Showing papers by "ExxonMobil published in 2006"

A catalogue of deep mantle plumes: New results from finite‐frequency tomography

Abstract: New finite-frequency tomographic images of S-wave velocity confirm the existence of deep mantle plumes below a large number of known hot spots. We compare S-anomaly images with an updated P-anomaly model. Deep mantle plumes are present beneath Ascension, Azores, Canary, Cape Verde, Cook Island, Crozet, Easter, Kerguelen, Hawaii, Samoa, and Tahiti. Afar, Atlantic Ridge, Bouvet(Shona), Cocos/Keeling, Louisville, and Reunion are shown to originate at least below the upper mantle if not much deeper. Plumes that reach only to midmantle are present beneath Bowie, Hainan, Eastern Australia, and Juan Fernandez; these plumes may have tails too thin to observe in the lowermost mantle, but the images are also consistent with an interpretation as “dying plumes” that have exhausted their source region. In the tomographic images, only the Eifel and Seychelles plumes are unambiguously confined to the upper mantle. Starting plumes are visible in the lowermost mantle beneath South of Java, East of Solomon, and in the Coral Sea. All imaged plumes are wide and fail to show plumeheads, suggesting a very weakly temperature-dependent viscosity for lower mantle minerals, and/or compositional variations. The S-wave velocity images show several minor differences with respect to the earlier P-wave results, including plume conduits that extend down to the core-mantle boundary beneath Cape Verde, Cook Island, and Kerguelen. A more substantial disagreement between P-wave and S-wave images reopens the question on the depth extent of the Iceland plume. We suggest that a pulsating behavior of the plume may explain the shape of the conduit beneath Iceland.

Large-scale and very-large-scale motions in turbulent pipe flow

Abstract: In the outer region of fully developed turbulent pipe flow very large-scale motions reach wavelengths more than 8, as the combination of all smaller motions, including the large-scale motions and the main turbulent motions. The main turbulent motions, defined as the motions small enough to be in a statistical equilibrium (and hence smaller than the large-scale motions) contribute relatively little to the Reynolds shear stress, but they constitute over half of the net Reynolds shear force.

Economic impact of workplace productivity losses due to allergic rhinitis compared with select medical conditions in the United States from an employer perspective.

Abstract: Objective: To evaluate the cost of lost productivity in the workplace due to allergic rhinitis compared to other selected medical conditions from an employer perspective.Setting and participants: A...

Development of a Detailed Gasoline Composition-Based Octane Model

Abstract: We present a model that predicts the research and motor octane numbers of a wide variety of gasoline process streams and their blends including oxygenates based on detailed composition. The octane number is correlated to a total of 57 hydrocarbon lumps measured by gas chromatography. The model is applicable to any gasoline fuel regardless of the refining process it originates from. It is based on the analysis of 1471 gasoline fuels from different naphtha process streams such as reformates, cat-naphthas, alkylates, isomerates, straight runs, and various hydroprocessed naphthas. Blends of these individual process streams are also considered in this work. The model predicts the octane number within a standard error of 1 number for both the research and motor octane numbers.

Catalytic Properties of Single Layers of Transition Metal Sulfide Catalytic Materials

Abstract: Single layer transition metal sulfides (SLTMS) such as MoS2, WS2, and ReS2, play an important role in catalytic processes such as the hydrofining of petroleum streams, and are involved in at least two of the slurry‐catalyst hydroconversion processes that have been proposed for upgrading heavy petroleum feed and other sources of hydrocarbon fuels such as coal and shale oils. Additional promising catalytic applications of the SLTMS are on the horizon. The physical, chemical, and catalytic properties of these materials are reviewed in this report. Also discussed are areas for future research that promise to lead to advanced applications of the SLTMS.

Detailed Composition-Based Model for Predicting the Cetane Number of Diesel Fuels

Abstract: We have developed a simple composition-based model for predicting the cetane number of diesel fuels with general applicability to any diesel fuel regardless of the refining process it originates from. The cetane number is correlated to a total of 129 different hydrocarbon lumps determined by a combination of supercritical fluid chromatography, gas chromatography, and mass spectroscopic methods. A total of 203 diesel fuels are considered in this study derived from various diesel-range refinery process streams and their commercial blends. Across the multitude of such process streams and blends, the model predicts the cetane number with a standard error of 1.25 numbers, which is well within the experimental error of the measurement.

