bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Common Impurities on the Phase Behavior of Carbon-Dioxide-Rich Systems: Minimizing the Risk of Hydrate Formation and Two-Phase Flow
Authors: Chapoy Antonin , Burgass Rod , Tohidi Bahman , Austell J. Michael , Eickhoff Charles 
Published: April 2011

Summary
Carbon dioxide (CO2) produced by carbon-capture processes is generally not pure and can contain impurities such as N2, H2, CO, H2 S, and water. The presence of these impurities could lead to challenging flow-assurance issues. The presence of water may result in ice or gas-hydrate formation and cause blockage. Reducing the water content is commonly required to reduce the potential for corrosion, but, for an offshore pipeline system, it is also used as a means of preventing gas-hydrate problems; however, there is little information on the dehydration requirements. Furthermore, the gaseous CO2-rich stream is generally compressed to be transported as liquid or dense-phase in order to avoid two-phase flow and increase in the density of the system. The presence of impurities will also change the system's bubblepoint pressure, hence affecting the compression requirement.
The aim of this study is to evaluate the risk of hydrate formation in a CO2-rich stream and to study the phase behavior of CO2 in the presence of common impurities. An experimental methodology was developed for measuring water content in a CO2-rich phase in equilibrium with hydrates. The water content in equilibrium with hydrates at simulated pipeline conditions (e.g., 4°C and up to 190 bar) as well as after simulated choke conditions (e.g., at -2°C and approximately 50 bar) was measured for pure CO2 and a mixture of 2 mol% H2 and 98 mol% CO2. Bubblepoint measurements were also taken for this binary mixture for temperatures ranging from -20 to 25°C.
A thermodynamic approach was employed to model the phase equilibria. The experimental data available in the literature on gas solubility in water in binary systems were used in tuning the binary interaction parameters (BIPs). The thermodynamic model was used to predict the phase behavior and the hydrate-dissociation conditions of various CO2-rich streams in the presence of free water and various levels of dehydration (250 and 500 ppm). The results are in good agreement with the available experimental data. The developed experimental methodology and thermodynamic model could provide the necessary data in determining the required dehydration level for CO2-rich systems, as well as minimum pipeline pressure required to avoid two-phase flow, hydrates, and water condensation.
Quantifying the Uncertainty in Estimates of Ultimately Recoverable World Conventional Oil Resources
Authors: Tien Chih-Ming , McVay Duane A. 
Published: April 2011

Summary
Since Hubbert proposed the "peak oil" concept to forecast ultimate recovery of crude oil for the US and the world, there have been countless debates over the timing of peak world conventional oil production rate and ultimate recovery. Forecasts presented in the literature can be grouped into those that are like Hubbert's, with an imminent peak, and those that do not predict an imminent peak. Although both groups have bases for their positions, viewpoints from the two groups are polarized and the debate is often heated. A big reason for the large divide between the two groups is the failure of both to acknowledge the significant uncertainty in their estimates. Although some authors attempt to quantify uncertainty, most use deterministic methods and present single values, with no ranges.
Our objective is to quantify the uncertainty in estimates of world conventional ultimately recoverable resources (URR) and time to peak oil rate. We use two different methodologies. First, we employ a mathematical modeling technique based on regression of historical production data using Hubbert's logistic model and a normal distribution model. However, we conduct the analyses probabilistically, considering errors in both the data and the model, which results in likelihood probability distributions for URR and time to peak rate. Second, we use a multiple-experts analysis to combine estimates from the multitude of papers presented in the literature, yielding an overall distribution for estimated world URR.
Both the mathematical modeling and the multiple-experts analysis indicate that there is considerable uncertainty in estimates of world conventional oil URR. Our best estimate is a P10–P90 range of 1.8–4.4 trillion bbl with a mean of 2.9 trillion bbl. Because of some conservative assumptions in our analysis, we believe the uncertainty is actually greater than indicated above, and the additional uncertainty is in the upside, resulting in larger P90 and mean values. In short, we do not have enough information at this time to say with reliability what the ultimate world conventional oil recovery will be. It could peak soon, somewhere in the distant future, or somewhere in between. It would be wise to consider all of these possible outcomes in planning and making decisions regarding capital investment and formulation of energy policy.
New Correlations of Acid-Fracture Conductivity at Low Closure Stress Based on the Spatial Distributions of Formation Properties
Authors: Mou Jianye , Zhu D.. , Hill A.D.. D. 
Published: April 2011

