bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Surfactant Mixtures on Microemulsion Phase Behavior
Authors: Magzymov Daulet , Qiao Changhe , Johns Russell T.
Published: October 2016

Surfactant feedstock for surfactant-polymer (SP) flooding field applications is commonly delivered as a blend of surfactant mixtures with a distribution of molecular weight (MW), rather than as a pure component. Moreover, two or more synthetic commercial surfactants with their own MW distributions are often injected simultaneously. In order to design an effective SP flooding process it is important to predict phase behavior of complex surfactant mixtures with changing formulation variables, such as temperature, pressure, oil EACN, brine salinity, and surfactant composition. The main challenges to model phase behavior of surfactant mixtures include distinct optimum conditions for each type of surfactant, limited information about the distribution of the surfactants in the commercial blends, different partitioning of surfactants in the excess phases and microemulsion phases, and dynamically altered surfactant composition due to selective adsorption, degradation, or differing partition coefficients.

In this paper, we present new mixing rules for our recently developed equation of state model to predict phase behavior of surfactant mixtures with changing compositions of two or more synthetic commercial grade surfactants. The model is based on the hydrophilic-lipophilic difference (HLD), net-average curvature (NAC), and mole fraction weighted ratios of surfactant blends (in terms of both multiple synthetic surfactants and their individual distributions). Significant chromatographic separation of surfactant mixture may occur as a result of distinct adsorption isotherms for different surfactant components. These composition changes can have a critical impact on the phase behavior of the mixture and the ultimate oil recovery.

Fish plots are constructed for varying water-oil ratios and surfactant compositions that show significant sensitivity to water-oil ratio and surfactant composition. When the injected chemicals do not separate (e.g. there is no selective adsorption, degradation, or selective partitioning), fish plots for a water-oil ratio of 1.0 are symmetric with surfactant concentration because the surfactant blend behaves as a pure surfactant pseudocomponent. For water-oil ratios not equal to 1.0, the surfactant blend can still be modeled as one pseudocomponent, as long as surfactant composition remains fixed, but the fish plot becomes asymmetric. Fish plots, however, are always asymmetric when surfactant composition changes. In such cases, the surfactants must be represented by multiple components with different characteristics and distributions. The results are illustrated using ternary and quaternary diagrams based on measured experimental data in the literature. The new model is included in our in-house compositional simulator PennSim, which shows that simulations of a surfactant flood with different adsorption isotherms can significantly change recovery.
Shale Stability When Drilling Deviated Wells: Geomechanical Modeling of Bedding Plane Weakness, Field X, Russian Platform
Authors: Konstantinovskaya Elena , Laskin Pavel , Eremeev Dmitry , Pashkov Alexei , Semkin Alexei , Karpfinger Florian , Yan Gongrui , Trubienko Olga
Published: October 2016

An oil and gas company is drilling horizontal wells in Lower Permian carbonate reservoir in the Field X, Russian Platform. The area is characterized by high risks of borehole instability in Upper Permian overburden shales that overlie Kungurian anhydrite and salt deposits and Artinsky fractured carbonate reservoir rocks. Deviated well trajectory in 245 mm (9 5/8”) section contribute to higher risks of borehole instability in overburden shales. 1D and 3D near-wellbore geomechanics modeling taking into account shear slip along bedding planes of weakness was carried out for deviated wells to optimize mud weight and reduce risks of wellbore instability. The plane-of-weakness failure criterion is adopted to identify the onset of rock sliding along a weak plane (bedding or fracture) in the anisotropic wellbore stability model. The influence of bedding orientation and wellbore trajectory on the borehole stability is considered in the model. Shale formation rock strength anisotropic parameters, i.e., cohesion, friction angle and tensile strength for bedding planes of weakness, were deduced from the intact rock matrix parameters as a normal practice of geomechanical modeling, as no core test data were available from the shales.

According to post-drill geomechanical analysis, borehole damage computed using the wellbore stability model with bedding planes of weakness is in agreement with drilling events (cavings, overpulls) occurred under insufficient mud weight in 245 mm section of deviated well A. In contrast, poor correspondence between modeled borehole breakouts and drilling events was obtained by using the conventional wellbore stability model. Deviated well trajectory and angle of attack at 45°± 5° in 245 mm section represent settings that are favorable for shear slip along bedding planes contributing to borehole instability. According to the modeling results, stable mud weight window in 245 mm section of well A narrows in the model with planes of weakness if compared to the model with intact rock only. Well trajectory optimization was recommended to keep angle of attack below 30° in shales and increase deviation in the underlying anhydrite and salt deposits. The anisotropic wellbore stability analysis applied for the first time in deviated wells of the Field X has shown that modeling of bedding plane of weakness in shales was essential to quantify the effect of shale strength variation with angle of attack on wellbore stability, and has to be considered in geomechanical modeling for drilling the wellbore safely and cost effectively.
Methodology for Determination of Low-Permeability Reservoirs Optimal Development Plan
Authors: Belonogov E. V. , Pustovskikh A. A. , Samolovov D. A. , Sitnikov A. N.
Published: October 2016

The purpose of this work is to identify the reservoir parameters at which efficiency of the line development system using horizontal wells with multi-stage hydraulic fracturing with waterflooding is lower that efficiency of the depletion drive development. The key factor reducing efficiency of developing such objects using the waterflooding methods is low reservoir pressure conductivity and, therefore, relatively long time of well productivity response to injection.