JPEG compression history estimation for color images

Abstract: We routinely encounter digital color images that were previously compressed using the Joint Photographic Experts Group (JPEG) standard. En route to the image's current representation, the previous JPEG compression's various settings-termed its JPEG compression history (CH)-are often discarded after the JPEG decompression step. Given a JPEG-decompressed color image, this paper aims to estimate its lost JPEG CH. We observe that the previous JPEG compression's quantization step introduces a lattice structure in the discrete cosine transform (DCT) domain. This paper proposes two approaches that exploit this structure to solve the JPEG Compression History Estimation (CHEst) problem. First, we design a statistical dictionary-based CHEst algorithm that tests the various CHs in a dictionary and selects the maximum a posteriori estimate. Second, for cases where the DCT coefficients closely conform to a 3-D parallelepiped lattice, we design a blind lattice-based CHEst algorithm. The blind algorithm exploits the fact that the JPEG CH is encoded in the nearly orthogonal bases for the 3-D lattice and employs novel lattice algorithms and recent results on nearly orthogonal lattice bases to estimate the CH. Both algorithms provide robust JPEG CHEst performance in practice. Simulations demonstrate that JPEG CHEst can be useful in JPEG recompression; the estimated CH allows us to recompress a JPEG-decompressed image with minimal distortion (large signal-to-noise-ratio) and simultaneously achieve a small file-size.

Automotive fuels and internal combustion engines: a chemical perspective

Abstract: Commercial transportation fuels are complex mixtures containing hundreds or thousands of chemical components, whose composition has evolved considerably during the past 100 years. In conjunction with concurrent engine advancements, automotive fuel composition has been fine-tuned to balance efficiency and power demands while minimizing emissions. Pollutant emissions from internal combustion engines (ICE), which arise from non-ideal combustion, have been dramatically reduced in the past four decades. Emissions depend both on the engine operating parameters (e.g. engine temperature, speed, load, A/F ratio, and spark timing) and the fuel. These emissions result from complex processes involving interactions between the fuel and engine parameters. Vehicle emissions are comprised of volatile organic compounds (VOCs), CO, nitrogen oxides (NOx), and particulate matter (PM). VOCs and NOx form photochemical smog in urban atmospheres, and CO and PM may have adverse health impacts. Engine hardware and operating conditions, after-treatment catalysts, and fuel composition all affect the amount and composition of emissions leaving the vehicle tailpipe. While engine and after-treatment effects are generally larger than fuel effects, engine and after-treatment hardware can require specific fuel properties. Consequently, the best prospects for achieving the highest efficiency and lowest emissions lie with optimizing the entire fuel–engine–after-treatment system. This review provides a chemical perspective on the production, combustion, and environmental aspects of automotive fuels. We hope this review will be of interest to workers in the fields of chemical kinetics, fluid dynamics of reacting flows, atmospheric chemistry, automotive catalysts, fuel science, and governmental regulations.

Method of drilling and producing hydrocarbons from subsurface formations

Abstract: A method associated with the production of hydrocarbons. In one embodiment, method for drilling a well is described. The method includes performing drilling operations at one or more wells to a subsurface location in a field to provide fluid flow paths for hydrocarbons to a production facility. The drilling is performed by (i) obtaining mechanical specific energy (MSE) data and other measured data during the drilling operations; (ii) using the obtained MSE data and other measured data to determine the existence of at least one limiter; (iii) obtaining and examining lithology data for the well; (iv) identifying a primary limiter of the at least one limiter based on the lithology data; and (v) adjusting drilling operations to mitigate at least one of the at least limiter.

