bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Study on Cuttings Transport With Foam Under Simulated Horizontal Downhole Conditions
Authors: Chen Z. , Ahmed R. M. , Miska S. Z. , Takach N. E. , Yu M. , Pickell M. B. , Hallman J. 
Published: January 2008

Summary
The use of drilling foams is increasing because foams exhibit properties that are desirable in many drilling operations. A good knowledge of cuttings transport efficiency under downhole conditions is essential for safe and economical foam drilling. Previous cuttings transport studies with foam are limited to low pressure and ambient temperature conditions. No experimental study has been conducted under downhole (i.e., elevated pressure and temperature) conditions. This paper presents an experimental study of cuttings transport with foam in a horizontal annulus under simulated downhole conditions.
Experiments were conducted to determine the effects of polymer additives, foam quality, flow velocity, temperature, and pressure on foam cuttings transport. Experiments were carried out at elevated pressures (100 to 400 psi) and temperature (80 to 170°F) conditions in a unique full-scale flow loop with a 73-ft long test section (5.76×3.5 in. concentric annulus). A field-tested commercial foam system consisting of surfactant (1% v/v) and hydroxylethylcellulose polymer (HEC) was used in the experiments. Three different polymer concentrations (0.0, 0.25, and 0.5% v/v) were tested. Foam quality was varied from 70 to 90%.
During a test, cuttings were injected continuously to the flow loop until a steady state condition was established in the test section. In-situ cuttings volumetric concentration (i.e., the ratio of the volume of cuttings in the suspension and the cuttings bed to the volume of the annulus) in the test section was determined using nuclear densitometers, load cell measurements, and by weighing cuttings flushed out of the flow loop. Test parameters recorded during the experiments were: liquid and gas injection rates, cuttings weight in injection and removal towers, mixture density, friction pressure loss, and pressure and temperature in the annulus.
Two flow patterns, stationary cuttings bed, and fully suspended flow, were observed during the cuttings transport tests. The flow pattern depends on polymer concentration, foam quality, and annular velocity. Annular flow velocity, foam quality, and polymer concentration all affect cuttings transport efficiency and frictional pressure loss. This paper will help to better design foam drilling and cleanup operations.
New Shape Factor for Vertically Fractured Well Produced at Constant Pressure
Authors: Haryanto E. 
Published: January 2008

Abstract
The Dietz shape factor is one of the key parameter for predicting production performance of oil and gas wells. Except for vertical well, the libraries of shape factor are currently available only for a well producing at a constant rate. This condition however is unlikely to occur in the reality as compared to condition under a constant pressure.
As hydraulic fracturing plays a major role in well stimulation to increase production, there is a need to develop Dietz shape factor for hydraulical vertical fracture well producing at a constant bottom hole pressure.
In this paper, by using reservoir simulation, the new shape factors are developed for closed rectangular reservoir, with single vertical fracture well, at infinite and finite fracture conductivity, under a constant bottom hole pressure. The new shape factors should replace Dietz shape factors for vertical hydraulic fracture well producing at a constant rate, particularly when evaluating the production performance of a vertical fracture well at a constant bottom hole pressure with finite fracture conductivity.
Fabrication of Synthetic Reservoir Rock Core and Application to NMR Logging
Authors: Ronan L. 
Published: January 2008

Abstract
The Petroleum industry for decades has relied on the acquisition and correct interpretation of reservoir logs to provide important reservoir information used to determine the "payzone" of the reservoir. One such logging tool is based on the principles of Nuclear Magnetic Resonance (NMR), the alignment of hydrogen proton spins with an applied magnetic field and the subsequent proton relaxation observed when the external magnetic force is removed. This technique has become a useful non destructive and seemingly matrix independent method for determining pore size distribution in fluid filled pores. However, the presence of paramagnetic material such as iron or manganese within reservoir rock, particularly sandstones, increases the proton relaxation rate and as a result the pore size distribution appears smaller and subsequent permeability calculations will be erroneous.
The significance of this paramagnetic material and its effect on surface relaxation is the essence of this study. There were two series of synthetic core samples created, one with a varying paramagnetic concentration and constant grain size and the other with a varying grain size and constant paramagnetic concentration. NMR experiments were conducted using these core samples to study the surface relaxivity effect
The NMR analysis of the synthetic core samples has shown a strong correlation to NMR theory.
An Integrated Method for Modeling Fluid Saturation Profiles and Characterising Geological Environments Using a Modified FZI Approach: Australian Fields Case Study
Authors: Biniwale S. 
Published: January 2008

