bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel a-Amylase Enzyme Stabilizer for Application at High Temperatures
Authors: Samuel Mathew , Mohsen Abdul Hameed , Ejan Aziz Bin , Ooi Yean Sang , Ashraf Shameed , Nasr-El-Din Hisham A. 
Published: July 2010

Summary
Cleanup of drilling-fluid filter cake in long horizontal and multilateral wells is a difficult task. Both mechanical and chemical means (acids, oxidizers, chelating agents, and enzymes) have been used in the field. However, these methods have serious limitations and can affect well performance adversely. Acids and oxidizers are very reactive, but are nonspecific. Enzymes can be used to degrade starch and xanthan polymers. The major limitation of enzymes is their inability to stay active at temperatures greater than 200°F.
The activity of enzymes at 207°F was less than 10% of their activity at 200°F. Previous studies to increase the stability enzymes were aimed at: (1) changing salinity, (2) changing the source of the enzymes, (3) using additives that alter the conformation of enzymes, or (4) modifying the enzymes chemically. These techniques did not maintain the activity of the enzymes at 200°F. For filter-cake removal, enzymes have been used globally at higher temperatures, though their activity is known to be much less than 2%.
This paper examines the use of chemicals that function as a stabilizer for enzymes up to 250°F. Optimized concentrations of this stabilizer not only inhibit the coagulation of enzymes at these high temperatures but also maintain the activity of enzymes at the high temperatures that are encountered in the oil field. Laboratory studies on the stability, compatibility, and filter-cake-damage reversal were conducted with stabilized-enzyme formulation.
Experimental results indicated that the new proprietary enzyme stabilizer was very effective in eliminating the deactivation tendency of enzymes at high temperatures. Conventionally, enzymes coagulated at temperatures greater than 140°F and charred when exposed to temperatures greater than 200°F, but in the presence of the stabilizer, precipitation and burning were not observed. When using an enzyme at high temperatures without the stabilizer, the burned residue accumulated on the surface, resulting in a thin film that reduced the permeability of the cake even further. High-pres- sure/high temperature (HP/HT) filtration studies using the enzyme stabilizer showed that this film was not formed, which resulted in a cake with much higher retained permeability.
Simulation of O/W Emulsion Flow in Alkaline/Surfactant Flood for Heavy Oil Recovery
Authors: Wang Jinxun , Dong Mingzhe 
Published: July 2010

Summary
The formation and flow of emulsions during alkaline flooding process plays an important role for improving heavy oil recovery. In this study alkaline/surfactant (A/S) flood tests were performed in sandpacks to demonstrate the effectiveness of sweep efficiency improvement by the in-situ generated oil-in-water (O/W) emulsion. High tertiary oil recoveries were obtained in sandpack flood tests. Experimental results were history matched by including the mechanisms of in-situ generation and flow of O/W emulsion, as well as the chemical adsorption and the reduction of interfacial tension involved in the chemical flooding process. The decrease in local water phase permeability caused by the entrapment of emulsion droplets was modelled using the filtration theory. Both the pressure response and the oil recovery improvement were fairly matched. Field-scale simulations were conducted to investigate the potential of A/S flooding for heavy oil reservoirs. Simulations showed promising results of chemical flooding for heavy oils. It was indicated that a certain length of waterflooding time would benefit the final oil recovery, and there existed an optimum chemical slug size. These laboratory results and the simulation technique are helpful in the simulation and design of field-scale projects of chemical flooding for enhanced heavy oil recovery.
Estimation of Bitumen and Solids Content in Fine Tailings Using Low-Field NMR Technique
Authors: Motta Cabrera Sandra C. , Bryan Jonathan L. , Kantzas Apostolos 
Published: July 2010

