bluuebunny/crossref_metadata_2025_split huggingface dataset:
Perforating for Fracturing: Theory vs. Field Experiences
Authors: Ceccarelli R. L. , Pace G. , Casero A. , Ciuca A. , Tambini M. 
Published: February 2010

Abstract
Perforations provide the communication between wellbore and formation resulting in a communication path both for injected and produced fluids from the reservoir. Many perforation parameters such as shot phasing, charges size, shot density, type of gun and length of interval play an important role in the correct execution of a fracturing job. Those parameters have to be engineered to guarantee easy formation breakdown, minimize near wellbore restrictions (or tortuosity) and be big enough to prevent proppant bridging while considering fracture treatment size, proppant concentration, proppant size and treatment flow rate. Ideal fracture initiation perforations would create a minimum injection pressure initiating a single fracture (not for shale gas reservoirs) and generate a fracture with minimum tortuosity at an achievable fracture initiation pressure. Best perforation practices are important during the decisional and designing phase but have to be confirmed by field experience even in well known reservoir where formation heterogenity, well deviation, local stress anomalies, cement bound and many other factors can result in unexpected behaviors that could compromise the success of the stimulation treatment.
In the following paper a briefly description of perforating theories and different field experiences are reported showing test results executed for a better perforation strategy. Unexpected deviations both from theory recommendations and from field analogies were analyzed as well as successful and unsuccessful remedial solutions in cases of injectivity issues.
Single-Trip Multiple-Zone Completion Technology Has Come of Age and Meets the Challenging Completion Needs of the Gulf of Mexico's Deepwater Lower Tertiary Play
Authors: Burger R. , Grigsby T. , Ross C. , Sevadjian E. , Techentien B. 
Published: February 2010

Abstract
The Gulf of Mexico hydrocarbon potential has confounded "naysayers," who once called it the Dead Sea. The planned development of the ultra deepwater lower-tertiary play is the latest chapter in the Gulf of Mexico's ongoing viability as a major hydrocarbon basin. To economically develop this challenging lower-tertiary play requires new completion technology to handle the long, stacked pay intervals. This has generated renewed interest in multi-zone completion technology. This technology is viewed as a method that hs the potential to increase completion efficiency as well as reduce overall completion cost. These systems were once considered too complex and risky for deepwater operations; but the hope that the technology could provide increased completion efficiency and alleviate some of the issues inherent with stacked completions in deepwater has again renewed interest in pursuing this technology. Thus, the latest generation of robust, cased-hole single-trip multiple-zone frac-pack completion systems has been developed. The renewed interest for development of these systems has also been the driving force for development of an openhole multiple-zone frac-pack completion system that could ultimately provide reductions in well construction cost.
This paper will provide the reader with a brief development history of cased-hole, single-trip multiple-zone completion systems and then the focus will shift to the latest generation of tool systems. The discussion will also include the reasons why the previous systems have not proliferated globally as an accepted mainstream sand-face completion technique. The sand face is one part of the completion equation. The methodology of integrating the uphole completions to the multizone sand-face completion will be briefly discussed.
The improved functionality of the newest multizone systems will be described and compared to the previous-generation systems. The presentation will cover the integration testing to qualify the newest multiple-zone system and will cover trial well installations. Deepwater case histories will be presented, if available by presentation time.
Upscaling of Deep Bed Filtration from Core to Near-Wellbore Region
Authors: Vaz A. S. , Bedrikovetsky P. , Furtado C. , de Souza A. L. 
Published: February 2010

Abstract
Deep bed filtration of suspensions in porous reservoirs with particle retention by the rock and consequent permeability decrease, takes place during seawater injection and re-injection of produced water in waterflood projects. The invasion of drilling fluid occurs during drilling and affects the return permeability and well index. Deep bed filtration of migrated fines during oil production from heavy-oil, high-clay-contents or low consolidated reservoirs affects well index impairment and fines production. The mathematical-modeling-based reliable prediction of suspension transport in rocks is the essential part of planning and design of the above mentioned technologies.
The mathematical models for suspension flow in homogeneous porous media are well developed and validated by numerous laboratory studies. Nevertheless, the above mentioned processes of oil production occur in near-well regions, where the drilling-induced heterogeneity adds to the natural heterogeneity. Yet, the models and laboratory studies for deep bed filtration in micro heterogeneous rocks are poorly available in the literature.
In the current paper, the analytical models for colloidal-suspension filtration in composite cores with different types of heterogeneity are derived. The breakthrough concentrations during suspension flow in cores with in-parallel, in-series and combined types of heterogeneity, as obtained from laboratory corefloods and from modeling, are found to be in a good agreement.
The analytical formulae for effective filtration coefficient for in-parallel, in-series and combined types of heterogeneity allow proposing the upper and lower estimates of upscaled filtration coefficient for flows in heterogeneous numerical grids with homogeneous cells.
Comparison of Scale Control Challenges between Production and PWRI Wells
Authors: Mackay Eric J. 
Published: February 2010

