Showing papers by "ExxonMobil published in 2004"

The Biomarker Guide

Abstract: The second edition of The Biomarker Guide is a fully updated and expanded version of this essential reference. Now in two volumes, it provides a comprehensive account of the role that biomarker technology plays both in petroleum exploration and in understanding Earth history and processes. Biomarkers and Isotopes in the Environment and Human History details the origins of biomarkers and introduces basic chemical principles relevant to their study. It discusses analytical techniques, and applications of biomarkers to environmental and archaeological problems. The Biomarker Guide is an invaluable resource for geologists, petroleum geochemists, biogeochemists, environmental scientists and archaeologists.

Well-to-wheels analysis of future automotive fuels and powertrains in the european context

Abstract: A consortium of CONCAWE, EUCAR and the EU Commission's JRC carried out a Well-to-Wheels analysis of a wide range of\automotive fuels and powertrains. The study gives an assessment of the energy consumption and greenhouse gas emissions for each pathway. It also considers macroeconomic costs and the market potential of alternative fuels.

Molecular Structure Effects On Laminar Burning Velocities At Elevated Temperature And Pressure

Abstract: The laminar burning velocities of 45 hydrocarbons have been investigated in a constant volume combustion vessel at elevated temperature and pressure. The mixtures are ignited in the center of a spherical vessel at an initial temperature of 450 K and pressure of 304 kPa. Data have been acquired over the stoichiometry range of 0.55 ≤ φ ≤ 1.4. The burning velocity is determined from a thermodynamic analysis of the pressure vs. time data. The results for alkanes and alkenes are consistent with trends previously identified in the literature, i.e., alkenes are faster than the corresponding alkane with the same carbon connectivity. For both alkanes and alkenes, branching lowers the burning velocity. In addition, terminal alkenes and alkynes are found to be slightly faster than internal alkenes and alkynes. The present study includes broader coverage of aromatics than previous literature reports. The burning velocities for aromatics show a strong dependence on the type and site of alkyl substitution; methyl substitution lowers the burning velocity more than substitution with larger alkyl groups. For multiple methyl group substitution, meta substitution lowers the burning velocity more than ortho/para. The physical and chemical kinetic bases for the variation of burning velocity with molecular structure are discussed with the aid of elemental flux analyses of simulations using detailed chemical kinetic mechanisms. A consistent trend is identified in which "fast" burning fuels have a higher flux into decomposition pathways that yield H atoms and C2 fragments, while "slow" fuels have a higher flux into pathways that form CH3 radicals. The data and analysis presented in this paper provide a comprehensive, fundamental basis for relating fuel structure effects to combustion efficiency and emissions.

Lateral and Upward Soil-Pipeline Interactions in Sand for Deep Embedment Conditions

Abstract: The soil–pipeline interactions in sand under lateral and upward movements are investigated with particular attention to the peak forces exerted on the pipe. The analytical solutions for estimating the peak forces are summarized and it is shown that, for deep embedment condition, there is large uncertainty in the true values since the bounds established by the analytical solutions are large. In order to find the solution for the peak force and to investigate its transition from shallow to deep failure mechanism, finite element analyses of lateral and upward pipe movements are performed for different embedment conditions. Two different soil models (Mohr–Coulomb and Nor–Sand models) are used for the simulations. The accuracy of the analysis is first examined by simulating experimental tank tests. The analysis is further extended to deeper embedment ratios of as large as 100. The obtained finite element results are used to construct a design chart for deep embedded pipelines.

Deep-water leveed-channel complexes of the Cerro Toro Formation, Upper Cretaceous, southern Chile

