Showing papers by "ExxonMobil published in 2012"

Grain assemblages and strong diagenetic overprinting in siliceous mudrocks, Barnett Shale (Mississippian), Fort Worth Basin, Texas

Abstract: Porosity, permeability, and total organic carbon (TOC) in a heterogeneous suite of 21 high-maturity samples (vitrinite reflectance 1.52–2.15%) from the Barnett Shale in the eastern Fort Worth Basin display few correlations with parameters of rock texture, fabric, and composition, these factors being mostly obscured by the effects of a protracted history of diagenesis. Diagenesis in these rocks includes mechanical and chemical modifications that occurred across a wide range of burial conditions. Compaction and cementation have mostly destroyed primary intergranular porosity. The porosity (average 5 vol. % by Gas Research Institute helium porosimetry) and pore size (8 nm median pore-throat diameter) are reduced to a degree such that pores are difficult to detect even by imaging Ar ion–milled surfaces with a field-emission scanning electron microscope. The existing porosity that can be imaged is mostly secondary and is localized dominantly within organic particulate debris and solid bitumen. The grain assemblage is highly modified by replacement. A weak pattern of correlation survives between bulk rock properties and the ratio of extrabasinal to intrabasinal sources of siliciclastic debris. Higher porosity, permeability, and TOC are observed in samples representing the extreme end members of mixing between extrabasinal siliciclastic sediment and intrabasinal-derived biosiliceous debris. Reservoir quality in these rocks is neither more strongly nor more simply related to variations in primary texture and composition because the interrelationships between texture and composition are complex and, importantly, the diagenetic overprint is too strong.

Thermochronologic evidence for plateau formation in central Tibet by 45 Ma

Abstract: The timing of Tibetan plateau development remains elusive, despite its importance for evaluating models of continental lithosphere deformation and associated changes in surface elevation and climate. We present new thermochronologic data [biotite and K-feldspar 40 Ar/ 39 Ar, apatite fi ssion track, and apatite (U-Th)/He] from the central Tibetan plateau (Lhasa and Qiangtang terranes). The data indicate that over large regions, rocks underwent rapid to moderate cooling and exhumation during Cretaceous to Eocene time. This was coeval with >50% upper crustal shortening, suggesting substantial crustal thickening and surface elevation gain. Thermal modeling of combined thermochronometers requires exhumation of most samples to depths of <3 km between 85 and 45 Ma, followed by a decrease in erosional exhumation rate to low values of <0.05 mm/yr. The thermochronological results, when interpreted in the context of the deformation and paleoaltimetric history, are best explained by a scenario of plateau growth that began locally in central Tibet during the Late Cretaceous and expanded to encompass most of central Tibet by 45 Ma.

Environmental Performance of Algal Biofuel Technology Options

Abstract: Considerable research and development is underway to produce fuels from microalgae, one of several options being explored for increasing transportation fuel supplies and mitigating greenhouse gas emissions (GHG). This work models life-cycle GHG and on-site freshwater consumption for algal biofuels over a wide technology space, spanning both near- and long-term options. The environmental performance of algal biofuel production can vary considerably and is influenced by engineering, biological, siting, and land-use considerations. We have examined these considerations for open pond systems, to identify variables that have a strong influence on GHG and freshwater consumption. We conclude that algal biofuels can yield GHG reductions relative to fossil and other biobased fuels with the use of appropriate technology options. Further, freshwater consumption for algal biofuels produced using saline pond systems can be comparable to that of petroleum-derived fuels.

Myelodysplastic syndrome and benzene exposure among petroleum workers: an international pooled analysis.

