bluuebunny/crossref_metadata_2025 huggingface dataset:
Internet communication and social anxiety among different social groups of adolescents
Authors: Kholmogorova A.B. , Avakyan T.V. , Klimenkova E.N. , Malyukova D.A.
Published: January 2016

The article presents the results of a study of social anxiety and social anhedonia symptoms in adolescents from different social groups, depending on channels of communication with other people they prefer — face-to-face contact, social networking, smartphones, Skype and various sites on the Internet. The study involved 110 people from two Moscow colleges and orphanage. In this study we have used complex of four methods, one of which — “Questionnaire of the channels of social communication” — used for the first time. Based on these results it is concluded that the most common ways of communication in mod-ern adolescents — face-to-face contact and social networks, which are used by them about equally often, however, the majority of adolescents prefer face-to¬face contact to all other channels of communication. Adolescents who prefer face-to-face contact to all other ways of communications, are more prosperous in terms of the two questionnaires of social anxiety (scale of social avoidance and distress — SADS; Watson, Friend, 1969; brief scale of fear of social evaluation — BENE; Leary, 1983) and the scale of the social anhedonia (RSAS; Eckblad et al, 1982) and ones who prefer to communicate in social networks have higher rates in all three questionnaires. It is suggested that the relationship between social anxiety and the frequency of use of social networking is not direct, but mediated by avoiding face-to-face contact. The mechanism of anxiety response leads to amplification of avoidance of face-to-face contact in everyday social situations and further strengthen of social anxiety.
This article was prepared with the financial support of the Russian Science Foundation (grant No. 14–18–03461).
Neuropsychological features of adolescents with Internet-addictive behavior
Authors: Malygin V.L. , Merkurieva Y.A.
Published: January 2016

The aim of this study was to investigate neuropsychological features of adolescents with the Internet-addictive behavior. The sample comprised 756 adolescents with 316 females (40,2%) and 340 males (59,8%). The mean age was 15,5 years. The main experimental group (42 adolescents) included only those respondents who had high levels of Internet addiction combined with the objective data from the questionnaire. The control group consisted of adolescents with no signs of Internet-dependent behavior of comparable age and sex (50 adolescents). The main group was formed by analyzing results of the IAD test (K. Young), the CIAS test (Chen) and objective data obtained from interviews with adolescents, their parents and teachers. Neuropsychological features revealed by conducting adapted neuropsychological test for adolescents (based on the Luria-90). Adolescents with Internet-addictive behavior significantly differ from healthy on indicators of functional disorders: attention, control and regulation of activities and mediated memorizing. Correlating this data with localization features, we note the functional weakness of hemispheric commissures and left anterior lobe and weakness of the first block of the brain (Luria). Adolescents with Internet-addictive behavior from the point of view of neuropsychology are characterized by functional disorders spatial praxis, attention, control and regulation of activity and mediated memorizing. Also they have functional weakness of hemispheric commissures and the first block of the brain.
Parent-child relationships as a factor of school bullying
Authors: Volikova S.V. , Kalinkina E.A.
Published: January 2016

The results present examination of schoolchildren of V—VIII grades from three Moscow schools. Regular or occasional bullying is experienced by more than 13% of participating children. Victims of bullying are more susceptible to verbal aggression from their peers. Appearance, behaviour, nationality, school achievements, — the factors that distinct the victims from their peers, — all may be a reason for bullying. Victims exhibit passive behaviours in bullying situations (try to ignore the situation, don’t tell about it, don’t seek for help, afraid of making the situation worse). Victims exhibit higher levels of depression, anxiety, more suicidal thoughts. The families of victims exhibit more problems in within-family communication, more formal control and critics toward children. Their mothers are less involved in the life of the kids and are less supportive.
The social status of a child in a group and its correlation with psychological, social-cognitive and behavioral characteristics
Authors: Ammon A.V. , Filippova E.V.
Published: January 2016

The relationship between peers is one of the most critical challenges of modern childhood. Research has shown the social status of a child in a group of peers influences not only his/her current well-being but his/her future psychological and physiological health condition. This article is devoted to the overview of foreign studies on social status of children and its correlation with different psychological, social-cognitive and behavioral characteristics of children with special attention to rejected and neglected children. Despite the popularity of the reviewed subject and vast amount of research on it, some correlations still need additional research.
Self-destructive behavior in adolescence and youth
Authors: Polskaya N.A. , Vlasova N.V.
Published: January 2016

The article presents the results of the empiric study of cognitive and personal factors of emotion regulation, risk of suicide, psychopathologic symptoms and self-injurious behavior. It is hypothesized that the risk of self-destructive behavior is connected to destructive cognitive strategies, dispositional factors of self-injurious and suicidal behavior and psychopathological symptoms. Participants: N=101, aged 13—21. Results: relations between scales of suicidal risk, psychopathological symptoms, self-injurious behavior and cognitive emotional regulation were revealed; differences between groups of instrumental and somatic self-injurers were shown; predictors of self-destructive behavior were defined by linear regression analysis. Summary: somatization, anxiety and psychoticism were related to factors of self-injurious behavior; connections between methods and factors of self-injurious behavior and factors of suicidal risk were discovered; cognitive emotional disregulation (rumination, self-accusation and accusation of others) were predictors of self-destructive behaviors and psychopathological symptoms.
Will Enhanced Depth-of-focus Intraocular Lenses Lead the Future in Premium Lenses?
Authors: Kılıç Aylin ,   Cataract and Refractive Surgeon, Dunya Eye Hospital, Istanbul, Turkey
Published: January 2016