Summary
The oil sands mining and extraction processes in Canada produce large volumes of tailings that are a mixture of mainly water, clay, sand, chemicals and bitumen. This mixture is transported to tailings ponds, where gravity segregation occurs. During this process, a stable suspension called mature fine tailings (MFT) is formed, which requires many years to fully consolidate. Therefore, land reclamation and water recirculation become significant environmental issues. For this reason, it is important to understand the tailings' content and their settling properties. This study uses the low-field nuclear magnetic resonance (NMR) technique to estimate the water, bitumen and solids composition of synthetic and real tailings samples through a bimodal compositional detection method under ambient conditions. NMR measurements were conducted in 15 minutes, which is a relatively fast measurement allowing for rapid monitoring of tailings compositions. The results show that the NMR technique can be a potential on-site fast measurement of composition and settling characteristics of tailings.
Viscosity and API Gravity Determination of Solvent Extracted Heavy Oil and Bitumen
Authors: Jiang Chunqing Dennis , Bennett Barry , Larter Steve R. , Adams Jennifer J. , Snowdon Lloyd 
Published: July 2010

Summary
This paper describes and discusses laboratory experiments showing that reliable determinations of viscosity usually cannot be made on high-viscosity samples of heavy oil or tar sand bitumen that have been solvent-extracted from core or cuttings samples with toluene or otherwise contaminated or diluted with this solvent. The toluene solvent cannot be quantitatively removed without damaging the bitumen sample because of the concomitant evaporation of volatile materials that act naturally as solvents in the bitumen. Only small amounts of natural or contaminant solvent are sufficient to effectively control the sample viscosity. Viscosity values determined on residual bitumen after solvent removal may be either higher or lower than the nominally correct value depending on whether excessive residual toluene solvent remains in the sample or excessive volatile material has been removed from the sample during the evaporation. On the other hand, the impact of solvent on the density (i.e., API gravity) of a sample is linear and there are several advantages to using solvent plus bitumen mixtures to determine density for high-viscosity samples.
Containment of a Vertical Tensile Region During Surfactant-Polymer Injection
Authors: Zuluaga Elizabeth , Schmidt Joseph H , Dean Rick , Pardo Carlos W. 
Published: July 2010

Summary
Many studies have been completed concerning the evaluation of fracture height growth during hydraulic fracturing. While there are analytical solutions available to estimate vertical fracture growth, a more comprehensive solution requires the use of coupled geomechanics-reservoir simulators (GMRS) that could also fully incorporate the effects of fluid-flow into the analysis. This paper introduces results from a new coupled in-house GMRS to estimate the extent of vertical tensile regions developed in the sand interval that could break into adjacent shales during surfactant-polymer injection for a well located onshore Asia. The reservoir was treated as an elastic material and the injection zone was treated as a zone of higher permeability after the weakly consolidated formation reached a tensile stress state.
The geomechanical information for the simulator was obtained from triaxial tests, well-logs and minifracs. Reservoir and fluid data were extracted from the in-house reservoir simulator model available for the field.
A half unit of a seven-spot pattern was evaluated by using an unstructured grid, which provided more geometric flexibility. The results indicated that injection rates higher than 4000 B/D (0.0074 m3/s) combined with viscosities greater than 10 cp (0.01 Pa-s) will cause the fracture to break into the shales penetrating into the bottom sand. On the other hand, injection rates lower than 2000 B/D (0.0037 m3/s) were shown to be safe, even for the highest viscosity injection fluid tested, viz 30 cp (0.03 Pa-s). Viscosities greater than 20 cp (0.02 Pa-s) cause the injection fluid to break into adjacent sands if flow rates are above 2000 B/D (0.0037 m3/s). As expected, the higher the viscosity and injection rate, the higher the tendency of the fractures to grow out of containment. A chart with safe limits for surfactant-polymer injection was provided to the business unit to guide them in the design of new injectors and provide safe conditions for surfactant-polymer injection.
A Turbulent Flow Model for Use in Numerical Evaluation of Air Quality
Authors: Settari A. , Lantz R.B. 
Published: July 2010

Abstract
Several articles have appeared recently which describe air quality models combining a wind flow calculation with the calculation of pollutant dispersion.Most of them use simplified methods to obtain the wind field. In the presentstudy, one of these methods (termed a modified potential method) is comparedwith a turbulent flow model based on the solution of the Navier-Stokes equations. A simple model of turbulence, suitable for environmental applications, is developed.
The comparative results show that the modified potential model is adequatefor many large-scale environmental studies. Its applicability is limited wherelocal effects associated with viscous flow are extremely important. Such casescan be more realistically simulated with the turbulent flow model, although atsignificantly higher costs.

