Bulletin Article

5773
 

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.

DL Abstract

3088
 
DL Abstract

The results of regional deep seismic acquisition in the South Atlantic continental margins have shed new lights on the birth and development of sedimentary basins formed during the Gondwana breakup. Recent models of mantle exhumation as observed in the deep water Iberian margin have been applied extensively to the interpretation of several basins in the Eastern Brazilian and West African conjugate margins. However, the tectonic development of these basins is markedly different from the magma-poor margins, and in this lecture we emphasize the contrasts from the tectono-sedimentary features imaged in deep-penetrating seismic profiles that extend from the platform towards the oceanic crust, which indicate that the Red Sea constitutes a better analogue for the birth of divergent continental margins.

Explorer Article

3167
 
Explorer Article

Shale may be the reservoir du jour, but a wide range of conventional reservoirs still hold promise in diverse regions throughout the world.

3166
 
Explorer Article

Discoveries were comparatively sparse, but they persisted steadily throughout the year. Here are some of the more significant discoveries of the past year.

3165
 
Explorer Article

A review of major oil and gas discoveries of 2013 shows a down year in terms of quantity—but that’s not the whole story.

Explorer Emphasis

8052
 

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

8050
 

Seismic Outlook: After several years of plenty, 2014 is expected to be a comparatively lean year for the seismic industry, a few localized hot-spots around the world notwithstanding.

2681
 
Explorer Emphasis Article

Quartet made its debut in the industry this year. The reviews are in and it looks like the value brought to the field is proving it to be innovative and time-saving.

2602
 

Latin America offers some of the most promising and most perplexing exploration prospects on the planet.

Explorer Regions and Sections

10772
 
Preparation for the FIFA World Cup was not the only event attracting international audiences to Brazil in May. AAPG’s Geosciences Technology Workshop (GTW) Brasil, "Stratigraphic Traps and Play Concepts in Deep Water Settings," brought in 143 geoscientists representing 12 countries from the Americas, Europe and Asia.

Workshop

Oslo Norway 16 March, 2015 19 March, 2015 10890
 
Oslo, Norway
16-19 March 2015

Permanent Reservoir Monitoring, also known as Life-of-Field Seismic, using permanently installed seismic cables, has been characterized by a few key marker projects but did not reach mainstream status during its first ten years. However, since the start of its second decade we have witnessed a flurry of new projects and activity so far, both in the Americas (Brazil) and Europe (Norway). Within a time span of about three years, these efforts combined are already dwarfing the efforts of the first 10 years.

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