Multifocal intraocular lenses (MF IOLs) continue to undergo modifications to enhance distance and near vision. Extended range of vision IOLs do not have multiple focal points as other MF IOLs do, so they do not cause any disturbance in distance vision and can compensate for chromatic aberrations.
Corneal Collagen Cross-linking for Keratoconus
Authors: Romano Vito ,   School of Medicine, University of Liverpool, Liverpool, UK,   Department of Corneal and External Eye Diseases, St Paul’s Eye Unit, Royal Liverpool University Hospital, Liverpool, UK,   Department of Corneal and External Eye Diseases, St Paul’s Eye Unit, Royal Liverpool University Hospital, Liverpool, UK,   Department of Corneal and External Eye Diseases, St Paul’s Eye Unit, Royal Liverpool University Hospital, Liverpool, UK,   Department of Corneal and External Eye Diseases, St Paul’s Eye Unit, Royal Liverpool University Hospital, Liverpool, UK, Baylis Oliver , Spiteri Natasha , Kaye Stephen B ,   Department of Eye and Vision Science, University of Liverpool, Liverpool, UK, Ahmad Sajjad ,   Department of Eye and Vision Science, University of Liverpool, Liverpool, UK
Published: January 2016

Corneal collagen cross-linking (CXL) is a successful technique used to slow the progression of corneal ectatic disease, mainly keratoconus. It is able to achieve this aim with a single application of vitamin B2 (riboflavin) and ultraviolet-A light to the corneal stroma where it results in crosslinks to form between the collagen fibres, resulting in corneal stiffening. We describe the different protocols, results and complications reported.
Trends and Discrepancies in Glaucoma Medical Therapy in Europe
Authors: Natale Renato De ,   Glaucoma Specialist, New Vision Eye Clinic, Nice, France
Published: January 2016

Prostaglandins are the most prescribed glaucoma drugs all over Europe; however, great differences exist from country to country in drugs prevalence. Generics represent an important glaucoma market share. The economic situation and local restriction to healthcare expenditure may influence physician choice in drugs prescription.
Social Integration of Immigrants within the Linguistically Diverse Workplace: A Systematic Review
Authors: Kaushik Vibha , Walsh Christine A. , Haefele Diana
Published: January 2016

As a consequence of international migration, a large number of workplaces are becoming linguistically diverse. This creates challenges for the workplace integration of immigrants and increases the risk of their social exclusion. A systematic review was conducted to determine the effects of linguistic diversity on social integration of immigrants within the workplace. Articles were identified by reviewing abstracts in electronic databases using key words related to linguistic diversity, social integration, immigrants and workplace. The search yielded ten peer reviewed articles, published in English, between 2000 and 2014. Information was extracted and synthesized from both quantitative and qualitative studies. The studies in this review were found to be concerned on three key areas of investigation: (1) social integration or social inclusion/exclusion, (2) social interaction and inter-group perception, and (3) accent discrimination. Smooth social and professional assimilation and the equality of opportunities for the immigrants were considered as the determining factors of their complete social integration in the workplace. Most studies in this review established a connection between social integration and local language skills; some also identified that factors such as racial discrimination and ethnicity based stereotyping contributed to social exclusion of immigrants, particularly when the studies involved visible minorities. The review enhances our understanding of challenges of complete social integration faced by immigrants and reinforces the need to invest in policies and program aimed at preventing marginalization of immigrants. However, due to limited number of studies identified by this review and the variation in findings, further research is necessary to investigate the role of linguistic diversity in the workplace integration of immigrants in immigrant receiving countries.  
A classificação da despesa com terceirizações no setor público e seus reflexos à luz da Lei de Responsabilidade Fiscal
Authors: Santos Vanessa Dos
Published: January 2016

Este estudo tem como objetivo identificar as despesas com terceirizações classificadas como serviços de terceiros — pessoa física — (elemento 36), que se caracterizam como despesas de pessoal para fins de análise no âmbito da Lei de Responsabilidade Fiscal (LRF). Apresenta amostras coletadas em 13 municípios do Estado de Santa Catarina, com análise de 5.810 empenhos, referentes aos anos de 2007 a 2010, perfazendo o total de R$ 33.269.928,90. Os principais gastos referentes a pessoal foram: a) folha de pagamento; b) profissionais da saúde; c) professores e coordenadores pedagógicos; d) contratação de contador e advogado; e) remuneração ao conselho tutelar. Observa-se que na administração municipal há classificação de despesa no elemento 36 que se caracteriza como pessoal, mas que, por conseguinte, não é computado na análise dos gastos de pessoal nos termos da LRF, não evidenciando, portanto, a totalidade desses gastos pelo Município, o que prejudica o processo de transparência da gestão pública municipal.
Mídias Sociais e a Esfera Pública
Authors: Fuchs Christian
Published: January 2016

