bluuebunny/crossref_metadata_2025 huggingface dataset:
Análise cinemática da locomoção de velocistas de 100m em ambiente específico de prova nas situações de andar, trotar e sprint
Authors: Barbosa Maria Stella Dias , Misuta Milton Shoiti
Published: March 2019

A análise biomecânica pode auxiliar via descrição do movimento de atletas por meio da quantificação de variáveis cinemáticas visando a identificação de padrões de movimento e assimetrias entre os membros visando melhorar o desempenho ou prevenir lesões. O objetivo consistiu em: a) determinar a trajetória do centro de massa nas situações de andar, o trotar e o sprint; e b) determinar o comprimento de passo, largura do passo, comprimento da passada, largura da passada nas situações de andar, o trotar e o sprint.
Caracterização metabólica e análise da expressão de miR-122 hepático na 2ª geração de mães alimentadas com dieta hiperlipídica durante a gestação e lactação
Authors: Mancini Mariana Camargo Silva , Torsoni Adriana Souza , Simino Laís Angélica de Paula , Panzarin Carolina , Fontana Marina F. , Torsoni Marcio Alberto , Milanski Marciane
Published: March 2019

A sobrecarga nutricional durante a gestação e o período pós natal precoce podem estar estreitamente relacionadas com o desenvolvimento de alterações permanentes na estrutura, fisiologia e metabolismo tanto da geração exposta diretamente ao estímulo da sobrecarga como à seus descendentes. Com objetivo de caracterizar importantes parâmetros bioquímicos e avaliar a expressão do miR 122, significativo no contexto da obesidade, do metabolismo energético, glicídico e lipídico e da programação metabólica, o presente estudo foi realizado com a segunda geração (F2) de proles provenientes de mães com obesidade induzida por dieta hiperlipídica durante períodos críticos do desenvolvimento, como a gestação e a lactação, para se avaliar os efeitos da obesidade materna em seus descendentes.
Análise estatística de grafos
Authors: Vallim Mariana Damião , Pinheiro Aluisio de Souza , Yasuda Clarissa Lin
Published: March 2019

A análise estatística é parte fundamental do estudo sistematico de modelos funcionais e estruturais de neuroimagens. Em particular, há um interesse no estudo das diferenças ao longo do tempo, funcionaiis e estruturais, entre pessoas com diagnósticos de quadro clínico normal e pacientes diagnosticados com eplepsia do lobo temporal. Por sua natureza, as neuroimagens são naturalmente representadas por grafos.
Avaliação da espessura de tecido mole craniofacial em indivíduos brasileiros de diferentes classes esqueléticas e tipos faciais
Authors: Zanon Mariana Fabbro , Neto Francisco Haiter , Gomes Amanda Farias , Moreira Debora Duarte , Groppo Francisco Carlos , Freitas Deborah Queiroz de
Published: March 2019

A Reconstrução Facial é um método auxiliar no processo de identificação de corpos decompostos ou esqueletizados. Uma das informações necessárias para a realização desse procedimento é a espessura de tecido mole craniofacial. Na população brasileira, há poucos trabalhos acerca da influência do padrão esquelético facial na espessura de tecido mole craniofacial. Assim, o objetivo neste estudo foi avaliar a espessura de tecido mole craniofacial nas diferentes classes esqueléticas e tipos faciais, por meio de exames de tomografia computadorizada de feixe cônico (TCFC). Foram analisadas 160 imagens de TCFC (80 homens e 80 mulheres, com idades entre 21 e 40 anos). Os pacientes foram classificados em Classe I, Classe II ou Classe III e em braquifacial, mesofacial ou dolicofacial. As mensurações de espessura de tecido mole em região de perfil facial foram realizadas em 10 pontos anatômicos, utilizando-se o CS 3D Imaging Software® 3.4.3. Todas as mensurações foram realizadas por dois examinadores em consenso. Observou-se que a espessura de tecido mole foi maior nas regiões de lábio superior e estômio de indivíduos classe III quando comparados aos das classes I e II, sendo estatisticamente significante. Houve diferenças estatisticamente significantes entre os tipos faciais na espessura de tecido mole nas regiões de lábio superior, estômio, lábio inferior e labiomental. Pode-se concluir que a classe esquelética e o tipo facial influenciam na espessura de tecido mole craniofacial.
Internacionalização na Unicamp
Authors: Volpato Mariana Kataoka , Andery Helena Maria Santana Sampaio
Published: March 2019

