bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trust-Region Newton Solver for Multiphase Flow and Transport in Heterogeneous Porous Media
Authors: Wang X. , Tchelepi H. A. 
Published: March 2013

Abstract
We describe a new nonlinear solver for immiscible two-phase transport in porous media, where viscous, buoyancy, and capillary forces are significant. The ‘fractional-flow’, F, is a nonlinear function of saturation and typically has inflection points and can be non-monotonic. The non-convexity and non-monotonicity of F are major sources of difficulty for nonlinear solvers. A modified Newton algorithm that employs trust-regions of the flux function to guide the Newton iterations is proposed. The flux function is divided into saturation trust regions. The delineation of these regions is dictated by the inflection, unit-flux, and end points. The saturation updates are performed such that two successive iterations cannot cross any trust-region boundary. If a crossing is detected, we ‘chop back’ the saturation value to the appropriate trust-region boundary. Our trust-region Newton solver has excellent convergence properties across the parameter space of viscous, buoyancy and capillary effects, and it represents a significant generalization of the inflection-point approach of Jenny et al. (JCP, 2009) for viscous dominated flows.
We analyze the nonlinear transport equation using low-order finite-volume discretization with phase-based upstream weighting. Then, we prove unconditional convergence of the trust-region Newton method irrespective of the timestep size for single-cell problems. For one-dimensional transport, numerical results across the full range of the parameter space of viscous, gravity and capillary forces indicate that our trust-region scheme is unconditionally convergent. That is, for any choice of the timestep size, the unique discrete saturation solution is found independently of the initial guess. For problems dominated by buoyancy and capillarity, the trust-region Newton solver overcomes the often severe limits on timestep size associated with existing methods. We use complex 3D reservoir models to demonstrate the effectiveness of the proposed nonlinear solver. Specifically, we use the top zone of the SPE 10 model (Tarbert formation) and the full SPE 10 model. Compared with state-of-the-art Newton-based nonlinear solvers, our trust-region solver results in superior convergence performance, and it reduces the total Newton iterations by more than an order of magnitude, which leads to a comparable reduction in the overall computational cost.
Estimation of Mutual Information and Conditional Entropy for Surveillance Optimization
Authors: Le Duc H. , Reynolds Albert C. 
Published: March 2013

Abstract
Given a suite of potential surveillance operations, we define surveillance optimization as the problem of choosing the operation that gives the minimum expected value of P90 minus P10 of a specified reservoir variable J (e.g. cumulative oil production) that will be obtained by conditioning J to the observed data. Two questions can be posed, namely: (1.) Which surveillance operation is expected to provide the greatest uncertainty reduction in J ? (2.) What is the expected value of the reduction in uncertainty that would be achieved if we were to undertake each surveillance operation to collect the associated data and then history-match the data obtained? In this work, we extend and apply a conceptual idea that we recently proposed for surveillance optimization to 2-D and 3-D water flooding problems. Our method is based on information theory where the mutual information between J and the random observed data vector Dobs is estimated using an ensemble of prior reservoir models. This mutual information reflects the strength of the relationship between J and the potential observed data and provides a qualitative answer to question 1. Question 2 is answered by calculating the conditional entropy of J in order to generate an approximation of the expected value of the reduction in P90 - P10 of J. The reliability of our method depends on obtaining a good estimate of the mutual information. We consider several ways to estimate the mutual information and suggest how a good estimate can be chosen. We validate the results of our proposed method with an exhaustive history-matching procedure.
The methodology provides an approximate way to decide which data should be collected to maximize the uncertainty reduction in a specified reservoir variable and to estimate the reduction in uncertainty that could be obtained. We expect this paper will stimulate significant research on the application of information theory and lead to practical methods and workflows for surveillance optimization.
An Unstructured Gridding Method for Densely-Spaced Complex Wells in Full-Field Reservoir Simulation
Authors: Fung Larry S. , Ding Xiang Y. , Dogru Ali H. 
Published: March 2013