Plasticized functionalized propylene copolymer adhesive composition

Abstract: This invention relates to an adhesive composition comprising: a random propylene polymer component having a heat of fusion of between 1 and 70 J/g and an mm triad tacticity index of at least 75%; and a functionalized polymer component comprising a C2-C20 olefin comprising at least 0.1 wt% of a functional group; wherein the adhesive composition has a T-Peel adhesion on a polar substrate at 2O0C of at least 175 N/m (1 lb/in) and a T-Peel adhesion on a non- polar substrate at 200C of at least 175 N/m Pa (1 lb/in) and where the polarity of the polar substrate is at least 0.10 units higher than the polarity of the non-polar substrate, wherein functionalized syndiotactic rich polyolefm polymer is present at 5 wt% or less, based upon the weight of the composition. This invention further relates to methods to produce the adhesive and articles comprising the adhesive.

Wellbore method and apparatus for completion, production and injection

Abstract: Apparatus associated with the production of hydrocarbons comprising a joint assembly comprising a main body portion having primary and secondary fluid flow paths, wherein the main body portion is attached to a load sleeve assembly at one end and a torque sleeve assembly at the opposite end. The load sleeve may include at least one transport conduit and at least one packing conduit. The main body portion may include a sand control device, a packer, or other well tool for use in a downhole environment. Included is a coupling assembly having a manifold region in fluid flow communication with the second fluid flow path of the main body portion and facilitating the make-up of first and second joint assemblies with a single connection.

Asphaltene Molecular Structure and Chemical Influences on the Morphology of Coke Produced in Delayed Coking

Abstract: The average chemical structure of asphaltenes present in a vacuum resid feed is related to the morphology of the coke that is produced in a delayed coker (shot coke vs sponge coke). A combination of solid-state 13C NMR, X-ray photoelectron spectroscopy (XPS), and elemental abundance was used to characterize the average chemical structure of several n-heptane asphaltenes from shot-coke- and sponge-coke-producing vacuum resid feeds. The chemical structural properties of the asphaltenes are discussed in relation to the coke morphology produced from the parent resid. The average asphaltene aromatic carbon per cluster size is between 14 and 22 carbon atoms, which corresponds to three-to-five-ring average clusters. When the ratio of aromatic carbon to unreactive (i.e., heterocyclic aromatic) nitrogen and sulfur in asphaltenes is <16, the feed tendency is to produce shot coke. Representative chemical structural models of asphaltenes reveal significant differences (1.5 cal/cm3)1/2 in the calculated solubility par...

Uplink scheduling in CDMA packet-data systems

Abstract: Uplink scheduling in wireless systems is gaining importance due to arising uplink intensive data services (ftp, image uploads etc.), which could be hampered by the currently in-built asymmetry in favor of the downlink. In this work, we propose and study algorithms for efficient uplink packet-data scheduling in a CDMA cell. The algorithms attempt to maximize system throughput under transmit power limitations on the mobiles assuming instantaneous knowledge of user queues and channels. However no channel statistics or traffic characterization is necessary. Apart from increasing throughput, the algorithms also improve fairness of service among users, hence reducing chances of buffer overflows for poorly located users.The major observation arising from our analysis is that it is advantageous on the uplink to schedule "strong" users one-at-a-time, and "weak" users in larger groups. This contrasts with the downlink where one-at-a-time transmission for all users has shown to be the preferred mode in much previous work. Based on the optimal schedules, we propose less complex and more practical approximate methods, both of which offer significant performance improvement compared to one-at-a-time transmission, and the widely acclaimed Proportional Fair (PF) algorithm, in simulations. When queue content cannot be fed back, we propose a simple modification of PF, Uplink PF (UPF), that offers similar improvement.

Crystal Structure of Zeolite MCM-68: A New Three-Dimensional Framework with Large Pores

Abstract: The crystal structure of the aluminosilicate MCM-68 was solved from synchrotron powder diffraction data by the program FOCUS. The unit cell framework contains Si100.6Al11.4O224. This material cryst...

Substrate effect on the melting temperature of thin polyethylene films.

Abstract: Strong dependence of the crystal orientation, morphology, and melting temperature (Tm) on the substrate is observed in the semicrystalline polyethylene thin films. The Tm decreases with the film thickness decrease when the film is thinner than a certain critical thickness, and the magnitude of the depression increases with increasing surface interaction. We attribute the large Tm depression to the decrease in the overall free energy on melting, which is caused by the substrate attraction force to the chains that competes against the interchain force which drives the chains to crystallization.

