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Sedimentology and Stratigraphy

Bulletin Article

Dolomites of the Boat Harbour Formation in the Northern Peninsula, western Newfoundland, Canada: Implications for dolomitization history and porosity control

The Boat Harbour Formation constitutes the upper part of the Lower Ordovician St. George Group on the Northern Peninsula, western Newfoundland. It ranges in thickness from 140 m (459 ft) at Main Brook to 96 m (315 ft) at Daniel's Harbour. Dolomitization of the carbonate sequence is more pervasive in the lower 30 to 40 m (98 to 131 ft) at Main Brook, whereas at Daniel's Harbour, the section is entirely dolomitized.

Added on 31 March, 2014

Bulletin Discussion

Modern internal waves and internal tides along oceanic pycnoclines: Challenges and implications for ancient deep-marine baroclinic sands: Discussion

In his article, “Modern internal waves and internal tides along oceanic pycnoclines: Challenges and implications for ancient deep-marine baroclinic sands” (Shanmugam, 2013), Shanmugam provides a very detailed account of processes involved in oceanic currents. He stresses that he has done this because he is concerned that the misinterpretation of baroclinic sands caused by turbidite deposits could have economic risks for the petroleum industry. As an example of one such possible misinterpretation, he refers to deep-water sands in the Kutei Basin in Indonesia that were described as turbidites by Saller et al. (2006).

Added on 31 March, 2014

Bulletin Discussion

Modern internal waves and internal tides along oceanic pycnoclines: Challenges and implications for ancient deep-marine baroclinic sands: Reply

It is gratifying to receive a prompt discussion from Dunham and Saller (2014) on my article (Shanmugam, 2013a). Although the focus of my article was on internal waves and internal tides, the primary purpose of their discussion is to defend and reiterate their original interpretation of Miocene deep-water sands as turbidites in the Kutei Basin, Indonesia (Saller et al., 2006). Even if some of these issues were debated earlier (Saller et al., 2008a; Shanmugam, 2008a), I welcome this timely opportunity to address the lingering problems associated with deep-water processes and related facies models.

Added on 31 March, 2014

Energy Policy Blog By Edith Allison

Two House Hearings on Oil and Gas Issues: A Chance to Listen and Comment

During the recent AAPG Congressional Visits Day, staff for the House Natural Resources Committee expressed interest in receiving input on issues and potential legislation from knowledgeable stakeholders. Here is an easy way to get involved in the process of informing Washington, D.C., decision makers: send a quick comment to the committee members in response to a particular hearing.

Added on 26 March, 2014

Energy Policy Blog By Edith Allison

Atlantic Seismic Surveys

BOEM has just issued its programmatic environmental impact statement (PEIS) for comment--through April 7. In announcing the decision, BOEM stated, that its review of geological and geophysical surveys in the Mid- and South-Atlantic planning areas '...establishes multiple mitigation measures designed to minimize the impacts to marine life while setting a path forward for survey activities that will update nearly four-decade-old data on offshore energy resources in the region.'

Added on 03 March, 2014

Explorer Article By Susan Eaton

Conference Conjugates Researchers, Explorers

Energized by the recent Statoil ASA-operated Bay du Nord light oil discovery in Newfoundland’s offshore Flemish Pass Basin, earth scientists are gearing up to host the fourth Atlantic Realm Conjugate Margins Conference in St. John’s, Newfoundland, Aug. 20-22.

Added on 01 March, 2014

Explorer Article By David Brown

Oklahoma Plays Offer Untapped Potential

Oklahoma! As-yet unlocked SCOOP and STACK plays have plen’y of room for maturation and development.

Added on 01 March, 2014

Bulletin Article

Compositional controls on early diagenetic pathways in fine-grained sedimentary rocks: Implications for predicting unconventional reservoir attributes of mudstones

Diagenesis significantly impacts mudstone lithofacies. Processes operating to control diagenetic pathways in mudstones are poorly known compared to analogous processes occurring in other sedimentary rocks. Selected organic-carbon-rich mudstones, from the Kimmeridge Clay and Monterey Formations, have been investigated to determine how varying starting compositions influence diagenesis.

Added on 28 February, 2014

Bulletin Article

Integrated reservoir characterization and simulation of a shallow, light-oil, low-temperature reservoir: Umiat field, National Petroleum Reserve, Alaska

Umiat field in northern Alaska is a shallow, light-oil accumulation with an estimated original oil in place of more than 1.5 billion bbl and 99 bcf associated gas. The field, discovered in 1946, was never considered viable because it is shallow, in permafrost, and far from any infrastructure. Modern drilling and production techniques now make Umiat a more attractive target if the behavior of a rock, ice, and light oil system at low pressure can be understood and simulated. The Umiat reservoir consists of shoreface and deltaic sandstones of the Cretaceous Nanushuk Formation deformed by a thrust-related anticline. Depositional environment imparts a strong vertical and horizontal permeability anisotropy to the reservoir that may be further complicated by diagenesis and open natural fractures. Experimental and theoretical studies indicate that there is a significant reduction in the relative permeability of oil in the presence of ice, with a maximum reduction when connate water is fresh and less reduction when water is saline. A representative Umiat oil sample was reconstituted by comparing the composition of a severely weathered Umiat fluid to a theoretical Umiat fluid composition derived using the Pedersen method. This sample was then used to determine fluid properties at reservoir conditions such as bubble point pressure, viscosity, and density. These geologic and engineering data were integrated into a simulation model that indicate recoveries of 12%–15% can be achieved over a 50-yr production period using cold gas injection from five well pads with a wagon-wheel configuration of multilateral wells.