Abstract
The oilfield industry is familiar with the challenges associated with controlling inorganic scale precipitation in production wells. There are well-established techniques and procedures that may be followed, including modelling and test work in the laboratory, and prevention and removal in the field. While the rate of scale accumulation is not routinely predicted as yet, know-how developed over decades of scale management means that engineers have access to the expertise and tools to be able to manage scale effectively in a large range of production scenarios.
However, similar expertise and tools have not yet been fully developed and applied for controlling scale precipitation in Produced Water Re-Injection (PWRI) wells. This is a particular concern in scenarios where the injection brine has a scaling tendency, for example if it consists of a mix of incompatible brines.
Some of the existing tools used for scale management in production wells may be used, such as thermodynamic predictions. In addition, of late there has been significant work on modelling rates of deposition in such systems. However, there are key differences between conventional production scenarios and PWRI systems in terms of scale inhibition. In production systems the reservoir may be considered as an upstream batch reactor, in which, if the precipitation reactions are occurring far enough from the wells, there is a benefit in terms of a reduced scaling tendency at the producers; hence the demands on inhibitors are lowered. In injection systems, however, there is no such sacrificial upstream reactor, and so the demands of scale inhibition may be more stringent.
These issues are discussed in depth in this paper, with detailed reference to field examples where PWRI has been used, including occasions where scale damage to injection systems occurred. Oxygen and corrosion control are identified as key interactions with scale management. As well as a comparison of scale control in production and PWRI wells, this paper will present a strategy for identifying and managing the scale risk in PWRI wells.
Tax and Subsidy Combinations for the Control of Car Pollution
Authors: Fullerton Don , West Sarah E 
Published: February 2010

Abstract
Despite technological advances, an individual car's emissions still cannot be measured reliably enough to impose a Pigovian tax. This paper explores alternative market incentives that could be used instead. We solve for second-best combinations of uniform taxes on gasoline, engine size, and vehicle age. For 1,261 individuals and cars in the 1994 Consumer Expenditure Survey, we record the car's model, year, and number of cylinders. We then seek a corresponding car in data from the California Air Resources Board that shows the car's engine size, fuel efficiency, and emissions per mile. We calculate the welfare improvement from a zero-tax scenario to the ideal Pigovian tax, and we find that 71 percent of that gain can be achieved by the second-best combination of taxes on gas, size, and vintage. A gas tax alone attains 62 percent of that gain. These results are robust to variation in the elasticity of substitution among goods.
Magnetohydrodynamic flows as Newtonian-type gravitational motions
Authors: Spyrou Nikolaos , Tsagas Christos 
Published: February 2010

AbstractWe study the motion of a magnetised, highly conductive fluid within the framework of Newtonian gravity. Our analysis examines whether and under what conditions magnetohydrodynamic flows can be represented as hydrodynamic ones and then as Newtonian-type gravitational motions. In the latter case we define a generalised effective density and an effective Poisson-type potential, which include the magnetic input and determine the dynamics of the magnetised system. Introducing the dynamical equivalence of the aforementioned two representations, we use it to test mass measurements based on purely gravitational motions. We also provide the generalised Raychaudhuri equation corresponding to the aforementioned effective potential and discuss its implications for the kinematics of the fluid.
Numerical investigation of heat transfer augmentation through geometrical optimization of vortex generators
Authors: Gorji Mofid , Mirgolbabaei Hessam , Barari Amin , Domairry Ganji 
Published: February 2010

AbstractIn this paper a two-dimensional numerical simulation of a steady incompressible and turbulent model has been carried out to study the effects of vortex generators in a compact heat exchanger in a curvilinear coordinate system. The mesh which is applied in this study is boundary fitted and has been smoothed by a Laplace operator. Experimental data of a former study has been applied to validate the numerical results. The effects of geometrical variation are studied by adjusting vortex generators’ inclination and relative cross location. The major issue of this study is the optimal trade-off by selecting an optimal geometric, considering the opposite influences of geometrical variation on Nusselt number and pressure drop.
In vitro synergistic anti-prion effect of cholesterol ester modulators in combination with chlorpromazine and quinacrine
Authors: Orrù Christina , Cannas M. , Vascellari Sarah , Angius Fabrizio , Cocco Pier , Norfo Claudia , Mandas Antonella , La Colla Paolo , Diaz Giacomo , Dessì Sandra , Pani Alessandra 
Published: February 2010

