Quantifying Asymmetric Parameter Interactions in Sensitivity Analysis: Application to Reservoir Modeling   总被引：1，自引：1，他引：0  

Darryl Fenwick  Céline Scheidt  Jef Caers 《Mathematical Geosciences》2014,46(4):493-511

In this paper, a new generalized sensitivity analysis is developed with a focus on parameter interaction. The proposed method is developed to apply to complex reservoir systems. Most critical in many engineering applications is to find which model parameters and parameter combinations have a significant impact on the decision variables. There are many types of parameters used in reservoir modeling, e.g., geophysical, geological and engineering. Some parameters are continuous, others discrete, and others have no numerical value and are scenario-based. The proposed generalized sensitivity analysis approach classifies the response/decision variables into a limited set of discrete classes. The analysis is based on the following principle: if the parameter frequency distribution is the same in each class, then the model response is insensitive to the parameter, while differences in the frequency distributions indicate that the model response is sensitive to the parameter. Based on this simple idea, a new general measure of sensitivity is developed. This sensitivity measure quantifies the sensitivity to parameter interactions, and incorporates the possibility that these interactions can be asymmetric for complex reservoir modeling. The approach is illustrated using a case study of a West Africa offshore oil reservoir.  相似文献   

Arsenic within the secondary environment resulting from geogenic inputs,Harlech Dome,United Kingdom     

Graham Bird  Hannah E. G. Bell  William T. Perkins 《Environmental Earth Sciences》2014,72(9):3521-3530

There has been a growing awareness of As in the environment due to both anthropogenic and geogenic loading. This study quantifies the presence of As in river water, river sediment and groundwater within the Harlech Dome region of the UK, an area underlain by Cambro–Ordovician aged mineralization. Published data regarding As levels in UK groundwater are relatively rare compared to elsewhere. Arsenic levels in groundwater (0.1–18 µg l^?1) and river sediment (1.5–142 mg kg^?1) exceed environmental quality guidelines and indicate the release of As into the secondary environment from predominantly geogenic sources. Modelling of dissolved As speciation using ORP–pH diagrams predicts the presence of As in both arsenate (As⁵⁺) and arsenous acid (As³⁺) species, which possess differing solubilities and mobilities. Calculation of enrichment factors (EFs) for As in river sediments, using Al as a reference element, indicates highest EFs, and therefore As release, occurs in streams draining the Coed-y-Brenin region in the south-east of the Harlech Dome. This area is underlain by an as yet unexploited porphyry copper deposit. Data indicate that the presence of potentially harmful elements within the environment may occur with or without the presence of major anthropogenic activity.  相似文献   

Mineralogy and major-element geochemistry of the lower Permian Greta Seam,Sydney Basin,Australia     

L. Zhao  C. R. Ward  D. French  I. T. Graham 《Australian Journal of Earth Sciences》2014,61(3):375-394

The mineralogy of the high-volatile bituminous coals and associated strata from the Greta seam, Sydney Basin, Australia, has been evaluated in this study. Although the seam is not immediately overlain by marine strata, percolation of marine water into the original peat bed is indicated by the petrological, mineralogical and geochemical characteristics, which resemble those of coals with marine roof strata. The upper and lower sections of the seam have contrasting mineralogy. Pyrite typically comprises 40 to 56 wt% of the mineral assemblage in the marine-influenced upper part of the seam section. The lower part contains much less pyrite (typically <5 wt%, organic-free basis), and also relatively abundant dawsonite (up to 14 wt%, organic-free basis). The minerals within most coal plies are largely of authigenic origin. These include pyrite, siderite, clay minerals (mainly kaolinite and Na-rich mixed-layer illite/smectite), and quartz, most of which have a relatively early, syngenetic origin. Minor Ti-bearing minerals, anatase or rutile, and phosphate minerals, fluorapatite and goyazite, were probably also formed during early diagenesis. Other minerals have features that indicate late-stage precipitation. These include abundant cleat- and fracture-filling dawsonite, which may be the result of reactions between earlier-precipitated kaolinite and Na₂CO₃- or NaHCO₃-bearing fluids. Minor albite may also be epigenetic, possibly precipitated from the same Ca–Al bearing fluids that formed the dawsonite. The most abundant detrital minerals in the Greta coals are quartz, poorly ordered kaolinite, illite and mixed-layer illite/smectite (I/S). These occur mainly in the floor, roof and other epiclastic horizons of the seam, reflecting periods of greater clastic influx into those parts of the original peat-forming environment. Detrital minerals are rare in the coals away from the epiclastic horizons, probably owing to almost complete sediment bypassing in the depositional system. Alternatively, any detrital minerals that were originally present may have been leached from the peat bed by diagenetic or post-diagenetic processes.  相似文献   