A mídia social tornou-se um termo chave em Estudos de Mídia e de Comunicação e no discurso público por caracterizar plataformas como Facebook, Twitter, YouTube, Wikipedia, LinkedIn, Wordpress, Blogspot, Weibo, Pinterest, Foursquare e Tumblr. Este artigo discute o papel do conceito da esfera pública para entender a mídia social criticamente. Vai contra a interpretação idealista de Habermas e a favor do entendimento cultural-materialista do conceito de esfera pública, baseado na economia política. Analisa que a noção original de Habermas deveria ser mais bem entendida como um método de crítica intrínseca do que algo que criticamente escrutiniza os limites da mídia e da cultura com base em relações de poder e econômica política. O artigo introduz um modelo teórico de mídia a serviço do público e o usa como base para identiﬁcar três antagonismos da esfera da mídia social contemporânea, nas áreas da economia, estado e sociedade civil. A conclusão é a de que esses limites só podem ser superados se a colonização do mundo da mídia social for enfrentada politicamente, para que a mídia social e a internet possam se tornar serviços públicos e bens comuns de mídia.
Matrix Permittivity Measurements for Rock Powders
Authors: Seleznev Nikita V. , Fellah Kamilla , Phillips John , Zulkipli Siti Najmi , Fournié Bastien
Published: January 2016

Formation water content is one of the key petrophysical quantities provided by dielectric logging. However, to determine water content from formation permittivity measurements, the rock matrix permittivity must be known. Uncertainty in the rock matrix permittivity values translates into uncertainty in the water-content estimate, which is especially important in low-porosity formations or complex lithologies. Matrix permittivity values are not well-known for a number of minerals and can also vary for the same type of mineral in different formations. Thus, a laboratory methodology for the accurate determination of matrix permittivity at dielectric logging frequencies is required to facilitate accurate log interpretation.

One can measure matrix permittivity values on solid plugs (Seleznev et al. 2011). However, the plug-based methodology can be challenging in very-low-permeability or unconventional reservoirs because of difficulties with plug drying. In addition, it is not readily applicable to unconsolidated formations. Finally, it may be impossible to cut solid plugs because of limited availability of rock material. Matrix permittivity measurements made on rock powders are capable of addressing all these issues.

We introduce a methodology for laboratory measurements of matrix permittivity on rock powders at 1 GHz. The methodology is based on conducting dielectric measurements on mixtures of rock powders and liquids with variable permittivities in a dielectric resonator. The permittivity of the rock matrix is inverted from a series of measurements obtained on pure liquids and powder/liquid mixtures. The methodology was benchmarked on a collection of samples representing common oilfield lithologies with matrix-permittivity values between 4.6 and 8.6. The reference matrix-permittivity values were first measured on solid plugs. Then, the plugs were crushed into powders, and the matrix permittivity values were determined on powders following the proposed methodology. The values obtained on powders matched the ones measured on solid plugs within 0.2 dielectric units, resulting in accuracies better than 1% for the water-filled porosity and better than 1,000 ppm for water salinity.

This new methodology was applied to a number of core samples from a carbonate reservoir offshore Sarawak, where dielectric logging was performed along with conventional core analysis. The resulting measured matrix permittivity values were then used to interpret the dielectric log measurement. Results showed a better estimation of water-filled porosity and of the textural MN parameter, equivalent to the Archie's cementation exponent in a water-bearing zone, than would have resulted from using “chartbook” values of matrix permittivity. A consistent and optimized interpretation was obtained in porosities ranging from 5% to more than 30%.
Landing String: Breaking the 2.5 Million Pounds Limit
Authors: Plessis Guillaume J. , Verhoef Richard , Ringstad Svein-Inge , Pangilinan Alberto , Liotta Joe
Published: January 2016

Landing heavy casing strings, which operating companies run in nowadays deeper prospects, is challenging and numerous papers have covered some aspects of the solutions used in these world class operations. To date most of these papers (Brock and al. 2010) (Chandler and al. 2012) cover casing landing application running up to 2.5 million pounds (1,250 sTon), which is the hoisting capacity of most offshore mobile drilling units. A trend is well established in the industry with more frequent requests for landing strings of higher tensile capacity for which designs exist with ratings of 2.75 or even 3.0 million pounds.

Reaching this level of tension in a string is demanding in terms of its own design and also brings additional challenges when it comes to hoisting it on the rig, sitting it on slips, torquing it, being able to shear it with BOP in the event that quick disconnect is required. Our group of authors covers these various aspects in this paper that addresses the impact of design choices and details the industry's best options for every landing string interface. Often, the system components are selected in isolation bringing partial answers to this industry challenge; the true answer goes beyond this and is an integrated solution.

