bluuebunny/crossref_metadata_2025_split huggingface dataset:
Treatment of SAGD Produced Waters Without Lime Softening
Authors: Bridle M. 
Published: January 2008

Abstract
The produced waters from Steam Assisted Gravity Drainage (SAGD) facilities are characterized by low concentrations of both total hardness (TH) and total dissolved solids (TDS) and high silica concentrations. Treatment of these waters to provide feed-water suitable for Once Through Steam Generators (OTSG) has traditionally included either hot or warm lime softeners (HLS/WLS) and ion exchange. The primary function of the lime softening process is for silica removal.
A proposed alternate process that utilizes ion exchange only and depends on the premise that provided the divalent and trivalent cations are reduced to the parts per billion (ppb) level, will allow the OTSG to operate at high silica concentrations. This process eliminates the need for a lime softening stage and savings in capital and operating costs are realized.
Steam-Fingering Phenomenon During SAGD Process
Authors: Ito Y. , Ipek G. 
Published: January 2008

Abstract
A steam chamber generally rises steadily in the channel sands of Athabasca oil sands during a SAGD operation. It is commonly known that steam chamber growth rate is mainly dependent to permeability. Once the steam chamber reaches the upper boundary, it starts to expand laterally. This is the basic concept of steam chamber growth of SAGD process in fine sands.
However, the growth of steam chamber measured through the analysis of temperature changes from observation wells behaves different in many instances than the commonly accepted steam chamber growth concept, explained above. In these observation wells, the steam chamber deviates from the usual behavior; sometimes stops and then resumes rising or shrinking, or even disappears during SAGD process. This can be caused by the specific nature of steam fingering phenomenon during SAGD operation.
Many simulation studies have been conducted to understand the steam rising phenomenon during SAGD operations. At the top of the steam chamber, steam fingers seemed to be created where steam flows through and the steam chamber expands vertically. If steam fingering actively develops, steam chamber grows steadily as expected. However, activity of fingering can be disturbed under certain conditions, which can result in various alterations in the growth of steam chamber.
In this paper, the steam fingering phenomenon during SAGD process is discussed with actual measured field data from four SAGD projects; UTF Phase A, UTF Phase B, Hangingstone and Surmount.
Numerical Studies of Gas Exsolution in a Live Heavy-Oil Reservoir
Authors: Uddin M. 
Published: January 2008

Abstract
Gas phase formation in supersaturated live heavy oil occurs by bubble nucleation and growth. Modeling the dynamics of these processes in cold production is essential, since they are key mechanisms in determining oil recovery. The greatest challenge in field scale simulations of cold production is to quantify the spatial and temporal changes of the gas exsolution and transport processes.
This paper describes a new kinetic model which, when coupled with a thermal reservoir simulator, can simulate the dynamics of gas exsolution and transport processes in a heavy oil reservoir. In this model, two relatively simple types of mass transfer equations predict bubble nucleation and growth in a live heavy reservoir. The model structure and parameters were investigated in comparison with a previously published model.
The capability of the proposed kinetic model to handle the dynamics of gas phase formation in a heavy oil reservoir was explored in two sets of laboratory experimental data. In set 1, numerical history matches of pressure data were performed for eight constant withdrawal rate experiments. In set 2, numerical history matches of oil and gas production data were performed for four pressure depletion experiments. A close agreement was achieved between numerical simulation and experimental results. The model can be applied in the field scale simulations of cold production to predict gas exsolution and gas builds up in an oil reservoir.
An Overview of Iterative Coupling Between Geomechanical Deformation and Reservoir Flow
Authors: Tran D. , Nghiem L. , Buchanan L. 
Published: January 2008

ABSTRACT
Recently, there is a strong interest in the modelling of reservoir fluid flow with geomechanical deformation. With the help of geomechanics, many physical phenomena can be explained, e.g. reservoir compaction and subsidence, casing failure or pore collapse. Several methods for coupling geomechanics to fluid flow in the reservoir have been proposed: fully coupled, iterative coupled and explicit coupled methods. The iterative coupled method has proven to be the most effective approach. However, no paper has discussed this method in detail from a reservoir engineering perspective. In this paper, the iterative coupling method is described step by step from the basic equations for geomechanics and reservoir flow to the coupling technique through porosity and permeability. This description is aimed at reservoir engineers with little background in geomechanics. A number of examples using different nonlinear constitutive models such as elasto-plasticity model, elastoplastic cap model and dilation-recompaction model are used to illustrate the importance of including geomechanics in reservoir simulation.
A Parametric Study of the Effects of Reservoir and Operational Properties on the Performance of Steam Displacement of Heavy Oil in Naturally Fractured Reservoirs
Authors: Cicek O. 
Published: January 2008