Abstract
Our studies on the role of cholesterol in prion infection/replication showed that brains and peripheral cells of sheep susceptible-to or suffering-from Scrapie were characterized by an altered cholesterol homeostasis, and that drugs affecting cholesterol ester pool were endowed with selective anti-prion activity in N2a cell lines infected with the 22L and RML prion strains. In these prion-infected N2a cell lines, we now report increased anti-prion activity of dual-drug combinations consisting of cholesterol ester modulators associated with prion inhibitors. Synergism was obtained with the cholesterol ester modulators everolimus, pioglitazone, progesterone, and verapamil associated with the anti-prion chlorpromazine, and with everolimus and pioglitazone associated with the anti-prion quinacrine. In addition, comparative lipid analyses in prion-infected vs. uninfected N2a cells, demonstrated a derangement of type and distribution of cholesterol ester, free cholesterol, and triglyceride pools in the infected cells. Single-drug treatments differently affected synthesis of the various lipid forms, whereas combined drug treatments appeared to restore a lipid profile similar to that of the untreated-uninfected cells. We conclude that the anti-prion synergistic effects of cholesterol ester modulators associated with the cholesterol-interfering anti-prion drugs chlorpromazine and quinacrine may arise from the ability of combined drugs to re-establish lipid homeostasis in the prion-infected cells. Overall, these data suggest that inhibition of prion replication can be readily potentiated by combinatorial drug treatments and that steps of cholesterol/cholesterol ester metabolism may represent suitable targets.
Enhancement of tyrosine hydroxylase expression by Cordyceps militaris
Authors: Sapkota Kumar , Kim Seung , Park Young , Choi Bong-Suk , Park Se-Eun , Kim Sung-Jun 
Published: February 2010

Abstract
Cordyceps militaris is a popular medicinal mushroom, and has received extensive attention for medical application because of its various physiological activities. However, there is limited information about the function of Cordyceps militaris on dopaminergic system. This study has attempted to evaluate the effect of cultured fruiting bodies of Cordyceps militaris extract (CME) on the expression of the tyrosine hydroxylase (TH) gene in PC12 cells and rat brain and stomach. Related mRNA levels were determined by the RT-PCR. Protein levels were measured by Western blot and immunohistochemistry. Our results demonstrated CME induced TH gene expression both in vitro and in vivo. Treatment of 10 µg/ml and 20 mg/kg CME to PC12 cells and rat cells yielded significant increases of TH protein levels. Significantly, TH immunoreactive neurons were detected not only in the brain but also in the stomach. TH-immunohistochemical staining was markedly enhanced in animals treated with CME compared to those in the untreated control. These results suggest that CME can upregulate the dopaminergic (DArgic) system, and may contribute to neuroprotection in neurodegenerative diseases.
Essential oil composition of two yarrow taxonomic forms
Authors: Judzentiene Asta , Mockute Danute 
Published: February 2010

AbstractDifferences in essential oil composition of wild Achillea millefolium L., collected at five habitats in Lithuania, where plants with pink (f. rosea) and white (f. millefolium) flowers grow together, were reported. For the first time, oils of different plant organs (inflorescences and leaves) of both forms from every population were analysed in detail. Chemical analysis was performed by GC and GC-MS. The most predominant constituents of the oils were nerolidol (9.4–31.9%, in 11 out of 20 samples), caryophyllene oxide (8.4–23.0%, 4 leaf oils), ß-pinene (8.0–15.2%, 2 samples), eudesmol (11.8–15.8%, 2 leaf oils) and 1,8-cineole (11.9%, one inflorescence oil). Domination of nerolidol was mostly characteristic of A. millefolium f. rosea essential oils (in 8 out of 10 oils). The inflorescences biosynthesised markedly larger amounts of nerolidol and ß-pinene than those of the leaves. An opposite correlation was observed for caryophyllene oxide and eudesmol. Chamazulene (≤2.7%) was determined only in six oils. The 65 identified constituents made up 75.4–96.5% of the oils.
Influence of reproductive status on the daily rhythms of oxidative stress markers in Ovis aries
Authors: Piccione Giuseppe , Giannetto Claudia , Fazio Francesco , Assenza Anna , Caola Giovanni 
Published: February 2010

AbstractChanges in circadian rhythms of dROMs, Oxy-ads and SHp during reproductive stages were studied in Comisana ewes. Twelve ewes were divided in two equal groups. The experimental group consisted of ewes undergoing gestation and lactation following artificial insemination and the control group consisted of non-pregnant ewes. Blood samples were collected every 3 h over a 24 h period, 20 days before insemination, on days 100 and 140 of pregnancy, on days 10, 30 and 200 post-partum and during the dry period. In the control group, blood samples were collected on the same days and with the same procedures as those used for the experimental group. A significant effect of time on all parameters studied was observed in the experimental group. Daily rhythms of the parameters studied were observed in the control group in all experimental conditions, and in the experimental group during pre-pregnancy and dry periods. We conclude that the reproductive status of sheep affects oxidative stress markers in blood and their circadian rhythms.
Rice pads: Novel devices for homogeneous fat suppression in the knee
Authors: Moriya Susumu , Miki Yukio , Yokobayashi Tsuneo , Kanagaki Mitsunori , Komori Yoshiaki , Ishikawa Mitsunori 
Published: February 2010