This paper presents an array of technologies, which allow operating companies to safely run casing strings weights in excess of today's standard and could serve as guidelines for drilling engineers when they plan deeper frontier prospects.
The Role of Filtercake in Wellbore Strengthening
Authors: Cook John , Guo Quan , Way Paul , Bailey Louise , Friedheim Jim
Published: January 2016

Recent experiments and associated modelling on wellbore strengthening have revealed the importance of the filtercake in inhibiting the growth of fractures that would otherwise cause lost circulation. As a result, this increases the pressure that the wellbore can sustain, during both drilling and cementing.

In preventive wellbore strengthening treatments, the rock formation is assumed to have no open fractures. Fractures are induced during the drilling process and the treatment inhibits their growth. This technique is most often used in drilling through depleted formations and has proven to be very effective. The basis of design is that particles of loss prevention material (LPM) in the drilling fluid are sized to enter the fractures, form a bridge within them, and then restrict fluid flow to the tip.

A second mechanism has also been identified. Several hundred block tests on sandstone samples have been performed using various fluids, from drilling muds to cements, under various treatment conditions. These tests revealed the importance of filtercake in preventive wellbore strengthening. Particles sized to block a specific fracture were not needed. Provided that the filtercake itself can bridge the very narrow fractures that form at early times, it can prevent the fluid flow into the fracture that then allows the fracture to extend and widen.

The properties, in particular the strength, of filtercake are important in determining the effectiveness of this kind of strengthening. Tests were performed to characterize filtercake and LPM effects on filtercake for both water and oil-base muds. Results showed that incorporation of particulate LPM to water-base mud filtercakes has little effect on the filtercake strength, but has appreciable effect on oil-base mud filtercake strength. Filtercake tensile strength is much more difficult to measure, particularly in relationship to the critical fracture width before the filtercake ruptures.
Crew Resource Management: A Proven Model for Leadership in the Oilfield
Authors: Tower Patrick , Motruk Lonny , Williams Austin , Allcorn Marc
Published: January 2016

Many industries have reflected on the complexity and inherent risks involved in their operations and have developed systems to maximize safety and increase efficiency. At the forefront of this revolution to perfect operational execution are those industries designated as High Reliability Organizations (HROs). HROs such as commercial aviation, health care and the fire service have "no fail missions" in which lives are at considerable risk during every operation and the cost of mistakes can be staggering. HROs typically recognize human error as the root cause of most significant incidents leading to the application of a human factors approach to operational execution, called Crew Resource Management (CRM).

Since April of 2013, one oilfield organization has joined these HROs in the pursuit of operational excellence through the application of CRM. Since integrating a CRM leadership model into all elements of their operations, empirical evidence collected pre and post implementation from Corporate HSE&Q data established an increase in safety and service quality at the tactical level of operations. Further evidence supplied through field case studies demonstrates that the employment of CRM in oilfield operations has a positive impact in optimizing efficiency in the execution of operations while mitigating risks and maximizing crew safety.

This paper provides a high level curriculum of a CRM program including strategies for implementation and integration of CRM tools and processes within frontline oilfield operations. Significant findings of this research are demonstrated methods used to overcome cultural challenges in embedding CRM in an organization. This includes approaches to break down barriers to acceptance by leaders and operators at all levels of the organization. Drawing from research, as well as a field case study, this paper will examine the positive operational effects of applying CRM as a leadership model for the oilfield. It will also suggest tactics and considerations for training and implementation of CRM.
Modeling Real-Time Sag in the Wellbore
Authors: Kulkarni Sandeep D. , Jamison Dale E. , Gollapalli Joshua S.
Published: January 2016

Weight material sag occurs during drilling operations when drilling fluids remain idle in the wellbore for time periods ranging from hours to several days at static or low-shear conditions. This paper presents a novel method of predicting real-time sag behavior in the wellbore. The method also accurately predicts the fluid mud weight collected at the surface as it is circulated out after a sag event, providing a significant advancement in drilling fluids engineering.

Weight material sag is broadly viewed as the settling of barite particles in drilling fluids (primarily oil-based) under various mechanisms. Fluid composition (barite size/concentration and oil/water ratio) and fluid properties (i.e., rheology) influence the barite settling rate. The well geometry (i.e., inclination and diameter) also affects sag behavior. In addition, well operating conditions (i.e., temperature, pressure, and time for which fluid is uncirculated) also influence sag severity. A comprehensive computational approach was developed to model the sag behavior in wellbores using fluids composition/properties and wellbore geometry/conditions information.

The wellbore sag model predicts information about the changing fluid composition along the wellbore depth as affected by sag, when the fluid in the well is under idle conditions (static or low shear). Specifically, for a wellbore section of a given inclination, the model provides quantitative density/rheology estimates of the barite-depleted zone at the top of the section and the barite-accumulated zone at the bottom. As the sag-affected fluid is circulated out after an idle period, the model also predicts the varied mud weight of the fluid collected at the surface and the corresponding transient bottomhole equivalent circulating density (ECD) as the circulation begins.