Abstract
Accurate representation of near-well flow is an important subject matter in reservoir simulation. In today’s field-scale reservoir simulation, cell-centered structured grids remain the predominant practice. Typically, well inflow performance of the perforated cells is connected to the finite-volume solution via well indices which may not be well defined when the wellbore intersects the finite-volume cells in a complex trajectory. Fine gridding is required to resolve the flow dynamics in the near-well regions. Strong grid orientation sensitivities can also contribute to the numerical errors and may require significant local grid refinement to alleviate. There are on-going R&D efforts on applying unstructured grids to better represent the near-well flow in reservoir simulation, but their applications are mainly in single-well study or sector modeling with a few wells. Some of the reasons cited for this include: (1) the lack of an effective, easy-to-use full-field complex well gridding tool; (2) the lack of supporting unstructured workflow for full-cycle reservoir simulation; (3) the cost of unstructured grid simulation; (4) the availability of post analysis and visualization tools for unstructured grid simulation.
The paper describes a method to generate unstructured grids which conform to complex well paths in field-scale simulation. The method uses a multi-level approach to place cells optimally within the solution domain based on the "regions of interests". The wellbore geometry is honored via the construction of a near-well grid that is complemented with multi-level quad-tree refinements to achieve the desired resolution in grid transition zones. The method includes an algorithm to remove small cells and pinching cells based on local grid quality measures and cell prioritization to honor well paths. The gridding process forms a component of a production level reservoir simulation workflow. The use of unstructured grid results in computational saving by placing cells where the resolution is needed. An in-house massively parallel simulator is used to run the unstructured grid models. Simulation examples for full-field applications with hundreds of complex wells using both structured grids and unstructured grids will be used to compare results, accuracy, and performance of the gridding method for reservoir simulation.
Analysis of the Stability of Explicit Reservoir Simulation Calculations
Authors: Watts J. W. , Moncorgé Arthur 
Published: March 2013

Abstract
Von Neumann analysis is the most commonly used method for determining stability of an explicit-in-time finite difference method. Watts and Ramé (1999) describe a different approach based on the error growth matrix for the finite difference method. In this approach, called herein the matrix method, stability is determined by computing the eigenvalues of the error growth matrix. An advantage of the matrix method is it is it deals rigorously with heterogeneities. However, in a practical application, the growth matrix is large, making the cost of computing the eigenvalues prohibitive. Watts and Ramé deal with this through a local calculation. This paper extends the work of Watts and Ramé, making it possible to consider separately the stability impact of individual components of the flow equation. It also includes detailed comparisons with the results of Von Neumann analysis.
This work’s primary application relates to research. It can be used to rigorously determine whether a particular explicit calculation is stable. This can lead to an improved understanding of the stability behavior of various computational methods and of various methods for predicting stability. In addition, the local form of it can be used to determine the stable timestep size in an explicit method or to determine what degree of implicitness is needed by individual blocks in an AIM calculation.
It is concluded that (1) the most accurate way to determine stability of an explicit-in-time reservoir simulation calculation is the matrix method; (2) the matrix method is computationally expensive and impractical to use in large, field-scale models; (3) the local version of the matrix method offers promise as a way to extend the matrix method to larger models and to use it to determine which blocks to treat implicitly in an AIM application; and (4) the boundary conditions required by the von Neumann method do not occur in actual applications.
The approach described here provides the researcher with a way to develop a better understanding of how individual components of the transport calculation affect stability, and it may provide a better way to determine stability in a practical setting.
Improving the Ensemble Optimization Method Through Covariance Matrix Adaptation (CMA-EnOpt)
Authors: Fonseca R. M. , Leeuwenburgh O. , Van den Hof P. M. , Jansen J. D. 
Published: March 2013

Abstract
Ensemble Optimization (EnOpt) is a rapidly emerging method for reservoir model based production optimization. EnOpt uses an ensemble of controls to approximate the gradient of the objective function with respect to the controls. Current implementations of EnOpt use a Gaussian ensemble with a constant standard deviation, i.e. a diagonal covariance matrix with entries that remain constant during the optimization process. The Covariance Matrix Adaptation Evolutionary Strategy (CMA-ES) is a gradient-free optimization method, developed in the ‘machine learning’ community, which also uses an ensemble of controls but with a covariance matrix that is continually updated during the optimization process. It has shown to be an efficient method for several difficult small dimension optimization problems and has recently been applied in the petroleum industry for well location and production optimization. In this study we investigated the scope to improve the computational efficiency of EnOpt through the use of covariance adaptation (CMA-EnOpt). We optimized water flooding of a multi-layer sector model containing multiple sealing and non-sealing faults. The controls used were inflow control valve settings at pre-defined time intervals for injectors and producers with undiscounted net present value as the objective function. We compared EnOpt and CMA-EnOpt starting from identical covariance matrices. We achieved slightly higher (0.7%-1.8%) objective function values and modest speed-ups with CMA-EnOpt compared to EnOpt, depending on choice of user-defined parameters in both algorithms. However, the major benefit of CMA-EnOpt is its robustness with respect to the initial choice of the covariance matrix. A poor choice of the initial matrix can be detrimental to EnOpt, whereas the CMA-EnOpt performance is near-independent of the initial choice.
Selecting Representative Models from a Large Set of Models
Authors: Sarma Pallav , Chen Wen H. , Xie Jiang 
Published: March 2013