Introduction
Mathematical modeling of atmospheric dispersion has been in increasing usein the evaluation of environmental impact for both existing sources and newplants. More and more emphasis is being placed on the need to satisfyshort-term (half an hour, one hour and twenty-four hours) air quality criteria.Predictions of short-term concentrations require more accurate simulationtechniques than predictions of annual averages. Short-term standards are morelikely to be exceeded in the vicinity of large sources and are influenced moreby terrain configuration than the long term annual standards.
A computer model for simulation of pollutant dispersion requires twoimportant parts: calculation of wind field (flow model) and calculation of theconcentration field (diffusion model). Most existing atmospheric dispersionmodels concentrate on the diffusion part and make very crude assumptions aboutthe wind field. The simplest approach to diffusion, used in several computer models, is based on Gaussian plume models. The basic formula for Gaussian plumemodels is derived assuming flat terrain and a constant mean wind invariable with height. The Gaussian distribution of concentration then follows from the assumption of constant diffusion coefficients. Various corrections have beenproposed to account for the influence of terrain and meteorology on the windfield and diffusion. However, these corrections (generally involving anassumption about the behaviour of the plume centerline) are empirical. As aresult, Gaussian models cannot adequately account for complex topography andmeteorology.
Factors Affecting Coking in Heavy Oil Cores, Oils and SARA Fractions Under Thermal Stress
Authors: Verkoczy B. 
Published: July 2010

Abstract
In previous work we demonstrated that minerals influence coking, combustion, and oil displacement. The effect is significant and seeminglyreservoir-specific. The magnitude and specific details, however, are much lessunderstood where the factors of surface area or the catalytic nature of themineral matrix are concerned. We recently performed a systematic study of thisphenomenon as part of Phase I of Saskatchewan Research Council's multiclient Thermal Studies project. A number of native cores from several heavy oilreservoirs, along with their corresponding matrices and oil thermal properties, were investigated. The results indicated that the surface area, as well as thesurface activity of the minerals, the asphaltene contents, and the nature ofthe oil, played a major role in coke (fuel) formation, depending on thereservoir type. Exploratory isothermal low-temperature oxidation (LTO) kineticstests on core materials, however, yielded somewhat conflicting results. It wasconcluded that in the rather complex oil system, several competing oxidationreactions interfere in some of the temperature domains, rendering the rate datasuspect. We felt the need to separate the oil into simpler and chemically morerepresentative constituents which would make the studies on oxidation andthermal cracking reactions more meaningful. We have adopted the existingseparation technique to obtain such fractions, i.e., saturates, aromatics, resins and asphaltenes (SARA). In previous work on some neat SARA fractions andin current work on several synthetic SARA cores, we have shown that thechemical group types tend to pyrolyse and produce coke independently of eachother. Therefore, the solid fuel formed from pyrolysis can be predicted from SARA test data for the whole oil or core sample. A meaningful experimentalapproach for the kinetics study of SARA fractions and synthetic cores will bediscussed in the text.
Laboratory and Field Validation of a Sealant System for Critical Plug-and-Abandon Situations
Authors: Nagelhout A.C.G.. C.G. , Bosma M.G.R.. G.R. , Mul P.J.. J. , Krol G.G.. G. , van Velzen J.F.G.. F.G. , Joldersma J.S.. S. , James S.G.. G. , Dargaud B.. , Schreuder G.J.R.. J.R. , Théry F.. 
Published: July 2010