The authors use NPV as a criterion of development efficiency. A certain example (low-permeability reservoirs of the Priobskoye field for which oil production is calculated using the methods of numerical hydrodynamic modelling) is considered. An analytical technical and economic model of low-permeability reservoir development in the depletion and using waterflooding with dimensionless parameters has been also built.

For each type of impact on a reservoir, the optimum parameters of the development system shall be determined to further compare efficiency of the depletion and development with waterflooding. The results of calculations based on the numerical model have been summarized in the form of a dimensional chart to determine efficiency of waterflooding low-permeability reservoirs of the Priobskoye field. The results of application of the analytical model are provided in the form of a dimensionless chart.
Optimized Workflows to Assist in Managing the Sour Gases & Oil Production in North Kuwait Jurassic Fields
Authors: Al- Mai N.. , Al-Failakawi A.. , Prakash R.. , Hajjeyah A. A. , Al-Qahtani S. B. , Wibowo A..
Published: October 2016

The complex Jurassic fields consist of eight onshore fractured carbonate fields, producing from four different structures. In the reservoir, fluids are in critical phase. Three out of the eight reservoirs are volatile oil and the remaining are Gas-condensates with high H2S & CO2. Currently ~35 wells are connected to the Early Production Facility (EPF) and the well deliverability is just enough to produce at the facility design capacity. As per the development strategy more wells will be connected to the facility for Long term tests (LTT) and booking reserves. As per the current development plan, additional processing facilities will be commissioned in next 2 years. Over seventy additional wells will be connected to these facilities with the target to triple production.

In order to achieve the targets of the Jurassic field development plan, a flagship DOF (Digital Oil Filed) program called KwIDF (Kuwait Integrated Digital Field) was deployed by instrumenting ~35 wells and developing 22 production surveillance and analytics workflows. These workflows encompass HSE, operations and engineering requirements of the asset. Phase-1 of this technology program was initiated in 2010 and deemed complete in mid-2012. Since then the maintenance and enhancements of the existing system was done by improving the workflows which assist in better management, decision making, field monitoring and operations.

This paper describes the new workflows which were built over the last 3 years where automated calculations run every hour to estimate flow rates for Oil, Gas, Water, H2S & CO2 based on combining real time well data and steady state nodal analysis models. The blended API workflow tracks the crude API density at the outlet of the Early Production Facility (EPF) and helps to prioritize wells to be connected to meet the target crude density. Similarly the H2S & CO2 monitoring workflows calculate the daily average H2S & CO2 rates and its percentage. These workflows along with the choke sensitivity workflow helps to optimize the production with the H2S & CO2 constraints.

With the expansion of the field, a technology upgrade is also being planned under a Jurassic KwIDF Phase-2 program. The technical design of KwIDF Phase-2 was completed on April 2015 and the new workflows to be developed have been identified. The new workflows will focus to improve the well performance monitoring, Virtual Flow Metering (VFM), Surface – Subsurface integration, Choke Management, hydrate control and well & pipeline integrity.
Pilot Installation of a Deep Gas Lift System Conveyed with Coiled Tubing Catenary Method Increases Production of an Idle Well in Brunei
Authors: Tahir H. Md , Whittaker A.. , Shanmugam N.. , Tapia W. R.
Published: October 2016

An oil well located offshore Southeast Asia, was completed with a dual string and after 20 years of production the drawdown decreased significantly even with gas lift mandrels located in the long string, 480m (1575ft.) above the lowest producing zone. A deep gas lift (DGL) system was installed based on field data that indicated the production could be improved by increasing the drawdown to optimize the gas lift performance.

One of the main limitations was the depth of the production packer for the gas injection production. The deep gas lift system was selected as it enables the gas injection point to be moved deeper into the well, which in turn results in the ability to create a greater drawdown. The lowermost gas lift mandrel was straddled with two packers and a crossflow assembly that provided dual flow paths in a single system as well as suspending 350m (1148ft.) of 1.5in coiled tubing (CT) that acted as the injection string to a predetermined depth.

The operation was the first of its kind in which the DGL system was conveyed with a CT Catenary system on board a dynamically positioned vessel (DP2); this enabled flexibility in deployment of the long bottomhole assemblies in small offshore platforms without the presence of a crane. For this operation, modifications were required in the original CT equipment to maintain well integrity, providing double barriers at every step of the installation. The DGL system was successfully and safely installed in a live well in 3 days. After its installation, the production rate increased tremendously.

Similar operations will benefit from understanding the rationale in the selection of the solution, the details of the installation with the CT catenary system, the barrier systems put in place during the open-hole installation, the depth correlation methods and the lessons learned.
Water Dew-Pointing with Subsea Gas Dehydration to Improve Pipeline and Flow Assurance Economics
Authors: Yeaw Si Huai , Gyllenhammar Emil
Published: October 2016

A prolonged period of relatively low oil prices has resulted in an industry-wide push to utilise field development technologies that provide better returns on investment. For deepwater and long distance tieback developments, both pipeline and flow assurance related expenses constitute the major components of both CAPEX and OPEX figures for the development.

