Sequence Stratigraphic Setting of Deepwater Systems
Published:January 01, 2006
2006. "Sequence Stratigraphic Setting of Deepwater Systems", 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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Sequence stratigraphy is the study of sedimentary rocks within a temporal framework. The basic premise is that marine sedimentary rocks were deposited in a series of cycles that result from the relative fall and rise of sea level. The depositional pattern can vary widely from basin to basin, depending upon variations in sediment supply and basin tectonics.
The fundamental mapping unit of sequence stratigraphy is a depositional sequence. Vail et al. (1977) defined a depositional sequence as “a stratigraphic unit composed of a relatively conformable succession of genetically related strata and bounded at its top and base by unconformities or their correlative conformities.” Depositional sequences can be mapped using seismic, wireline log, and outcrop data.
What distinguishes sequence stratigraphy from other paradigms is that strata are interpreted within a chronostratigraphic framework. Chronostratigraphy can be determined using different types of data sets. High-resolution bio stratigraphy is essential to the dating of sequences and determining paleo-environments. Correlation of bedding (stratal) surfaces defines time lines based on physical stratigraphy. Finally, seismic reflections are generated at stratal boundaries, and tend to follow them within the limits of seismic resolution. Thus, seismic reflections, with certain exceptions, represent time lines within the limits of their resolution. This key chronostratigraphic feature makes seismic reflections ideal tools for defining the chronostratigraphy of a sedimentary basin and for correlating strata.
The most controversial aspect of sequence stratigraphy is that sequence boundaries of the same age can be found in basins worldwide; therefore, sequence boundaries are considered
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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.