About: Chevron Corporation is a company organization based out in Rotterdam, Netherlands. It is known for research contribution in the topics: Catalysis & Alkyl. The organization has 10768 authors who have published 14568 publications receiving 271788 citations. The organization is also known as: Chevron México & Chevron.
Papers published on a yearly basis
TL;DR: The Sea-Level Changes: An Integrated Approach (SEPM) conference as discussed by the authors was a forum for an interdisciplinary exchange of ideas on sea-level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues.
Abstract: Sea-Level Changes: An Integrated Approach - In October 1985, SEPM sponsored a four-day conference entitled ?Sea-Level Changes ? An Integrated Approach.? The purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea-level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues. The conference was successful in bringing together scientists from industry, academia, and government, representing all of the major geosciences disciplines. Presentations of many new papers, plus significant releases of data that were previously held proprietary, provided fertile ground for discussion. This much-cited volume represents the best of the material presented at the conference. Includes the early ?Vail? chart.
TL;DR: The anoxic aquatic environment is a mass of water so depleted in oxygen that virtually all aerobic biologic activity has ceased as discussed by the authors, where the demand for oxygen in the water column exceeds the supply.
Abstract: The anoxic aquatic environment is a mass of water so depleted in oxygen that virtually all aerobic biologic activity has ceased. Anoxic conditions occur where the demand for oxygen in the water column exceeds the supply. Oxygen demand relates to surface biologic productivity, whereas oxygen supply largely depends on water circulation, which is governed by global climatic patterns and the Coriolis force. Organic matter in sediments below anoxic water is commonly more abundant and more lipid-rich than under oxygenated water mainly because of the absence of benthonic scavenging. The specific cause for preferential lipid enrichment probably relates to the biochemistry of anaerobic bacterial activity. Geochemical-sedimentologic evidence suggests that potential oil source beds are and have been deposited in the geologic past in four main anoxic settings as follows. 1. Large anoxic lakes: Permanent stratification promotes development of anoxic bottom water, particularly in large lakes which are not subject to seasonal overturn, such as Lake Tanganyika. Warm equable climatic conditions favor lacustrine anoxia and nonmarine oil source bed deposition. Conversely, lakes in temperate climates tend to be well oxygenated. 2. Anoxic silled basins: Only those landlocked silled basins with positive water balance tend to become anoxic. Typical are the Baltic and Black Seas. In arid-region seas (Red and Mediterranean Seas), evaporation exceeds river inflow, causing negative water balance and well-oxygenated bottom waters. Anoxic conditions in silled basins on oceanic shelves also depend upon overall climatic and water-circulation patterns. Silled basins should be prone to oil source bed deposition at times of worldwide transgression, both at high and low paleolatitudes. Silled-basin geometry, however, does not automatically imply the presence of oil source beds. 3. Anoxic layers caused by upwelling: These develop only when the oxygen supply in deep water cannot match demand owing to high surface biologic productivity. Examples are the Benguela Current and Peru coastal upwelling. No systematic correlation exists between upwelling and anoxic conditions because deep oxygen supply is often sufficient to match strongest demand. Oil source beds and phosphorites resulting from upwelling are present preferentially at low paleolatitudes and at times of worldwide transgression. 4. Open-ocean anoxic layers: These are present in the oxygen-minimum layers of the northeastern Pacific and northern Indian Oceans, far from deep, oxygenated polar water sources. They are analogous, on a reduced scale, to worldwide "oceanic anoxic events" which occurred at global climatic warmups and major transgressions, as in Late Jurassic and middle Cretaceous times. Known marine oil source bed systems are not randomly distributed in time but tend to coincide with periods of worldwide transgression and oceanic anoxia. Geochemistry, assisted by paleogeography, can greatly help petroleum exploration by identifying paleoanoxic events and therefore widespread oil source bed systems in the stratigraphic record. Recognition of the proposed anoxic models in ancient sedimentary basins should help in regional stratigraphic mapping of oil shale and oil source beds.
University of Alberta1, ExxonMobil2, University of Houston3, Louisiana State University4, Queen's University5, University of Pretoria6, University of Nebraska–Lincoln7, University of Texas at Austin8, Dalhousie University9, New Mexico State University10, University of Texas at Arlington11, University of South Carolina12, University of Toronto13, Colorado School of Mines14, Chevron Corporation15, University of Saskatchewan16, University of Fribourg17, Durham University18, Royal Dutch Shell19
TL;DR: In this paper, a model-independent framework of genetic units and bounding surfaces for sequence stratigraphy has been proposed, based on the interplay of accommodation and sedimentation (i.e., forced regressive, lowstand and highstand normal regressive), which are bounded by sequence stratigraphic surfaces.