This paper presents how subsea dehydration technology could be used as a novel solution to reduce development costs by solving pipeline issues related to multiphase flow. It also outlines the two potential application scenarios for subsea dehydration, with Specific focus on the hybrid topsides-subsea development scenario. Key features of the subsea dehydration system are provided, with descriptions of the main subsea technology components.
The Evolution of Multizone Stand Alone Screen Completion Practices in Mahakam Delta A Pilot Project Result
Authors: Wijaya R.. , Muryanto B.. , Wahyudhi F.. , Isdianto-Maharanoe M.. , Styward B.. , Kadrie M.. , Al-Sakaf N.. , Dahnil-Maulana M.. , Saputra R.. , Az-Zariat A.. , Armelia-Suska R.. , Anggiriani-Putri A.. , Eko-Jatmiko C..
Published: October 2016

Tunu is a giant gas field located in Delta Mahakam, East Kalimantan, Indonesia operated by Total E&P Indonesie. The field development targets two domains: Tunu Shallow Zone (TSZ) and Tunu Main Zone (TMZ). The primary objective of TSZ completion is to have a cost effective sand control methodology to ensure economic vialibility of the wells since TSZ consist of small elliptical shaped deltaic sand bodies containing low reserve gas pockets with a typically short production life.

Multi zone single trip gravel pack (MZ-STGP) systems have been utilized as sand control completion methodology. Technical limitations of these techniques in terms of zone spacing, number of zones and well deviations drove the need developping an alternative completion technique. Using short screen assembly and open-hole isolation technology, a unique multi zone open hole stand alone screen (MZ- SAS) system was developed.

The initial development consists of 14 wells. Both low and high angle deviated wells, numbers of different completion jewelries and different type of reservoir drill-in fluids (RDIF) have been used over the initial phase of the development. The objective of this paper is to review the evolution and improvements in the drilling, fluid, completion and specific post well completion strategy. This has provided a best practice for future completions in the development of similar reservoirs in the portfolio.
Predictors of efficiency in municipal waste management in Tshwane municipalities, South Africa
Authors: Worku Zeleke
Published: October 2016

A survey was conducted in local municipalities in the Tshwane region of Gauteng Province in South Africa in order to assess and evaluate the efficiency with which municipal waste is collected, disposed of, processed and recycled by local municipalities in Tshwane based on data gathered from 1,035 businesses. Efficiency in waste management was assessed by using a structural time-based model designed for evaluating efficiency as a function of the length of time required to manage and process municipal waste. Adherence to municipal bylaws and procedures recommended for solid waste management by businesses by the City of Tshwane was graded based on ISO 14000 and ISO 14031 standards and guidelines. The study found that efficiency in waste management was adversely influenced by lack of adherence to municipal bylaws and regulations, wrong perception on the benefits of proper waste management, and failure to provide customers with waste disposal bins, in a decreasing order of importance.
Keywords: Tshwane municipalities, waste management, efficiency, logit analysis. JEL Classification: Q53, C25
Assessment of the consumer purchase intentions of organic food at the Hazel food market in Pretoria, South Africa
Authors: Naidoo Vinessa , Henry Ramatsetse Makate
Published: October 2016

This study on environmental economics has noticed that a growing concern for healthy food and environmentally friendly production has resulted in increased attention towards organic food. In South Africa, the market for organic food is still in the infancy stage. Food marketers continue to grapple in designing marketing campaigns to attract organic food consumers. Using a survey method, self-completed questionnaires were collected from customers aged 18 and above, by means of convenience sampling technique from a sample of 120 customers at the Hazel food market (HFM) in Pretoria. A total of 118 questionnaires were received back. STATA software was used to analyze the data. This is a quantitative study in which data analysis consisted of descriptive statistics, the Chi-square test and reliability analysis. The results suggested that customers at HFM have the intention to purchase organic food. The major findings of the study indicated that factors such as consumer values, attitude, subjective norm and perceived behavioral control significantly influence consumer’s intention to purchase organic food. This study intends to provide valuable insights into current studies of consumer behavior towards organic food in South Africa. Potential beneficiaries of this research study include consumers, vendors and government agencies.
Keywords: environmental economics, consumer purchase intention, theory of planned behavior, organic food. JEL Classification: Q5, M31
Dos o tres cosas que quisiera saber sobre la antropología del fitness
Authors: Martínez Dueñas William Andrés
Published: October 2016

En esta ocasión me he tomado el atrevimiento de sugerir a nuestros potenciales autores y lectores un tema que considero relevante en lo que podemos llamar estudios de la cultura popular. Como se anuncia en el título, el tema gira en torno a la noción de fitness. Digo noción porque no se hace referencia al concepto muy bien desarrollado en las ciencias naturales, sino a la apropiación polisémica de éste en torno a las prácticas y representaciones contemporáneas sobre el cuerpo, asociadas a ideas tecno-científicas de salud y acondicionamiento físico.
Produção científica e “produtivismo”: há alguma luz no final do túnel?
Authors: Yamamoto Oswaldo Hajime , Tourinho Emmanuel Zagury , Bastos Antônio Virgílio Bittencourt , Menandro Paulo Rogério Meira
Published: October 2016