Abstract
This research effort discusses the effects of a comprehensive range of fluid, rock-fluid and operational properties on the efficiency of steam injection in naturally fractured reservoirs with heavy oil. For this purpose, a fully implicit dual-porosity/dual-permeability simulator is developed, and the model is applied to an inverted nine-spot pattern in a naturally fractured reservoir with heavy oil. The effects of the reservoir and operational properties on the steam displacement of heavy oil are studied comparatively in naturally fractured reservoirs with and without interacting matrix blocks and in approximate single porosity realizations of these naturally fractured reservoirs.
The field scale numerical model is three-dimensional and three phase accounting for capillary, gravitational and viscous forces. The model solves for (nHC+5) primary variables simultaneously, where nHC is the number of hydrocarbon components. The fully implicit model formulates all reservoir and operational parameters as functions of all the primary variables. The model is linearized using the Newton-Raphson method. A direct and an iterative solver is used in the solution of the system of linear equations.
The simulations of steam injection in naturally fractured systems are carried out for long periods of time in order to test the features of the model under strained conditions. The model is verified against the Fourth and Sixth SPE Comparative Solution Projects.
This study should help in screening naturally fractured reservoirs for steam injection, and in designing steam injection operations in these reservoirs. The comparative analysis of the effects of reservoir and the operational parameters in naturally fractured reservoirs should provide insight into the range of confidence of heavy oil recovery from naturally fractured reservoirs by steam injection.
Assessment and Development of Heavy-Oil Viscosity Correlations
Authors: Hossain M. S. , Sarica C. , Zhang H.-Q. , Rhyne L. , Greenhill K. L. 
Published: January 2008

Abstract
Heavy oil always poses a great challenge to production and transportation systems due to its high viscosity. This paper evaluates fourteen dead, eight saturated and nine under saturated live oil viscosity correlations against a databank consisting of heavy oil data from various parts of the world with wide ranges of temperature, pressure and fluid compositions. The existing empirical viscosity correlations were mostly developed for significantly lighter oils. Most of them cannot reasonably predict the heavy oil viscosity at low temperatures. Three new empirical correlations for dead, saturated and under saturated oils are developed that are applicable for the heavy oils with API gravity ranging from 10 to 22.3. When compared with the databanks, the new dead oil, saturated and under saturated oil viscosity correlations showed 3 to 50%, 3 to 13% and 22 to 27% improvement over the existing best correlations, respectively. Saturated, Aromatics, Resin and Asphaltenes (SARA) data of some heavy oils were also analyzed to understand the role of the asphaltene and resins in heavy oil viscosity.
Improving the Performance of SAGD
Authors: Das S. 
Published: January 2008

Abstract
In the recent years several SAGD projects have been initiated for the recovery of heavy oil and bitumen. Every operator is coming across new learning almost every day, although most of this information is proprietary. This paper presents a general discussion, supported by simulation and analytical results, on the different aspects of improving the performance of SAGD operations. The first component is the well bore design, which has to match with the gravity drainage rate. Operating pressure plays a significant role in the rate of recovery. Lower operating pressure reduces the SOR, lower H2S production, may reduce the silica dissolution, thereby, reduce the water treatment issues. However, low pressure operation increases the challenges of lifting the fluid to the surface. Steam additives may be the other option to increase the energy efficiency of the process.
Type Curves for Production Prediction and Evaluation of Coalbed Methane Reservoirs
Authors: Aminian K. , Ameri S. , Bhavsar A. B. , Lakshminarayanan S. 
Published: January 2008

Abstract
Prediction and analysis of the coalbed methane (CBM) production is challenging especially at the early stages of the recovery when production is subject to two-phase flow conditions. CBM reservoirs are dual-porosity systems that are characterized by a complex interaction of coal matrix and cleat system that are coupled through desorption process. As a result, the conventional methods cannot be utilized to predict CBM production. Currently, only numerical models (simulators) can be used to predict (CBM) production behavior since they incorporate the unique flow and storage characteristics of CBM reservoirs. Often, the number of variables needed for evaluation of a given prospect is greater than that typically measured. In such cases, parametric studies are conducted to evaluate the impacts of reservoir properties on recovery factor, well performance, and future revenues. However, parametric studies with a reservoir simulator is cumbersome, time consuming and expensive. Therefore, there is a need for scientific, user-friendly tools that can assist the typical gas producers in evaluation of CBM prospects.
This study presents a set of production type curves for CBM reservoirs. A reservoir model that incorporates the unique flow and storage characteristics of CBM reservoirs was employed to generate the type curves. Our previous study (SPE 91482) introduced a new set of dimensionless groups that led to development of unique set of type curves. The impact of basic reservoir characteristics was also investigated to confirm the uniqueness of the type curves. This study investigates the impact of key parameters including isotherm constants and relative permeability data on the type curves. The type curves can be used to predict and/or analyze gas and water the production from CBM wells both during de-watering and stable gas production phases. The issues concerning the application and limitation of the type curves are also presented. Finally, a type curves-based simple yet reliable tool with graphical user interface (GUI) was developed. This tool can be used for predicting and analyzing production performance of CBM reservoirs with simple and straight forward input requirements. This tool is particularly useful for parametric studies to evaluate CBM prospects.
Post-Fracture Performance Diagnostics for Gas Wells with Finite-Conductivity Vertical Fractures
Authors: Rushing J. A. , Sullivan R. B. , Blasingame T. A. 
Published: January 2008

