. Some important aspects of the profitability of deepwater settings, such as oil quality, are reviewed. Due to the current confidentiality of deepwater data, we will address the conceptual aspects of deepwater systems, with fewer specific details as in reservoirs and traps.
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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.