Abstract: Background Benzene at high concentrations is known to cause acute myeloid leukemia (AML), but its relationship with other lymphohematopoietic (LH) cancers remains uncertain, particularly at low concentrations. In this pooled analysis, we examined the risk of five LH cancers relative to lower levels of benzene exposure in petroleum workers. Methods We updated three nested case-control studies from Australia, Canada, and the United Kingdom with new incident LH cancers among petroleum distribution workers through December 31, 2006, and pooled 370 potential case subjects and 1587 matched LH cancer-free control subjects. Quantitative benzene exposure in parts per million (ppm) was blindly reconstructed using historical monitoring data, and exposure certainty was scored as high, medium, or low. Two hematopathologists assigned diagnoses and scored the certainty of diagnosis as high, medium, or low. Dose-response relationships were examined for five LH cancers, including the three most common leukemia cell-types (AML, chronic myeloid leukemia [CML], and chronic lymphoid leukemia [CLL]) and two myeloid tumors (myelodysplastic syndrome [MDS] and myeloproliferative disease [MPD]). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using conditional logistic regression, controlling for age, sex, and time period. Results Cumulative benzene exposure showed a monotonic dose-response relationship with MDS (highest vs lowest tertile, >2.93 vs ≤0.348 ppm-years, OR = 4.33, 95% CI = 1.31 to 14.3). For peak benezene exposures (>3 ppm), the risk of MDS was increased in high and medium certainty diagnoses (peak exposure vs no peak exposure, OR = 6.32, 95% CI = 1.32 to 30.2) and in workers having the highest exposure certainty (peak exposure vs no peak exposure, OR = 5.74, 95% CI = 1.05 to 31.2). There was little evidence of dose-response relationships for AML, CLL, CML, or MPD. Conclusions Relatively low-level exposure to benzene experienced by petroleum distribution workers was associated with an increased risk of MDS, but not AML, suggesting that MDS may be the more relevant health risk for lower exposures.

How clay grain coats inhibit quartz cement and preserve porosity in deeply buried sandstones: Observations and experiments

Abstract: Observations and hydrothermal experiments were used to derive new information about how clay grain coats inhibit quartz cement and preserve porosity in deeply buried sandstones. Samples of deeply buried, porous sandstones with different types of clay coats were split in two, coats removed from one of each pair of splits, and grain surfaces inspected with scanning electron microscopy. Quartz grains in a fluvial-deltaic sandstone buried to 115C had no visible authigenic quartz on grain surfaces cleaned of diagenetic chlorite coats, though well-developed overgrowths occurred on nearby, naturally uncoated grains. However, in similar sandstones buried to 164C, quartz-grain surfaces exposed by chlorite-coat removal were covered with small (5 m), mainly anhedral, syntaxial quartz overgrowths. Similar overgrowths were observed under various detrital and diagenetic clay coats in porous eolian sandstones buried to temperatures up to 215C. We conclude that clay coats may retard quartz nucleation at moderate temperatures, but at high temperatures, many coats permit quartz nucleation and preserve porosity by limiting cement growth. To investigate cement growth-limitation mechanisms, samples with coats removed were subjected to quartz-cementing conditions in a hydrothermal reactor. During experiments, the naturally occurring small overgrowths on clay-cleaned grains coalesced and grew, suggesting that clay particles in coats inhibit cement growth by forming barriers to early-overgrowth coalescence. Although the fraction of grain-surface coverage is the primary control on cement inhibition by coats, cement growth–interference textures vary with coat type, providing a mechanism by which coat composition may be a secondary control on inhibitory effectiveness. In deeply buried sandstones, quartz cement can fill significant microporosity within diagenetic chlorite coats, potentially affecting mechanical and petrophysical rock properties.

Prediction of CO2 Adsorption Properties in Zeolites Using Force Fields Derived from Periodic Dispersion-Corrected DFT Calculations

Abstract: We demonstrate a new approach to develop transferable force fields describing molecular adsorption in zeolites by combining dispersion-corrected density functional theory (DFT) calculations and classical atomistic simulations. This approach is illustrated with the adsorption of CO2 in zeolites. Multiple dispersion-corrected DFT methods were tested for describing CO2 adsorption in sodium-exchanged ferrierite. The DFT-D2 approach was found to give the best agreement with high level quantum chemistry results and experimental data. A classical force field for CO2 adsorption in siliceous zeolites was then developed on the basis of hundreds of DFT-D2 calculations that probed the full range of accessible volume in purely siliceous chabazite (Si-CHA) via random sampling. We independently performed experiments with Si-CHA measuring CO2 isotherms and heats of adsorption by microcalorimetry. Excellent agreement was obtained between adsorption isotherms predicted with our first-principles-derived force field and our ...