Summary
This paper presents case histories and discusses the laboratory validation of a sealant system for plug-and-abandon (P&A) operations in critical gas wells close to habitations. To ensure long-term isolation both inside and outside the original casing, the plan was to mill out the casing and cement and to place the plug from rock face to rock face. The milled-out section was planned so that in the worst-case scenario, the differential gas pressure would have to be supported by 25 m of cement plug, even though a greater height of cement would be placed inside the original casing above the milled-out section.
Two cement systems were designated as candidates for the plugging operation with slurry properties suitable for the application. The gas-sealing ability of the selected systems was validated with both small-scale and large-scale tests. One system, exhibiting both high flexibility and expansion, met the stringent specifications and did not leak until a differential pressure of more than four times the specification was applied. The paper will discuss the parameters of the selected system, thus providing guidelines for system selection for critical plugging operations. A detailed case history of one well (two plugs) is given along with the results from four other wells.
An Assessment of the Productivity of Multilateral Completions
Authors: Raghavan R. , Ambastha A.K. 
Published: July 2010

Abstract
A mathematical model is developed in order to evaluate the productivity ofmultilateral completions. The model may also be used to understand and discernthe pressure behaviour of multilateral completions. The ability to incorporatethe location of each lateral rigorously is the unique feature of the model. Asa result of the development of this model, it is now possible to calculaterapidly the efficacy of various options and to incorporate this completionscheme in numerical models to evaluate the possible influences of interference, boundaries, changes in reservoir properties, etc.

Introduction
Even a perfunctory survey of the literature indicates that, althoughmultiple lateral completions are quite common, there is a dearth of informationon methods to compute productivity, to devise procedures to evaluate thecompletion efficacy, and to forecast performance. The goal of this paper is todevelop a mathematical model to attain these general objectives. To ourknowledge, the results presented in this paper are not available in theliterature. The principal feature of the analytical model described here isthat it is possible to examine the influence of the location of the laterals ofthe multilateral system rigorously and completely. The specific contributionsof this work are as follows:to develop a model that may be used to designfor specific configurations of horizontal sections and evaluate theconsequences that follow from this choice,to screen candidates for thistype of completion scheme, andto discuss transient behaviour and outlinea methodology to analyze pressure tests with a view to determine reservoirproperties and completion efficiency. Before considering the specific detailsof this work, we note that myriad completion schemes are referred to asmultilateral wells. In this paper, we refer to a system with one or morehorizontal sections in a single zone that produce against a common pressure andproducing string as a multilateral completion. Methods are outlined to extendthe scheme discussed here to multiple, non-communicating zones.
Combined Effect of Inflammatory Gene Polymorphisms and the Risk of Ischemic Stroke in a Prospective Cohort of Subjects With Type 2 Diabetes: A Go-DARTS Study
Authors: Palmer Colin N.A. , Kimber Charlotte H. , Doney Alex S.F. , Proia Anna S. , Morris Andrew D. , Gaetani Eleonora , Quarta Miriam , Smith Roy C. , Pola Roberto 
Published: July 2010

OBJECTIVE
We have previously observed that genetic profiles determined by the combination of five functionally significant single nucleotide polymorphisms (SNPs) (rs1800795, rs5498, rs5361, rs1024611, and rs679620) of genes encoding prototypical inflammatory molecules are associated with history of ischemic stroke. Here we tested the ability of this multigenic model to predict stroke risk in a large population-based prospective cohort of subjects with type 2 diabetes.

RESEARCH DESIGN AND METHODS
This study was conducted using a prospective cohort of individuals with type 2 diabetes participating in the Go-DARTS (Genetics of Diabetes Audit and Research in Tayside Scotland) study, which includes genetic and clinical information of patients with diabetes within the Tayside region of Scotland, U.K. The above-mentioned inflammatory SNPs were investigated in 2,182 Go-DARTS participants. We created an inflammatory risk score (IRS), ranging from 0 to 5, according to the number of “at-risk” genotypes concomitantly carried by a given individual. The primary outcome was the occurrence of fatal or nonfatal stroke of any kind. Mean follow-up time was 6.2 ± 1.1 years.

RESULTS
The incidence of stroke increased according to the IRS. The IRS was significantly and independently associated with increased stroke risk after adjustment for other conventional risk factors (hazard ratio 1.34 [95% CI 1.1–1.7]; P = 0.009). The highest hazard ratio for stroke was found in subjects concomitantly carrying &gt;3 proinflammatory variations and in subjects without previous cardiovascular diseases.