The wellbore sag model predictions, especially the variation in the mud weight of the fluid collected at the surface after the sag event, were tested on several wells and fluid systems. The model provided good correlations between measured and predicted fluid density, typically less than 0.1 lbm/gal. The model accurately demonstrates how certain fluids show good sag resistance in some wells yet fail in some complex wells. The model also shows excellent sag resistance of certain specialized fluids in complex wells, which is in agreement with the field observation.

A method to accurately determine real-time sag in the field has been a long-standing need. The successfully validated wellbore sag model, which captures the combined effect of fluids composition/properties and wellbore geometry/conditions, could serve as a useful tool for mud engineers to evaluate the sag behavior. It could also enable fast decision making at the rig site to optimize fluid formulations and operating conditions for sag management.
Selecting Optimum Drilling Parameters by Incorporating Vibration and Drilling Efficiency Models
Authors: Al Dushaishi M. F. , Nygaard R. , Andersen M. , Jeffery C. , Hellvik S. , Saasen A. , Hareland G.
Published: January 2016

To avoid severe vibrations, different drillstem (or drillstring) vibration models have been used to predict and avoid resonance regions by selecting bottom hole assembly (BHA) components and operating parameters such as weight on bit (WOB) and RPM. The overall efficiency of the drilling operations can be evaluated using either a mechanical specific energy model or an inverted rate of penetration (ROP) model. The key output from the analysis described herein is a method to improve drilling efficiency by incorporating a drillstem vibration model with an ROP model.

A data set including vibrational data was collected from a section of a well drilled in the North Sea to analyze the level of drilling efficiency for the drilled section. A drillstem vibration model was created using nonlinear finite strain theory, including coupled axial, torsional and lateral vibration modes. To optimize the drilling process, the vibration model was integrated with an ROP model. The vibration model calculates the critical speeds for a given BHA at a given depth, supplied with an operational window for WOB and RPM combinations that gives the optimal combination in therms of ROP.

By analyzing the drilling variables such as WOB, rotational speed, and ROP, the drilling operational effectiveness was evaluated. The operational window with low vibration level and with the potential maximum instantaneous ROP was chosen to be the optimum drilling scenario for the target hole section. The model was verified with the analysis of the collected field data where the level of drilling efficiency was obtained for the different sections drilled. This paper presents a new methodology to increase drilling performance by means of drillstem vibration and ROP modeling.
Method for Pore Pressure Estimation Using Mechanical Specific Energy and Drilling Efficiency
Authors: Majidi Reza , Albertin Martin , Last Nigel
Published: January 2016

Pre-drill prediction of formation pore pressure and pressure detection while drilling to recognize deviations from the expected pressure are important inputs for well planning and operational decision making.

A method is proposed to determine pore pressure from a combination of downhole drilling mechanics parameters and in-situ rock and stress data using the concept of mechanical specific energy (MSE) and drilling efficiency (DE). This pore pressure estimation method (termed "DEMSE") is based on the theory that energy spent at the bit to remove a volume of rock is a function of the differential pressure (wellbore pressure minus pore pressure) that the rock is subjected to during drilling.

A workflow is provided that illustrates the steps required to estimate pore pressure from drilling parameters and rock/stress data using DEMSE method. Pore pressure estimated from the DEMSE method is compared with a pore pressure estimate using a conventional sonic log based empirical technique for a deep water well in the Gulf of Mexico. Pore pressure estimates from the DEMSE method generally agree in magnitude and trend with the pressure estimates derived from sonic log data.

The results of the DEMSE method have also been compared with pore pressure estimates from the classical d-exponent (dXc) methodology. Unlike the d-exponent methodology, which is an empirical correlation that considers only weight on bit (WOB), DEMSE is an energy based approach that takes into account both torque and WOB. Moreover, the normal compaction trendline (NCT) used in the DEMSE method can be correlated to a normal compaction porosity trendline; the same NCT used as a basis for conventional log-based pore pressure estimates. This gives the DEMSE method a significant advantage over the dXc method, in terms of predictive capability, by reducing the subjectivity that is involved in dXc-based pore pressure estimates.

Finally, the importance of using downhole vs. surface data for pore pressure estimation purposes, specifically torque measurements at the bit, is illustrated through a field example. These findings suggest that downhole drilling mechanics data, when properly utilized, can provide reliable independent estimates of pore pressure in real-time at the bit, and for post well analysis to assist with constructing pore pressure forecasts.
Buckling of Tubular Strings in Open Sea
Authors: Kyllingstad Åge
Published: January 2016

An analytical model for lateral buckling of near vertical tubular strings is presented in the paper. It applies both for marine risers and for drill strings used during riser less drilling. The model represents a tool for predicting critical compression force at the lower end and for calculating critical shortening length of the buckled string in situations when the top site heave compensation or tensioner system fails.

The static lateral deflection of the string is described by a fourth order differential equation that can be linearized for small inclinations. Non-trivial analytic solutions include homogeneous and inhomogeneous Airy functions that can be combined to satisfy various boundary conditions and shortening lengths. The effect of an optional side force is also included in the solutions.