Abstract
In order to make the field development decision making and planning process tractable, the decision-makers usually need a few representative models (for example, P10, P50, P90 models) selected from a large ensemble of reservoir models. This ensemble of models may have been obtained from a static and/or dynamic modeling process involving uncertainty quantification (ED), history matching, optimization or other workflows. The usual approach to select a few models is using various variants of clustering. This selection process is not only suboptimal, but it could also be quite difficult to do if multiple output responses and/or percentiles are required and the number of models is large. The current approach in most oil companies is even more naïve, wherein, such models are chosen manually or using Excel spreadsheets. Thus, due to the unavailability of good approaches, representative models are usually chosen based on one or two criteria. Use of such models in the decision making process can lead to sub-optimal decisions. As such, there is a need to automatically select a small set of statistically representative models from a larger set based on multiple decision criteria.
We propose a new model selection approach, namely minimax approach, which can simultaneously and efficiently select a few reservoir models from a large ensemble of models by matching target percentiles of multiple output responses (for example, matching P10, P50 and P90 of OPC, WPC and OOIP), while also obtaining maximally different models in the input uncertainty space. The approach requires the simultaneous solution of two minimax combinatorial optimization problems. Since this requires the solution a complex multi-objective optimization problem, we instead convert the problem to the solution of a single constrained minimax optimization problem. We propose the solution of this optimization problem using a global exhaustive search (for small problems), and a very efficient greedy method wherein a simpler optimization problem can be solved directly by enumeration or by Markov chain Monte Carlo methods for larger problems with many models, target percentiles and variables. The new approach is implemented in Chevron’s in-house uncertainty quantification software called genOpt and tested with multiple synthetic examples and field cases. The results demonstrate that the proposed approach is much more efficient than clustering and solution quality is generally better than clustering. For some models, minimax was orders of magnitude faster than clustering. The new approach could help business units select P10, P50 and P90 models efficiently for decision making and planning.
Economic Costs of Diabetes in the U.S. in 2012
Authors:   American Diabetes Association
Published: March 2013

OBJECTIVE
This study updates previous estimates of the economic burden of diagnosed diabetes and quantifies the increased health resource use and lost productivity associated with diabetes in 2012.

RESEARCH DESIGN AND METHODS
The study uses a prevalence-based approach that combines the demographics of the U.S. population in 2012 with diabetes prevalence, epidemiological data, health care cost, and economic data into a Cost of Diabetes Model. Health resource use and associated medical costs are analyzed by age, sex, race/ethnicity, insurance coverage, medical condition, and health service category. Data sources include national surveys, Medicare standard analytical files, and one of the largest claims databases for the commercially insured population in the U.S.

RESULTS
The total estimated cost of diagnosed diabetes in 2012 is $245 billion, including $176 billion in direct medical costs and $69 billion in reduced productivity. The largest components of medical expenditures are hospital inpatient care (43% of the total medical cost), prescription medications to treat the complications of diabetes (18%), antidiabetic agents and diabetes supplies (12%), physician office visits (9%), and nursing/residential facility stays (8%). People with diagnosed diabetes incur average medical expenditures of about $13,700 per year, of which about $7,900 is attributed to diabetes. People with diagnosed diabetes, on average, have medical expenditures approximately 2.3 times higher than what expenditures would be in the absence of diabetes. For the cost categories analyzed, care for people with diagnosed diabetes accounts for more than 1 in 5 health care dollars in the U.S., and more than half of that expenditure is directly attributable to diabetes. Indirect costs include increased absenteeism ($5 billion) and reduced productivity while at work ($20.8 billion) for the employed population, reduced productivity for those not in the labor force ($2.7 billion), inability to work as a result of disease-related disability ($21.6 billion), and lost productive capacity due to early mortality ($18.5 billion).