Abstract
This paper presents an integrated technique for evaluating the production performance of gas wells with finite-conductivity vertical fractures. Our methodology combines conventional pressure transient test analysis with new material balance decline type curves developed specifically for gas wells with finite-conductivity, vertical fractures. We utilize short-term pressure buildup test analysis to enhance the production data analysis, particularly for interpretation of early-time transient flow behavior. We illustrate—with several field cases—that both techniques can be integrated to provide not only a more consistent and systematic analysis methodology, but also a more accurate assessment of stimulation effectiveness.
Impact of Viscous Fingering on the Prediction of Optimum WAG Ratio
Authors: Juanes Ruben , Blunt Martin J. 
Published: January 2008

Summary
In miscible flooding, injection of solvent is often combined with water to reduce the mobility contrast between injected and displaced fluids and control the degree of fingering. Using traditional fractional-flow theory, Stalkup estimated the optimum watersolvent ratio (or WAG ratio) when viscous fingering effects are ignored, by imposing that the solvent and water fronts travel at the same speed. Here we study how the displacement efficiency and the mobility ratio across the solvent front vary with the WAG ratio when fingering is included in the analysis. We do so by computing analytical solutions to a 1D model of two-phase, three-component, first-contact miscible flow that includes the macroscopic effects of viscous fingering. The macroscopic model, originally proposed by Blunt and Christie (1993, 1994), employs an extension of the Koval fingering model to multiphase flows. The premise is that the only parameter of the model—the effective mobility ratio—must be calibrated dynamically until self-consistency is achieved between the input value and the mobility contrast across the solvent front. This model has been extensively validated by means of high-resolution simulations that capture the details of viscous fingering and carefully-designed laboratory experiments.
The results of this paper suggest that, while the prediction of the optimum WAG ratio does not change dramatically by incorporating the effects of viscous fingering, it is beneficial to inject more solvent than estimated by Stalkup's method. We show that, in this case, both the pore volumes injected (PVI) for complete oil recovery and the degree of fingering are minimized.
On the Computation of the GCD of 2-D Polynomials
Authors: Tzekis Panagiotis , Karampetakis Nicholas , Terzidis Haralambos 
Published: January 2008

On the Computation of the GCD of 2-D PolynomialsThe main contribution of this work is to provide an algorithm for the computation of the GCD of 2-D polynomials, based on DFT techniques. The whole theory is implemented via illustrative examples.
Reduction in the Number of PAL Macrocells in the Circuit of a Moore FSM
Authors: Barkalov Alexander , Titarenko Larysa , Chmielewski Sławomir 
Published: January 2008

Reduction in the Number of PAL Macrocells in the Circuit of a Moore FSMOptimization methods of logic circuits for Moore finite-state machines are proposed. These methods are based on the existence of pseudoequivalent states of a Moore finite-state machine, a wide fan-in of PAL macrocells and free resources of embedded memory blocks. The methods are oriented to hypothetical VLSI microcircuits based on the CPLD technology and containing PAL macrocells and embedded memory blocks. The conditions of effective application of each proposed method are shown. An algorithm to choose the best model of a finite-state machine for given conditions is proposed. Examples of proposed methods application are given. The effectiveness of the proposed methods is also investigated.
On the consideration of automatic as well as controlled psychological processes in aggression
Authors: Berkowitz Leonard 
Published: January 2008

