Bulletin Article

3253
 

Analog outcrops are commonly used to develop predictive reservoir models and provide quantitative parameters that describe the architecture and facies distribution of sedimentary deposits at a subseismic scale, all of which aids exploration and production strategies. The focus of this study is to create a detailed geological model that contains realistic reservoir parameters and to apply nonlinear acoustic full-waveform prestack seismic inversion to this model to investigate whether this information can be recovered and to examine which geological features can be resolved by this process.

Outcrop data from the fluviodeltaic sequence of the Book Cliffs (Utah) are used for the geological and petrophysical two-dimensional model. Eight depositional environments are populated with average petrophysical reservoir properties adopted from a North Sea field. These units are termed lithotypes here. Synthetic acoustic prestack seismic data are then generated with the help of an algorithm that includes all internal multiples and transmission effects. A nonlinear acoustic full-waveform inversion is then applied to the synthetic data, and two media parameters, compressibility (inversely related to the square of the compressional wave velocity vP) and bulk density, ρ, are recovered at a resolution higher than the shortest wavelength in the data. This is possible because the inversion exploits the nonlinear nature of the relationship between the recorded data and the medium contrast properties. In conventional linear inversion, these details remain masked by the noise caused by the nonlinear effects in the data. Random noise added to the data is rejected by the nonlinear inversion, contributing to improved spatial resolution. The results show that the eight lithotypes can be successfully recovered at a subseismic scale and with a low degree of processing artifacts. This technique can provide a useful basis for more accurate reservoir modeling and field development planning, allowing targeting of smaller reservoir units such as distributary channels and lower shoreface sands.

3249
 

Data derived from core and well-logs are essentially one-dimensional and determining eolian system type and likely dimensions and orientation of architectural elements present in subsurface eolian reservoir successions is typically not possible from direct observation alone. This is problematic because accurate predictions of the three-dimensional distribution of interdune and dune-plinth elements that commonly form relatively low-permeability baffles to flow, of net:gross, and of the likely distribution of elements with common porosity-permeability properties at a variety of scales in eolian reservoirs is crucial for effective reservoir characterization.

Direct measurement of a variety of parameters relating to aspects of the architecture of eolian elements preserved as ancient outcropping successions has enabled the establishment of a series of empirical relationships with which to make first-order predictions of a range of architectural parameters from subsurface successions that are not observable directly in core. In many preserved eolian dune successions, the distribution of primary lithofacies types tends to occur in a predictable manner for different types of dune sets, whereby the pattern of distribution of grain-flow, wind-ripple, and grain-fall strata can be related to set architecture, which itself can be related back to original bedform type.

Detailed characterization of individual eolian dune sets and relationships between neighboring dune and interdune elements has been undertaken through outcrop studies of the Permian Cedar Mesa Sandstone and the Jurassic Navajo Sandstone in southern Utah. The style of transition between lithofacies types seen vertically in preserved sets, and therefore measurable in analogous core intervals, enables predictions to be made regarding the relationship between preserved set thickness, individual grain-flow thickness, original bedform dimensional properties (e.g., wavelength and height), the likely proportion of the original bedform that is preserved to form a set, the angle of climb of the system, and the likely along-crest variability of facies distributions in sets generated by the migration of sinuous-crested bedforms. A series of graphical models depict common facies arrangements in bedsets for a suite of dune types and these demonstrate inherent facies variability.

Explorer Article

2522
 
Explorer Article

EIA's Petroleum Supply Monthly report shows oil production in the lower 48 states has increased over the last three years.

2503
 

Geoscience students from the University of Utah took the top prize in this year’s Imperial Barrel Award competition, beating out 10 other teams from geology and geophysical departments from around the world.

Explorer Division Column EMD

3800
 

Every six months, chairs of the Energy Minerals Division committees convene and report on developments in the areas they cover. In this column, we highlight important observations from these recent reports.

139
 

A recent story about Shell’s withdrawal from a long-lived project on in situ production of shale oil from oil shale was an interesting example of over-interpretation of a small dataset.

Explorer Emphasis

11288
 
Explorer Emphasis Article
“These days, shows like The Big Bang Theory seem to pass for science content.” That’s Scott Sampson, one of this year’s AAPG Geosciences in the Media Award winners.
10191
 
Explorer Emphasis Article

The time-worn phrase "everything old is new again" is an apt description for much of the revved-up activity in the oil patch these days.

10188
 
Explorer Emphasis Article

As the Bakken, Eagle Ford, Marcellus and other shale plays make national news, the Cane Creek reservoir might be the dark horse poised to emerge as another major shale play. 

Explorer Policy Watch

11266
 
Explorer Policy Watch
Over the course of four months the House Natural Resources Committee, chaired by Doc Hastings (R-Wash.), or its Energy and Mineral Resources Subcommittee, chaired by Doug Lamborn (R-Colo.), hosted seven hearings celebrating energy education and employment.

Field Seminar

Grand Junction Colorado United States 04 September, 2014 11 September, 2014 86
 
Grand Junction, Colorado, United States
4-11 September 2014

Participants will learn through the use of spectacular outcrops, subsurface datasets, and stratigraphic modeling how these systems tracts and key surfaces (flooding surfaces and sequence boundaries) may be recognized.

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.

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