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Brian P. West

Bio: Brian P. West is an academic researcher from ExxonMobil. The author has contributed to research in topics: Mantle (geology) & Probabilistic neural network. The author has an hindex of 15, co-authored 26 publications receiving 696 citations. Previous affiliations of Brian P. West include University of Washington & Oregon State University.

Papers
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Journal ArticleDOI
TL;DR: In this paper, textural analysis is applied to 3D seismic volumes and a neural network classifier is used to map seismic facies in three-dimensional data, which can be used for geologic and lithologic facies analysis of complex mixed-impedance reservoirs.
Abstract: 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 anlaysis 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 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). Figure 1. Examples of seismic facies and potential associated geologic fill. A seismic facies can be defined as a stratigraphic region in the seismic data volume that has a characteristic reflection pattern distinguishable from those of other areas on the basis of reflection amplitude, continuity, geometry, and/or internal configuration of reflectors. Inherent in …

138 citations

Journal ArticleDOI
01 Aug 1998-Nature
TL;DR: In this article, a source of increased magma supply, coinciding with the known Indian-Pacific mantle isotopic boundary, has propagated into the eastern AAD, displacing the chaotic terrain and replacing it with normal sea floor.
Abstract: Oceanic crust formed over the past 30 million years at the Australian–Antarctic discordance (AAD) is characterized by chaotic sea-floor topography, reflecting a weak magma supply from an unusually cold underlying mantle. During the past 3–4 million years, however, a source of increased magma supply, coinciding with the known Indian–Pacific mantle isotopic boundary, has propagated into the eastern AAD, displacing the chaotic terrain and replacing it with normal sea floor. Pacific mantle reached the eastern boundary of the AAD at least 7 million years ago, but it was not until 3–4 million years ago that lavas derived from Pacific mantle were first erupted within the AAD. This long hiatus, combined with the ridge–transform geometry across the AAD boundary, constrains the locus of mantle migration to a narrow, relatively shallow region, directly beneath the spreading axis of the Southeast Indian ridge.

79 citations

Patent
Brian P. West1, Steven R. May1
13 Sep 2001
TL;DR: In this paper, a probalistic neural network is constructed from the calculated initial textural attributes, in which textural attribute are calculated throughout the volume of seismic data, with the calculated final textural features are classified using the constructed probabilistic neural networks.
Abstract: Seismic facies are identified in a volume of seismic data (101), wherein a plurality of initial textural attributes representative of the volume of seismic data are calculated (103), with a probalistic neural network is constructed from the calculated initial textural attributes (107), in which textural attributes are calculated throughout the volume of seismic data (108), with the calculated final textural attributes are classified using the constructed probalistic neural network (111).

57 citations

Patent
29 Aug 2002
TL;DR: In this article, near-offset and far-offset seismic data volumes are aligned by first selecting a plurality of time shifts and then filtering the determined areas of high time shift and low cross-correlation from the initial time-shift volume.
Abstract: Near-offset and far-offset seismic data volumes are time-aligned by first selecting a plurality of time shifts. The near-offset and far-offset seismic data volumes are cross-correlated at the plurality of time shifts. An initial time-shift volume and a maximum correlation volume are created from the maximal cross-correlations at the plurality of time shifts. Areas of high time shift from the initial time-shift volume and areas of low cross-correlation from the maximum correlation volume are determined. The determined areas of high time shift and low cross-correlation are filtered from the initial time-shift volume, generating a filtered time-shift volume. The filtered time-shift volume is applied to the far-offset seismic volume to generate a time-aligned far-offset volume.

40 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, a combination of approaches is required to estimate the major and trace element abundances in the depleted mantle (DM), the source for mid-ocean ridge basalts (MORBs).
Abstract: [1] We present an estimate for the composition of the depleted mantle (DM), the source for mid-ocean ridge basalts (MORBs). A combination of approaches is required to estimate the major and trace element abundances in DM. Absolute concentrations of few elements can be estimated directly, and the bulk of the estimates is derived using elemental ratios. The isotopic composition of MORB allows calculation of parent-daughter ratios. These estimates form the “backbone” of the abundances of the trace elements that make up the Coryell-Masuda diagram (spider diagram). The remaining elements of the Coryell-Masuda diagram are estimated through the composition of MORB. A third group of estimates is derived from the elemental and isotopic composition of peridotites. The major element composition is obtained by subtraction of a low-degree melt from a bulk silicate Earth (BSE) composition. The continental crust (CC) is thought to be complementary to the DM, and ratios that are chondritic in the CC are expected to also be chondritic in the DM. Thus some of the remaining elements are estimated using the composition of CC and chondrites. Volatile element and noble gas concentrations are estimated using constraints from the composition of MORBs and ocean island basalts (OIBs). Mass balance with BSE, CC, and DM indicates that CC and this estimate of the DM are not complementary reservoirs.

