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Sedimentology and Stratigraphy

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Bulletin Article

7969
 

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.

7968
 

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.

Environmental Geosciences Article

5780
 
We use sediment ages and mercury (Hg) concentrations to estimate past and future concentrations in the South River, Virginia, where Hg was released between 1930 and 1950 from a manufacturing process related to nylon production. In a previous study, along a 40 km (25 mi) reach, samples were collected from 26 of 54 fine-grained deposits that formed in the lee of large wood obstructions in the channel and analyzed for grain size, Hg concentration, and organic content. We also obtained radiometric dates from six deposits. To create a history that reflects the full concentration distribution (which contains concentrations as high as 900 mg/kg [900 ppm]), here, we treat the deposits as a single reservoir exchanging contaminated sediments with the overlying water column, and assume that the total sediment mass in storage and the distribution of sediment ages are time invariant. We use reservoir theory to reconstruct the annual history of Hg concentration on suspended sediment using data from our previous study and new results presented here. Many different reconstructed histories fit our data. To constrain results, we use information from a well-preserved core (and our estimate of the total mass of Hg stored in 2007) to specify the years associated with the peak concentration of 900 mg/kg. Our results indicate that around 850 kg (1874 lb) of Hg was stored in the deposits between 1955 and 1961, compared to only 80 kg (176 lb) today. Simulations of future Hg remediation suggest that 100-yr timescales will be needed for the South River to remove Hg-contaminated sediments from the channel perimeter through natural processes.
5779
 

 SONAR, historical and aerial photographs, and vibracoring were used to assess the type and thickness distribution of sediments impounded by Gold Ray Dam on the Rogue River in southern Oregon. From these data, a volume of about 400,000 cubic yards (

Equation EG13006eq1

) of sediment was determined for the inundated area of the reservoir.

Overall, sediment volumes in the impounded part of the reservoir were less than expected. There are three possibilities that may explain the perceived absence of sediment: (1) the gradient of the Rogue River in this stretch is less, and therefore sediment yields are less; (2) the extraction of gravels and/or other impediments upstream decreased the availability of sediments delivered into the reservoir; and/or (3) sediment was deposited by a prograding delta that filled in the inundated area of the floodplain upstream from Gold Ray Dam. The amount of sediment deposited on this inundated floodplain may have been as much as 1,800,000 cubic yards (Equation EG13006eq2), bringing the total amount of sediment impounded by Gold Ray Dam to Equation EG13006eq3 yards (Equation EG13006eq4).

Applied sedimentology is not only vital to developing a depositional model for the filling of a reservoir, but also providing insights into depositional and erosional changes that will occur upon the removal of a dam. In particular, the processes of delta formation, reoccupation of abandoned channels, and avulsion are paramount in determining sediment accumulation and distribution in reservoirs.

Explorer Article

8582
 

A three-day international conference honoring the life and work of the late AAPG Honorary member David Roberts, entitled “Basin Dynamics and Petroleum Systems: Geophysics, Structure, Stratigraphy, Sedimentology and Geochemistry.” will be held April 14-16 at Royal Holloway University, London, England.

8486
 

Robert G. Loucks, a senior research scientist at the Bureau of Economic Geology, University of Texas at Austin, is one of this year’s Robert R. Berg Outstanding Research Award winners. 

8060
 

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.

8045
 

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

Explorer Historical Highlight

8590
 

Great Britain in the late 18th and early 19th centuries was undergoing great change. The Industrial Revolution was in full flood and there was an insatiable desire for coal to turn the wheels of industry.

Wiki Article

9050
 

From AAPG Wiki: A salt flat.

Forum

Oklahoma City Oklahoma United States 29 May, 2014 29 May, 2014 3810
 
Oklahoma City, Oklahoma, United States
29 May 2014
Join us for an intensive one-day forum which will focus on optimizing the exploration and development of the Woodford Shale. We're looking at recent findings in geochemistry and geomechanics to understand how best to drill and complete the reservoir, and also where the productive limits may be.

Short Course

Houston Texas United States 19 August, 2014 21 August, 2014 1509
 
Houston, Texas, United States
19-21 August 2014

Here is an introduction to the tools and techniques that geologists and geophysicists use to locate gas and oil, that drillers use to drill the wells and that petroleum engineers use to test and complete the wells and produce the gas and oil. Exercises throughout the course provide practical experience in well log correlation, contouring, interpretation of surface and subsurface, contoured maps, seismic interpretation, well log interpretation, and decline curve analysis.

Austin Texas United States 29 April, 2014 01 May, 2014 1518
 
Austin, Texas, United States
29 April - 1 May 2014

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.

Houston Texas United States 08 December, 2014 11 December, 2014 1517
 
Houston, Texas, United States
8-11 December 2014

This course is designed to give participants the basic working tools to explore and develop hydrocarbons in salt basins. Because no two basins are alike, the focus is on understanding the processes and styles of salt-related deformation. At course completion participants should be able to under the depositional setting of layered evaporites, describe the mechanics of salt flow, interpret salt and stratal geometries associated with diapirs, salt welds, and minibasins, and assess more accurately the risks in the exploration of salt basins.

Workshop

Muscat Oman 20 October, 2014 22 October, 2014 8553
 
Muscat, Oman
20-22 October 2014

This three-day workshop will be dedicated to sharing knowledge, ideas, and workflows pertaining to exploration for stratigraphically trapped hydrocarbon accumulations in the Middle East. The workshop will emphasize case studies involving both carbonates and clastics — in order to help focus explorationists in their search for these types of traps. 

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