Abstract: The Cerro Toro Formation in the Torres del Paine National Park, southern Chile, contains a series of deep-water channel complexes deposited in an elongate Andean foreland basin during the Late Cretaceous. This stratigraphic interval represents an essentially continuous depositional record of migrating, leveed-channel complexes. Collectively, the channel-fill units in the study area form a belt approximately 5 km (3 mi) wide and several hundred meters thick. Within the study area, four sets of channel complexes are identified. This paper focuses on the best exposed of these channel-complex sets (channel-complex set 3). The channels are filled by bedded conglomerate and amalgamated sandstones interpreted to represent the deposits of high-concentration turbidity currents and debris flows. Large-scale cross-beds in some of the conglomerates indicate significant bed-load transport of gravel- and cobble-forming bars in the channels. Channel axis to margin facies changes between clast-supported conglomerate and either (1) thick-bedded sandstone or (2) matrix-supported conglomerate are observed. Channel-fill facies lie on erosional surfaces that cut into adjacent interchannel facies. Beds thin and onlap these surfaces toward the channel margins. Shale or siltstone drapes of the channel cuts are uncommon and laterally discontinuous. Bed continuity between channel and adjacent, interchannel facies is not observed. The interchannel strata are interpreted to represent levee successions that bound the channels. Stratigraphy in the levee units is defined to include (1) basal, sandy lobe deposits comprised of medium- to thick-bedded turbidites and (2) overbank facies consisting primarily of packages of fining- and thinning-upward, fine-grained, thin-bedded turbidites. This vertical succession is transitional. Distal levee facies include mudstones with thin-bedded, laterally continuous sandstones. Proximal levee facies include mudstones with both thin- and thick-bedded sandstones; however, the thick-bedded sandstones have lower lateral continuity. The proximal levee facies have a higher sandstone percentage than the distal levee, but also have greater depositional and postdepositional complexity, with sand-filled crevasses, erosional truncation, and slumped beds. Field observations suggest that these leveed channels formed in stages that are represented by depositional and/or erosional events. In chronological order, these are (1) an initial stage of relatively unconfined, sand-rich deposition; (2) aggradation of a mud-rich, confining levee system resulting from overbank deposition as turbidity flows bypass the area; (3) erosion as the channel becomes entrenched or as the channel migrates; and (4) filling of the channel-margin relief by onlap of channel-fill sediments. These stages appear to have repeated several times during the formation of a series of channel complexes. In these ways, the Cerro Toro Formation appears analogous to leveed-channel systems observed in late Pleistocene submarine fans and subsurface examples.

Genesis and characterization of dolomite, Arab-D Reservoir, Ghawar field, Saudi Arabia

Abstract: This study reports the results of an investigation into the nature, origin and significance of linear dolomite trends across the Arab-D reservoir in Ghawar field. In the course of this study, three distinct types of dolomite were identified based on petrographic and geochemical criteria: fabric-preserving (FP), non-fabric-preserving (NFP) and baroque dolomite. Fabric-preserving (FP) dolomite is very finely crystalline dolomite in which details of the original limestone fabric are usually well preserved. Beds of FP dolomite typically occur as thin, sheet-like or stratigraphic layers that are always intimately associated with the overlying anhydrite. This dolomite is interpreted to have formed very early in the diagenetic history of the sediment, by dense, highly evaporated magnesium-rich brines associated with the overlying anhydrite. In contrast, NFP dolomite is a medium crystalline, non-baroque dolomite in which all traces of the original limestone fabric have been obliterated. This dolomite also typically occurs as stratigraphic beds, although it is not restricted to the uppermost part of the Arab-D but occurs throughout the reservoir. The NFP dolomite is the most common type present in the reservoir, and is interpreted on the basis of its general geochemical similarity to the FP dolomites to have mostly formed from hypersaline fluids, although some NFP dolomite is thought to represent a transitional form with the third dolomite type, baroque dolomite. Strontium isotopic ratios suggest that both the FP and most of the NFP dolomite formed very early, at or shortly after deposition of the original sediment. The third type of dolomite, baroque, is a coarsely crystalline dolomite with “saddle-shaped” crystals displaying undulose extinction in thin section. It is rare in the reservoir and appears to be limited to wells that contain abnormally thick sections of dolomite; in extreme cases, baroque dolomite is vertically pervasive. Geochemically, baroque dolomite is distinctive with high iron and very low oxygen isotopic compositions, and is interpreted to have formed from high temperature fluids during burial diagenesis. These fluids are suggested to have ascended up into the reservoir from depth along a fault/facture system, relatively late in the diagenetic history of the rock.

Hydrocarbon recovery from impermeable oil shales

Abstract: An economic method for in situ maturing and production of oil shale or other deep-lying, impermeable resources containing immobile hydrocarbons. Vertical fractures are created using horizontal or vertical wells. The same or other wells are used to inject pressurized fluids heated to less than approximately 370~ C, and to return the cooled fluid for reheating and recycling. The heat transferred to the oil shale gradually matures the kerogen to oil and gas as the temperature in the shale is brought up, and also promotes permeability within the shale in the form of small fractures sufficient to allow the shale to flow into the well fractures where the product is collected commingled with the heating fluid and separated out before the heating fluid is recycled.