Calcium Modification of Spinel Inclusions in Aluminum-Killed Steel: Reaction Steps

Abstract: Calcium treatment is a well-established way to modify solid alumina inclusions to liquid or partially liquid calcium aluminates. Spinels (Al2O3·xMgO) can also form in liquid steel after aluminum deoxidation. Like alumina, the spinels can be modified readily to liquid inclusions by a calcium treatment. The modification of spinels was studied by observing the transient evolution of inclusions, in laboratory and industrial heats. Spinel modification involves the preferential reduction of MgO from the spinel, with Mg dissolving in the steel, and it proceeds through transient calcium sulfide formation, just like in the case of alumina inclusions. Because magnesium dissolves in steel after the calcium treatment of spinels, the reoxidation of the melt will produce new spinels.

Linear Elastic and Cohesive Fracture Analysis to Model Hydraulic Fracture in Brittle and Ductile Rocks

Abstract: Hydraulic fracturing technology is being widely used within the oil and gas industry for both waste injection and unconventional gas production wells. It is essential to predict the behavior of hydraulic fractures accurately based on understanding the fundamental mechanism(s). The prevailing approach for hydraulic fracture modeling continues to rely on computational methods based on Linear Elastic Fracture Mechanics (LEFM). Generally, these methods give reasonable predictions for hard rock hydraulic fracture processes, but still have inherent limitations, especially when fluid injection is performed in soft rock/sand or other non-conventional formations. These methods typically give very conservative predictions on fracture geometry and inaccurate estimation of required fracture pressure. One of the reasons the LEFM-based methods fail to give accurate predictions for these materials is that the fracture process zone ahead of the crack tip and softening effect should not be neglected in ductile rock fracture analysis. A 3D pore pressure cohesive zone model has been developed and applied to predict hydraulic fracturing under fluid injection. The cohesive zone method is a numerical tool developed to model crack initiation and growth in quasi-brittle materials considering the material softening effect. The pore pressure cohesive zone model has been applied to investigate the hydraulic fracture with different rock properties. The hydraulic fracture predictions of a three-layer water injection case have been compared using the pore pressure cohesive zone model with revised parameters, LEFM-based pseudo 3D model, a Perkins-Kern–Nordgren (PKN) model, and an analytical solution. Based on the size of the fracture process zone and its effect on crack extension in ductile rock, the fundamental mechanical difference of LEFM and cohesive fracture mechanics-based methods is discussed. An effective fracture toughness method has been proposed to consider the fracture process zone effect on the ductile rock fracture.

Multiscale InSAR Time Series (MInTS) analysis of surface deformation

Abstract: [1] We present a new approach to extracting spatially and temporally continuous ground deformation fields from interferometric synthetic aperture radar (InSAR) data. We focus on unwrapped interferograms from a single viewing geometry, estimating ground deformation along the line-of-sight. Our approach is based on a wavelet decomposition in space and a general parametrization in time. We refer to this approach as MInTS (Multiscale InSAR Time Series). The wavelet decomposition efficiently deals with commonly seen spatial covariances in repeat-pass InSAR measurements, since the coefficients of the wavelets are essentially spatially uncorrelated. Our time-dependent parametrization is capable of capturing both recognized and unrecognized processes, and is not arbitrarily tied to the times of the SAR acquisitions. We estimate deformation in the wavelet-domain, using a cross-validated, regularized least squares inversion. We include a model-resolution-based regularization, in order to more heavily damp the model during periods of sparse SAR acquisitions, compared to during times of dense acquisitions. To illustrate the application of MInTS, we consider a catalog of 92 ERS and Envisat interferograms, spanning 16 years, in the Long Valley caldera, CA, region. MInTS analysis captures the ground deformation with high spatial density over the Long Valley region.

GEOTRACES intercalibration of neodymium isotopes and rare earth element concentrations in seawater and suspended particles. Part 1: reproducibility of results for the international intercomparison

Abstract: One of the key activities during the initial phase of the international GEOTRACES program was an extensive international intercalibration effort, to ensure that results for a range of trace elements and isotopes (TEIs) from different cruises and from different laboratories can be compared in a meaningful way. Here we present the results from the intercalibration efforts on neodymium isotopes and rare earth elements in seawater and marine particles. Fifteen different laboratories reported results for dissolved 143Nd/144Nd ratios in seawater at three different locations (BATS 15 m, BATS 2000 m, SAFe 3000 m), with an overall agreement within 47 to 57 ppm (2σ standard deviation of the mean). A similar agreement was found for analyses of an unknown pure Nd standard solution carried out by 13 laboratories (56 ppm), indicating that mass spectrometry is the main variable in achieving accurate and precise Nd isotope ratios. Overall, this result is very satisfactory, as the achieved precision is a factor of 40 better than the range of Nd isotopic compositions observed in the global ocean. Intercalibration for dissolved rare earth element concentrations (REEs) by six laboratories for two water depths at BATS yielded a reproducibility of 15% or better for all REE except Ce, which seems to be the most blank-sensitive REE. Neodymium concentrations from 12 laboratories show an agreement within 9%, reflecting the best currently possible reproducibility. Results for Nd isotopic compositions and REE concentrations on marine particles are inconclusive, and should be revisited in the future.