Abstract
Laboratory derived capillary pressure data can be seen as an important tool for the purpose of establishing water saturation- height relationships as a function of rock type, forming the basis for a number of petroleum engineering and geoscience estimates. A modified ‘FZI-λ’ method, capable of giving better estimates of fluid distribution for Australian reservoirs, is proposed. The new methodology is particularly well suited for interpolating among different lithologies and diverse rock types as evident from a comparison with other methods reported in the literature, using a case study of the Griffin area fields.
Reconciliation of capillary pressure data with core and log data can be advantageous for better reservoir description. In this work, the Carman-Kozeny (C-K) equation based Hydraulic Flow Zone Unit (HU or FZU) methodology has been found ideal in characterizing geologic depositional environments and modelling fluid saturation profiles. For this purpose, the concept of ‘Global Characteristic Envelopes’ (GCEs) has been introduced, to analyse geological and petrophysical characteristics and for the integration and correlation among the wells. Capillary pressure data, based on such FZU and depositional grouping, may be further used for modeling saturation profiles over the uncored intervals and allows meaningful averages to be assigned for geocellular modeling and reservoir simulation.
Permeability Prediction Using Artificial Neural Network (ANN): A Case Study of Uinta Basin
Authors: Singh S. 
Published: January 2008

Abstract
The purpose of this paper is to develop a methodology to predict the permeability for wells in the same field using conventional logs (Gamma Ray, Neutron logs and Density log). This methodology involves the application of Error Back Propagation Neural Network. The advantages of this learning algorithm is that, an error in the final output gets back propagated and gradually updates the weight and hence leads to the best network structure.
Present study was made using published literature on Uinta Basin, southwest Utah field (available on Utah Geological Survey's (UGS) website). It has an areal extent of 14900 km2. In this, study data from 13 wells was taken. Data from seven cored wells in the field was used for training, and subsequently prediction and verification was done on core permeability for remaining six wells.
The result of this study shows that ANN generated permeability is consistent with core analysis result. This study was done using MATLAB® 6.1’s ANN Toolbox.
Compressible Streamlines and Three-Phase History Matching
Authors: Cheng Hao , Oyerinde Dayo , Datta-Gupta Akhil , Milliken William 
Published: January 2008

Summary
Reconciling high-resolution geologic models to field production history is still by far the most time-consuming aspect of the workflow for both geoscientists and engineers. Recently, streamline-based assisted and automatic history-matching techniques have shown great potential in this regard, and several field applications have demonstrated the feasibility of the approach. However, most of these applications have been limited to two-phase water/oil flow under incompressible or slightly compressible conditions.
We propose an approach to history matching three-phase flow using a novel compressible streamline formulation and streamline-derived analytic sensitivities. First, we use a generalized streamline model to account for compressible flow by introducing an "effective density" of total fluids along streamlines. This density term rigorously captures changes in fluid volumes with pressure and is easily traced along streamlines. A density-dependent source term in the saturation equation further accounts for the pressure effects during saturation calculations along streamlines. Our approach preserves the 1D nature of the saturation equation and all the associated advantages of the streamline approach with only minor modifications to existing streamline models. Second, we analytically compute parameter sensitivities that define the relationship between the reservoir properties and the production response, viz. water-cut and gas/oil ratio (GOR). These sensitivities are an integral part of history matching, and streamline models permit efficient computation of these sensitivities through a single flow simulation. Finally, for history matching, we use a generalized travel-time inversion that has been shown to be robust because of its quasilinear properties and converges in only a few iterations. The approach is very fast and avoids much of the subjective judgment and time-consuming trial-and-error inherent in manual history matching.
We demonstrate the power and utility of our approach using both synthetic and field-scale examples. The synthetic case is used to validate our method. It entails the joint integration of water cut and gas/oil ratios (GORs) from a nine-spot pattern in reconstructing a reference permeability field. The field-scale example is a modified version of the ninth SPE comparative study and consists of 25 producers, 1 injector, and aquifer influx. Starting with a prior geologic model, we integrate water-cut and GOR history by the generalized travel-time inversion. Our approach is very fast and preserves the geologic continuity.
An Output Controllability Problem for Semilinear Distributed Hyperbolic Systems
Authors: Zerrik E , Larhrissi R , Bourray H 
Published: January 2008