Abstract: Sequence stratigraphy emphasizes facies relationships and stratal architecture within a chronological framework. Despite its wide use, sequence stratigraphy has yet to be included in any stratigraphic code or guide. This lack of standardization reflects the existence of competing approaches (or models) and confusing or even conflicting terminology. Standardization of sequence stratigraphy requires the definition of the fundamental model-independent concepts, units, bounding surfaces and workflow that outline the foundation of the method. A standardized scheme needs to be sufficiently broad to encompass all possible choices of approach, rather than being limited to a single approach or model. A sequence stratigraphic framework includes genetic units that result from the interplay of accommodation and sedimentation (i.e., forced regressive, lowstand and highstand normal regressive, and transgressive), which are bounded by ‘sequence stratigraphic’ surfaces. Each genetic unit is defined by specific stratal stacking patterns and bounding surfaces, and consists of a tract of correlatable depositional systems (i.e., a ‘systems tract’). The mappability of systems tracts and sequence stratigraphic surfaces depends on depositional setting and the types of data available for analysis. It is this high degree of variability in the precise expression of sequence stratigraphic units and bounding surfaces that requires the adoption of a methodology that is sufficiently flexible that it can accommodate the range of likely expressions. The integration of outcrop, core, well-log and seismic data affords the optimal approach to the application of sequence stratigraphy. Missing insights from one set of data or another may limit the ‘resolution’ of the sequence stratigraphic interpretation. A standardized workflow of sequence stratigraphic analysis requires the identification of all genetic units and bounding surfaces that can be delineated objectively, at the selected scale of observation, within a stratigraphic section. Construction of this model-independent framework of genetic units and bounding surfaces ensures the success of the sequence stratigraphic method. Beyond this, the interpreter may make model-dependent choices with respect to which set of sequence stratigraphic surfaces should be elevated in importance and be selected as sequence boundaries. In practice, the succession often dictates which set of surfaces are best expressed and hold the greatest utility at defining sequence boundaries and quasi-chronostratigraphic units. The nomenclature of systems tracts and sequence stratigraphic surfaces is also model-dependent to some extent, but a standard set of terms is recommended to facilitate communication between all practitioners.
TL;DR: In this paper, the absolute concentration of steranes, terpanes, and paraffins (n + iso) in combination with internal ratios of individual biomarkers such as primary/secondary terpane, 17α(H)-trisnorhopane/18α( H)-triscope II (both maturation specific), 5β/5α-steranes, 5β-sterane/17α (H)-hopanes and rearranged steranes/5β-teranes (all migration oriented), 5α/ 5α-stanes and
Abstract: Novel biological marker parameters are applied to problems of geochemical correlation of crude oils in the McKittrick Field, California. An attempt is described to distinguish four diagenetic parameters; namely, source input, source maturation, migration and ‘in reservoir’ maturation. The tools include the absolute concentration of steranes, terpanes and paraffins (n + iso) in combination with internal ratios of individual biomarkers such as primary/secondary terpanes, 17α(H)-trisnorhopane/18α(H)-trisnorhopane II (both maturation specific), 5β/5α-steranes, 5β-steranes/17α(H)-hopanes and rearranged steranes/5α-steranes (all migration oriented), 5α/5α-steranes and a number of terpane ratios of partially unknown chemical structure (source input specific). Among other new correlation parameters are: two series of mass chromatograms (m/e 253 and 239), signaling monoaromatized steranes, a series of presumably rearranged steranes (m/e 259), and a series of methylhopanes (m/e 205). The results obtained on the molecular level exceed the degree of information obtainable from organic geochemical ‘bulk’ parameters such as yields of saturates, aromatics, sulfur compounds and C13/C12 ratios by far; however, both types of parameters are mutually supporting. All conclusions are consistent with subtle stratigraphie and overall geologic prerequisites.
ExxonMobil1, University of Houston2, University of Pretoria3, University of Nebraska–Lincoln4, University of Texas at Austin5, New Mexico State University6, University of Texas at Arlington7, University of South Carolina8, University of Toronto9, University of the Balearic Islands10, Chevron Corporation11, University of Saskatchewan12, University of Fribourg13, Royal Dutch Shell14
TL;DR: Catuneanu et al. as discussed by the authors used a neutral approach that focused on model-independent, fundamental concepts, because these are the ones common to various approaches and this search for common ground is what they meant by "standardization", not the imposition of a strict, inﬂexible set of rules for the placement of sequence-stratigraphicsurfaces.
Abstract: 1. RationaleWe thank William Helland-Hansen for his compliments andfeedbackonourpaper.Weaimedtoestablishaconsensusinsequencestratigraphy by using a neutral approach that focused on model-independent, fundamental concepts, because these are the onescommon to various approaches. This search for common ground iswhat we meant by ‘standardization’, not the imposition of a strict,inﬂexible set of rules for the placement of sequence-stratigraphicsurfaces. Our work is meant to eliminate the present state ofmethodological and nomenclatural confusion within sequence strati-graphy, which is largely the result of uncoordinated effort in thedevelopment of the method and the proliferation of terminology thatis unnecessarily complex.The model-independent (i.e., common to various approaches;Figs. 10 and 22 in Catuneanu et al., 2009) notions provide thepractitioner with the ‘tools’ to identify the fundamental ‘buildingblocks’ in the rock record on the basis of observations of facies and/or
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