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8045
 
Explorer Article

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

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.

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.

7966
 

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.

7965
 

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 (lt1) 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.

7963
 
Organic-carbon–rich shales of the lower Marcellus Formation were deposited at the toe and basinward of a prograding clinothem associated with a Mahantango Formation delta complex centered near Harrisburg, Pennsylvania. Distribution of these organic-carbon–rich shales was influenced by shifts in the delta complex driven by changes in rates of accommodation creation and by a topographically high carbonate bank that formed along the Findlay-Algonquin arch during deposition of the Onondaga Formation. Specifically, we interpret the Union Springs member (Shamokin Member of the Marcellus Formation) and the Onondaga Formation as comprising a single third-order depositional sequence. The Onondaga Formation was deposited in the lowstand to transgressive systems tract, and the Union Springs member was deposited in the transgressive, highstand, and falling-stage systems tract. The regional extent of parasequences, systems tracts, and the interpreted depositional sequence suggest that base-level fluctuations were primarily caused by allogenic forcing—eustasy, climate, or regional thermal uplift or subsidence—instead of basement fault reactivation as argued by previous workers. Paleowater depths in the region of Marcellus Formation black mudrock accumulation were at least 330 ft (100 m) as estimated by differences in strata thickness between the northwestern carbonate bank and basinal facies to the southeast. Geochemical analysis indicates anoxic to euxinic bottom-water conditions. These conditions were supported by a deep, stratified basin with a lack of circulation.
7962
 
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.
5768
 
Predicting the presence and connectivity of reservoir-quality facies in otherwise mud-prone fluvial overbank successions is important because such sand bodies can potentially provide connectivity between larger neighboring sand bodies. This article addresses minor channelized fluvial elements (crevasse-splay and distributary channels) and attempts to predict the connectivity between such sand bodies in two interseam packages of the Upper Permian Rangal Coal Measures of northeastern Australia. Channel-body percent as measured in well logs was 2% in the upper (Aries-Castor) interseam and 17% in the lower (Castor-Pollux) interseam. Well spacing were too great to allow accurate correlation of channel bodies. The Ob River, Siberia, was used as a modern analog to supply planform geometric measurements of splay and distributary channels so that stochastic modeling of channel bodies was possible. The resulting models demonstrated that (1) channel-body connectivity is more uniform between minor distributary channels than between crevasse-splay channels; (2) relatively good connectivity is seen in proximal positions in splays but decreases distally from the source as channel elements diverge; and (3) connectivity tends to be greater down the axis of splays, with more isolated channel bodies occurring at the margins.
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In-Person Training
Salt Lake City Utah United States 14 September, 2014 21 September, 2014 151
 
Salt Lake City, Utah, United States
14-21 September 2014

Participants will learn a specific and comprehensive methodology for finding and developing conventional and unconventional oil and gas resources associated with lake deposits. The seminar will start with the Quaternary Bonneville basin in Utah, to build familiarity with lacustrine depositional processes. Participants then examine world-famous exposures of organic-rich mudstone, fluvial sandstone, and carbonate microbialite facies in Wyoming.

Barcelona Spain 22 September, 2014 26 September, 2014 153
 
Barcelona, Spain
22-26 September 2014

Participants will examine illustrative outcrops of thrusts, fault-related folds, stratal architectures and facies of depositional systems affected by growing structures, which are good analogues for hydrocarbon reservoirs. Objectives include interpreting complex thrust structures, identifying and understanding strain and fracture systems in fold-thrust belts, and analyzing patterns of growth strata in areas with synsedimentary folding.

Denver Colorado United States 25 October, 2014 26 October, 2014 9125
 
Denver, Colorado, United States
25-26 October 2014

Unconventional petroleum systems are becoming much more important world wide in oil and gas exploration and development. This field trip will examine several unconventional systems in the Denver and Florence-Canon City basins.

Houston Texas United States 10 November, 2014 10 November, 2014 10401
 
Houston, Texas, United States
10 November 2014

A one-day series of lectures covers the basic architecture of particulate sedimentary rocks, methods for petrologic characterization, grain assemblages, and diagenesis, including compaction, cementation, grain replacement, and fracturing. Examples of the nature and causes of reservoir quality variations in sandstones at low and high temperatures are provided with a focus on using the character of the primary grain assemblage as a predictive guide to what will happen in the subsurface.

Houston Texas United States 12 November, 2014 12 November, 2014 10570
 
Houston, Texas, United States
12 November 2014

This course is designed to present the concepts of sedimentary geochemistry and biogeochemistry, along with the framework to interpret elemental and mineralogical records in such organic rich mudstone sequences.

Houston Texas United States 27 January, 2015 28 January, 2015 8997
 
Houston, Texas, United States
27-28 January 2015

Reserve your space now to learn how and where new knowledge and technology geology, engineering, and geophysics come together to make deepwater and shelf exploration and development more successful. 

14 February, 3000 14 February, 3000 7812
 
14 February, 3000 14 February, 3000 7816
 
14 February, 3000 14 February, 3000 7813
 
14 February, 3000 14 February, 3000 7815
 
Online Training
01 January, 2013 01 January, 9999 1459
 
1 January 2013 - 1 January 9999

There are more approximately 1,000 oil and gas fields in the world that have been classified as "giant," containing more than 500 million barrels of recoverable oil and /or 3 trillion cubic feet of gas.

13 December, 2012 13 December, 2012 1494
 
13 December 2012

The course will review core data, petrophysical comparisons, rock physics modeling (including pseudo logs and mechanical properties).

24 October, 2013 24 October, 2013 1499
 
24 October 2013

This e-symposium will be introducing signal processing techniques as a means to maximize extracting geomechanical data from petrophysical logs.

07 November, 2013 07 November, 2013 1500
 
7 November 2013

This e-symposium presentation places the interpretation of deep-water turbidites discernible in 3-D seismic inversion data within a geological context.

08 December, 2011 08 December, 2011 1480
 
8 December 2011

This e-symposium focuses on methods for predicting connectivity within clastic fluvial systems.

28 April, 2011 28 April, 2011 1471
 
28 April 2011

The Niobrara Petroleum System of the U.S. Rocky Mountain Region is a major tight petroleum resource play.

17 February, 2011 17 February, 2011 1469
 
17 February 2011

This presentation is designed for exploration/production geologists and geological managers or reservoir engineers.

11 November, 2010 11 November, 2010 1465
 
11 November 2010

This e-symposium is ideal for geologists, geophysicists, engineers and other geoscientists who are involved in gas shale exploration and production.

29 April, 2010 29 April, 2010 1457
 
29 April 2010

This presentation will focus on the seismic stratigraphic and seismic geomorphologic expression of deep-water deposits, including both reservoir and non-reservoir facies.

22 October, 2009 22 October, 2009 1452
 
22 October 2009

This course can help you gain the ability to describe the complex and highly variable reservoirs, which are typified by complex internal heterogeneity.

14 February, 3000 14 February, 3000 7817
 
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