Evaluation of kinetic uncertainty in numerical models of petroleum generation

Abstract: Oil-prone marine petroleum source rocks contain type I or type II kerogen having Rock-Eval pyrolysis hydrogen indices greater than 600 or 300–600 mg hydrocarbon/g total organic carbon (HI, mg HC/g TOC), respectively. Samples from 29 marine source rocks worldwide that contain mainly type II kerogen (HI = 230–786 mg HC/g TOC) were subjected to open-system programmed pyrolysis to determine the activation energy distributions for petroleum generation. Assuming a burial heating rate of 1C/m.y. for each measured activation energy distribution, the calculated average temperature for 50% fractional conversion of the kerogen in the samples to petroleum is approximately 136 7C, but the range spans about 30C (121–151C). Fifty-two outcrop samples of thermally immature Jurassic Oxford Clay Formation were collected from five locations in the United Kingdom to determine the variations of kinetic response for one source rock unit. The samples contain mainly type I or type II kerogens (HI = 230–774 mg HC/g TOC). At a heating rate of 1C/m.y., the calculated temperatures for 50% fractional conversion of the Oxford Clay kerogens to petroleum differ by as much as 23C (127–150C). The data indicate that kerogen type, as defined by hydrogen index, is not systematically linked to kinetic response, and that default kinetics for the thermal decomposition of type I or type II kerogen can introduce unacceptable errors into numerical simulations. Furthermore, custom kinetics based on one or a few samples may be inadequate to account for variations in organofacies within a source rock. We propose three methods to evaluate the uncertainty contributed by kerogen kinetics to numerical simulations: (1) use the average kinetic distribution for multiple samples of source rock and the standard deviation for each activation energy in that distribution; (2) use source rock kinetics determined at several locations to describe different parts of the study area; and (3) use a weighted-average method that combines kinetics for samples from different locations in the source rock unit by giving the activation energy distribution for each sample a weight proportional to its Rock-Eval pyrolysis S2 yield (hydrocarbons generated by pyrolytic degradation of organic matter).

Seismic velocity structure of the rifted margin of the eastern Grand Banks of Newfoundland, Canada

Abstract: [1] We present a compressional seismic velocity profile of the crust of the eastern margin of the Grand Banks of Newfoundland, Canada. This velocity model was obtained by a tomographic inversion of wide-angle data recorded on a linear array of 24 ocean bottom seismometers (OBSs). At the landward side, we imaged a crustal thickness of 27 km in Flemish Pass and beneath Beothuk Knoll, which is thinner than the 35-km-thick crust of the central Grand Banks. We therefore assume that the eastern rim of the Grand Banks stretched uniformly by 25%. Farther seaward, the continental crust tapers rapidly beneath the continental slope to ∼6 km thickness. In the distal margin we find a 60-km-wide zone with seismic velocities between 5.0 and 6.5 km s−1 that thins to the southeast from 6 to 2 km, which we interpret as highly extended continental crust. Contrary to other seismic studies of the margins of the Grand Banks, we find seismic velocities of 8 km s−1 and higher beneath this thin crustal layer in the continent-ocean transition. We conclude that mantle was locally emplaced at shallow levels without significant hydration from seawater or serpentinized mantle was removed along a decollement in the final stages of continental rifting. The outer edge of highly extended continental crust borders a 25-km-wide zone where seismic velocities increase gradually from 6.3 km s−1 just below the top of acoustic basement to 7.7 km s−1 at 5 km below basement. We interpret this area as a relatively narrow zone of exhumed and serpentinized continental mantle. Seaward, we imaged a thin and laterally heterogeneous layer with a seismic velocity that increases sharply from 5.0 km s−1 in basement ridges to 7.0 km s−1 at its base, overlying mantle velocities between 7.8 and 8.2 km s−1. We interpret this area as unroofed mantle and very thin oceanic crust that formed at an incipient, magma-starved, ultraslow spreading ridge. A comparison of the conjugate rifted margins of the eastern Grand Banks and the Iberia Abyssal Plain show that they exhibit a similar seaward progression from continental crust to mantle to oceanic crust. This indicates that before continental breakup, rifting exhumed progressively deeper sections of the continental lithosphere on both conjugate margins. A comparison between the continent-ocean transition of the Grand Banks and Flemish Cap shows that the final phase of continental rifting and the formation of the first oceanic crust required more time at the Grand Banks margin than at the southeastern margin of Flemish Cap.