1,432 citations

Journal ArticleDOI
TL;DR: A seismic attribute is a quantitative measure of a seismic characteristic of interest as mentioned in this paper, which has been integral to reflection seismic interpretation since the 1930s when geophysicists started to pick traveltimes to coherent reflections on seismic field records.
Abstract: A seismic attribute is a quantitative measure of a seismic characteristic of interest. Analysis of attributes has been integral to reflection seismic interpretation since the 1930s when geophysicists started to pick traveltimes to coherent reflections on seismic field records. There are now more than 50 distinct seismic attributes calculated from seismic data and applied to the interpretation of geologic structure, stratigraphy, and rock/pore fluid properties. The evolution of seismic attributes is closely linked to advances in computer technology. As examples, the advent of digital recording in the 1960s produced improved measurements of seismic amplitude and pointed out the correlation between hydrocarbon pore fluids and strong amplitudes (“bright spots”). The introduction of color printers in the early 1970s allowed color displays of reflection strength, frequency, phase, and interval velocity to be overlain routinely on black-and-white seismic records. Interpretation workstations in the 1980s provided...

437 citations

Journal ArticleDOI
TL;DR: In this article, a 3D radially anisotropic S velocity model of the whole mantle (SAW642AN) is presented using a large three component surface and body waveform data set and an iterative inversion for structure and source parameters based on NACT.
Abstract: SUMMARY We present a 3-D radially anisotropic S velocity model of the whole mantle (SAW642AN), obtained using a large three component surface and body waveform data set and an iterative inversion for structure and source parameters based on Non-linear Asymptotic Coupling Theory (NACT). The model is parametrized in level 4 spherical splines, which have a spacing of ! 8 " . The model shows a link between mantle flow and anisotropy in a variety of depth ranges. In the uppermost mantle, we confirm observations of regions with VSH > VSV starting at ! 80 km under oceanic regions and ! 200 km under stable continental lithosphere, suggesting horizontal flow beneath the lithosphere. We also observe a VSV > VSH signature at ! 150‐300 km depth beneath major ridge systems with amplitude correlated with spreading rate for fast-spreading segments. In the transition zone (400‐700 km depth), regions of subducted slab material are associated with VSV > VSH, while the ridge signal decreases. Whilethemid-mantlehasloweramplitudeanisotropy( VSV in the lowermost 300 km, which appears to be a robust conclusion, despite an error in our previous paper which has been corrected here. The 3-D deviations from this signature are associated with the large-scale low-velocity superplumes underthecentralPacificandAfrica,suggestingthatVSH >VSV isgeneratedinthepredominant horizontal flow of a mechanical boundary layer, with a change in signature related to transition to upwelling at the superplumes.

376 citations

Journal ArticleDOI
TL;DR: A survey of core-complex literature can be found in this article, where the authors discuss processes and questions relevant to the formation and evolution of core complexes in continental and oceanic settings, highlight the significance of core complex for lithosphere dynamics and propose a few possible directions for future research.
Abstract: Core-complex formation driven by lithospheric extension is a first-order process of heat and mass transfer in the Earth. Core-complex structures have been recognized in the continents, at slow- and ultraslow-spreading mid-ocean ridges, and at continental rifted margins; in each of these settings, extension has driven the exhumation of deep crust and/or upper mantle. The style of extension and the magnitude of core-complex exhumation are determined fundamentally by rheology: (1) Coupling between brittle and ductile layers regulates fault patterns in the brittle layer; and (2) viscosity of the flowing layer is controlled dominantly by the synextension geotherm and the presence or absence of melt. The pressure-temperature-time-fluid-deformation history of core complexes, investigated via field- and modeling-based studies, reveals the magnitude, rate, and mechanisms of advection of heat and material from deep to shallow levels, as well as the consequences for the chemical and physical evolution of the lithosphere, including the role of core-complex development in crustal differentiation, global element cycles, and ore formation. In this review, we provide a survey of ∼40 yr of core-complex literature, discuss processes and questions relevant to the formation and evolution of core complexes in continental and oceanic settings, highlight the significance of core complexes for lithosphere dynamics, and propose a few possible directions for future research.

290 citations

Journal ArticleDOI
TL;DR: A variety of geophysical data indicates that long wavelength temperature variations of the asthenosphere depart from the mean by ±200°C, not the ±20°C adopted by plume theoreticians as mentioned in this paper.
Abstract: A variety of geophysical data indicates that long wavelength temperature variations of the asthenosphere depart from the mean by ±200°C, not the ±20°C adopted by plume theoreticians. The ‘normal’ variation, caused by plate tectonic processes (subduction cooling, continental insulation, small‐scale convection) encompasses the temperature excesses that have been attributed to hot jets and thermal plumes. Geophysical estimates of the average potential temperature of the upper mantle are about 1400°C. Asthenospheric convection at ridges, rifts and fracture zones and at the onset of continental breakup is intrinsically 3D, giving rise to shallow pseudoplume‐like structures without deep thermal instabilities. Deep narrow thermal plumes are unnecessary and are precluded by uplift and subsidence data. The locations and volumes of ‘midplate’ volcanism appear to be controlled by lithospheric architecture, stress and cracks.

276 citations