Testing the basin-centered gas accumulation model using fluid inclusion observations: Southern Piceance Basin, Colorado

Abstract: The Upper Cretaceous Mesaverde Group in the Piceance Basin, Colorado, is considered a continuous basin-centered gas accumulation in which gas charge of the low-permeability sandstone occurs under high pore-fluid pressure in response to gas generation. High gas pressure favors formation of pervasive systems of opening-mode fractures. This view contrasts with thatofothermodelsoflow-permeabilitygasreservoirsinwhich gas migrates by buoyant drive and accumulates in conventional traps, with fractures an incidental attribute of these reservoirs. We tested the aspects of the basin-centered gas accumulation model as it applies to the Piceance Basin by determining the timing of fracturegrowth and associated temperature,pressure, and fluid-composition conditions using microthermometry and Raman microspectrometry of fluid inclusions trapped in fracture cement that formed during fracture growth. Trapping temperatures of methane-saturated aqueous fluid inclusions record systematic temperature trends that increase from approximately 140 to 185°C and then decrease to approximately 158°C over time, which indicates fracture growth during maximum burial conditions. Calculated pore-fluid pressures for methanerich aqueous inclusions of 55 to 110 MPa (7977–15,954 psi) indicate fracture growth under near-lithostatic pressure conditions consistent with fracture growth during active gas maturation and charge. Lack of systematic pore-fluid–pressure trends

PETROTOX: an aquatic toxicity model for petroleum substances.

Abstract: A spreadsheet model (PETROTOX) is described that predicts the aquatic toxicity of complex petroleum substances from petroleum substance composition. Substance composition is characterized by specifying mass fractions in constituent hydrocarbon blocks (HBs) based on available analytical information. The HBs are defined by their mass fractions within a defined carbon number range or boiling point interval. Physicochemical properties of the HBs are approximated by assigning representative hydrocarbons from a database of individual hydrocarbons with associated physicochemical properties. A three-phase fate model is used to simulate the distribution of each structure among the water-, air-, and oil-phase liquid in the laboratory test system. Toxicity is then computed based on the predicted aqueous concentrations and aquatic toxicity of each structure and the target lipid model. The toxicity of the complex substance is computed assuming additivity of the contribution of the individual assigned hydrocarbons. Model performance was evaluated by using direct comparisons with measured toxicity data for petroleum substances with sufficient analytical characterization to run the model. Indirect evaluations were made by comparing predicted toxicity distributions using analytical data on petroleum substances from different product categories with independent, empirical distributions of toxicity data available for the same categories. Predictions compared favorably with measured aquatic toxicity data across different petroleum substance categories. These findings demonstrate the utility of PETROTOX for assessing environmental hazards of petroleum substances given knowledge of substance composition.

Determination of structural building blocks in heavy petroleum systems by collision-induced dissociation Fourier transform ion cyclotron resonance mass spectrometry.

Abstract: Collision-induced dissociation Fourier Transform ion cyclotron resonance mass spectrometry (CID-FTICR MS) was developed to determine structural building blocks in heavy petroleum systems. Model compounds with both single core and multicore configurations were synthesized to study the fragmentation pattern and response factors in the CID reactions. Dealkylation is found to be the most prevalent reaction pathway in the CID. Single core molecules exhibit primarily molecular weight reduction with no change in the total unsaturation of the molecule (or Z-number as in chemical formula CcH2c+ZNnSsOoVNi). On the other hand, molecules containing more than one aromatic core will decompose into the constituting single cores and consequently exhibit both molecular weight reduction and change in Z-numbers. Biaryl linkage, C1 linkage, and aromatic sulfide linkage cannot be broken down by CID with lab collision energy up to 50 eV while C2+ alkyl linkages can be easily broken. Naphthenic ring-openings were observed in CI...