An Output Controllability Problem for Semilinear Distributed Hyperbolic SystemsThe paper aims at extending the notion of regional controllability developed for linear systems to the semilinear hyperbolic case. We begin with an asymptotically linear system and the approach is based on an extension of the Hilbert uniqueness method and Schauder's fixed point theorem. The analytical case is then tackled using generalized inverse techniques and converted to a fixed point problem leading to an algorithm which is successfully implemented numerically and illustrated with examples.
Optimal Approximation, Simulation and Analog Realization of the Fundamental Fractional Order Transfer Function
Authors: Djouambi Abdelbaki , Charef Abdelfatah , Besançon Alina 
Published: January 2008

Optimal Approximation, Simulation and Analog Realization of the Fundamental Fractional Order Transfer FunctionThis paper provides an optimal approximation of the fundamental linear fractional order transfer function using a distribution of the relaxation time function. Simple methods, useful in systems and control theories, which can be used to approximate the irrational transfer function of a class of fractional systems for a given frequency band by a rational function are presented. The optimal parameters of the approximated model are obtained by minimizing simultaneously the gain and the phase error between the irrational transfer function and its rational approximation. A simple analog circuit which can serve as a fundamental analog fractional system is obtained. Illustrative examples are presented to show the quality and usefulness of the approximation method.
The Choice of the Forms of Lyapunov Functions for a Positive 2D Roesser Model
Authors: Kaczorek Tadeusz 
Published: January 2008

The Choice of the Forms of Lyapunov Functions for a Positive 2D Roesser ModelThe appropriate choice of the forms of Lyapunov functions for a positive 2D Roesser model is addressed. It is shown that for the positive 2D Roesser model: (i) a linear form of the state vector can be chosen as a Lyapunov function, (ii) there exists a strictly positive diagonal matrixPsuch that the matrixATPA - Pis negative definite. The theoretical deliberations will be illustrated by numerical examples.
Redundancy Relations for Fault Diagnosis in Nonlinear Uncertain Systems
Authors: Shumsky Alexey 
Published: January 2008

Redundancy Relations for Fault Diagnosis in Nonlinear Uncertain SystemsThe problem of fault detection and isolation in nonlinear uncertain systems is studied within the scope of the analytical redundancy concept. The problem solution involves checking the redundancy relations existing among measured system inputs and outputs. A novel method is proposed for constructing redundancy relations based on system models described by differential equations whose right-hand sides are polynomials. The method involves a nonlinear transformation of the initial system model into a strict feedback form. Algebraic and geometric tools are used for this transformation. The features of the method are made particular for uncertain systems with a linear structure.
Object Library of Algorithms for Dynamic Optimization Problems: Benchmarking SQP and Nonlinear Interior Point Methods
Authors: Błaszczyk Jacek , Karbowski Andrzej , Malinowski Krzysztof 
Published: January 2008

Object Library of Algorithms for Dynamic Optimization Problems: Benchmarking SQP and Nonlinear Interior Point MethodsThe main purpose of this paper is to describe the design, implementation and possibilities of our object-oriented library of algorithms for dynamic optimization problems. We briefly present library classes for the formulation and manipulation of dynamic optimization problems, and give a general survey of solver classes for unconstrained and constrained optimization. We also demonstrate methods of derivative evaluation that we used, in particular automatic differentiation. Further, we briefly formulate and characterize the class of problems solved by our optimization classes. The solution of dynamic optimization problems with general constraints is performed by transformation into structured large-scale nonlinear programming problems and applying methods for nonlinear optimization. Two main algorithms of solvers for constrained dynamic optimization are presented in detail: the sequential quadratic programming (SQP) exploring the multistage structure of the dynamic optimization problem during the solution of a sequence of quadratic subproblems, and the nonlinear interior-point method implemented in a general-purpose large-scale optimizer IPOPT. At the end, we include a typical numerical example of the application of the constrained solvers to a large-scale discrete-time optimal control problem and we use the performance profiles methodology to compare the efficiency and robustness of different solvers or different options of the same solver. In conclusions, we summarize our experience gathered during the library development.
Real-Valued GCS Classifier System
Authors: Cielecki Łukasz , Unold Olgierd 
Published: January 2008

