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This study evaluates the proportion, length, and effective properties of thin (0.003-0.7 m [0.01-2.3 ft]) shale beds and drapes in tidally influenced channels within a compound valley fill with a focus on estimating geologically based effective rock properties. The Cretaceous Ferron Sandstone is an outcrop analog for fluvial-tidal systems with primary reservoirs being deposited as tidally influenced valley filling point bars. The study outcrops expose three valley systems in Neilson Wash of Utah. Light detection and ranging-derived digital outcrop models have been used to characterize shale length, width, thickness, and frequency of each valley fill succession. Long, uncommon, and anisotropic shales in valley 1 (VI) were deposited in a braided setting with little tidal influence. In contrast, shales in valley 2 (V2) were abundant, short, common, and equidimensional, suggesting deposition by more tidally influenced meandering rivers. Short, frequent, and equidimensional shales in valley 3 (V3) were deposited in single-thread meandering rivers with less tidal influence. A sandstone-shale model was used to estimate the effects of shales on vertical to horizontal permeability ratio (kv/kh). The unique character of each depositional unit was reflected in resultant kv/kh distributions. The valley fill deposits, VI, V2, and V3, had average ky/kh ratios of 0.11, 0.09, and 0.17, respectively. More tidally influenced reservoirs such as the studied V2 had short but frequent shales, which resulted in low kv/kh estimates. Estimates of kv/kh for valleys that predominantly contained fluvial point bar deposits with lesser tidal influence (VI and V3) were higher. The results of this study highlight the link between shale heterogeneity, reservoir architecture, and inferred flow parameters. [ABSTRACT FROM AUTHOR]

The Turonian Notom delta is one of the Ferron fluvial-deltaic wedges deposited in the Cretaceous foreland basin of North America and is well exposed in the Henry Mountains region, Utah. This article uses variable sampling of measured sections of the fluvial-deltaic wedge along a 19-mi (30-km) outcrop belt to address correlation uncertainties in sparse data sets, such as are common in subsurface studies. A high-resolution sequence-stratigraphic analysis based on 58 measured sections, extensive walking out of beds, and field photomosaics shows that the wedge is composed of 43 parasequences, 18 parasequence sets, and six depositional sequences. Resampling the outcrop belt with 13 sections provides a sparse data set. Correlations using the data set show considerable uncertainties. Fluvial complexity is greatly underestimated, and in the extreme case, only 40% of the fluvial bodies are identified. Overcorrelation results in as much as 400% exaggeration of sandstone width and thickness. Some of the uncertainties can be reduced by incorporating nonmarine sequence-stratigraphic models and various techniques that allow a more reasonable evaluation of fluvial body geometry. With sparse data, uncertainties also arise in marine successions. A key challenge is to identify and correlate the small-scale units, particularly forced regressive deposits. Many of their diagnostic features that can be easily recognized from outcrops and cores may not be as easily detected from well logs and on seismic data. In subsurface studies where sparse data are observed, integrating detailed facies analysis cores and sequence-stratigraphic concepts is critical to predict the occurrence and understand the architecture of such deposits. [ABSTRACT FROM AUTHOR]

Pleistocene fluvial, estuarine, marine, and deltaic deposition systems were identified in the uppermost 80 m (262 ft) of the central Gulf of Thailand modern continental shelf, situated approximately 70 m (-230 ft) below sea level. Integration of offshore three-dimensional (3-D) seismic reflection data, high-resolution shallow-penetration two-dimensional (2-D) seismic reflection sparker and boomer profiles, and shallow geotechnical borehole measurements enabled the identification of seven depositional sequences. The 3-D plan-view images at successive time slices exhibit single meandering channels (as much as 600 m [1969 ft] wide and channel belts (as much as 10 km [6.2 mi] wide) deposited in the shelf during times of subaerial exposure. Additional geomorphic features imaged include incised valleys, interfluves, oxbow lakes, neck and chute cutoffs, and point-bar meander scrolls showing evidence of expansion and translation. The high-resolution 2-D profiles, with a tuning thickness of approximately 25 cm (~9.8 in.), enabled the discrimination of high-frequency stratigraphic discontinuities (sequence boundaries) and allowed a detailed bed-scale seismic facies characterization of fluvial (point bars), deltaic (clinoforms), estuarine, and marine deposits within a sequence-stratigraphic context. The complete succession shows that most fluvial systems lie within incised valleys in the lower parts of each depositional sequence, fluvial channels show a degradational stacking pattern, and no evidence of fluvial aggradation is observed; aggradation is limited to hemipelagic sedimentation during marine incursions. A shallow (<35 m [<115 ft]) single-story incised valley was described in detail, placing particular emphasis on the recognition criteria and the controls on valley formation and preservation potential of different systems tracts in an inner-shelf location. The 3-D characterization of this system allowed differentiation of sand-prone point-bar deposits and mud-prone abandonment channel facies. The sinuous but continuous mud-filled channel may act as a lateral muddy barrier or baffle that can potentially subdivide a reservoir system into discrete compartments. [ABSTRACT FROM AUTHOR]