Summary
Because of irregular fracture surfaces caused by heterogeneities such as variations in local mineralogy and variations in leakoff behavior, we use a correlation to calculate fracture conductivity in acid fracturing. An acid-fracture-conductivity correlation consists of two parts: conductivity at zero closure stress and the rate of conductivity change with closure stress. Existing correlations do not consider the effect of variations in formation properties and were developed on the basis of laboratory experiments that use core samples with dimensions of only a few inches. On the other hand, acid-fracture simulators have grid sizes of several feet to tens of feet. Therefore, correlations should be scaled up properly when used in a fracture simulator. This paper presents new correlations to obtain the conductivity at zero closure stress. This conductivity can then be incorporated in acid-fracture-conductivity models that consider the effect of closure stress.
In this study, an extensive numerical study was performed using an intermediate-scale acid-fracture model with total dimensions comparable to a gridblock size in an acid-fracturing simulator and grid sizes comparable to core-sample sizes used in laboratory acid-fracture-conductivity tests. In this model, the distributions of permeability and mineralogy along the fracture faces are geostatistically generated. The model generates fracture-surface-etching profiles as a function of acid contact time, from which we can obtain fracture-width distributions when the fracture surfaces have come in contact at low closure stress. We then calculate the fracture conductivity by solving for the flow rate through this irregular domain for a fixed ∆p across the domain. By analyzing the relationship between the fracture conductivity created and statistical properties of the permeability and mineralogy distributions, we developed new acid-fracture-conductivity correlations for low closure stress. These correlations can be used directly to better predict the primary coefficient in the widely used Nierode-Kruk (Nierode and Kruk 1973) correlation of acid-fracture conductivity. This work allows the Nierode-Kruk (N-K) correlation to be scaled up to the dimensions appropriate for use in an acid-fracturing simulator.
Light- and Heavy-Solvent Impacts on Solvent-Aided-SAGD Process: A Low-Pressure Experimental Study
Authors: Li Weiqiang , Mamora Daulat , Li Yamin 
Published: April 2011

Summary
Coinjecting solvent with steam under steam-assisted gravity-drainage (SAGD) process to reduce the required steam amount for heavy-oil production has gained importance in recent years. The objective of this experimental study was to investigate the drainage mechanism of coinjecting light and heavy solvents to improve production performance.
A 2D cross-sectional low-pressure scaled physical model was constructed. The model represented a half-symmetry cross section of a typical SAGD drainage in the Athabasca formation. Using an infrared camera, we visualized and recorded expansion of the steam chamber and temperature distribution. The fluid injection rate, pressure, and temperature, and produced-liquid volumes were also recorded.
The results show that the relative condensation time of solvent and steam results in different production performances. Light solvent, delivered in the vapour phase to the entire fluid interface, reduces the bitumen viscosity along the whole vapour-chamber boundary, but it may build a thick gas blanket that may reduce the heat transfer from the high-temperature vapour chamber to the surrounding low-temperature bitumen. Coinjecting a suitable multicomponent-solvent mixture, including a heavy solvent, can enhance the production performance by altering the condensation dynamics of the light hydrocarbons.
The conclusions from this study can be used to design suitable solvent mixtures and coinjection strategies to deliver a higher production rate, higher recovery factor with lower cumulative steam required/oil ratio (CSOR), and lower cumulative energy required for oil production (CEOR) from SAGD performance.
Experimental Investigation of the Viscous Effect on Two-Phase-Flow Patterns and Hydraulic Performance of Electrical Submersible Pumps
Authors: Trevisan Francisco E. , Prado Mauricio 
Published: April 2011

