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PSGD-Related Articles

Explorer Article By Heather Saucier

PROWESS Honors Historic Earthquake Survivor

Ruth Schmidt, one of the first 100 women members of AAPG, is celebrated for her brilliant and adventurous career geologic career.

Added on 01 April, 2014

Explorer Article By Louise Durham

Permeability Trumps Storage in Shale Play

Shale formations can confound even the savviest geoscientist when it comes to determining the inner workings of the rock. After expert evaluation, even the most attractive prospecting deal can be a tough sell. And there’s almost always a new piece to each of these puzzles that requires some sophisticated high-tech explaining.

Added on 01 April, 2014

Bulletin Article

Structural analysis of a salt-cored transfer zone in the South Timbalier Block 54, offshore Gulf of Mexico: Implications for restoration of salt-related extensional structures

The style of faulting in offshore Louisiana, Gulf of Mexico, is characterized by short, arcuate regional and counterregional growth faults, which commonly form complex transfer zones above shallow, Miocene level salt bodies. South Timbalier Block 54 (ST54) constitutes one such area where a basinward-dipping regional and a landward-dipping counterregional growth fault form a convergent transfer zone.

Added on 31 March, 2014

Explorer Director’s Corner By David Curtiss

Innovation, Collaboration Create New Value For AAPG

How can AAPG create and deliver value to its members, volunteers, customers, the oil and gas industry, and to society? After all, that’s why we exist as an organization. But what is value, anyway?

Added on 01 March, 2014

Explorer Article By Susan Eaton

AAPG Distinguished Lecturer Mohriak Focuses on Red Sea's Analogies

Current AAPG Distinguished Lecturer Webster Mohriak is one of the confirmed keynote speakers for the upcoming Atlantic Realm Conjugate Margins Conference, set this August in St. John’s, Newfoundland. Retiring in 2011 after

Added on 01 March, 2014

Explorer Emphasis Article By Emily Llinás

'Geoscientists Dream' Complicated By Politics, PR

Winning Hearts and Minds: Colombia and Latin American prospects offer high promise and difficult hurdles in the form of local political and public resistance.

Added on 01 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

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

Evolution of shelf-margin clinoforms and deep-water fans during the middle Eocene in the Sorvestsnaget Basin, southwest Barents Sea

Interpretation of seismic data from the Sorvestsnaget Basin, southwest Barents Sea, demonstrates gradual middle Eocene basin infilling (from the north) generated by southward-prograding shelf-margin clinoforms. The basin experienced continued accommodation development during the middle Eocene because of differential subsidence caused by the onset of early Eocene sea-floor spreading in the Norwegian-Greenland Sea, faulting, salt movement, and different tectonic activity between the Sorvestsnaget Basin and Veslemoy high. During this time, the margin shows transformation from an initially high-relief margin to a progradation in the final stage. The early stage of progradation is characterized by the establishment of generally oblique clinoform shifts creating a flat shelf-edge trajectory that implies a gentle falling or stable relative sea level and low accommodation-to-sediment supply ratio (1) in the topsets. During the early stage of basin development, the high-relief margin, narrow shelf, stable or falling relative sea level, seismicity, and presumably high sedimentation rate caused accumulation of thick and areally extensive deep-water fans. Seismic-scale sandstone injections deform the fans. A fully prograding margin developed when the shelf-to-basin profile lowered, apparently because of increased subsidence of the northern part. This stage of the basin development is generally characterized by the presence of sigmoid clinoform shifts creating an ascending shelf-edge trajectory that is implying steady or rising relative sea level with an accommodation-to-sediment supply ratio of greater than 1, implying sand accumulation on the shelf. This study suggests that some volume of sand was transported into the deep water during relative sea level rise considering the narrow shelf and inferred high rates of sediment supply.

Added on 28 February, 2014

Bulletin Article

Geometry, kinematics, and displacement characteristics of tear-fault systems: An example from the deep-water Niger Delta

We use three-dimensional seismic reflection data and new map-based structural restoration methods to define the displacement history and characteristics of a series of tear faults in the deep-water Niger Delta. Deformation in the deep-water Niger Delta is focused mostly within two fold-and-thrust belts that accommodate downdip shortening produced by updip extension on the continental shelf. This shortening is accommodated by a series of thrust sheets that are locally cut by strike-slip faults. Through seismic mapping and interpretation, we resolve these strike-slip faults to be tear faults that share a common detachment level with the thrust faults. Acting in conjunction, these structures have accommodated a north –south gradient in westward-directed shortening. We apply a map-based restoration technique implemented in Gocad to restore an upper stratigraphic horizon of the late Oligocene and use this analysis to calculate slip profiles along the strike-slip faults. The slip magnitudes and directions change abruptly along the lengths of the tear faults as they interact with numerous thrust sheets. The discontinuous nature of these slip profiles reflects the manner in which they have accommodated differential movement between the footwall and hanging-wall blocks of the thrust sheets. In cases for which the relationship between a strike-slip fault and multiple thrust faults is unclear, the recognition of this type of slip profile may distinguish thin-skinned tear faults from more conventional deep-seated, throughgoing strike-slip faults.

Added on 28 February, 2014

Hot Items

Explorer Article By Barry Friedman

US Energy Forecast: Even Cloudier Than Usual

It isn’t news to anyone that prediction is difficult, especially when it’s the future (as a great man once said). Uncertainty and unpredictability are just a part of the job of tracking and predicting the future supply and demand of energy. That being the case, when energy analysts say that the current level of uncertainty is particularly high, it might be easy to dismiss it as a “dog bites man” story. It isn’t.

Added on 04 June, 2024

Explorer Director’s Corner By David Curtiss

Introducing the New EXPLORER, New Digital Newsletters

Perhaps you did a double take pulling the April issue of EXPLORER from the mailbox. What is this? If you joined AAPG in the last 40 years, you’ve only known EXPLORER in its long-standing tabloid format. It worked well for many years as our advertisers – particularly seismic companies – loved the large format and the ability to display their data on a sweeping canvas. For readers, it was a little more awkward.

Added on 01 April, 2024

Explorer Geophysical Corner By Kenneth Bredesen,Kurt Marfurt,Ritesh Sharma,Satinder Chopra

Impact of Reprocessing Seismic Data

Advancements in processing and imaging techniques have continued over the last several decades, which have gradually improved the quality of the processed surface seismic data. When the quality of the existing seismic data is not adequate to perform an interpretation task reasonably, then the interpreter looks for other options. Is it feasible to acquire a new survey? In the absence of an improved survey, will reprocessing of seismic data be a good option?

Added on 01 December, 2023

Explorer Article By J.K. Dietrich

Natural Increase of Oil Column Buoyancy and the Instability of Caprock Seals

A new type of buoyancy model can be used to understand the source of residual oil zones, both thick and thin, to help determine the likelihood that economically viable recoverable oil resides in transition zones of imbibition reservoirs. Application of a buoyancy and breech model will fill a void in reservoir characterization. It will help distinguish between TZs and ROZs, the first of which allows application of primary and secondary (waterflooding) oil recovery methods and the second of which requires more difficult CO2-enhanced oil recovery projects.

Added on 08 May, 2024

Explorer Historical Highlights By Jorge Navarro Comet

Casablanca: Spain's Biggest Oil Field

The Casablanca oil field, discovered in 1975 and located on the Mediterranean shelf edge, has been greatly significant in the world’s offshore oil industry activity, besides being by far the biggest oil field in Spain.

Added on 01 March, 2019

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