Two catalyst process for making olefin

Abstract: This invention is to a process of making olefin, particularly ethylene and propylene, from an oxygenate feed. The invention uses two or more zeolite catalysts. Examples of zeolite catalysts include a first catalyst containing of ZSM-5, and a second catalyst containing a 10-ring molecular sieve, including but not limited to, ZSM-22, ZSM-23, ZSM35, ZSM-48, and mixtures thereof. The ZSM-5 can be unmodified, phosphorous modified, steam modified having a micropore volume reduced to not less than 50% of that of the unsteamed ZSM-5, or various mixtures thereof.

Selection of model parameters for off-line parameter estimation

Abstract: Mechanistic dynamic models often contain unknown parameters whose values are difficult to determine even with highly specialized laboratory experiments. A practical approach is to estimate such parameters from available process data. Typically only a subset of the parameters can be estimated due to restrictions imposed by the model structure, lack of measurements, and limited data. We present a simple parameter selection method which accounts for the first two factors independent of the data available for parameter estimation. The magnitude of each parameter effect on the measured variables is quantified by applying principal-component analysis to the steady-state parameter-output sensitivity matrix. The uniqueness of each parameter effect is determined by computing the minimum distance between the sensitivity vector of the particular parameter and the vector spaces spanned by sensitivity vectors of the parameters already selected for estimation. A recursive algorithm that provides a tradeoff between the magnitude and linear independence of parameter effects yields a ranking of the parameters according to their inherent ease of estimation. The parameter-selection procedure is applied to the problem of kinetic parameter estimation for an industrial model of a polymerization reactor. For this specific example, the proposed method yields superior estimation results than those obtained with a parameter-selection technique based on the Fisher information matrix (FIM).

Dolomitization: from conceptual to numerical models

Abstract: Abstract Dolomitization requires not only favourable thermodynamic and kinetic conditions, but also a fluid-flow mechanism to transport reactants to and products from the site of dolomitization. This paper reviews work that seeks to provide a quantitative framework for conceptual models of dolomitization, using analytical and, particularly, numerical simulation models of fluid flow and rock-water interaction. This approach is starting to yield new insights into the major controls on the rate and pattern of fluid flux, and the resultant dolomitization. Three sets of forces can drive the fluid flow required for dolomitization: elevation (topographic) head of meteoric water and/or seawater; gradients in fluid density due to variation in salinity and/or temperature; and pressure due to sedimentological and/or tectonic compaction. However, in many situations individual flow mechanisms may not operate in isolation. Rather fluid flow will commonly be a product of a number of different drives acting simultaneously. The balance between drives will change over time with variations in relative sea-level, climate, platform geometry and palaeogeography (which collectively comprise the critical boundary conditions). The simplistic prediction of dolomite body geometry from a single driving force may be misleading, as fluid flow will critically depend both on the boundary conditions and the distribution of permeability. Indeed, even for single driving forces, model predictions change significantly as simplistic assumptions are relaxed and these key parameters are specified with increasing realism. The coupled modelling of dolomitization reactions within the flow field is less tractable than that of groundwater circulation because the kinetics of dolomitization are less well understood, particularly at lower temperatures. Dolomitization is likely to occur along a reaction front, where a favourable balance is struck between mass transport and reaction kinetics. For instance, in simulations of geothermal convection dolomitization focuses along the 50–60 °C isotherm. Dolomitization reactions are favoured by higher temperatures in deeper zones, but rates are limited by low flow because of lower permeability. Although flow rates are higher in shallow more permeable carbonates, lower temperatures limit reactions. High flow rates during reflux of platform-top brines give rapid dolomitization. This is associated with porosity occlusion in front of and behind the broad zone of replacement dolomitization driven by anhydrite cementation and overdolomitization, respectively. Lithological heterogeneities strongly affect the pattern of dolomitization, which is highly focused within more permeable beds and those with a higher reactive surface area. While we focus here on dolomitization, models can also provide insights into diagenetic processes such as marine calcite cementation and aragonite, calcite and evaporite dissolution by refluxing brines, and by seawater circulation below the aragonite and calcite compensation depths. However, it is important to be aware of the assumptions and limitations of the numerical model(s) used. Particular attention must be paid to specification of boundary conditions, permeability and reactive surface area. The uncritical application of numerical techniques to particular cases of dolomitization is at best uninformative and at worst misleading. Careful application of these techniques offers great promise for well-constrained field problems, with greater inclusion of natural heterogeneity and time-variant boundary conditions. We also need to model feedbacks between diagenesis and porosity-permeability, and to include platform growth in simulations of slower diagenetic processes.