O presente texto apresenta a estratégia desenvolvida pelaárea de Psicologia na Capes para avaliar a produção científica dosprogramas da área. A proposta consiste no estabelecimento de limitesquantitativos de produção bibliográfica por programa, proporcionais aonúmero de docentes permanentes, de forma a permitir uma avaliaçãoprioritariamente qualitativa da produção. O confronto dos indicadoresdas últimas avaliações trienais sugere, ainda que tendencialmente,a eficácia do procedimento. São discutidas as características e aslimitações dessa estratégia para a avaliação da pós-graduação.
Identidade das Ciências Humanas e métricas de avaliação: Qualis periódicos e classificação de livros
Authors: Massini-Cagliari Gladis
Published: October 2016

O objetivo deste texto é discutir as métricas de avaliaçãoadotadas pela Capes no processo de avaliação dos programas de pósgraduaçãodo País na área de Ciências Humanas, especialmente asclassificações do Qualis (periódicos) e de livros.
Proposta de criação de um indicador para análise da adequação da coleção do Portal de Periódicos da Capes à produção científica nacional
Authors: De Mattos Max Cirino , Fernandes Wesley Rodrigo , Cendón Beatriz Valadares
Published: October 2016

A partir da análise dos estudos realizados sobre o Portal de Periódicos da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes), este trabalho propõe a criação de um indicador automático de avaliação da adequação do conteúdo do Portal à produção de teses e dissertações cadastradas na Biblioteca Digital Brasileira de Teses e Dissertações (BDTD) do Instituto Brasileiro de Informação em Ciência e Tecnologia (IBICT). São descritos os passos básicos para a criação desse indicador e as ponderações sobre a sua viabilidade tecnológica. Ao final, são discutidos possíveis impactos e a importância desse indicador para a avaliação da adequação do Portal de Periódicos da Capes em relação às necessidades informacionais da comunidade científica brasileira. O indicador forneceria informações para a implementação de medidas de adaptabilidade contínua do Portal às necessidades de seus usuários.
Fundamentos para o conteúdo e a implementação da pós-graduação em Ecologia
Authors: Ferraz Gonçalo , Machado Glauco , R. Guimarães Jr. Paulo , Koehler Samantha
Published: October 2016

A recente expansão do investimento brasileiro na pósgraduação em Ecologia cria uma oportunidade de progresso nos programas de treinamento. Não há progresso sem metas, e as metas de um esforço conjunto se beneficiam da partilha de valores fundamentais. Este artigo contribui para o debate em curso, propondo um conjunto de áreas de conhecimento fundamentais para a formaçãodo ecólogo. A Matemática, a Estatística e a Evolução são apresentadas como ‘pilares’; a História Natural, a Lógica e a Retórica são vistas como o ‘cimento’ que dá consistência ao treinamento. Finalmente, sem deixar de frisar a importância da criatividade local, propomos um conjunto de princípios gerais de implementação para transformar os valores fundamentais em uma realidade de treinamento inovadora e produtiva.
A pesquisa em linguagem e tecnologia na Universidade Federal de Minas Gerais
Authors: Paiva Vera Lúcia Menezes de Oliveira e
Published: October 2016

Este artigo apresenta uma visão geral da pesquisa sobrelinguagem e tecnologia nos últimos 12 anos na Universidade Federalde Minas Gerais, incluindo uma breve descrição da pesquisa sobreliteratura e tecnologia. As teses e dissertações produzidas no Programade Pós-Graduação em Estudos Linguísticos foram divididas em cincogrupos temáticos: características da linguagem/discurso; leitura; escrita;ensino e aprendizagem; e ambientes virtuais de aprendizagem. A grandemaioria desses estudos é constituída de estudos de caso. Os dadosforam coletados por meio de entrevista, observação e questionários.Há uma predominância de estudos sobre o ensino e a aprendizagem epoucos estudos sobre a interação na web. Conclui-se que a pesquisa éincapaz de acompanhar a velocidade da inovação tecnológica.
As necessidades de informação subjacentes ao processo decisório no espaço que circunda a regulação da pós-graduação no Brasil
Authors: Presser Nadi Helena , Araújo José Renato Da Silva , Araújo José Renato da Silva , Júnior Marcos Antônio Gomes Falcão
Published: October 2016

Este artigo apresenta reflexões sobre o processo decisório naesfera de ação que regula a pós-graduação das universidades públicase privadas e sobre as necessidades de informação subjacentes àtomada de decisão. O objeto empírico desta pesquisa estendeu suaação no ambiente informacional do Programa de Pós-Graduação emCiência da Informação do Departamento da Ciência da Informação daUniversidade Federal de Pernambuco. Entrevistas semiestruturadascom o coordenador do programa e o documento de área das CiênciasSociais Aplicadas I subsidiaram o estudo. Mesmo produzindoresultados complexos, identificou-se que muitas decisões racionaissão decompostas em elementos compreensíveis, e as necessidadesde informação que surgem do processo decisório são identificadas.
Mestrado profissional em Defesa Agropecuária: criação, implementação e resultados preliminares
Authors: Vilela Evaldo Ferreira , Callegaro Geraldo Magela , Gama Sofia Kiyomi Iba da
Published: October 2016