The paper discusses the validity of the underlying assumptions, such as linearity, simplified boundary conditions, and the neglecting of dynamic effects. Finally, the theory is successfully compared with experimental results from a small scale physical model.
Well Placement Optimization in a Gas Condensate Reservoir to Prevent Condensate Banking
Authors: Evans Edward , Ghalambor Ali , Orangi Abdollah
Published: January 2016

Horizontal wells with multistage hydraulic fractures have become the most common practice to obtain viable commercial production from shale and tight gas reservoirs. With a marked increase of gas production emerging from these tight reservoirs, it is necessary to further study the effects of formation damage due to condensate dropout and how best to prevent and mitigate this damage. There are two common ways to mitigate and treat condensate banking. The first method is to fracture the existing well. This allows bypassing the condensate and therefore increasing well productivity. The second method is to shut-in the well and allow pressure to build up so that the dropped out liquids are revaporized back into the gas. These options, respectively, involve large capital expenses and temporary decrease of production. Before deploying these solutions, the condensate dropout damage can be strongly reduced at no (field) cost by optimizing the well location.

This objective in this study was to determine the optimum well location to mitigate formation damage due to condensate dropout in a tight gas well. Compositional reservoir simulations were conducted with different condensate gas ratios and relative permeability curves to quantify the loss of productivity due to formation damage under different conditions. The target formation was 100 ft thick, and a tartan grid was used to represent the hydraulic fractures within the tight gas well.

This study determined that well placement plays a key role in preventing damage due to condensate banking. The optimized placement of the well can drastically enhance the viability of a project by allowing for a larger recovery.
A Comparative Study on Operational Performance of Advanced Low Friction Residue-Free Fracturing Fluid versus Conventional Fluid Systems
Authors: Schnoor Eli , Singh Dipti , Russell Aaron , Jespersen Matt , Lewis Chad
Published: January 2016

This paper compares the operational performance of a newly developed low friction, nearly residue-free (LF-RF) fluid system to a conventional derivatized guar-based fluid system and an existing nearly residue-free (RF) fluid system. The RF system has provided increased well production in numerous applications; however, the system requires lower treating rates due to increased friction. During recent field operations, the LF-RF system surpassed previous treating rates, which were previously unattainable, while maintaining maximum fluid cleanup.

The friction responses between the RF, LF-RF, and derivatized guar-based fluids were assessed through quantitative analysis of surface treating pressures. All comparisons between fluid systems were made between wells on the same pad with the same completion method. The wells used in this study were all located in the Denver/Julesburg (DJ) basin and pumped using the same hybrid treatment design. Along with field data, laboratory testing was conducted to compare the viscosity profiles of the LF-RF and derivatized guar-based fluid, which were used in the field.

Guar-based fracturing fluids have long been the industry standard. However, these fluids produce insoluble residue on breaking, which can reduce proppant pack conductivity and adversely affect well production. The RF fluid is an ultraclean, proven system, which has been successfully pumped in more than 16,000 stages. This fluid leaves virtually no insoluble residue, which has led to increased production from unconventional reservoirs. Yet, the RF fluid tends to exhibit increased treating pressures compared to guar-based fluids, which might require lower treating rates during operations. Additionally, a higher gel loading is necessary with the RF fluid to achieve comparable viscosities to the guar-based fluids. The new LF-RF fluid system retains all the beneficial cleanup properties of the RF system, while providing improved friction reduction. Intervals pumped with the LF-RF fluid provided lower treating pressures compared to those pumped with RF fluid, even at increased treating rates. With the improved friction reduction verified, the LF-RF fluid was pumped alongside a derivatized guar-based system at 80 bbl/min; a rate well beyond that which the RF fluid is generally pumped. The LF-RF fluid successfully placed all proppant and had similar treating pressures to the derivatized guar-based system toward the heel of the well. The LF-RF fluid was also able to accomplish this using a gel loading comparable to the derivatized guar-based system.

Through quantitative analysis of the surface treating pressures, the LF-RF system has demonstrated increased friction reduction compared to the existing RF system. The improved friction reduction allows the LF-RF fluid to be pumped at high rates, expanding the range of possible well and treatment designs which this fluid system can accommodate.
Field Results and Experimental Comparative Analysis of Sodium and Nonsodium Chelant-Based HF Acidizing Fluids for Sand Control Operations
Authors: Smith Alyssa LaBlanc , Woon Geok Cheen , Smits Ferry , Govinathan Kesavan , Yong Wei-Jin , Beuterbaugh Aaron , Garcia Enrique A.
Published: January 2016

Field results and laboratory data are presented for the purpose of identifying best practices for two different acidizing fluids based on chelating agents containing hydrofluoric (HF) acid employed in clean-up treatments in high-rate water pack completions (HRWP). The HF fluids are a newly introduced aminopolycarboxylic acid (APCA), pH 2.5 to 3 that contains sodium ions, and an established hydroxycarboxylic acid (HCA) fluid, pH 3, sodium-free.