Tectonic processes during oblique collision: Insights from the St. Elias orogen, northern North American Cordillera

Abstract: [1] Oblique convergence in the St. Elias orogen of southern Alaska and northwestern Canada has constructed the world's highest coastal mountain range and is the principal driver constructing all of the high topography in northern North America. The orogen originated when the Yakutat terrane was excised from the Cordilleran margin and was transported along margin-parallel strike-slip faults into the subduction-transform transition at the eastern end of the Aleutian trench. We examine the last 3 m.y. of this collision through an analysis of Euler poles for motion of the Yakutat microplate with respect to North America and the Pacific. This analysis indicates a Yakutat-Pacific pole near the present southern triple junction of the microplate and predicts convergence to dextral-oblique convergence across the offshore Transition fault, onland structures adjacent to the Yakutat foreland, or both, with plate speeds increasing from 10 to 30 mm/yr from southeast to northwest. Reconstructions based on these poles show that NNW transport of the collided block into the NE trending subduction zone forced contraction of EW line elements as the collided block was driven into the subduction-transform transition. This suggests the collided block was constricted as it was driven into the transition. Constriction provides an explanation for observed vertical axis refolding of both earlier formed fold-thrust systems and the collisional suture at the top of the fold-thrust stack. We also suggest that this motion was partially accommodated by lateral extrusion of the western portion of the orogen toward the Aleutian trench. Important questions remain regarding which structures accommodated parts of this motion. The Transition fault may have accommodated much of the Yakutat-Pacific convergence on the basis of our analysis and previous interpretations of GPS-based geodetic data. Nonetheless, it is locally overlapped by up to 800 m of undeformed sediment, yet elsewhere shows evidence of young deformation. This contradiction could be produced if the overlapping sediments are too young to have accumulated significant deformation, or GPS motions may be deflected by transient strains or strains from poorly understood fault interactions. In either case, more data are needed to resolve the paradox.

Lubricating fluids with enhanced energy efficiency and durability

Abstract: The present invention comprises novel lubricating compositions, automotive gear lubricating compositions, and fluids useful in the preparation of finished automotive gear lubricants and finished gear oils, and methods of preparation thereof. One embodiment of the present invention comprises a lubricating composition comprising a blend of a PAO having a viscosity of greater than or equal to about 40 cSt. at 100° C. and less than or equal to about 1,000 cSt. at 100° C. and an ester having a viscosity of less than or equal to about 2.0 cSt. at 100° C., wherein said blend of said PAO and said ester has a viscosity index greater than or equal to the viscosity index of the PAO.

Pressure swing reforming for fuel cell systems

Abstract: The present invention provides an improvement in the process of producing hydrogen from hydrocarbon-containing streams. A cyclic reforming process, referred to as pressure swing reforming, provides an efficient means for producing a hydrogen containing synthesis gas for fuel cell applications. Pressure swing reforming may be integrated with shift reactions, preferential oxidation, and membrane separation, achieving thermal and material efficiencies relative to conventional hydrogen production. In one embodiment, at least some synthesis gas which is first produced in the pressure swing reforming process is combusted with air to provide the heat for the regeneration step of the pressure swing reforming process.

Vertebrate Burrows from Triassic and Jurassic Continental Deposits of North America and Antarctica: Their Paleoenvironmental and Paleoecological Significance

Abstract: Comparisons of recently identified Triassic and Jurassic continental trace fossils in North America and Antarctica to modern mammal and reptilian burrows facilitate the identification and interpretation of the ancient burrows as vertebrate in origin, indicating advanced behaviors. Hollow, bowl-shaped depressions in the Petrified Forest Member of the Upper Triassic Chinle Formation in Petrified Forest National Park, Arizona, are interpreted as nest-holes constructed possibly by phytosaurs, aeotosaurs, turtles, or rauisuchians. Large-diameter, multiple-branching, and interconnected burrows in the Owl Rock Member of the Chinle Formation in southeastern Utah are tentatively interpreted as vertebrate burrows indicating communal behavior. Complex, large-diameter burrows in the Salt Wash Member of the Upper Jurassic Morrison Formation near the Henry Mountains in southern Utah are interpreted as burrow systems of fossorial mammals. Large-diameter, gently dipping, simple, subhorizontal burrows in the Salt Wash Mem...