Este trabalho apresenta e discute a experiência pioneira doProjeto Inovação Tecnológica para Defesa Agropecuária – InovaDefesa(UFV, CTagro/MCTI e CNPq) – na implantação de cursos de mestradoprofissional em Defesa Agropecuária em universidades brasileiras,no período 2008-2012. Foram criados e estão em funcionamentomestrados em três universidades federais (UFV, UFRB e UFMG) e emoutras três também federais (UFPR, Ufra, Ufes) estão em preparaçãopropostas semelhantes. As informações utilizadas no preparo desteestudo foram obtidas de entrevistas com os coordenadores dosreferidos cursos, cujos principais beneficiários são organizações dosetor público, principalmente, a Secretaria de Defesa Agropecuária doMinistério da Agricultura, Pecuária e Abastecimento e as secretariasestaduais de Agricultura.
Perfil dos pesquisadores na área de Fisioterapia e Terapia Ocupacional no Conselho Nacional de Desenvolvimento Científico e Tecnológico
Authors: Freire Rafael Silveira , Oliveira Eduardo Araújo , Silveira Marise Fagundes , Martelli Daniella Reis Barbosa , Oliveira Maria Cristina L. , Júnior Hercílio Martelli
Published: October 2016

Este estudo avaliou o perfil dos bolsistas de produtividade científica da área de Fisioterapia e Terapia Ocupacional no Conselho Nacional de Desenvolvimento Científico e Tecnológico. Foram analisados os currículos Lattes de todos os pesquisadores das referidas áreas do conhecimento. As variáveis analisadas foram: gênero, categoria do bolsista, instituição de origem, tempo de conclusão do doutorado, artigos publicados, publicação de livros e capítulos e orientações de iniciação científica e pós-graduação. Entre os pesquisadores, houve predomínio do gênero feminino, com a maioria dos bolsistas na categoria 2, distribuídos por seis estados da Federação, com predomínio de São Paulo e Minas Gerais. Todos os bolsistas encontram-se vinculados a instituições de ensino superior. Esses resultados permitem uma reflexão sobre aprodução científica em áreas em expansão e podem propiciar discussões a respeito do aumento contínuo por financiamento junto às agências de fomento à pesquisa.
Innovatív szennyvíztisztítási módszer vizsgálata kommunális szennyvíz kémiai kezelésére
Authors: Truzsi Alexandra , Bodnár Ildikó , Fülöp Zoltán
Published: October 2016

A VízTEC Zrt. és a Debreceni Vízmű Zrt. vezetősége kölcsönösen kifejezte azon szándékát, hogy a debreceni szennyvíztisztító telep intenzifikálásának vizsgálatára vonatkozóan kijelöljön egy kutatási időszakot. Ezen időszak alatt a VízTEC Zrt. új fejlesztésű terméke, a VIRON Plus 40 koagulálószer kerül kipróbálásra. A kutatás célja a VIRON Plus 40-el történő intenzifikálás lehetőségeinek vizsgálata a debreceni szennyvíztisztító telepen. Az új generációs koagulálószerek feladatai a szervetlen foszfor kicsapatásán túlmutatnak, illetve egyre bővülnek. A modern szennyvíztelep már nemcsak megtisztítja a vizet, hanem energiát és hasznosítható iszapterméket állít elő. A megfelelő energiamérleg, költséghatékonyság és a szén-dioxid kibocsátás minimalizálása fokozódó hangsúlyt kap az üzemeltetésben.
Determination of calibration function for fatigue crack propagation by measurment surface deformation
Authors: Glaser B. , Gubeljak Nenad , Gubeljak P. , Veg A.
Published: October 2016

Components and structures exposed to elastic dynamic loading respond with elastic strains on the surface of the material. Mechanical response could be monitored by deformations on the surface. The measurements and monitoring of these parameters could be performed with electronic devices for on-line measurements, controlled by computerized systems. In the case of fatigue crack initiation and propagation the cyclic strain amplitude deviated from initial strain response (mean value and amplitude). Implementation of appropriate monitoring system supported by computerized programs for evaluation, analyses and activation represent important means to safe service component or construction. To evaluate flaw depth growth, the strain gauge measuring sensors could be used. These sensors measure surface deformation relaxation due to flaw depth growth. The monitoring of the material under cyclic loading could be performed with experimentally determined calibration curve, representing deformation on the surface and depth of the semi-elliptical crack growth on the surface or cross section of the material. The goal of this paper is describe electronic device and experimental procedure in order to determine calibration function.
New possibilities for weld assessment using inverse wavefield extrapolation
Authors: Wassink Casper , Chougrani K. , Van der Ent J.
Published: October 2016