CONCLUSIONS
The estimated total economic cost of diagnosed diabetes in 2012 is $245 billion, a 41% increase from our previous estimate of $174 billion (in 2007 dollars). This estimate highlights the substantial burden that diabetes imposes on society. Additional components of societal burden omitted from our study include intangibles from pain and suffering, resources from care provided by nonpaid caregivers, and the burden associated with undiagnosed diabetes.
Reviews
Authors: Underhill Frank , Brett  , Harrison  , McInnis Edgar 
Published: March 2013

Sumner Welles, The Time for Decision, reviewed by Frank Underhill Walter Lippmann, U.S. Post War Aims, reviewed by Frank Underhill James T. Shotwell, The Great Decision, reviewed by Frank Underhill Hugh Gibson, The Road to Foreign Policy, reviewed by Frank Underhill Georges Gurvitch, Sociology of Law, reviewed by G. S. Brett G. G. Coulton, Fourscore Years: An Autobiography, reviewed by G. B. Harrison Charles Callan Tansill, Canadian-American Relations, 1875-1911, reviewed by Edgar McInnis C. T . Prouty, ed., George Gascoigne's A Hundreth Sundrie Flowres, reviewed by N. J. E. Frederick L. W. Wood, Understanding New Zealand, reviewed by A. B. Walter Nash, New Zealand: A Working Democracy, reviewed by A. B.
Reviews
Authors: Underhill Frank , Woodhouse A. S. P. , Sirluck Ernest 
Published: March 2013

John Bartlet Brebner, North Atlantic Triangle: the Interplay of Canada, the United States and Great Britain, reviewed by Frank H. Underhill David Dallin, The Big Three, reviewed by Frank H. Underhill Crane Brinton, The United States and Britain, reviewed by Frank H. Underhill Nathaniel Peffer, America's Place in the World, reviewed by Frank H. Underhill George Soule, America's Stake in Britain's Future, reviewed by Frank H. Underhill Denis Saurat, Milton, Man and Thinker [2nd edition, revised], reviewed by A. S. P. Woodhouse C. M. Bowra, From Virgil to Milton, reviewed by A. S. P. Woodhouse Douglas Bush, Paradise Lost in Our Time: Some Comments, reviewed by A. S. P. Woodhouse G. Rostrevor Hamilton, Hero or Fool? A study of Milton's Satan, reviewed by A. S. P. Woodhouse Ross Munro, Gauntlet to Overlord: the Story of the Canadian Army, reviewed by Ernest Sirluck
Reviews
Authors: Wilson H.S/ , Wallace Malcolm , Roper Gordon , Saunders Doris 
Published: March 2013

J.W.H. Atkins, English Literary Criticism: The Renascence, reviewed by H.S. Wilson Basil Mathews, Booker T. Washington: Educator and Interracial Interpreter, reviewed by Malcolm W. Wallace Robert Cantwell, Nathaniel Hawthorne: The American Years, reviewed by Gordon Roper W.K. Wimsatt, Jr., Philosophic Words: A Study of Style and Meaning in the RAmbler and Dictionary of Samuel Johnson, reviewed by Gordon Roper
Reviews
Authors: Abrams M.H. , Buchanan M.A. , Wilkins Ernest , Strakhovsky Leonid 
Published: March 2013

Kathleen Coburn, ed., The Philosophical Lectures of Samuel Taylor Coleridge, reviewed by M. H. Abrams Miguel de Cervantes Saavedra, The Ingenious Gentleman Don Quixote de la Mancha, Complete in Two Parts, reviewed by M. A. Buchanan J. E. Shaw, Guido Cavalcanti's Theory of Love: The Canzone d'Amore and Other Related Problems, reviewed by Ernest H. Wilkins Isaac Deutscher, Stalin: A Poltical Biography, reviewed by Leonid I. Strakhovsky
Reviews
Authors: Wasteneys H. , Underhill F. H. , Goudge T. A. , Knox R. S. 
Published: March 2013

B. P. Babkin, Pavlov: A Biography, reviewed by H. Wasteneys Julian Amery, The Life of Joseph Chamberlain. Volume IV, 1901-1903, At the Height of His Power, reviewed by F. H. Underhill H. J. Paton, In Defence of Reason, reviewed by T. A. Goudge David Daiches, Robert Burns, reviewed by R.S. Knox
Reviews
Authors: Anderson Theodore , Frank Roberta , Fleming John , Rajan Tilottama , Whiteside Anna , Cook Eleanor 
Published: March 2013