Summary
Using a visualization prototype built from original electrical-submersible-pump (ESP) components and with minimal geometrical modifications, a pioneer experimental procedure was developed and conducted to address the viscous effect on liquid/gas two-phase flow through these types of pumps.
Based on dimensionless groups that govern centrifugal-pump single-phase performance, two-phase experiments were conducted at different shaft speeds (15, 25, and 30 Hz), with nonslip void fractions (up to 5%), and viscosity values of 46 to 161 cp, while liquid rates were kept constant at 60% of the maximum rate at the defined shaft speed. High-speed video footage was taken from the entire impeller flow channel, and stage incremental pressure was measured.
The authors identified four liquid/air flow patterns inside the impeller channels: agglomerated bubbles, gas pocket, segregated gas, and intermittent gas. By comparing the images with the differential-pressure data, it was concluded that the agglomerated-bubbles pattern is responsible for the initial head degradation and that the surging event coincides with the gas-pocket structure, indicating that this is an interface-instability problem. Another conclusion made was that the increase in viscosity caused surging to occur at lower void fractions, which could be compensated for by increasing rotational speed.
The significance of this work is given by the fact that several authors hae investigated centrifugal-pump performance under two-phase flow; however, previous experiments have been conducted only with water as the liquid, thus neglecting the viscous effect on the two-phase-flow mixture. In most of the petroleum industry's applications, ESPs operate with oil and natural gas. The present work begins the task of addressing this knowledge gap between scientific research and field applications.
Latest Technological Advances in Rod Pumping Allow Achieving Efficiencies Higher Than With ESP Systems
Authors: Takacs Gabor , Belhaj Hadi 
Published: April 2011

Summary
Two of the most important artificial-lift methods applied in oil wells are sucker-rod pumping (SRP) and electrical submersible pumping (ESP, with thousands of installations all over the world. Their operational features and application ranges are quite different, but in many cases either of them can be used in a given well. The final selection of the proper method has to be on the basis of energy efficiency, and the one requiring the least amount of surface power input is selected. This paper provides the necessary background for evaluating the effectiveness of the two lift methods investigated and for pinpointing the requirements of achieving maximum power efficiency of artificial lifting.
The power flow in the pumping system is investigated, and the sources of power losses, along with their usual ranges, are described. The overall power efficiency of the system is defined by a simple formula that provides the necessary insight into the main components of the power losses occurring in different system elements. A thorough investigation of the efficiency components allows one to find the factors that most markedly influence the total system's power requirement. As shown in the paper, the most important requirement for achieving maximum effectiveness is the proper choice of the pumping mode (i.e., the combination of plunger size, stroke length, and pumping speed).
The calculation of energy losses in the components of the ESP system is detailed, and the relative importance of the individual losses is shown. Because the components of the ESP system are connected in series, a relatively simple formula can be used to describe the effect of electrical and hydraulic losses on the efficiency of the total system. The terms of the final formula were investigated for their importance and contribution to the overall effectiveness of the ESP system. Results of this investigation provide crucial information that explain how to design an ESP system that provides the highest power efficiency. The practical use of the proposed calculation models is illustrated by presenting an example case where a relatively high liquid rate (1,300 B/D) from the same well is produced by rod pumping and by ESP. Detailed installation designs resulted in several different operation modes for both SRP and ESP. The paper demonstrates that using the latest technologies (e.g., high-strength sucker-rod connections), SRP can compete successfully with ESP installations by attaining higher energy efficiencies.
Pump Intake Pressure Determined From Fluid Levels, Dynamometers, and Valve-Test Measurements
Authors: Rowlan O. Lynn , McCoy James N. , Podio Augusto L. 
Published: April 2011

Summary
Three pump-intake-pressure (PIP) calculation methods available for wells artificially lifted with sucker rods are discussed in detail in this paper. The values of PIP obtained from acoustic fluid-level measurements in wells with moderate pump submergence can yield PIP estimates that agree with those of pump fluid-load analysis. If PIPs determined using these methods do not agree, then the operator must review the data quality and may reduce the deviation by adjusting certain parameters affecting the calculations. Field data for a significant group of wells are used to compare the PIP results of the three methods. The results show that the PIP computed using the maximum and minimum pump dynamometer loads usually calculates a PIP that is too low, while the PIPs computed using the valve test loads are usually too high. Recommendations are presented for quality control of the computed values.
Presentations of pyogenic liver abscess in one UK centre over a 15-year period
Authors: Bosanko NC , Chauhan A , Brookes M , Moss M , Wilson PG 
Published: April 2011