New technological capabilities in both girth weld Non Destructive Testing (NDT) and girth weld material characterization open the door for new ways of weld assessment. The paper gives examples of new technologies currently being developed in NDT and investigates how these technologies could add value, in the field, on weld testing and assessment. The guiding principle in this investigation is that the data gathered in NDT should be sufficient for making an engineering decision. It will be argued that this is not currently the case as NDT is now used in a qualitative check on the welding process rather than a quantitative information source on the weld strength.An overview of technologies like Inverse Wave Extrapolation (IWEX), Full Matrix Capture (FMC), and Sampling Phased Array (SPA) will be given. These technologies show promise to increase the quality of data received from Automated Ultrasonic Testing (AUT) of pipeline girth weld. The most important improvement is that an image of the defect is generated, in three dimensions, which allows for improved assessment of the impact of detected flaws on the weld strength. The paper will then show how these new capabilities could be combined with new technology in material testing and finite element calculations, which has specific value for strain based pipeline designs. The result is a vision on the future of girth weld assessment.
Combined numerical-experimental framework for strain based design and flaw assessment of girth welds
Authors: Hertelé Stijn , Denys Rudi , Van Minnebruggen Koen , Verstraete Matthias , De Waele Wim
Published: October 2016

An increasing number of transmission pipelines have to be installed and operated in harsh conditions, due to the diminishing reserves of exploited fossil fuel sources. Under certain environment related circumstances, longitudinal plastic strains are imposed. When tensile, these may induce failure in girth welds in conjunction with the inevitable presence of weld defects. A large number of factors related to environment, material, geometry and operating conditions influence the tensile strain capacity and, hence, the acceptability of girth weld flaws. Therefore, a project specific development of guidelines in this strain based context is recommended. This paper provides systematic frameworks on (a) how to design pipelines under strain based conditions, and (b) how to assess girth weld flaws that were detected using non destructive testing. Attention is given to several technical and economical aspects related to the selection and qualification of pipe and weld metals, and to the evaluation of flaw acceptability. Both frameworks comprise a combined experimental-numerical approach, collecting project development reports from literature with research carried out at Soete Laboratory. Concretely, four in-house realizations are adopted: the UGent equation for strain capacity, the curved wide plate tension test, the UGent stress-strain equation and a finite element model of full scale pressurized pipe tension testing. The proposed frameworks aim to facilitate in performing thorough and economically justifiable strain based design and assessment processes.
Parametric finite element model for spiral welded pipes sections loaded in tension
Authors: Van Minnebruggen Koen , Thibaux Philippe , Van Wittenberghe Jeroen , Denys Rudi , De Waele Wim
Published: October 2016

Spiral welded pipes gain interest for oil and gas transportation in strain based design projects. Here, the structural response of the pipe with an environmentally imposed global plastic strain is of critical importance. However, a current lack of knowledge about the structural response of a spiral welded pipeline hinders the application in a strain based design context. This response is not only influenced by material properties, but also by geometrical characteristics. To understand these complex phenomena, finite element simulations can be considered. The finite element models need to incorporate all important factors to obtain a representative analysis. This paper describes the approach and structure used to develop such model. To obtain a high degree of automation and flexibility, the authors have developed a parametric script that allows creating a three dimensional curved wide plate test geometry taken from a spiral welded pipe. The model allows to modify pipe geometry, weld and heat affected zone geometry and material properties including Hill’s 1948 yield criterion to account for anisotropic material response. Pipe geometry includes helical forming angle, diameter, pipe profile and wall thickness with possible thickness variations. Weld and heat affected zone geometry include geometrical weld reinforcement of root and/or cap, fusion line profile and misalignment. A flaw, with variable size, is introduced in the weld metal or heat affected zone. To obtain an accurate description of the actual geometry, coordinate transformation schemes are incorporated that start from a flat plate with a simplified girth weld geometry. It is concluded that the proposed model is ready for use with a good view on mesh quality and output accuracy.
Evolution of anisotropy of sheet metals during plastic deformation
Authors: Safaei Mohsen , De Waele Wim
Published: October 2016

Sheet metals generally exhibit a considerable anisotropy due to their crystallographic texture. The mechanical anisotropic characteristics of the sheet metal have a great influence on the shape of the specimen after the deformation. Therefore many successful phenomenological models have been proposed for use in Finite Ele-ment (FE) codes to simulate the anisotropic behavior of a material. The anisotropy is mainly described on the basis of the initial Lankford coefficients and/or yield stresses along the orthotropic (rolling and transverse) and diagonal axes of the sheet metals. The different yield functions make use of different combinations of these constant parameters to represent a 3-dimensional surface (in case of plane stress) determining the transition between elastic and plastic deformation. Generally, the evolution of anisotropy is not considered in the formulation of a constitutive model. Therefore we studied the effects of plastic work on the evolution of anisotropic behavior. The experiments consist of conventional tensile testing of specimens taken at different orientations with respect to the rolling direction. Strain measurements are performed by means of an optical measurement technique. A simple (but powerful) technique for considering distortional anisotropy applicable to any yield criterion is presented. This technique is based on the polynomial definition for instantaneous Lankford coefficient combined with Newton-Raphson iteration. The same approach is applied for evolution of yield stress.
Alkali treatment and its effect on tribological properties of natrually woven coconut sheath polyester composite
Authors: Siva I. , Winowlin Jappes J.T. , Szakal Z. , Sukumaran Jacob
Published: October 2016