Time-reversal checkpointing methods for RTM and FWI

Abstract: Time-domain seismic simulation can form the basis of reverse time depth migration and full-waveform inversion. These applications need to temporally crosscorrelate a forward simulation state with an adjoint simulation state and therefore need to be able to access each time step of a forward simulation in time-reverse order. This requires saving all forward states for all times (which can require more memory than is typically available on a computer system for many problems of interest), or the ability to checkpoint information and rapidly recompute forward simulation states as needed. Prior work has suggested how to do the latter by optimally choosing which forward simulation time steps to checkpoint, thereby enabling the most efficient reuse of memory buffers and minimizing recomputation. The optimal trade-off between memory usage and recomputation can be further improved under the assumption that the information needed to do temporal crosscorrelation is smaller than the information required to restart a simulation from a given time step. This assumption is true for many geophysical problems of interest. The modification can yield a reduction in the memory requirement and recomputation time. The tested examples applied to isotropic elastic reverse time migration and anisotropic viscoelastic full-waveform inversion.

Carbon dioxide capture and storage: Seven years after the IPCC special report

Abstract: Carbon dioxide capture and storage (CCS) entails separating carbon dioxide from coal-, biomassor gas-fired power plants or other large industrial sources, transporting the carbon dioxide by pipeline, injecting it deep underground, and storing it indefinitely in geological reservoirs including depleted oil and gas fields, and saline aquifers. CCS is envisioned to reduce carbon dioxide (CO2) emissions to the atmosphere when applied to large facilities that use fossil fuels. Applied to biomass, it may also lower CO2 concentrations in the atmosphere while supplying energy. The publication of the United Nations Intergovernmental Panel on Climate Change (IPCC) (2005) Special Report on CCS (SRCCS) raised the profile of CCS, particularly among the expert community dealing with international climate policy (Meadowcroft and Langhelle 2009). The expert community now commonly sees CCS as a major option for reducing global emissions of CO2. The technology plays a major role in long-term scenarios where there is significant reduction in greenhouse gas emissions (Clarke et al. 2009; IEA 2010a). For CCS to play such a major role, the separation, transport and storage would have to handle large volumes of CO2, and involve huge investments in facilities and infrastructure. The SRCCS conveyed some key insights. First, it clearly indicated that in principle, CCS is technically feasible. It also found that subsurface endowments of geological storage are probably massive, but regionally distributed and still highly uncertain. Mitig Adapt Strateg Glob Change (2012) 17:563–567 DOI 10.1007/s11027-012-9391-5

Reactive Transport Modeling of Brine Reflux: Dolomitization, Anhydrite Precipitation, and Porosity Evolution

Abstract: Both geothermal convection and brine reflux drive circulation of sea-water- derived fluids through carbonate platforms during early burial, but dynamic interactions between heat and solute transport and resulting diagenesis are at present poorly understood. This paper describes high-resolution reactive transport model (RTM) simulations that suggest that reflux of 85 ppt brines rapidly restricts geothermal convection to the platform margin, with flow focused in the more permeable shallow carbonates. In a baseline simulation, involving an elongate, 25-km-wide grain-dominated packstone platform, brine reflux resulted in complete dolomitization beneath the 5-km-wide brine pool in 335 ky. The dolomite body then extends downward at c. 22 m/100 ky into an underlying broad area of partial dolomitization. This process enhances porosity at shallow depth, but beneath the dolomite body precipitation of anhydrite occludes porosity and limits the depth of reflux. In contrast, geothermal convection at the platform margin forms a smaller partially dolomitized body over a longer time (< 60% dolomite after 1 My), with very minor associated anhydrite cementation. Reflux diagenesis is sensitive to platform geometry, with higher rates of fluid flow increasing the depth of alteration beneath the brine pool for a circular platform compared to the linear baseline. Fluid flow across thermal gradients enhances reaction rates, and ignoring heat transport by 85 ppt brine reflux underestimates the extent of reflux dolomite by 25% and associated anhydrite by 90%. The depth and rate of anhydritization is sensitive to the geothermal heat flux, whereas platform-top temperatures affect dolomitization rate. Reflux diagenesis is also sensitive to brine density, which affects both fluid flow and reaction rates. Sediment permeability and reactive surface area (RSA) are key intrinsic controls on diagenesis. Where the permeability structure permits sufficient fluid flow, diagenesis preferentially affects more reactive fine-grained sediments. However, as flow rates decline, reactions become focused in the more permeable but less reactive sediments. Simulations thus shed light on why in some settings reflux preferentially dolomitizes muddy sediments, but elsewhere favors grainstones. Once active reflux ceases, brines continue to flow in the subsurface, but this “latent reflux” causes only minor dolomitization due to prior Mg2+ consumption at shallow depth.