Background and aim: Pyogenic liver abscess (PLA) has been a condition of high mortality, improving over recent decades with combined antibiotic and percutaneous drainage. We aimed to identify the presenting features, diagnosis, microbiology, treatment and outcome for patients over a 15-year period at an inner-city hospital. Methods: Patients with an appropriate discharge diagnosis were identified and case records retrospectively analysed. Results: A total of 73 patient records were analysed. Common presenting features were anorexia, abdominal pain, fever, vomiting and weight loss with raised white cell count, C-reactive protein, alkaline phosphatase and hypoalbuminaemia. The delay following symptom onset to presentation was a mean of 17.3 days. The inclusion of PLA as a possible diagnosis on admission was only considered in 1% of cases. Positive blood or abscess culture was achieved in 63% of cases. We recorded a hospital mortality rate of 11%. Conclusions: In this sample, PLA was rarely considered as a possible diagnosis at presentation. There are common presenting features, which should prompt early investigation. Our microbiological yield was lower than in some studies and may be due to the early empirical use of antibiotics, without microbiological guidance. Percutaneous drainage and antibiotic treatment remain the mainstay of management. The underlying cause for PLA is often not identified. Emerging septicaemia or underlying malignancy were strong predictors of mortality.
What Psychologists Know and Believe about Memory: A Survey of Practitioners
Authors: Magnussen Svein , Melinder Annika 
Published: April 2011

SummaryWe surveyed 858 licensed psychologists, members of the Norwegian Psychological Association, about their knowledge and beliefs about human memory. The results were compared to the results of parallel surveys of legal professionals and lay persons, and evaluated in the light of the results of current memory science. The results indicate that psychologists are not memory experts qua psychologists; as a group, psychologists do not score above the level of knowledge of lay persons or trial judges on issues of eyewitness memory, and a substantial minority of the sample of respondents harbours scientifically unproven ideas of memory. The implications of these findings for psychological practice, with special reference to the court room, are briefly discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Base‐Mediated Direct Arylation of Pyrrole Derivatives
Authors: Vakuliuk Olena , Koszarna Beata , Gryko Daniel T. 
Published: April 2011

AbstractIt appears that transition metal catalysts are not necessary to perform the direct arylation of electron‐rich heterocycles with aryl iodides and bromides. Lithium tert‐butoxide in DMF promotes this reaction for a variety of N‐alkyl‐ and N‐arylpyrroles as well as for benzofuran and some other electron‐rich aromatic compounds and provides the desired products in moderate to high yields. In contrast to all previous reports on the Pd‐catalyzed direct arylation of indolizine, the reaction mediated by lithium tert‐butoxide proceeds selectively at position 5.
Kinetic Resolution of α‐Bromoamides: Experimental and Theoretical Investigation of Highly Enantioselective Reactions Catalyzed by Haloalkane Dehalogenases
Authors: Westerbeek Alja , Szymański Wiktor , Wijma Hein J. , Marrink Siewert J. , Feringa Ben L. , Janssen Dick B. 
Published: April 2011