Real-Valued GCS Classifier SystemLearning Classifier Systems (LCSs) have gained increasing interest in the genetic and evolutionary computation literature. Many real-world problems are not conveniently expressed using the ternary representation typically used by LCSs and for such problems an interval-based representation is preferable. A new model of LCSs is introduced to classify realvalued data. The approach applies the continous-valued context-free grammar-based system GCS. In order to handle data effectively, the terminal rules were replaced by the so-called environment probing rules. The rGCS model was tested on the checkerboard problem.
Asymmetric Synthesis of Polyfunctionalized Mono‐, Bi‐, and Tricyclic Carbon Frameworks via Organocatalytic Domino Reactions
Authors: Enders Dieter , Hüttl Matthias R. M. , Raabe Gerhard , Bats Jan W. 
Published: January 2008

AbstractAn asymmetric organocatalytic multi‐component domino reaction is used as a key process for the stereoselective synthesis of polysubstituted mono‐ and bicyclic cyclohexene‐carbaldehydes. Furthermore, the extension of the domino reaction and further synthetic transformations of the cascade products were investigated. The combination of the three‐step cascade with an intramolecular Diels–Alder reaction opens up an entry to tricyclic decahydroacenaphthylene and decahydrophenalene skeletons, which are valuable characteristic carbon cores of natural products.
Association study of the 15q11‐q13 maternal expression domain in Japanese autistic patients
Authors: Kato Chieko , Tochigi Mamoru , Ohashi Jun , Koishi Shinko , Kawakubo Yuki , Yamamoto Kenji , Matsumoto Hideo , Hashimoto Ohiko , Kim Soo‐Yung , Watanabe Keiichiro , Kano Yukiko , Nanba Eiji , Kato Nobumasa , Sasaki Tsukasa 
Published: January 2008

AbstractChromosome 15q11‐q13 has been a focus of genetic studies of autism susceptibility, because cytogenetic abnormalities are frequently observed in this region in autistic patients. An imprinted, maternally expressed gene within the region may have a role in autistic symptomatology. In the present study, we investigated the association between autism and the maternal expression domain (MED) in the region, containing the UBE3A and ATP10C genes, and the upstream imprinting center (IC), which mediates coordinate control of imprinted expression throughout the region. We analyzed 41 single nucleotide polymorphisms (SNPs) in 166 patients with autism and 416 controls from a Japanese population. As a result, a statistically significant difference after correction for multiple testing was observed between the patients and controls in the genotypic distribution of SNP rs7164989 (SNP8 in this study) located in SNRPN, whose promoter corresponds to the IC (P = 0.018, corrected for multiple testing). In the analysis of a four‐marker haplotype located in ATP10C, a statistically significant difference after correction for multiple testing was observed in the frequency of one haplotype between male patients and controls (permutation P = 0.033, corrected for multiple testing). Thus, the present study may suggest the association between autism and the MED or the upstream IC in chromosome 15q11‐q13 in the Japanese population. © 2008 Wiley‐Liss, Inc.
Association study between polymorphisms in glutathione‐related genes and methamphetamine use disorder in a Japanese population
Authors: Hashimoto Tasuku , Hashimoto Kenji , Miyatake Ryosuke , Matsuzawa Daisuke , Sekine Yoshimoto , Inada Toshiya , Ozaki Norio , Iwata Nakao , Harano Mutsuo , Komiyama Tokutaro , Yamada Mitsuhiko , Sora Ichiro , Ujike Hiroshi , Iyo Masaomi 
Published: January 2008