In the recent years natural fibres have drawn great interest for its bio-degradability, low cost and its availability in nature. Among different types of natural fibres, naturally woven coconut sheath fibres are one of the recently explored alternatives for synthetic fibres. These fibres are generally treated with alkali for enhancing mechanical properties and reinforcing characteristics. Tribological applications like gears, cams, bearings, etc. can be benefited from such composites. In most cases chemical treatment are done favouring the structural properties however, their influence on tribological properties are rather not considered. In the current research, hybrid composites (polyester resin with naturally woven coconut sheath (N) and glass fibres (G)) were tested against hardened steel counterface in a pin on disc configuration. Tests were performed at 40 N normal force and 3.5 m/s sliding velocity. From the results all hybrid combinations except (NNN) shows degrading wear properties with the alkaline treatment. The friction properties are modified by having low friction coefficients for all combinations except NGN and GGG hybrids. From the observed SEM images the surface morphology of NNN hybrid significantly differs from the rest of the combinations in both treated and untreated specimens. The partial removal of individual phase (resin) prevails in untreated specimen for which the fibres are highly visible. However, such phenomenon is not dominant in the alkali treated material showing better reinforcing behaviour complimenting low friction properties. The alkali treated specimen has reduced fibre size comparing the untreated specimen which results in low wear resistance. Compromise between friction and wear properties between each other the untreated fibres are best suited for tribological applications. Furthermore, investigations on treatment process and other treatments might have some influence in tribological behaviour.
TRIBOLOGICAL BEHAVIOUR OF THE LOW AND HIGH VISCOSITY PEEK AGAINST STEEL USING DIFFERENTS CONTACT PRESSURES
Authors: Rodriguez Vanessa , Sukumaran Jacob , Perez Yeczain , De Baets Patrick , Ando Matyas
Published: October 2016

In the market of polymers for tribological applications polyetheretherketone (PEEK) are often used for satisfying requests coming from industry regarding enhanced properties such as, thermal stability, friction and wear resistance. These properties promote the material to be used in so called high performance tribological applications. However, fundamental mechanisms governing friction and wear are not yet fully understood and neither is the influence of composition parameters. An important parameter is PEEK’s viscosity during manufacturing process which is heated up to semi-solid state, between its glass transition and melting temperature. This paper studies the friction and wear performance of low and high viscosity PEEK and pure PEEK under dry reciprocating sliding contact. The tests were performed in large scale specimens under flat-on-flat configuration to determine the transitions in tribological behaviour at different contact pressures. Tests were carried out at controlled atmosphere with 25 °C and a relative humidity of 50%. Contact pressures parameters were 4, 8 and 10 MPa used at a sliding speed of 20 mm/s. Post mortem analyses were carried out by means of 2-D surface topography and optical microscopy. The results show that the pure PEEK exhibits low coefficient of friction and wear rate when the contact pressure increase and similar behave for high and low viscosity PEEK.
FRICTION AND WEAR RESPONSE OF TiB2-B4C CERAMICS
Authors: Perez Yeczain , Bonny Koen , De Baets Patrick , Staia M. H. , Neis P.D. , Ferreira N.F. , Malek O. , Vleugels Jozef , Lauwers Bert
Published: October 2016

Rotating sliding wear experiments on TiB2-B4C have been conducted at room temperature (25 °C) in dry conditions according to the ASTMG99-95a standard. SiC balls were used as static counterpart. The disk specimens were surface finished by polishing. The tests were performed using different rotating sliding speeds from 0.1 up to 1.5 m/s with a mean Hertzian contact pressure of 1.2 GPa. Balls and disk specimens were analyzed by 2-D and 3-D surface topography, SEM and optical microscopy. The experimental results demonstrated that the sliding velocity influences both friction coefficient and wear rate values of TiB2-B4C ceramics. It was shown, that the wear rate varied between 3.64E-7 to 8.43E-7 mm3/Nm. Wear mechanisms such as polishing, abrasion and wear debris formation have been identified by means of SEM and EDX technique.
TRANSFER LAYER DYNAMICITY IN ROLL-SLIP OF POLYMER METAL PAIRS
Authors: Sukumaran Jacob , Rodriguez Vanessa , Nguyen TD , De Pauw Jan , Matyas Ando , De Baets Patrick
Published: October 2016

Polymer-metal pairs are found in many engineering applications, especially in rolling/sliding conditions. Transfer layer formation is imperative in friction and wear investigations on using these tribo-pairs. In the existing literature quantitative description was given for the formation of protective layer from the post mortem analysis (preferentially for sliding configurations). Since there is a dynamicity involved in the transfer layer the straight forward answer from the quantitative postmortem responses is rather uncertain. In the current research, rolling/sliding tests were performed for polymer and it’s composite against metal to explore the underlying mechanisms using both qualitative and quantitative approaches. The tests were performed with intermediate pauses to observe the surface changes where characterization based on surface morphology and roughness (Ra) are used. The results show that the transfer layer deposition occurs in four stages which are explained from the view point of change in Surface roughness Ra in correspondence to its micrographs of the surface topography. The four stages can be categorized as 1. Scouring 2. Running-in 3. Transition and 4. Steady stage. Results show that in polymers the Ra increases during the scouring stage subsequently it decreases on reaching the steady stage. In steel counter parts the Ra does not change significantly during the scouring period. However, the Ra increases in the running-in period followed by a transition region leading to a steady state. Among the polymer and its composites the pure polymer shows significant change in roughness due to the difference in strength. The change in Ra for steel in the steady region also depends upon the contact materials, the mechanical and tribological properties of the polymer. Thus the stages can be used to study the transfer layer behaviour and understand the underlying mechanism in segregating the wear mechanisms both quantitatively and qualitatively.
TRIBOLOGICAL BEHAVIOUR OF POLYMER BEARINGS UNDER DRY AND WATER LUBRICATION
Authors: Nguyen T.D. , Sukumaran J. , De Pauw J. , De Baets P.
Published: October 2016