Inference of Solar Magnetic Field Parameters from Data with Limited Wavelength Sampling     

Graham  Jonathan D.  López Ariste  Arturo  Socas-Navarro  Hector  Tomczyk  Steven 《Solar physics》2002,208(2):211-232

We investigate the diagnostic potential of polarimetric measurements with filtergraph instruments. Numerical simulations are used to explore the possibility of inferring the magnetic field vector, its filling factor, and the thermodynamics of model atmospheres when only a few wavelength measurements are available. These simulations assume the magnetic Sun to be represented by Milne–Eddington atmospheres. The results indicate that two wavelength measurements are insufficient to reliably determine the magnetic parameters, regardless of whether magnetograph techniques or least-squares fitting inversions are used. However, as few as four measurements analyzed with the inversion technique provide enough information to retrieve the intrinsic magnetic field with an accuracy better than 10% in most cases.  相似文献   

Use of GIS and dasymetric mapping for estimating tsunami-affected population to facilitate humanitarian relief logistics: a case study from Phuket,Thailand     

Jitt-Aer  Kiatkulchai  Wall  Graham  Jones  Dylan  Teeuw  Richard 《Natural Hazards》2022,113(1):185-211

Natural Hazards - The 2004 Indian Ocean tsunami led to improvements in Thailand’s early warning systems and evacuation procedures. However, there was no consideration of better aid delivery,...  相似文献   

The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance     

J. Todd Hoeksema  Yang Liu  Keiji Hayashi  Xudong Sun  Jesper Schou  Sebastien Couvidat  Aimee Norton  Monica Bobra  Rebecca Centeno  K. D. Leka  Graham Barnes  Michael Turmon 《Solar physics》2014,289(9):3483-3530

The Helioseismic and Magnetic Imager (HMI) began near-continuous full-disk solar measurements on 1 May 2010 from the Solar Dynamics Observatory (SDO). An automated processing pipeline keeps pace with observations to produce observable quantities, including the photospheric vector magnetic field, from sequences of filtergrams. The basic vector-field frame list cadence is 135 seconds, but to reduce noise the filtergrams are combined to derive data products every 720 seconds. The primary 720 s observables were released in mid-2010, including Stokes polarization parameters measured at six wavelengths, as well as intensity, Doppler velocity, and the line-of-sight magnetic field. More advanced products, including the full vector magnetic field, are now available. Automatically identified HMI Active Region Patches (HARPs) track the location and shape of magnetic regions throughout their lifetime. The vector field is computed using the Very Fast Inversion of the Stokes Vector (VFISV) code optimized for the HMI pipeline; the remaining 180^° azimuth ambiguity is resolved with the Minimum Energy (ME0) code. The Milne–Eddington inversion is performed on all full-disk HMI observations. The disambiguation, until recently run only on HARP regions, is now implemented for the full disk. Vector and scalar quantities in the patches are used to derive active region indices potentially useful for forecasting; the data maps and indices are collected in the SHARP data series, hmi.sharp_720s. Definitive SHARP processing is completed only after the region rotates off the visible disk; quick-look products are produced in near real time. Patches are provided in both CCD and heliographic coordinates. HMI provides continuous coverage of the vector field, but has modest spatial, spectral, and temporal resolution. Coupled with limitations of the analysis and interpretation techniques, effects of the orbital velocity, and instrument performance, the resulting measurements have a certain dynamic range and sensitivity and are subject to systematic errors and uncertainties that are characterized in this report.  相似文献   

The role of perched aquifers in hydrological connectivity and biogeochemical processes in vernal pool landscapes,Central Valley,California     