PatentMiner: topic-driven patent analysis and mining

Abstract: Patenting is one of the most important ways to protect company's core business concepts and proprietary technologies. Analyzing large volume of patent data can uncover the potential competitive or collaborative relations among companies in certain areas, which can provide valuable information to develop strategies for intellectual property (IP), R&D, and marketing. In this paper, we present a novel topic-driven patent analysis and mining system. Instead of merely searching over patent content, we focus on studying the heterogeneous patent network derived from the patent database, which is represented by several types of objects (companies, inventors, and technical content) jointly evolving over time. We design and implement a general topic-driven framework for analyzing and mining the heterogeneous patent network. Specifically, we propose a dynamic probabilistic model to characterize the topical evolution of these objects within the patent network. Based on this modeling framework, we derive several patent analytics tools that can be directly used for IP and R&D strategy planning, including a heterogeneous network co-ranking method, a topic-level competitor evolution analysis algorithm, and a method to summarize the search results. We evaluate the proposed methods on a real-world patent database. The experimental results show that the proposed techniques clearly outperform the corresponding baseline methods.

Quantitative Viscoelastic Mapping of Polyolefin Blends with Contact Resonance Atomic Force Microscopy

Abstract: The storage modulus (E′) and loss modulus (E″) of polyolefin blends have been mapped on the nanoscale with contact resonance atomic force microscopy (CR-FM), a dynamic contact mode of atomic force microscopy (AFM). Modulus values measured on various components within a blend of polyethylene, polypropylene, and polystyrene compared favorably with expected moduli of individual pure components at the contact resonance frequency that were calculated from bulk dynamic mechanical analysis (DMA) measurement results. Absolute storage modulus values were in good agreement with DMA results, while the loss modulus values obtained from CR-FM were consistently lower than those acquired from DMA. Application of CR-FM to an elastomer-containing blend resulted in moduli map artifacts due to the elastomer’s high adhesion and low storage modulus, illustrating its limitation in quantifying viscoelastic properties of soft elastomers. In spite of this current limitation, the results presented in this paper demonstrate the pot...

Bedload Transport of Mud Across A Wide, Storm-Influenced Ramp: Cenomanian–Turonian Kaskapau Formation, Western Canada Foreland Basin

Abstract: Mudstone-dominated shallow-marine rocks of the Kaskapau Formation were deposited on a low-gradient ramp that spanned the foredeep of the Western Canada foreland basin during the late Cenomanian to middle Turonian. Organic-, clay-rich, and silt-rich mudstone accumulated on the flank of the forebulge, > 200 km from the western shoreline. Within this mudstone, a large proportion of the clay minerals are organized into silt- and very fine sand-size aggregate grains. These aggregates were produced both in the water column as marine snow and phytodetritus and also through reworking of previously deposited cohesive mud to form intraclasts. The latter, along with siliceous silt grains, form wave- and combined-flow ripples, graded beds, scour-fills, and ripple-tail lamination. Where sand-size sediment (comprising detrital siliceous, calcareous bioclastic, or phosphatic grains) is present, it is molded into combined-flow ripples, HCS, gutter casts, and lags. Thus all sediment grades indicate storm- wave and current reworking of the sea floor at a distance of > 200 km offshore. The common occurrence of clay minerals in the form of aggregate grains, organized into combined-flow ripples and parallel lamination, implies advective transport of clay minerals as bedload, driven by combined flows across a very low-gradient ramp. On the distal part of this ramp, latest Cenomanian rocks include thin tongues of SW-prograding quartz-rich sandstone that was derived from an emergent forebulge. This source was drowned during the early Turonian eustatic rise when the sediment abruptly changed to organic-rich mudstone dominated by clay-mineral aggregates. This compositional change was mainly a response to a sudden increase in distance to detrital sources in the west, rather than a dramatic increase in water depth. Throughout much of early to middle Turonian time, the sea floor in the forebulge region lay above effective storm wave base for silt, estimated at ~ 70 m. At sea-level lowstands, wave winnowing and erosion of the sea floor concentrated bioclastic lags at the top of siltier-upward sequences; lags are interpreted to correspond to falling-stage, lowstand, and early transgressive systems tract deposits on the western margin of the basin. Previous studies may have substantially overestimated water depth for organic- and clay-rich calcareous mudstones in the Western Interior Seaway.