Controlled combustion for regenerative reactors

Abstract: The overall efficiency of a regenerative bed reverse flow reactor system is increased where the location of the exothermic reaction used for regeneration is suitably controlled. The present invention provides a method and apparatus for controlling the combustion to improve the thermal efficiency of bed regeneration in a cyclic reaction/regeneration processes. The process for thermal regeneration of a regenerative reactor bed entails (a) supplying the first reactant through a first channel means in a first regenerative bed and supplying at least a second reactant through a second channel means in the first regenerative bed, (b) combining said first and second reactants by a gas mixing means situated at an exit of the first regenerative bed and reacting the combined gas to produce a heated reaction product, (c) passing the heated reaction product through a second regenerative bed thereby transferring heat from the reaction product to the second regenerative bed.

Construction comprising tie layer

Abstract: This disclosure relates to a vulcanizable layered composition comprising at least two layers and at least one tie layer, wherein the first layer of the two layers comprises an fluid permeation prevention layer, the second layer of the two layers comprises at least one high diene rubber, and the tie layer comprises a mixture of : (1) about 50 to about 100 weight % of at least one halogenated isobutylene containing elastomer; (2) about 0 to about 50 weight % of at least one high diene elastomer; (3) about 20 to about 50 weight % of at least one filler; (4) about 0 to about 30 weight % of at least one processing oil; (5) about 1 to about 20 parts per hundred (phr) of at least one tackifier; and (6) at least about 0.2 to about 15 parts per hundred of rubber (phr) of a curing system for the elastomers; wherein THE fluid permeation prevention layer preferably comprises: (A) at least 10% by weight, based on the total weight of the polymer composition, of at least one thermoplastic engineering resin component, preferably one or more nylon resins, and (B) at least 10% by weight, based on the total weight of the polymer composition, of at least one elastomer component, preferably a brominated isobutylene p-methylstyrene copolymer, and where the total amount of the component (A) and the component (B) is not less than 30% by weight based on the total weight of the polymer composition, wherein the elastomer component (B) is dispersed in a vulcanized or partially vulcanized state, as a discontinuous phase, in a matrix of the thermoplastic resin component (A) in the polymer composition.

P-derived organic cations as structure-directing agents: synthesis of a high-silica zeolite (ITQ-27) with a two-dimensional 12-ring channel system.

Abstract: Recently, efforts have been made to synthesize large-pore, multidimensional zeolite frameworks as a basis for new catalysts to improve various hydrocarbon conversions. A new aluminosilicate zeolite, ITQ-27, has been prepared using the phosphorus-containing structure-directing agent, dimethyldiphenylphosphonium. Its crystal structure was determined in its calcined form by direct methods (FOCUS) on synchrotron powder diffraction data (lambda = 0.8702 A) after the unit cell and space group were determined from tilt electron diffraction experiments on individual microcrystals. The material crystallizes in space group Fmmm, where a = 27.7508(5) A, b = 25.2969(7) A, and c = 13.7923(4) A. The final model, refined by Rietveld methods, comprises seven unique T-sites forming a framework with straight 12-MR channels that are connected by 14-MR openings between them. (Corresponding 12-ring pore dimension is 6.94 A x 6.20 A.) Since access from one 14-MR opening to the next is through the 12-MR channel, the structure is best described as a two-dimensional, 12-MR framework.

Wellbore apparatus and method for completion, production and injection

Abstract: A method and apparatus associated with the production of hydrocarbons is disclosed. In one embodiment, an apparatus includes a tubular member having a central opening within an internal portion of the tubular member, wherein the central opening allows hydrocarbons to flow through the tubular member. Also, the tubular member includes openings between the central opening and a region external to the tubular member. In addition to the tubular member, at least two adjacent wire segments are disposed around the tubular member. The at least two adjacent wire segments create at least two flow paths to the central opening. Also, the at least two adjacent wire segments form at least two openings configured to prevent particles greater than a specific size from entering the openings in the tubular member.