Mark Cable Rains  Graham E. Fogg  Thomas Harter  Randy A. Dahlgren  Robert J. Williamson 《水文研究》2006,20(5):1157-1175

Relatively little is known about the role of perched aquifers in hydrological, biogeochemical, and biological processes of vernal pool landscapes. The objectives of this study are to introduce a perched aquifer concept for vernal pool formation and maintenance and to examine the resulting hydrological and biogeochemical phenomena in a representative catchment with three vernal pools connected to one another and to a seasonal stream by swales. A combined hydrometric and geochemical approach was used. Annual rainfall infiltrated but perched on a claypan/duripan, and this perched groundwater flowed downgradient toward the seasonal stream. The upper layer of soil above the claypan/duripan is ～0·6 m in thickness in the uplands and ～0·1 m in thickness in the vernal pools. Some groundwater flowed through the vernal pools when heads in the perched aquifer exceeded ～0·1 m above the claypan/duripan. Perched groundwater discharge accounted for 30–60% of the inflow to the vernal pools during and immediately following storm events. However, most perched groundwater flowed under or around the vernal pools or was recharged by annual rainfall downgradient of the vernal pools. Most of the perched groundwater was discharged to the outlet swale immediately upgradient of the seasonal stream, and most water discharging from the outlet swale to the seasonal stream was perched groundwater that had not flowed through the vernal pools. Therefore, nitrate‐nitrogen concentrations were lower (e.g. 0·17 to 0·39 mg l^?1) and dissolved organic carbon concentrations were higher (e.g. 5·97 to 3·24 mg l^?1) in vernal pool water than in outlet swale water discharging to the seasonal stream. Though the uplands, vernal pools, and seasonal stream are part of a single surface‐water and perched groundwater system, the vernal pools apparently play a limited role in controlling landscape‐scale water quality. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

H2 in molecular shocks: observations from 2 to 12 microns     

M. J. Richter  J. R. Graham  G. S. Wright  D. M. Kelly  J. H. Lacy 《Astrophysics and Space Science》1995,233(1-2):67-70

We present spectroscopy of the molecular shock in the supernova remnant IC 443. The H₂ level populations in IC 443 are nearly identical to Orion Peak 1 (Brand et al. 1988; Parmar et al. 1994) and are consistent with a partially dissociative J-shock. The similarity with Orion suggests the shock processes which dominate the emission in both regions are essentially identical.  相似文献   

The Millennium Galaxy Catalogue: bulge–disc decomposition of 10 095 nearby galaxies     

Paul D. Allen  Simon P. Driver  Alister W. Graham  Ewan Cameron  Jochen Liske  Roberto De Propris 《Monthly notices of the Royal Astronomical Society》2006,371(1):2-18

We present near-infrared (NIR) adaptive optics-assisted spectroscopic observations of the  CO (Δμ= 2)  absorption bands towards the centre of the giant elliptical galaxy NGC 1399. The observations were made with NAOS-CONICA (on the European Southern Observatory's Very Large Telescope) and have a full width at half-maximum resolution of 0.15 arcsec (14 pc). Kinematic analysis of the observations reveals a decoupled core and strongly non-Gaussian line-of-sight velocity profiles in the central 0.2 arcsec (19 pc). NIR imaging also indicates an asymmetric elongation of the central isophotes in the same region.
We use spherical orbit-superposition models to interpret the kinematics, using a set of orthogonal 'eigen-velocity profiles' that allow us to fit models directly to spectra. The models require a central black hole of mass  1.2^+0.5_−0.6× 10⁹ M_⊙  , with a strongly tangentially biased orbit distribution in the inner 40 pc.  相似文献   

Lost and abandoned nets in deep-water gillnet fisheries in the Northeast Atlantic: retrieval exercises and outcomes     

Large  Philip A.; Graham  Norman G.; Hareide  Nils-Roar; Misund  Robert; Rihan  Dominic J.; Mulligan  Myles C.; Randall  Peter J.; Peach  David J.; McMullen  Philip H.; Harlay  Xavier 《ICES Journal of Marine Science》2009,66(2):323-333

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