Recent studies of shelf-margin deltas in the Gulf of Mexico lack three-dimensional (3-D) seismic interpretation that allows prediction of lithology distribution, deformation features, and overall reservoir heterogeneity, and only a few 3-D studies of shelf-margin deltas in other parts of the world exist. This paper examines the 3-D geomorphology and internal facies architecture within a sequence-stratigraphic framework of a shelf-margin delta in a salt dome minibasin, within the Gulf of Mexico, offshore Louisiana, using 3-D seismic data. The 3-D data also allow an evaluation oft.he potential pathways for sediment bypass from delta front to slope and deep-water depositional environments. The delta consists of a series of offlapping sandy clinoforms, interpreted as being associated with a prolonged forced regression and ensuing lowstand of eustatic sea level, related to oxygen isotope stage 6, which lasted for about 45 k.y. The lowstand delta is onlapped by a transgressive mud wedge and is underlain and capped by regionally persistent highstand mudstones. The central part of the delta shows intradeltaic syndepositional growth faults, likely triggered by deposition of heavy delta-front sands over mobile prodeltaic muds, reflecting the river-dominated nature of the delta. A postdepositional shallow-water mass transport complex (MTC), which moved almost perpendicular to the direction of the regional delta progradation, remobilizes the deltaic deposits. The MTC was likely induced by uplift of the adjacent western salt dome. We hypothesize that the high degree of syndepositional and postdepositional deformation is related to the prolonged nature of the eustatic lowstand, as well as the salt tectonics. Tfibutive submarine slope channels form down-dip of the delta front and may also reflect incision during the prolonged eustatic lowstand. The salt tectonics caused focusing of the dispersed delta-front sediments, mostly originating from terminal distributary channels, into the convergent tributive slope-channel system. Although this is an unstable supply-dominated shelf-margin delta, the salt tectonics likely prevented the delta from avulsing once it reached the shelf edge and also caused the focusing of dispersed sediment effectively into a point source for delivery to deep-water systems. This contrasts with less confined high-sediment supply delta systems farther along the coast, which lack linked submarine deposits because they reach the shelf mar- gin before maximum eustatic lowstand and avulse before building significant deep-water systems. [ABSTRACT FROM AUTHOR]

The Cenomanian Second Frontier sandstone, one of the major producing units of the Frontier Formation in the Powder River Basin, Wyoming, is a basin-isolated sand body that pinches out to zero thickness in both seaward and basinward direction. The Second Frontier has previously been viewed as a single, relatively homogeneous, wave-dominated sediment succession. Our high-resolution study, integrating detailed facies relationships in outcrop, core, and well logs, shows that the Second Frontier sandstone comprises an offlapping parasequence set, formed from seven regionally mappable wave-dominated parasequences. The parasequences are bounded by minor flooding surfaces that represent previously unrecognized potential flow barriers or baffles. Parasequence boundaries are oriented obliquely to the well-defined regional north-northwest-south-southeast-elongated trend of the unit, and successive parasequences offlap to the south in an along-strike direction. The seaward pinchout of the Second Frontier sandstone is depositional in nature, as illustrated by well-preserved healing-phase deposits, whereas the basinward pinch-out is caused by marine truncation over a tectonically uplifted area. Parasequence architecture was strongly affected by syndepositional tectonic movement, which determined both (1) the distribution of the entire parasequence set, forming a depositional remnant, and (2) the position and shape of parasequences internal to the remnant. The Second Frontier is thus interpreted as a depositional remnant of a once more extensive wave-dominated deltaic shoreface complex. [ABSTRACT FROM AUTHOR]

The article offers information on several American Association of Petroleum Geologists (AAPG) honorees for 2007. It includes Arnold H. Bouma, recipient of the Sidney Powers Memorial Award, John J. Amoruso, recipient of the Michel T. Halbouty Outstanding Leadership Award, and Jonny Wu recipient of the Ziad Beydoun Memorial Award.