Thermal effects on the performance of floating ring bearings for turbochargers

Abstract: Physical models and fast computational programs aim to improve the design and performance of turbocharger (TC) rotordynamics. Most commercial automotive TCs incorporate floating ring bearings (FRBs) owing to their low cost and reduced power losses. However, persistent subsynchronous motions afflict this type of rotor/bearing system, albeit reaching limit cycles that enable their continuous operation. FRBs comprise two fluid films in series and are prone to show one or two subsynchronous instabilities over extended speed ranges of operation. A flow model for prediction of FRB forced response is detailed here. The model incorporates a lumped-parameter thermal energy balance for estimation of the lubricant viscosity and thermal growth of the rotor, bearing and floating ring. The FRB model, fully integrated into a non-linear rotordynamics computational program, predicts the floating ring speed, journal and ring eccentricities, power loss and the rotordynamic force coefficients of the inner and outer f...

A Study of the Separation Principle in Size Exclusion Chromatography

Abstract: Size exclusion chromatography (SEC) separates polymer molecules according to their size in dilute solution, but what size to use has been a matter of debate for 35 years. In 1967, Benoit and co-workers found an excellent correlation between elution volume and a dynamically based molecular size, the hydrodynamic volume VH, for a wide range of species and large-scale molecular architectures. However, both theory and simulations assume a thermodynamic separation principle. This assumption is based on experimental observations that elution volumes are independent of flow rates. Thus, one might surmise that the radius of gyration Rg is a more appropriate size measure for purposes of universal SEC calibration, although the calculations of Casassa and co-workers on star polymers suggest some other thermodynamically based size may be required. In an attempt to resolve this dilemma, we undertook an extensive study of SEC with three groups of nearly monodisperse polymerslinear polystyrenes, linear polyethylenes, an...

Multiple-point simulation integrating wells, three-dimensional seismic data, and geology

Abstract: There are two significant challenges in building a reservoir model integrating all available information. One challenge is that wells and seismic data measure the reservoir at different scales of resolution. The other challenge lies in how to account for conceptual geological knowledge with resolution at multiple scales.In this paper, we present a case study of integrating well data, seismic data, and conceptual geologic models. The well and seismic data are of good quality, but conventional well-seismic data calibration indicates that the seismic data are unable to fully differentiate sand from shale. The reason for this poor well-seismic data calibration is that well log and seismic data measure the reservoir at different scales. Well logs are able to differentiate sand from shale, whereas seismic data are better at detecting larger scale depositional geometries.A new workflow is presented to deal with this problem. First, principal component analysis clustering is used to identify characteristic patterns of certain depositional facies, from which sandy and shaly channels are interpreted. Next, multiple-point geostatistical simulation is performed to build a depositional-facies model, which integrates both hard and soft data but also incorporates realistic depositional-facies geometries provided by our geological knowledge of this reservoir. Finally, different lithofacies (sand and shale) indicators and corresponding petrophysical properties are simulated honoring the limited well data.The results show that not only are the geological features better reproduced, but also is the uncertainty about the reservoir significantly reduced because of a better integration of corresponding three-dimensional seismic data.

Hydrocarbon synthesis process using pressure swing reforming

Abstract: The invention provides a method for producing liquid hydrocarbons by first generating in a pressure swing reformer a synthesis gas stream having a mole ratio of H 2 :CO greater than 2:1. Then, a portion of the hydrogen is separated to produce a synthesis gas stream having a mole ratio of H 2 :CO of about 2:1 which steam is then introduced into a hydrocarbon synthesis reactor for conversion to liquid products.

Solid oxide fuel cell systems having temperature swing reforming

Abstract: The present invention provides an improvement in the process of producing energy from fuel cells. A cyclic reforming process, referred to as temperature swing reforming, provides an efficient means for producing a hydrogen containing synthesis gas for use in solid oxide fuel cell applications. In one embodiment, at least some synthesis gas which is first produced in the temperature swing reforming process is combusted with air to provide the heat for the regeneration step of the temperature swing reforming process. The syngas produced in TSR is particularly well suited for use in solid oxide fuel cell applications.

Integration of hydrogen and power generation using pressure swing reforming

Abstract: The invention provides a method for generating power with a gas turbine which utilizes pressure swing reforming under conditions that facilitate CO2 capture. First a synthesis gas stream at a first pressure is produced in a pressure swing reformer. Next the synthesis gas stream is subjected to a high temperature water gas shift process to produce a CO2 containing hydrogen enriched stream from which hydrogen and CO2 each are separated. The separated hydrogen in turn is combusted with air to produce a gas turbine and the separated CO2 is easily sequestered.