Loss tangent imaging: Theory and simulations of repulsive-mode tapping atomic force microscopy

Abstract: An expression for loss tangent measurement of a surface in amplitude modulation atomic force microscopy is derived using only the cantilever phase and the normalized cantilever amplitude. This provides a direct measurement of substrate compositional information that only requires tuning of the cantilever resonance to provide quantitative information. Furthermore, the loss tangent expression incorporates both the lost and stored energy into one term that represents a fundamental interpretation of the phase signal in amplitude modulation imaging. Numerical solutions of a cantilever tip interacting with a simple Voigt modeled surface agree with the derived loss tangent to within a few percent.

High vinyl terminated propylene based oligomers

Abstract: This invention relates to a co-oligomer having an Mn of 300 to 30,000 g/mol comprising 10 to 90 mol % propylene and 10 to 90 mol % of ethylene, wherein the oligomer has at least X % allyl chain ends, where: 1) X=(−0.94 (mole % ethylene incorporated)+100), when 10 to 60 mole % ethylene is present in the co-oligomer, and 2) X=45, when greater than 60 and less than 70 mole % ethylene is present in the co-oligomer, and 3) X=(1.83*(mole % ethylene incorporated)−83), when 70 to 90 mole % ethylene is present in the co-oligomer. This invention also relates to a homo-oligomer, comprising propylene, wherein the oligomer has: at least 93% allyl chain ends, an Mn of about 500 to about 20,000 g/mol, an isobutyl chain end to allylic vinyl group ratio of 0.8:1 to 1.2:1.0, and less than 100 ppm aluminum. This invention also relates to a process of making homo-oligomer, comprising propylene, wherein the productivity is greater than 4500 g/mmol Hf (or Zr)/hour.

Magma accumulation rates and thermal histories of plutons of the Sierra Nevada batholith, CA

Abstract: Zircon U–Pb geochronology results indicate that the John Muir Intrusive Suite of the central Sierra Nevada batholith, California, was assembled over a period of at least 12 Ma between 96 and 84 Ma. Bulk mineral thermochronology (U–Pb zircon and titanite, 40Ar/39Ar hornblende and biotite) of rocks from multiple plutons comprising the Muir suite indicates rapid cooling through titanite and hornblende closure following intrusion and subsequent slow cooling through biotite closure. Assembly of intrusive suites in the Sierra Nevada and elsewhere over millions of years favors growth by incremental intrusion. Estimated long-term pluton assembly rates for the John Muir Intrusive Suite are on the order of 0.001 km3 a−1 which is inconsistent with the rapid magma fluxes that are necessary to form large-volume magma chambers capable of producing caldera-forming eruptions. If large shallow crustal magma chambers do not typically develop during assembly of large zoned intrusive suites, it is doubtful that the intrusive suites represent cumulates left behind following caldera-forming eruptions.

Granger Causality for Time-Series Anomaly Detection

Abstract: Recent developments in industrial systems provide us with a large amount of time series data from sensors, logs, system settings and physical measurements, etc. These data are extremely valuable for providing insights about the complex systems and could be used to detect anomalies at early stages. However, the special characteristics of these time series data, such as high dimensions and complex dependencies between variables, as well as its massive volume, pose great challenges to existing anomaly detection algorithms. In this paper, we propose Granger graphical models as an effective and scalable approach for anomaly detection whose results can be readily interpreted. Specifically, Granger graphical models are a family of graphical models that exploit the temporal dependencies between variables by applying L1-regularized learning to Granger causality. Our goal is to efficiently compute a robust "correlation anomaly" score for each variable via Granger graphical models that can provide insights on the possible reasons of anomalies. We evaluate the effectiveness of our proposed algorithms on both synthetic and application datasets. The results show the proposed algorithm achieves significantly better performance than other baseline algorithms and is scalable for large-scale applications.