AbstractWithout slighting the important role played by controlled psychological processes in human aggression, this paper recommends that considerable systematic attention should also be given to the operation of automatic processes in bringing about this behavior. The concepts of automaticity and impulsivity are discussed briefly and it is proposed that many impulsive actions, particularly antisocial ones, are due to failures of restraint after they were initiated involuntarily. A number of experiments are reviewed in which situational stimuli automatically instigated or heightened aggressive inclinations. These have to do with associations in hostility displacement, reactions to stigmatized persons, and association in aggressive reactions to media violence. The last‐mentioned studies deal especially with factors affecting the selection of the target for aggression. In discussing these findings it is suggested that after the crucial situational features had automatically initiated the sequence of determinants, the aggression displayed could have been due either to a hostile appraisal of the target or the activation of aggression‐related bodily reactions as well as hostile ideas. It is also hypothesized that in at least one of the studies, an experienced negative affect might have instigated the aggression independently of any appraisals. Aggr. Behav. 34:117–129, 2008. © 2008 Wiley‐Liss, Inc.
Synthesis of Fe‐MCM‐41 from silatrane and FeCl3 via sol–gel process and its epoxidation acivity
Authors: Thitsartarn W. , Gulari E. , Wongkasemjit S. 
Published: January 2008

AbstractAn iron‐containing mesoporous molecular sieve, or Fe‐MCM‐41, was successfully synthesized the via sol–gel technique using silatrane and FeCl3 as the silicon and iron sources, and was characterized using various techniques. Many factors were investigated, namely, reaction temperature and time, calcination rate, and iron amount in the reaction mixture. It was found that the optimum conditions in which to synthesize Fe‐MCM‐41 was to carry out the reaction at 60 °C for 7 h using a 1 °C min−1 calcination rate and a 550 °C calcination temperature. The catalytic activity and selectivity of styrene epoxidation using hydrogen peroxide showed that the selectivity of the styrene oxide reached 65% at a styrene conversion of 22% over the 1%wt catalyst. Copyright © 2008 John Wiley & Sons, Ltd.
A novel route to perovskite lead zirconate titanate from glycolate precursors via the sol–gel process
Authors: Tangboriboon N. , Jamieson A. , Sirivat A. , Wongkasemjit S. 
Published: January 2008

AbstractA perovskite lead zirconate titanate was synthesized by the sol‐gel process, using lead glycolate, sodium tris(glycozirconate) and titanium glycolate as the starting precursors. For the mole ratio Pb:Zr:Ti of 1:0.5:0.5 [Pb(Zr0.5Ti0.5)O3], TGA‐DSC thermal analysis indicated that the percentage of ceramic yield was 55.8, close to the calculated chemical composition value of 49.5. The exothermic peak occurred at 268 °C below the theoretical Curie temperature of 400 °C. The pyrolysis of Pb(Zr0.5Ti0.5)O3 of the perovskite phase was investigated in terms of calcination temperature and time. The structure obtained was of the tetragonal form when calcined at temperatures below 400 °C; it transformed to the tetragonal and the cubic forms of the perovskite phase on calcination above the Curie temperature, as verified by X‐ray data. The lead zirconate titanate synthesized and calcined at 400 °C for 1 h had the highest dielectric constant, the highest electrical conductivity and the dielectric loss tangent of 10 190, 0.803 × 10−3 (Ω.m)−1 and 1.513 at 1000 Hz, respectively. The lead zirconate titanate powder synthesized has potential applications as an electronic material. Copyright © 2008 John Wiley & Sons, Ltd.
Use of special education services by children with orofacial clefts
Authors: Yazdy Mahsa M. , Autry Andrew R. , Honein Margaret A. , Frias Jaime L. 
Published: January 2008

AbstractBACKGROUND:Our objective was to evaluate the use of special education services by children with orofacial clefts (OFCs).METHODS:We linked the birth certificates of children born from 1982–2001 in five counties of metropolitan Atlanta to a population‐based birth defects surveillance system to identify children with OFCs, and to the special education files for the school years 1992–2004 to identify children who used special education services. The special education data contained exceptionalities and services rendered for each school year. Prevalence ratios (PRs) and 95% CIs were calculated. The data were stratified by race/ethnicity, maternal education, type of OFC, and the presence of associated major malformations. In addition, we assessed the age at which special education began and the amount of time spent receiving services.RESULTS:Of the 777 children with OFCs, 201 (26%) were in special education at least 1 year compared with 8% of the children who had no major birth defects, yielding a PR of 3.2 (95% CI: 2.9–3.6). The most common exceptionality or service for children with an OFC was speech and language services. Compared with children with no birth defects, children with an OFC were four times more likely to be in this exceptionality (PR 3.8; 95% CI: 3.3–4.3). After excluding children in speech and language services, children with OFCs were still more likely to use special education services (PR 2.4; 95% CI: 1.7–3.2).CONCLUSIONS:Children with OFCs used special education services more often than children without birth defects. This information can help in planning for future population needs. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.