Background: In magnetic resonance imaging (MRI) of the knee joint, when imaging the knee in a flexed position using the chemical-shift-selective (CHESS) method, lingering fat signals in the popliteal region are sometimes seen. Purpose: To investigate whether a pad filled with rice (rice pad) placed in the popliteal space is effective in eliminating the lingering fat signals in MR images of the flexed knee, based on the hypothesis that the use of a rice pad would improve the fat suppression effect. Material and Methods: Subjects were 10 healthy volunteers (five males, five females; age, 20–45 years) from whom images were taken using CHESS. Images were obtained with: 1) the knee extended and nothing placed underneath; 2) the knee bent with a sponge placed underneath; and 3) the knee bent with a rice pad placed underneath. The effectiveness of suppressing fat signals was visually assessed by one radiologist and one radiological technologist. Results: The fat suppression effect in images obtained with the knee extended was good. In contrast, the images made with a sponge under the knee had conspicuous lingering fat signals for nearly all subjects. In the images made with a rice pad under the knee, a uniformly good fat signal suppression effect was seen in all patients, and the assessment score was far higher than that with the sponge pillow ( P<0.001). Conclusion: Lingering fat signals were suppressed with the use of a rice pad, and fat-suppressed images of the knee joint using CHESS were found to be improved.
Assessment of hip dysplasia and osteoarthritis: Variability of different methods
Authors: Troelsen Anders , Rømer Lone , Kring Søren , Elmengaard Brian , Søballe Kjeld 
Published: February 2010

Background: Reliable assessment of hip dysplasia and osteoarthritis is crucial in young adults who may benefit from joint-preserving surgery. Purpose: To investigate the variability of different methods for diagnostic assessment of hip dysplasia and osteoarthritis. Material and Methods: By each of four observers, two assessments were done by vision and two by angle construction. For both methods, the intra- and interobserver variability of center-edge and acetabular index angle assessment were analyzed. The observers’ ability to diagnose hip dysplasia and osteoarthritis were assessed. All measures were compared to those made on computed tomography scan. Results: Intra- and interobserver variability of angle assessment was less when angles were drawn compared with assessment by vision, and the observers’ ability to diagnose hip dysplasia improved when angles were drawn. Assessment of osteoarthritis in general showed poor agreement with findings on computed tomography scan. Conclusion: We recommend that angles always should be drawn for assessment of hip dysplasia on pelvic radiographs. Given the inherent variability of diagnostic assessment of hip dysplasia, a computed tomography scan could be considered in patients with relevant hip symptoms and a center-edge angle between 20° and 30°. Osteoarthritis should be assessed by measuring the joint space width or by classifying the Tönnis grade as either 0–1 or 2–3.
Use of noun morphology by children with language impairment: the case of Hungarian
Authors: Lukács Ágnes , Leonard Laurence B. , Kas Bence 
Published: February 2010

Background: Children with language impairment often exhibit significant difficulty in the use of grammatical morphology. Although English‐speaking children with language impairment have special difficulties with verb morphology, noun morphology can also be problematic in languages of a different typology.Aims: Hungarian is an agglutinating language with multiple suffixation, in which both regular‐class and irregular‐class nouns contain the same recognizable grammatical markers, but the two classes differ in their morphophonology and productivity. Such typological characteristics provide a good basis for evaluating processing accounts of language impairment such as the morphological richness account.Methods & Procedures: We examined the production of Hungarian irregular and regular noun morphology through elicited production of nouns with plural, accusative case and plural plus accusative case suffixes in an older (8–10 years) and a younger (4–7 years) group of children with language impairment and two verbal control groups matched on vocabulary size. The children's accuracy was scored both in terms of grammatical function (whether plural and/or accusative case was appropriately marked) and morphophonology (whether the production reflected the phonotactic form required for the stem plus suffix).Outcomes & Results: The younger children with language impairment were less accurate than the younger verbal control children when two suffixes (marking plural and accusative case) were required, at least when noun stem classes were regular. All groups showed significant overgeneralization of stem forms with correct selection of suffixes. However, there were strong word frequency effects in the language impairment, but not in the verbal control groups.Conclusions & Implications: Much of the data were consistent with predictions of the morphological richness account. However, there was also evidence suggestive of differences between the language impairment and verbal control groups in their representations. In particular, the children with language impairment seemed to rely more (though not exclusively) on memorized items in the lexicon.