Functionalized propylene copolymer adheside composition

Abstract: This invention relates to an adhesive composition comprising a functionalized random propylene polymer (FRPP) having at least 0.1 wt% of a functional group, a heat of fusion of between 0.5 and 70 J/g, and an mm triad tacticity index of at least 75%, where the adhesive has a T-Peel adhesion on a polar substrate at 20°C of at least 175 N/m (1 lb/in) and a T-Peel adhesion on a non-polar substrate at 20°C of at least 175 N/m (1 lb/in) where the polarity of the polar substrate is at least 0.10 units higher than the polarity of the non-polar substrate. Methods to produce the adhesive and articles comprising the adhesive are also disclosed.

Hydrocarbon resid processing

Abstract: The invention concerns integration of hydroprocessing and steam cracking. A feed comprising crude or resid-containing fraction thereof is severely hydrotreated and passed to a steam cracker to obtain an olefins product.

Thermal transformations of nitrogen and sulfur forms in peat related to coalification

Abstract: The chemical pathways for nitrogen and sulfur transformations during coalification are elucidated by comparing the chemical forms of unaltered peats, lignites, and coals and pyrolyzed peats. Nitrogen forms are characterized by a combination of X-ray photoelectron spectroscopy (XPS) and 15N nuclear magnetic resonance (NMR). In unaltered peats, the 15N NMR and XPS nitrogen (1s) spectra are consistent with the presence of amide nitrogen. When peat is pyrolyzed, the main peak in the 15N NMR spectrum broadens and shifts from −260 ppm to −245 ppm, which is consistent with the loss of some amide nitrogen and the appearance of pyrrolic nitrogen forms. The pyrolyzed peat shows a new XPS peak that appears at 398.6 eV, which is characteristic of pyridinic nitrogen. These results indicate that a thermal transformation of amide nitrogen into pyrrolic and pyridinic forms occurs after thermal stress that is roughly equivalent to lignitification. High total nitrogen levels are found in pyrolyzed peats relative to lignite...

Petroleum Expulsion Part 1. Theory of Kerogen Swelling in Multicomponent Solvents

Abstract: An extended Flory−Rehner and Regular Solution Theory model framework has been developed for interpreting the swelling behavior of kerogen toward solvents. Thermodynamic parameters controlling the swelling response of kerogen are the solubility parameter, the cross-link density, and the volume fraction of the kerogen network veq that minimizes its elastic strain energy, termed “native swelling”. These parameters are obtained by optimizing the match between theoretical predictions and experimental swelling data of kerogen for neat solvents. A good match between theory and experiment is obtained for Draupne Type II kerogen. These results imply that this kerogen behaves like a cross-linked elastomer network and that the interaction with the solvents used involves nonspecific interactions. This model framework enables prediction of the kerogen's response to solvent mixtures. This is an important step toward modeling hydrocarbon expulsion from kerogen during petroleum generation. If the composition of the mixtu...

Fault dating in the Canadian Rocky Mountains: Evidence for late Cretaceous and early Eocene orogenic pulses

Abstract: Fault rocks from the classic Rocky Mountain foreland fold-and-thrust belt in southwestern Canada were dated by Ar analysis of clay grain-size fractions. Using X-ray diffraction quantification of the detrital and authigenic component of each fraction, these determinations give ages for individual faults in the area (illite age analysis). The resulting ages cluster around 72 and 52 Ma (here called the Rundle and McConnell pulses, respectively), challenging the traditional view of gradual forward progression of faulting and thrust-belt history of the area. The recognition of spatially and temporally restricted deformation episodes offers field support for theoretical models of critically stressed wedges, which result in geologically reasonable strain rates for the area. In addition to regional considerations, this study highlights the potential of direct dating of shallow fault rocks for our understanding of upper-crustal kinematics and regional tectonic analysis of ancient orogens.