AbstractHaloalkane dehalogenases from five sources were heterologously expressed in Escherichia coli, isolated, and tested for their ability to achieve kinetic resolution of racemic α‐bromoamides, which are important intermediates used in the preparation of bioactive compounds. To explore the substrate scope, fourteen α‐bromoamides, with different Cα‐ and N‐substituents, were synthesized. Catalytic activity towards eight substrates was found, and for five of these compounds the conversion proceeded with a high enantioselectivity (E value >200). In all cases, the (R)‐α‐bromoamide is the preferred substrate. Conversions on a preparative scale with a catalytic amount of enzyme (enzyme:substrate ratio less 1:50 w/w) were all completed within 17–46 h and optically pure α‐bromoamides and α‐hydroxyamides were isolated with good yields (31–50%). Substrate docking followed by molecular dynamics simulations indicated that the high enantioselectivity results from differences in the percentage of the time in which the substrate enantiomers are bound favourably for catalysis. For the preferred (R)‐substrates, the angle between the attacking aspartate oxygen atom of the enzyme, the attacked carbon atom of the substrate, and the displaced halogen atom, is more often in the optimal range (>157°) for reactivity. This can explain the observed enantioselectivity of LinB dehalogenase in a kinetic resolution experiment.
Silver Hexafluoroantimonate‐Catalyzed Three‐Component [2+2+1] Cycloadditions of Allenoates, Dual Activated Olefins, and Isocyanides
Authors: Li Jian , Liu Yuejin , Li Chunju , Jia Xueshun 
Published: April 2011

AbstractThe intermolecular [2+2+1] multicomponent cycloadditions from readily available allenoates, dual activated olefins and isocyanides catalyzed by silver hexafluoroantimonate were studied. This protocol allowed the syntheses of highly functionalized five‐membered carbocycles with exclusive regioselectivity and stereoselectivity in an efficient and atom‐economical manner.
Intramolecular Palladium‐Catalyzed Aminocarboxylation of Olefins as a Direct Route to Bicyclic Oxazolidinones
Authors: Borsini Elena , Broggini Gianluigi , Fasana Andrea , Galli Simona , Khansaa Maisaa , Piarulli Umberto , Rigamonti Micol 
Published: April 2011

AbstractAn efficient, direct synthesis of oxazolidinones fused to six‐membered heterocyclic rings starting from carbamate‐protected aminoalkenes has been developed. This procedure is based on an oxidative palladium(II)‐catalyzed reaction performed in the presence of stoichiometric copper chloride, which is determinant to promote the formation of the bicyclic product and prevent the isolation of the monocyclic amination product. Oxazolidinone compounds arise from a domino aminocarboxylation process through the direct intervention of the carbamate oxygen after the initial palladium‐promoted transfer of the nitrogen atom on the CC double bond.
Pyrazinium Salts as Efficient Organocatalysts of Mild Oxidations with Hydrogen Peroxide
Authors: Ménová Petra , Kafka František , Dvořáková Hana , Gunnoo Smita , Šanda Miloslav , Cibulka Radek 
Published: April 2011

AbstractA series of 3‐substituted pyrazinium tetrafluoroborates was prepared as simple analogues of flavinium salts which are efficient organocatalysts for oxidations with hydrogen peroxide. It was shown that pyrazinium derivatives with an electron‐withdrawing substituent catalyze mild oxidations of sulfides to sulfoxides and Baeyer–Villiger oxidations in a similar way to flavinium catalysts. The most reactive catalyst, 3‐cyanopyrazinium tetrafluoroborate, was efficiently employed in preparative sulfoxidations of aromatic and aliphatic sulfides as well as in Baeyer–Villiger oxidations of cyclobutanones. A proposed mechanism for the catalysis is based on the formation of pyrazine hydroperoxide which is the agent oxidizing the substrate.
Hafnium Triflate as an Efficient Catalyst for Direct Friedel–Crafts Reactions of Chromene Hemiacetals
Authors: Wu Yan‐Chao , Li Hui‐Jing , Liu Li , Demoulin Nicolas , Liu Zhe , Wang Dong , Chen Yong‐Jun 
Published: April 2011

AbstractThe direct Friedel–Crafts reaction of chromene hemiacetals with indoles, furans and sterically hindered anilines has been accomplished with high selectivity and excellent yields in the presence of a catalytic amount of hafnium triflate [Hf(OTf)4, 0.1 mol%, 0–40 °C]. The mild conditions tolerate various sensitive functional and protecting groups, and the products were confirmed unambiguously from their spectra and by single‐crystal X‐ray analysis. This direct Friedel–Crafts reaction of chromene hemiacetals should inspire and encourage the consideration of hafnium triflate in the development of mild reaction conditions for the efficient derivatization of hemiacetal‐containing compounds.