This study attempts to evaluate the performance of polymer journal bearings (PET and UHMWPE) sliding against Inconel stainless steel in both dry and lubricated condition. Four types of ‘lubricant’ are included: distilled water; demineralized water; tap water and river water. The tests were carried out in a so called “Stribeck” configuration with a projected pressure of about 0.3 MPa at room temperature and sliding speed ranging from 0 to 1.07 m/s respectively. The study indicates that polymer bearings with four types of water lubricant give better tribological behaviour compared to those in dry sliding contact. Besides, with water lubrication, UHMWPE shows low friction at starting, but it does not go down much over the course of the tests. Meanwhile, although PET indicates quite higher friction at the beginning, it then shows a clearly decreasing trend.
Design of a fretting fatigue test rig with compliant springs
Authors: De Pauw Jan , De Baets Patrick , De Waele Wim , Hojjati-Talemi Reza
Published: October 2016

Fretting is a small amplitude oscillatory movement which occurs between contacting bodies who are subjected to cyclic loading or vibrations. In the contact area arise stresses -normal and tangential- causing stress concentrations and surface degradation. Fretting in combination with ordinary fatigue will reduce the plain fatigue lifetime due to the additional stresses and surface degradation. Applications susceptible to fretting fatigue are for instance connections techniques. By nature they have contacting bodies and transfer loads or vibrations. Connection techniques commonly seen in the field of fretting fatigue are lap-joints, dovetail connections and spline connections.Although mitigating or managing fretting fatigue is industrially relevant, academic research is confined and only revealed basic insights. Therefore, we developed a fretting fatigue test rig at Soete Laboratory. The paper describes the design of the test rig and points out some important features. To study the general phenomenon of fretting fatigue we selected a coupon scale test rig rather than a full scale test rig where only one application can be studied. The specimens used are one dog bone specimen and two indentation pads which make contact with the dog bone specimen. The normal force FN between the specimen and the pads is close loop controlled with a hydraulic actuator. A second hydraulic actuator controls the dynamic force Ffat in the dog bone specimen. A third force FT is introduced during dynamic loading between the dog bone specimen and the pads by means of compliant springs. The combination of these three forces: FN, Ffat, FT in the contact area gives rise to the fretting fatigue phenomenon. The test rig at Soete laboratory can be used to study fretting fatigue and examine mitigations such as surface texturing, surface work hardening, etc.
Survey on techniques to detect micro-cracks in steel after bending
Authors: De Smedt B. , Abdel Wahab M. , Hojjati R. , Hertschap K.
Published: October 2016

In this paper, different methods to detect micro-cracks were compared. Their capability of detecting fatigue induced micro-cracks in metal was evaluated, as well as the possibility to apply them to detect micro-cracks induced by bending in steel plates. All methods found in literature use one of fourdifferent physical phenomena. Out of these methods, the use of magnetic induced Eddy Currents and the use of Digital Image Correlation proved to be most interesting to detect micro-cracks in steel plates after bending. Also an FEA analysis was performed to detect the critical zones in bended specimens
Influence of notch orientation on ductile tearing in SENT specimens
Authors: Turtelboom Robin , Vandenbroucke Pieter , Van Minnebruggen Koen , Hertelé Stijn , Verstraete Matthias , De Waele Wim
Published: October 2016

There is a growing interest for the use of spiral welded pipes in strain based design related applications. Since the influence of the spiral weld on the plastic behaviour of the pipe is not yet fully understood, further research on this topic is required. An important aspect of this plastic behaviour is the effect of mixed mode loading on weld defects located in the helical weld. This paper elaborates on the first experimental trials to evaluate ductile tearing by means of single edge notched tensile specimen (SENT) testing with slanted notches. Tests were performed on two SENT specimens, one with a slanted notch and another with a straight notch in order to investigate the influence of mixed mode loading. The crack mouth opening displacement and crack extension were determined experimentally by means of digital image correlation and potential drop measurements respectively. The crack extension and the potential drop measurements were related by means of finite element simulations.
Review on the possible tool materials for friction stir welding of steel plates
Authors: Sierens Arne , Vanvooren Jasmien , Deplus K. , Faes Koen , De Waele Wim
Published: October 2016

The friction stir welding (FSW) process is mainly used in industrial applications for joining low melting temperature materials such as aluminium and magnesium. FSW has many advantages in comparison with conventional fusion arc welding. Therefore the interest to use this technique for joining steel plates has grown. However such usage is still limited because of the lack of adequate tool materials. This review gives an overview of possible tool materials for FSW of steels focussing on tungsten, tungsten carbide, pcBN and a few ultra-high temperature ceramics.
SCAD Journal Volume 6, Issue 1
Authors: Hertelé Stijn
Published: October 2016

SCAD Journal Volume 6, Issue 1, First pages