AbstractAccumulating evidence suggests that oxidative stress plays a role in the mechanisms of action of methamphetamine (METH) in the brain. In the present study, we investigated the association between the genetic polymorphisms among glutathione (GSH)‐related enzymes; glutathioneS‐transferases (GSTs) such as GSTT1 (Non‐deletion/Null), GSTT2 (Met139Ile), GSTA1 (−69C/T), and GSTO1 (Ala140Asp); glutathione peroxidase 1 (GPX1) (Pro198Leu); and glutamate‐cysteine ligase modifier (GCLM) subunit and METH use disorder in a Japanese population. Two hundred eighteen METH abusers and 233 healthy controls were enrolled in the study. There was a significant difference in GSTT1 genotype frequency between patients with METH psychosis and controls (P = 0.039, odds ratio: 1.52, 95% CI 1.03–2.24). Furthermore, the frequency (66.0%) of the GSTT1 null genotype among prolonged‐type METH psychotic patients with spontaneous relapse was significantly higher (P = 0.025, odds ratio: 2.43, 95% CI 1.13–5.23) than that (44.4%) of transient‐type METH psychotic patients without spontaneous relapse. However, there were no associations between the polymorphisms of other genes and METH abuse. The present study suggests that the polymorphism of the GSTT1 gene might be a genetic risk factor of the development of METH psychosis in a Japanese population. © 2008 Wiley‐Liss, Inc.
Impact of the internet and scholar age distribution on academic citation age
Authors: Barnett George A. , Fink Edward L. 
Published: January 2008

AbstractThis article examines the impact of the Internet and the age distribution of research scholars on academic citation age with a mathematical model proposed by Barnett, Fink, and Debus (1989) and a revised model that incorporates information about the online environment and scholar age distribution. The modified model fits the data well, accounting for 99.6% of the variance for science citations and 99.8% for social science citations. The Internet's impact on the aging process of academic citations has been very small, accounting for only 0.1% for the social sciences and 0.8% for the sciences. Rather than resulting in the use of more recent citations, the Internet appears to have lengthened the average life of academic citations by 6 to 8 months. The aging of scholars seems to have a greater impact, accounting for 2.8% of the variance for the sciences and 0.9% for the social sciences. However, because the diffusion of the Internet and the aging of the professoriate are correlated over this time period, differentiating their effects is somewhat problematic.
Reproductive consequences of oral arsenate exposure during pregnancy in a mouse model
Authors: Hill Denise S. , Wlodarczyk Bogdan J. , Finnell Richard H. 
Published: January 2008

AbstractBACKGROUND: The second most common of all structural birth defects, neural tube defects (NTDs), affect approximately 2.6/1,000 births worldwide, and 1/1,000 births in the United States. Of the many environmental agents suspected of being teratogenic, arsenic (As) is capable of inducing NTDs in laboratory animals. METHODS: We evaluated the teratogenicity of oral exposure on embryonic day (E) 7.5 and E:8.5 to As 4.8, 9.6, or 14.4 mg/kg (as sodium arsenate) in an inbred mouse strain, LM/Bc/Fnn, that does not exhibit spontaneous neural tube malformations. Control and arsenic‐treated dams (20 per treatment group) were weighed daily, and evaluated for signs of maternal toxicity. Fetuses were evaluated for soft tissue and skeletal malformations. RESULTS: There was no maternal toxicity as evidenced by losses in maternal body weight following As treatment. However, liver weights were lower in all As‐treated groups, suggesting hepatotoxicity due to As exposure. The number of litters affected with an NTD (exencephaly) in each treatment group was: 0, 1, 5, and 9 for control, As 4.8, 9.6, or 14.4, respectively, which exhibited a positive linear trend. There was evidence for trends between As dose and the number of litters displaying vertebral (p<0.001) and calvarial (p<0.01) abnormalities, components of the axial skeleton. Mean fetal weight of all As‐treated groups was significantly less than in control. DISCUSSION: In our model, maternal oral treatment with As induced NTDs. It also significantly increased the frequency of axial skeletal anomalies in the offspring exposed in utero, and reduced mean fetal weight, without evidence of maternal toxicity. Birth Defects Res (Part B). © 2008 Wiley‐Liss, Inc.