Added on 28 February, 2014

Bulletin Article

Constraining the origin of reservoirs formed by sandstone intrusions: Insights from heavy mineral studies of the Eocene in the Forties area, United Kingdom central North Sea

The presence of hydrocarbon-bearing sandstones within the Eocene of the Forties area was first documented in 1985, when a Forties field (Paleocene) development well discovered the Brimmond field. Further hydrocarbons in the Eocene were discovered in the adjacent Maule field in 2009. Reservoir geometry derived from three-dimensional seismic data has provided evidence for both a depositional and a sand injectite origin for the Eocene sandstones. The Brimmond field is located in a deep-water channel complex that extends to the southeast, whereas the Maule field sandstones have the geometry of an injection sheet on the updip margin of the Brimmond channel system with a cone-shape feature emanating from the top of the Forties Sandstone Member (Paleocene). The geometry of the Eocene sandstones in the Maule field indicates that they are intrusive and originated by the fluidization and injection of sand during burial. From seismic and borehole data, it is unclear whether the sand that was injected to form the Maule reservoir was derived from depositional Eocene sandstones or from the underlying Forties Sandstone Member. These two alternatives are tested by comparing the heavy mineral and garnet geochemical characteristics of the injectite sandstones in the Maule field with the depositional sandstones of the Brimmond field and the Forties sandstones of the Forties field. The study revealed significant differences between the sandstones in the Forties field and those of the Maule and Brimmond fields), both in terms of heavy mineral and garnet geochemical data. The Brimmond-Maule and Forties sandstones therefore have different provenances and are genetically unrelated, indicating that the sandstones in the Maule field did not originate by the fluidization of Forties sandstones. By contrast, the provenance characteristics of the depositional Brimmond sandstones are closely comparable with sandstone intrusions in the Maule field. We conclude that the injectites in the Maule field formed by the fluidization of depositional Brimmond sandstones but do not exclude the important function of water from the huge underlying Forties Sandstone Member aquifer as the agent for developing the fluid supply and elevating pore pressure to fluidize and inject the Eocene sand. The study has demonstrated that heavy mineral provenance studies are an effective method of tracing the origin of injected sandstones, which are increasingly being recognized as an important hydrocarbon play.

Added on 28 February, 2014

VG Abstract By Keith Gerdes

Tethyan Carbonates - Linking Tropical Seas and Crashing Plates to Some of the Largest Oil and Gas Fields in the World

The carbonate sequences that were deposited in the now exhumed Tethyan Ocean influence many aspects of our lives today, either by supplying the energy that warms our homes and the fuel that powers our cars or providing the stunning landscapes for both winter and summer vacations. They also represent some of the most intensely studied rock formations in the world and have provided geoscientists with a fascinating insight into the turbulent nature of 250 Million years of Earth’s history. By combining studies from the full range of geoscience disciplines this presentation will trace the development of these carbonate sequences from their initial formation on the margins of large ancient continental masses to their present day locations in and around the Greater Mediterranean and Near East region. The first order control on growth patterns and carbonate platform development by the regional plate-tectonic setting, underlying basin architecture and fluctuations in sea level will be illustrated. The organisms that contribute to sequence development will be revealed to be treasure troves of forensic information. Finally, these rock sequences will be shown to contain all the ingredients necessary to form and retain hydrocarbons and the manner in which major post-depositional tectonic events led to the formation of some of the largest hydrocarbon accumulations in the world will be demonstrated.

Request a visit from Keith Gerdes!

Added on 24 August, 2015

DL Abstract By Tao Sun

Integrated Reservoir Characterization and Modeling with Computational Stratigraphy

As oil and gas exploration and production occur in deeper basins and more complex geologic settings, accurate characterization and modeling of reservoirs to improve estimated ultimate recovery (EUR) prediction, optimize well placement and maximize recovery become paramount. Existing technologies for reservoir characterization and modeling have proven inadequate for delivering detailed 3D predictions of reservoir architecture, connectivity and rock quality at scales that impact subsurface flow patterns and reservoir performance. Because of the gap between the geophysical and geologic data available (seismic, well logs, cores) and the data needed to model rock heterogeneities at the reservoir scale, constraints from external analog systems are needed. Existing stratigraphic concepts and deposition models are mostly empirical and seldom provide quantitative constraints on fine-scale reservoir heterogeneity. Current reservoir modeling tools are challenged to accurately replicate complex, nonstationary, rock heterogeneity patterns that control connectivity, such as shale layers that serve as flow baffles and barriers.

Request a visit from Tao Sun!

Added on 20 July, 2022

Sedimentology and Stratigraphy

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