Colin Chase, ed., The Dating of Beowulf, reviewed by Theodore M. Anderson Stanley B. Greenfield and Fred C. Robinson, A Bibliography of Publications on Old English Literature from the Beginnings to the End of 1972, reviewed by Roberta Frank Jacques Rustin, Le Vice à la mode: étude sur le roman français du XVIIIe siècle de 'Manon Lescaut' à l'apparition de 'La Nouvelle Héloïse', reviewed by John A. Fleming Thomas McFarland, ed., Romanticism and the Forms of Ruin: Wordsworth, Coleridge, and Modalities of Fragmentation, reviewed by Tilottama Rajan Ruth Amossy, Les Jeux de l'allusion littéraire dans 'Un beau ténébreux' de Julien Gracq, reviewed by Anna Whiteside John Hollander, The Figure of Echo: A Mode of Allusion in Milton and After, reviewed by Eleanor Cook
Reviews
Authors: MacLaren  , Weinberg Henry , Blissett William , Moyal Gabriel 
Published: March 2013

Percy G. Adams, Travel Literature and the Evolution of the Novel, reviewed by I. S. MacLaren Emile Zola, Correspondence, IV, 1880–1883, reviewed by Henry H. Weinberg Neil Corcoran, The Song of Deeds: A Study of The Anathemata of David Jones, reviewed by William Blissett Thomas Dilworth, ed., Inner Necessities: The Letters of David Jones to Desmond Chute, reviewed by Wiliam Blissett Philip Pacey, David Jones and Other Wonder Voyagers, reviewed by William Blissett Elizabeth Ward, David Jones, Mythmaker, reviewed by William Blissett Jacques Derrida, Signéponge/Signsponge, reviewed by Gabriel Moyal
Reviews
Authors: Fortier Mark 
Published: March 2013

Valda Blundell, John Shepherd, and Ian Taylor, eds., Relocating Cultural Studies: Developments in Theory and Research, reviewed by Mark Fortier Brian Boigan, ed., Culture Lab, reviewed by Mark Fortier Jessica Bradley and Lesley Johnstone, eds., Sightlines: Reading Contemporary Canadian Art, reviewed by Mark Fortier Canadas Semiotext(e) 17, reviewed by Mark Fortier Reading 'Kim' Right, reviewed by Mark Fortier Frank Davey, Karla's Web: A Cultural Investigation of the Mahaffy-French Murders, reviewed by Mark Fortier Ioan Davies, Cultural Studies and Beyond: Fragments of Empire, reviewed by Mark Fortier John Fekete, Moral Panic Biopolitics Rising, reviewed by Mark Fortier Sarah Franklin, Celia Lury, and Jackie Stacey, Off-Centre: Feminism and Cultural Studies, reviewed by Mark Fortier Henry A. Giroux and Peter McLaren, eds., Between Borders: Pedagogy and the Politics of Cultural Studies, reviewed by Mark Fortier Lawerence Grossberg, Cary Nelson, and Paul Treichler, eds., Cultural Studies, reviewed by Mark Fortier Jerry D. Leonard, ed., Legal Studies as Cultural Studies: A Reader in (Post)modern Critical Theory, reviewed by Mark Fortier John O'Neill, The Missing Child in Liberal Theory: Towards a Covenant Theory of Family, Community, Welfare and the civic State, reviewed by Mark Fortier
Iddin-Dagan, un gestionnaire à Ṭâbatum
Authors: Ziegler Nele 
Published: March 2013

Iddin-Dagan était l’intendant ( abu bîtim ) de Ṭâbatum au début du règne de Zimrî-Lîm. Dans la présente contribution, trois lettres de cet homme au roi de Mari sont publiées (A [A.322+M.6597], B [A.2992] et C [A.2157]) ainsi qu’une lettre d’Aqba-ahum (D [A.600]). Ces lettres traitent de la gestion des travaux agricoles et des ressources humaines et matérielles manquantes pour faire face aux travaux. Dans la lettre A, la mainmise du gouverneur de Qaṭṭunân sur les réserves de Ṭâbatum est dénoncée.