Flow testing was conducted at the anticipated bottomhole static temperature (BHST) of 270°F in synthetic packed columns with formation sand. However, the field conditions at which the treatments were run corresponded to a BHST of 202 to 216°F and a bottomhole pressure (BHP) of 1,800 to 2,000 psi. The permeability of the sands was 89 to 162 md. Comparative data and results stemming from laboratory testing and field use of the HF/chelant fluids are analyzed for concentrations of 1 and 1.4% HF and APCA at 0.6 M, and 1% HF with HCA. Field data and production results are discussed for two set of wells treated with each type of HF fluid.

The chemical differences, reactivity and characteristics among the APCA/ and HCA/ -HF fluids on formation sand and on formation core are described. Fluid testing excluded acid preflush and NaCl or KCl was the sole brine employed. Laboratory results indicate that both HF fluids are compatible with the brines used within the scale of the experiment and provide full or increased relative permeability. The field application of the APCA/HF fluid in HRWP appears to perform less efficiently, requiring longer pumping times, than the HCA/HF fluid. A salient observation from laboratory testing indicates greater effectiveness at pH 2.5 vs. 3 for the APCA/HF fluid. A differentiating characteristic is that the APCA/HF fluid can be used to treat heterogeneous sandstone with moderate carbonate content and HCA/HF is mostly compatible with clean sandstone unless an acid preflush is incorporated. The operational outcomes observed during the field use of the APCA/HF fluid appear to indicate significant differences in laboratory vs. field performance requiring further assessment to identify appropriate practices in HRWP.

The APCA/HF fluid can stabilize problematic ions in the spent fluid without the need for acid preflushes and without maintaining highly acidic conditions. The effective field use of the newly developed APCA/HF fluid containing Na+ with and without an acid preflush indicates that future work with this type of stimulation fluid is viable in matrix acidizing.
Numerical Modeling of a Soil‐Borehole Thermal Energy Storage System
Authors: Catolico Nora , Ge Shemin , McCartney John S.
Published: January 2016

Core Ideas

Borehole thermal energy storage is studied with a 3D transient fluid flow and heat transfer model.

BTES heat extraction efficiency increases with decreasing soil thermal conductivity.

BTES efficiency decreases with convective heat losses associated with high soil permeability.

Borehole thermal energy storage (BTES) in soils combined with solar thermal energy harvesting is a renewable energy system for the heating of buildings. The first community‐scale BTES system in North America was installed in 2007 at the Drake Landing Solar Community (DLSC) in Okotoks, AB, Canada, and has since supplied >90% of the thermal energy for heating 52 homes. A challenge facing BTES system technology is the relatively low efficiency of heat extraction. To better understand the fluid flow and heat transport processes in soils and to improve BTES efficiency of heat extraction for future applications, a three‐dimensional transient coupled fluid flow and heat transfer model was established using TOUGH2. Measured time‐dependent injection temperatures and fluid circulation rates at DLSC were used as model inputs. The simulations were calibrated using measured soil temperature time series. The simulated and measured temperatures agreed well with a subsurface having an intrinsic permeability of 1.5 × 10−14m2, thermal conductivity of 2.0 W m−1°C−1, and a volumetric heat capacity of 2.3 MJ m−3°C−1. The calibrated model served as the basis for a sensitivity analysis of soil thermal and hydrological parameters on BTES system heat extraction efficiency. Sensitivity analysis results suggest that: (i) BTES heat extraction efficiency increases with decreasing soil thermal conductivity; (ii) BTES efficiency decreases with background groundwater flow; (iii) BTES heat extraction efficiency decreases with convective heat losses associated with high soil permeability values; and (iv) unsaturated soils show higher overall heat extraction efficiency due to convection onset at higher intrinsic permeability values.
On asymptotic efficiency of goodness of fit tests for Pareto distribution based on characterizations
Authors: Obradovic Marko
Published: January 2016

In this paper we present a characterization for Pareto distribution. We
propose two new goodness of fit tests based on this characterization and two
tests based on Rossberg?s characterization. We calculate their Bahadur
efficiencies against different alternatives and compare the tests. We also
find a class of locally optimal alternatives for each test.
Meander knots and links
Authors: Radovic Ljiljana , Jablan Slavik
Published: January 2016

We introduced concept of meander knots, 2-component meander links and
multi-component meander links and derived different families of meander knots
and links from open meanders with n ? 16 crossings. We also defined
semi-meander knots (or knots with ordered Gauss code) and their product.
Gold nanostructures sputtered on zinc oxide thin film and corning glass substrates
Authors: Szabó Ondrej , Flickyngerová Soňa , Ignat Teodora , Novotný Ivan , Tvarozek Vladimír
Published: January 2016

