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Imagine the Mediterranean Sea drying out. Imagine the late Permian, as the Earth warmed and dried, and much of life faced extinction. Now put the two together, and you have the basis of an analog examined in the presentation “The Messinian Mediterranean Crisis: A Model for the Permian Delaware Basin?” at the upcoming AAPG International Conference and Exhibition in Istanbul, Turkey.
Over the last two decades, numerical and physical experiments have repeatedly generated insights that contradict the
sequence stratigraphic model that is near-universally used to interpret ancient
strata in terms of relative changes in sea-level. This presentation will
re-examine Upper Cretaceous strata (Blackhawk Formation, Castlegate Sandstone, Mancos
Shale) exposed in the Book Cliffs, east-central Utah, USA, which are widely
used as an archtype for the sequence stratigraphy of marginal-marine and
shallow-marine strata. Stratigraphic architectures in these strata are classically
interpreted to reflect forcing by relative sea level, but key aspects can
instead be attributed to autogenic behaviors and variations in sediment flux.
This lecture presents a history of sea-level changes focusing on the last 100 Myr. Prior to the Oligocene (ca. 33.5 Ma), the Earth had been a warm, high CO2 Greenhouse world that was largely ice-free back to 260 Ma, though recent evidence suggests that 15-25 m sea-level changes observed may have been caused by growth and decay of small, ephemeral ice sheets. The growth and decay of a continental scale ice sheet in Antarctica caused 50-60 m variations on the 106 yr scale beginning ~33.5 million years ago (Ma).
IODP Expedition 313 (New Jersey shallow shelf) cored a 3-hole transect across Miocene seismic clinothems (prograding sigmoidal sequences) in topset, foreset, and bottomset locations, providing an opportunity to integrate seismic, log, and core data into a sequence stratigraphic framework.
Our interpretations of sequences and systems tracts are made independent of any preconceived relative sea-level curves. Rather, we use basic seismic, core, and stratigraphic principles to recognize sequence boundaries, Maximum Flooding Surface, transgressive surfaces, and facies successions within sequences.
Sequence stratigraphy is the study of genetically related facies within a framework of chronostratigraphically significant surfaces. Paleontologic data, integrated with seismic and well log data, are an integral part of sequence stratigraphic analysis.
"Breakthrough elegance": ExxonMobil geologists Jeff Ottmann and Kevin Bohacs shared their highly-coveted knowledge on sweet spots and producibility thresholds at a recent Geosciences Technology Workshop on Unconventional Reservoir Quality.
This article describes a 250-m (820-ft)-thick upper Eocene deep-water clastic succession. This succession is divided into two reservoir zones: the lower sandstone zone (LSZ) and the upper sandstone zone, separated by a package of pelitic rocks with variable thickness on the order of tens of meters. The application of sequence-stratigraphic methodology allowed the subdivision of this stratigraphic section into third-order systems tracts.
The LSZ is characterized by blocky and fining-upward beds on well logs, and includes interbedded shale layers of as much as 10 m (33 ft) thick. This zone reaches a maximum thickness of 150 m (492 ft) and fills a trough at least 4 km (2 mi) wide, underlain by an erosional surface. The lower part of this zone consists of coarse- to medium-grained sandstones with good vertical pressure communication. We interpret this unit as vertically and laterally amalgamated channel-fill deposits of high-density turbidity flows accumulated during late forced regression. The sandstones in the upper part of this trough are dominantly medium to fine grained and display an overall fining-upward trend. We interpret them as laterally amalgamated channel-fill deposits of lower density turbidity flows, relative to the ones in the lower part of the LSZ, accumulated during lowstand to early transgression.
The pelitic rocks that separate the two sandstone zones display variable thickness, from 35 to more than 100 m (115–>328 ft), indistinct seismic facies, and no internal markers on well logs, and consist of muddy diamictites with contorted shale rip-up clasts. This section is interpreted as cohesive debris flows and/or mass-transported slumps accumulated during late transgression.
The upper sandstone zone displays a weakly defined blocky well-log signature, where the proportion of sand is higher than 80%, and a jagged well-log signature, where the sand proportion is lower than 60%. The high proportions of sand are associated with a channelized geometry that is well delineated on seismic amplitude maps. Several depositional elements are identified within this zone, including leveed channels, crevasse channels, and splays associated with turbidity flows. This package is interpreted as the product of increased terrigenous sediment supply during highstand normal regression.
Numerous studies of sediment-dispersal systems have focused on the relative role of allogenic versus autogenic controls, and their stratigraphic imprint. Advancing our understanding of these vital issues depends heavily on geochronology.
This course will alternate between lectures and practical exercises involving cores, logs and seismic data.
A succession of exercises and complementary
lectures will expose the participants to deep-water depositional systems, facies analysis, chronostratigraphic framework, comparison of local to global depositional patterns, and application of an integrated approach to stratigraphic analyses using multiple data sets.
This short course is designed to provide information to facilitate exploration for microbial carbonate buildups and associated reservoir facies and to assist with the formulation of development plans for fields producing from microbial carbonates. The course consists of a series of seven lectures supplemented by core samples.
The overall goal of this course is to provide tools for efficient and effective re-exploration and development. It uses a two-part approach. First it uses petrophysical analysis to understand all that can be derived from examination of standard open-hole logs. This is followed by integrated approaches to discover key factors controlling oil and gas distribution in carbonate reservoirs in the greater Midcontinent USA. Methodologies and workflows reviewed include geosteering and evaluation of horizontal wells and optimizing carbon storage utilization and management.
This course presents the concepts and practical applications of sequence stratigraphy for petroleum exploration.
This field seminar will give participants an overview about the geology, reservoir engineering and operation aspects of the Lodgepole-Bakken-Three Forks Petroleum System. Excellent outcrops illustrate how facies, reservoir properties and rock strength can vary along a lateral well bore. Engineers, geologists and operators will find this especially interesting.
The Hay River region in the Northwest Territories is one of the best locations in North America for the examination of Devonian carbonates, and the Pine Point mine site is one of the best localities for viewing the fabrics and geometries associated with hydrothermal dolomitization.
Participants will learn through the use of spectacular outcrops, subsurface datasets, and stratigraphic modeling how these systems tracts and key surfaces (flooding surfaces and sequence boundaries) may be recognized.
Recognition and Correlation of the Eagle Ford, Austin Formations in South Texas can be enhanced with High Resolution Biostratigraphy, fossil abundance peaks and Maximum Flooding Surfaces correlated to Upper Cretaceous sequence stratigraphic cycle chart after Gradstein, 2010.
This presentation is designed for exploration/production geologists and geological managers or reservoir engineers.
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