Sinuous channels are common bathymetric features on Earth's continental margins. Until now, the 3D stratigraphy of these features has primarily been inferred from 3D seismic studies and from limited 2D outcrop exposures of ancient successions. The Beacon Channel Complex of the Permian upper Brushy Canyon Formation is an exceptionally wellexposed example of a 3D exposure of a sinuous slope channel system. The Beacon Channel Complex crops out on five cliff facies in an area of approximately 1 km 2 (0.625 mi 2 ). Nearly one complete wavelength of sinuosity is recorded in the outcrop.An integrated data set was used to evaluate the high-resolution, 3D stratigraphy of the Beacon Channel Complex. The stratigraphy of the Beacon Channel Complex is grouped into a hierarchical framework: one channel complex, two channel elements, and five channel stories. Each hierarchical level is empirically related to internal trends of erosional/ depositional energy, thickness, aspect ratio, and amalgamation ratio. Detailed field mapping reveals that the Beacon Channel Complex laterally migrated by both sweep and swing which temporally affected channel sinuosity. Phases of increasing sinuosity are related to channel downcutting, increasing swing, and basinward sweep, whereas phases of decreasing sinuosity are associated with channel filling, decreased swing, and landward sweep. Cross sections at various positions through the sinuous channel reveal patterns associated with facies and architectural asymmetry, reservoir connectivity, cross-sectional area, and preservation potential.The Beacon Channel Complex is an excellent reservoir and outcrop analog to many of Earth's sinuous slope channels on the basis of sinuosity, stratigraphic architecture, and grain size of its fill. This study provides additional knowledge of the 3D stratigraphy and processes of sinuous slope channels and offers a unique perspective that complements studies based on 3D seismic images of subsurface systems and nearseafloor studies of modern systems.
In this study, we present an application of textural analysis to 3D seismic volumes. Specifically, we combine image textural analysis with a neural network classification to quantitatively map seismic facies in three-dimensional data. Key advantages of this approach are: 1) it produces a detailed 3D facies classification volume (whereas manual seismic facies classifications are typically 2D maps), 2) it enables rapid and quantitative analysis of the increasingly large seismic volumes available to the interpreter, and 3) it eliminates many time-consuming tasks, thereby freeing the interpreter to focus on determining seismic facies and integrating them into a geologic framework.Finally, we extend our textural analysis-based seismic facies classification technique to interpretation of AVO attribute volumes, such as "A + B" (AVO intercept + gradient), to reduce the inherent nonuniqueness of seismic facies to geologic and lithologic facies, and simplify the facies analysis of complex, mixed-impedance reservoirs. Seismic facies analysis.Seismic facies analysis is a powerful qualitative technique used in stratigraphic analysis from seismic data and in hydrocarbon exploration. Seismic facies are groups of seismic reflections whose parameters (such as amplitude, continuity, reflection geometry, and frequency) differ from those of adjacent groups. Seismic facies analysis involves two key steps-(1) seismic facies classification (i.e., seismic facies are defined, and lateral/vertical extents delineated) and (2) interpretation (i.e., analysis of vertical/lateral associations, map patterns, and calibration to wells) to produce a geologic and depositional interpretation. This interpretation step is required because there is a nonunique relationship between seismic data, seismic facies, and depositional environment or rock property relationships ( Figure 1).In the past, the seismic facies mapping or classification step has occurred through time-consuming, manual methods. Seismic facies are conventionally delineated in the context of mapped horizons (i.e., the interpreter analyzes seismic facies that occur between mapped horizons). This is done by examining successive vertical sections through the seismic volume to determine the dominant seismic facies that occurs between the mapped horizons, and posting this information on a map. The output of this step is therefore a 2D map that generalizes the distribution of seismic facies vertically within a mapped interval. In large and complex areas, it may be difficult to map different seismic facies consistently.Manual seismic facies mapping, although time-consuming and qualitative, has proven extremely useful for hydrocarbon exploration and reservoir characterization, even when seismic facies cannot be uniquely related to physical properties. A skilled interpreter's knowledge and experience contribute greatly to the success of seismic facies analysis. However, with increasingly large 3D seismic volumes, a more efficient and quantitative, 3D or volume-based approach is required but one w...
Exceptional oblique-dip exposures of submarine fan complexes of the Brushy Canyon Fm. allow reconstruction of channel geometries and reservoir architecture from the slope to the basin floor. The Brushy Canyon conslsts of 1,500 ft. of basinally restricted sandstones and siltstones that onlap older carbonate slope deposits at the NW margin of the Delaware Basin. This succession represents a lowstand qequence set comprised of lugher frequency sequences that were deposited in the basin during subaerial exposure and bypass of the adjacent carbonate shelf. Progradational sequence stacking patterns reflect changing position and character of the slope as it evolved from a relict, carbonate margin, to a constructional, siltstone-dominated slope. Lowstand fan systems tracts consist of sharp-based, laterally extensive, sand-prone basin floor deposits and large, sand-filled channels encased in siltstones on the slope. The abandonment phase of each sequence (lowstand wedge-transgressive systems tract) consists of basinward-thinning siltstones that drape the basin floor fans. The slope-tobasin distnbution of lithofacies is attributed to a three stage cycle of: 1) erosion, mass wasting, and sand bypass on the slope with concurrent deposition from sand-rich flows on the basin floor, 2) progressive backfilling of feeder channels with variable fill during waning stages of deposition, and 3) cessation of sand delivery to the basin and deposition of laterally-extensive siltstone wedges. Paleocurrents and channel distributions indicate SE-E sediment transport from the NW basin margin via closely spaced point sources.
Sandstones and siltstones of the Permian ( Guadalupian) Brushy Canyon Formation were deposited in 50 to more than 300m of water in the Delaware Basin of west Texas. The transition from slope to basin-floor palaeoenvironments is exposed in a 24 km lang transect of extensive outcrops that occur along the western flanks of the Guadalupe and Delaware mountains.Several types of deep-water channels occur in the study area. Individual channels were filled with thickbedded sandstones that were deposited by highdensity sediment gravity flows, thin-bedded classical turbidites that were deposited by low-density turbidity currents, or siltstones that were deposited from suspension. Many channel-fills change facies laterally from amalgamated turbidite sandstones in channel axes to thin-bedded turbidites and siltstones along channel margins. Cross-bedded sandstones that occur as lag deposits at the bases of some channels are interpreted to have been deposited tractively by highdensity sediment gravity flows that carried most of their sediment Ioads further basinward. Siltstone drapes occur along the bases and margins of some channels, are common in slope and proximal basinfloor palaeoenvironments and are interpreted to reflect channel abandonment Levee deposits are common in the Brushy Canyon Formation. Strata! geometries along many channel margins indicate aggradation of adjacent levee deposits during channel filling. Levee deposits commonly include laterally continuous, thin-bedded classical turbidites that were deposited by low-density flows. However, near channel margins, levees can include thick-bedded, amalgamated turbidites that were deposited by high-and low-density flows and crossbedded sandstones that were deposited tractively by high-density flows. Along channel margins, palaeocurrents were commonly oriented parallel to slightly oblique to the channel trend and lenticular sandstone beds are common. In levee deposits, palaeocurrents generally were oriented 20-60° away from the adjacent channel margin.
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