CONCLUSIONS
This large prospective cohort study provides evidence that SNPs of genes encoding prototypical inflammatory molecules may be used to create multigenic models that predict stroke risk in subjects with type 2 diabetes.
Homogeneous Insulin and C-Peptide Sensors for Rapid Assessment of Insulin and C-Peptide Secretion by the Islets
Authors: Heyduk Ewa , Moxley Michael M. , Salvatori Alison , Corbett John A. , Heyduk Tomasz 
Published: July 2010

OBJECTIVE
Glucose-stimulated islet insulin or C-peptide secretion experiments are a fundamental tool for studying and assessing islet function. The goal of this work was to develop Ab-based fluorescent homogenous sensors that would allow rapid, inexpensive, near-instantaneous determinations of insulin and C-peptide levels in biological samples.

RESEARCH DESIGN AND METHODS
Our approach was to use molecular pincer design (Heyduk et al., Anal Chem 2008;80:5152–5159) in which a pair of antibodies recognizing nonoverlapping epitopes of the target are modified with short fluorochrome-labeled complementary oligonucleotides and are used to generate a fluorescence energy transfer (FRET) signal in the presence of insulin or C-peptide.

RESULTS
The sensors were capable of detecting insulin and C-peptide with high specificity and with picomolar concentration detection limits in times as short as 20 min. Insulin and C-peptide levels determined with the FRET sensors showed outstanding correlation with determinations performed under the same conditions with enzyme-linked immunosorbent assay. Most importantly, the sensors were capable of rapid and accurate determinations of insulin and C-peptide secreted from human or rodent islets, verifying their applicability for rapid assessment of islet function.

CONCLUSIONS
The homogeneous, rapid, and uncomplicated nature of insulin and C-peptide FRET sensors allows rapid assessment of β-cell function and could enable point-of-care determinations of insulin and C-peptide.
Identification of De Novo Synthesized and Relatively Older Proteins
Authors: Jaleel Abdul , Henderson Gregory C. , Madden Benjamin J. , Klaus Katherine A. , Morse Dawn M. , Gopala Srinivas , Nair K. Sreekumaran 
Published: July 2010

OBJECTIVE
The accumulation of old and damaged proteins likely contributes to complications of diabetes, but currently no methodology is available to measure the relative age of a specific protein alongside assessment of posttranslational modifications (PTM). To accomplish our goal of studying the impact of insulin deficiency and hyperglycemia in type 1 diabetes upon accumulation of old damaged isoforms of plasma apolipoprotein A-1 (ApoA-1), we sought to develop a novel methodology, which is reported here and can also be applied to other specific proteins.

RESEARCH DESIGN AND METHODS
To label newly synthesized proteins, [ring-13C6]phenylalanine was intravenously infused for 8 h in type 1 diabetic participants (n = 7) during both insulin treatment and 8 h of insulin deprivation and in nondiabetic participants (n = 7). ApoA-1 isoforms were purified by two-dimensional gel electrophoresis (2DGE) and assessment of protein identity, PTM, and [ring-13C6]phenylalanine isotopic enrichment (IE) was performed by tandem mass spectrometry.

RESULTS
Five isoforms of plasma ApoA-1 were identified by 2DGE including ApoA-1 precursor (pro-ApoA-1) that contained the relatively highest IE, whereas the older forms contained higher degrees of damage (carbonylation, deamidation) and far less IE. In type 1 diabetes, the relative ratio of IE of [ring-13C6]phenylalanine in an older isoform versus pro-ApoA-1 was higher during insulin deprivation, indicating that de novo synthesized pro-ApoA-1 more rapidly accumulated damage, converting to mature ApoA-1.

CONCLUSIONS
We developed a mass spectrometry–based methodology to identify the relative age of protein isoforms. The results demonstrated accelerated oxidative damage to plasma ApoA-1, thus offering a potential mechanism underlying the impact of poor glycemic control in type 1 diabetic patients that affects a patient's risk for vascular disease.