Ground-penetrating radar (GPR) has been used to image the three-dimensional (3-D) internal structure (and, thus, the 3-D facies architecture) of a top-truncated delta front in the topmost parasequence in the Wall Creek Sandstone Member of the Frontier Formation in Wyoming and to estimate the distribution of low-permeability concretions throughout the 3-D GPR volume. The interpretation of the 3-D GPR data is based both on correlations with outcrop and on calibration with core data from holes within the survey grid. Two main radar facies (RF) are identified. Radar facies 1 corresponds to tide-influenced mouth bars formed by a unidirectional flow during delta progradation or bidirectional flow during tides, whereas RF2 is correlated with laterally migrating channels developed on previous bar deposits. The delta-front foreset beds dip in the same direction as the dominant paleocurrent indicators. The GPR interpretation is consistent with the outcrop interpretation that, following a regressive period, bars and channels were developed at the Raptor Ridge site before subsequent transgressive ravinement. The individual 3-D deltaic facies architectures were reconstructed from the 3-D GPR volume and indicate that the depositional units are larger than the survey grid. Cluster analysis of the GPR attributes (instantaneous amplitudes and wave numbers) calibrated with the cores and the outcrop was used to predict the distribution of near-zero permeability concretions throughout the 3-D GPR volume; clusters of predictive attributes were defined and applied separately in the bars and channels. The predicted concretions in the bars and the channels are 14.7 and 10.2% by volume, respectively, which is consistent with those observed in the cores (14.7 and 10.5%, respectively), and their shape and thickness are also generally in consonance with those in the outcrop and cores. The estimated concretions are distributed in an aggregate pattern with irregularly shaped branches within the 3-D GPR volume, indicating that the cementation does not follow a traditional center-to-margin pattern. The concretions and 3-D geological solid model provide cemented flow baffles and a 3-D structural framework for 3-D reservoir modeling, respectively. [ABSTRACT FROM AUTHOR]

Ground-penetrating radar (GPR) measurements, in conjunction with outcrop sedimentology, were carried out at Murphy Creek reservoir in the Upper Cretaceous Turonian Wall Creek Member of the Frontier Formation in Wyoming. The objectives were to apply GPR to map geometrical details of a top-truncated lowstand delta front and to estimate the volumes of the prograding bar deposits of the delta lobe. Eleven GPR profiles totaling about 4400 m (14,435 ft) were acquired using 50-MHz antennas on a coarsely spaced, two-dimensional grid of lines lying parallel and perpendicular to the average depositional dip. Ground-penetrating radar reflections were detected from within the outcrop to a depth of about 10-15 m (33-49 ft). Four southerly dipping major surfaces identified in the GPR data are correlated with the boundaries of progradational delta-front facies, stacked as distal mouth-bar deposits, in the outcrop. The major boundaries correspond to lithological changes between relatively clean sandstones that are interpreted to have been deposited during floods with high sediment supply, alternating with bioturbated sandstones and mudstones deposited during interflood periods with correspondingly low sedimentation rates. These two lithological units, which also correspond to the two main GPR facies, repeat at least three times with no change in dominant average sand-grain size. Subsequent erosion by transgressive ravinement caused the significantly truncated lowstand delta long after the sandstones were deposited. The bar assemblage volume at successive stages of growth is estimated using measurements from the outcrop and the GPR data. The migrating bars have an estimated average half-lenght of 650 m (2132 ft); a lower bound on the average volume of the bar is 3.9 x 106 m³ (1.37 x 108 ft³). As the volume of the bars increases, the bar deposites appear to have a landward as well as a basinward component of accretion. [ABSTRACT FROM AUTHOR]

The article presents updates on the American Association of Petroleum Geologists (AAPG) Education Committee as of December 2010. The committee revealed ideas and products in the 2009-2010 fiscal year including online courses like e-symposia, and a self-study Open Courseware program backed by the AAPG Foundation. The Education Committee seeks to aid and offer consultation to the AAPG Education Directorate in order to develop AAPG education initiatives in the U.S. and abroad.