Forming of Au nanostructures on Corning glass substrates and transparent
conductive oxide ZnO:Al thin films by the RF diode sequential sputtering is
presented. The morphology of Au structures was analysed by scanning electron
microscopy (SEM) with the free ImageJ software, the optical properties were
evaluated by UV-Vis spectrometry and micro-Raman spectroscopy. The sputtering
power density (deposition rate) and nominal Au thickness caused changes in
the sizes (10 - 1000 nm2) and nearest neighbour NN distances (4 - 40 nm) of
Au nanostructures. The morphology of nanostructures exhibited the LogNormal
distribution of the size of nanostructures. The lowest sputtering power
density/deposition rate (9 mW/mm2/0.12 nm s-1) was optimal to get both the
high optical transparency and a superior activity surface-enhanced Raman
scattering of 11-mercaptoundecanoic acid adsorbed on the Au/ZnO:Al film.
Linearization of broadband two-way microstrip Doherty amplifier
Authors: Males-Ilic Natasa , Djoric Aleksandra , Atanaskovic Aleksandar
Published: January 2016

The linearization of a broadband two-way microstrip Doherty amplifier
designed for application in the frequency range 0.9-1.0 GHz is considered in
this paper. The amplifier characterized by the maximum output power 8 W is
designed in microstrip technique for broadband applications. For
linearization purposes, the second- and fourth-order nonlinear signals are
extracted at the output of the peaking cell, adjusted in amplitude and phase
and fed at the input and output of the carrier transistor over the microstrip
hairpin band-pass filters. The effects of the linearization are considered
through the simulation for two sinusoidal signals with different frequency
interval between them setting on from 5 MHz and going up to30 MHz at
different input power levels up to saturation, as well as for an Orthogonal
frequency division multiplexing (OFDM) digitally modulated signal.
Concept of integral protection of apple and pear
Authors: Velickovic Milovan , Golijan Jelena
Published: January 2016

This paper implies current and economically significant diseases and pests of
an apple and pear, i.e. problems of integral protection of these species of
fruits in our country. Measures for their prevention are recommended
regarding an adequate period. Special consideration is given to the diseases
such as Venturia pyrina, Venturia inaequalis, Monilinia fructigena,
Podosphaera leucotricha and Chondrostereum purpureum, as well as to pests
such as Cydia pomonella, Cacopsylla pyri, Cacopsilla pyrisuga, Eryiophidae,
Panonychus ulmi and Aphididae. The demand and importance of mass
implementation of the concept of integral production in terms of obtaining
biologically more valuable and ecologically safer fruits, i.e. preservation
of the environment and health have been implied.
An application of classical and instrumental methods of analysis in quality control of beer
Authors: Rajkovic Milos , Sredovic-Ignjatovic Ivana , Ignjatovic Ljubisa , Nedovic Viktor , Prijic Slobodan
Published: January 2016

In order to control the quality of beer and raw materials for production of
beer in Belgrade Beer Industry (BIP), water is analyzed (city, technological
and demineralized water). Measurements of pH values indicated the increased
pH values in the sample of tehnological water, which had no impact on wort
hopping, since the tested samples of wort, young beer and final product had a
pH value within the expected range. After processing city water, a sample of
tehnological water was found with increased carbonate hardness, which is
caused by the increased content of sodium hydrogen carbonate. Analysing the
titration alkalinity, titration acidity and buffering power, it was found
that the alkalinity was decreasing which is in accordance with the
determination of pH values of wort and beer samples (young beer and final
product). Analyzing the content of anions and cations in the examined water
samples, it has been shown that the concentration of these examinated anions
(Cl-, NO3 -, SO4 2- and PO4 3-) and cations (NH4 +, Na+, K+, Ca2+, Mg2+) are
within the limits prescribed by the Regulations on hygienic safety of
drinking water, and thus by the Regulations of quality and other requirements
for beer. The contents of anions in wort and beer samples (young beer and
final product) were determined by ion chromatography method. The contents of
sulphate and nitrate ions were within the recommended limits. The
concentration of chloride ions was above 150 mg/dm3, which may have an impact
on the sensory properties of beer, while changes in the content of phosphate
ions were insignificant.
Effects of Moringa oleifera root extract on the performance and serum biochemistry of Escherichia coli challenged broiler chicks
Authors: Abiodun Bolu , Adedeji Aderibigbe , Taiwo Ologe , Gbenga Adeyeye
Published: January 2016

The antibacterial and phytochemical effects of aqueous extracts of Moringa
oleifera roots on E. coli challenged broiler chicks were investigated. Ninety
one-day old broiler chicks were orally inoculated with E. coli at 1.23?108
CFU/ml and then divided into six treatment dose levels: 5g/l, 10g/l, and
15g/l Moringa root extract (MRE), positive control, negative control and a
standard (commercial antibiotics). The extract showed no significant
difference (P>0.05) in performance, carcass and nutrient retention indices of
birds compared to the controls. However, at 10g/l dose level, serum
parameters including cholesterol and uric acid were higher (P<0.05) at
118.9Mmol/l and 4.07Mmol/l respectively, but lower in total protein (4.40g/l,
P<0.05). Birds fed 15g/l dosage had lower (P<0.05) serum cholesterol level
(77.503Mmol/l) and lower (P<0.05) mortality (1%) compared to other treatments
(2.2-3.3%) and the negative control (5.5%). The findings of this study
suggest that the active ingredients from Moringa oleifera roots could
significantly assist in combating endogenous pathogenic activities.