A internacionalização do ensino superior como parte de processos mais amplos de globalização é fenômeno da contemporaneidade (Aupetit, 2005; Knight 2012; Lima e Contel, 2011). No Brasil, desde este século, a internacionalização passou a fazer parte da agenda das políticas nacionais para o ensino superior e consolidou-se também como tema de investigação acadêmica (Morosini, 2006; Sampaio e Saes, 2014). A Unicamp participa duplamente desse processo: como produtora, por meio de seus pesquisadores, de conhecimento sobre o tema e também como protagonista de iniciativas de internacionalização no contexto do ensino superior do país. Este projeto de pesquisa propõe entender como ocorre a internacionalização na Unicamp tendo como recorte empírico os seus cursos de engenharia. Para atingir esse objetivo, a pesquisa recorre a diversos procedimentos metodológicos: levantamento e análise de dados quantitativos sobre mobilidade estudantil e docente, pesquisa documental, entrevistas semi estruturadas com coordenadores de cursos e aplicação de questionário aos intercambistas de cursos de engenharia da Unicamp.
Caracterização da epidemiologia e perfil de resistência bacteriana e a conduta médica adotada para as Infecções do Trato Urinário não complicadas de origem comunitária em um pronto atendimento
Authors: Medeiros Mariana Real Bispo , Moriel Patricia , Mattos Karen Prado Herzer , Ribeiro Mayra Carvalho
Published: March 2019

O presente estudo busca traçar o perfil de sensibilidade do principal causador de ITU’s e compreender a conduta médica adotada para casos de ITU’s não complicada de origem comunitária. Para isso, foi feito o levantamento de prontuários de atendimento durante o 1º semestre de 2017 e o levantamento de todas as uroculturas positivas para E. Coli no período de 01/10/2015 a 30/09/2017. A hipótese que motivou, e foi provada no estudo, foi de que uma vez que não existe protocolo de tratamento de ITUs na Unidade de Atendimento Referenciado (UER) do Hospital de Clínicas da Universidade Estadual de Campinas (HC/UNICAMP), muitas culturas seriam solicitadas sem necessidade; que não haverá uma prescrição padrão seguindo o que está recomendado pelo Ministério da Saúde; e haverá um número grande de bactérias resistentes ao antibiótico prescrito. Com os dados obtidos até então não é possível distinguir um padrão entre os atendimentos realizados no PS-UER HC/UNICAMP para hipótese diagnóstica de ITU não complicada, evidenciado pela divergência importante na prescrição e duração de tratamentos antimicrobianos, tratamentos complementares e exames. Tal fato é alarmante pois infecções de trato urinário são uma das causas de infecção mais frequente na população e estão sujeitas a aquisição de resistência com grande facilidade e em muitos casos as opções terapêuticas estão restritas.
Mudanças e continuidades dos marcos legais do curso de pedagogia no Brasil
Authors: Brandt Andressa Graziele , Hobold Márcia de Souza
Published: March 2019

Objetiva-se na presente pesquisa analisar os quatro marcos legais do curso de Pedagogia no Brasil, no que se refere as mudanças e continuidades acerca dos currículos para a formação de professores. Apresenta-se como questão central de pesquisa: Para atingir a proposta aqui elucidada, propusemo-nos a responder ao seguinte questionamento: Que elementos de continuidade e de mudança estão expressos nos quatro marcos legais do curso de Pedagogia no Brasil? É uma pesquisa de abordagem qualitativa, com desenvolvimento de análise documental da legislação do curso de Pedagogia, por meio da técnica a análise de conteúdo para a obtenção/elaboração das análises propostas. Os autores basilares dessa pesquisa são Bissolli da Silva (2010) e Scheibe (2003). Os resultados parciais mostraram os quatro marcos legais que constituíram os currículos dos cursos de Pedagogia ao longo de sua constituição histórica, são: 1) Decreto-lei nº 1190/1939; 2) Parecer nº 251/62; 3) Parecer nº 252/69; e Resolução CFE nº 2/69; e 4) Parecer CNE/CP nº 5/2005; e Resolução CNE/CP nº 1/2006. Constatou-se que os quatro marcos legais apresentam elementos de mudança e continuidade que influenciaram diretamente a constituição histórica dos currículos de formação de professores no país.
Da universidade à commoditycidade
Authors: Mikolaiczyk Fernanda de Aragão
Published: March 2019

Refletir sobre a Universidade, historicamente concebida como locus da Educação Superior, interessa a todos que vivem em sua órbita – estudantes, professores, técnicos –, como àqueles que a veem como importante instituição produtora de saber científico e formação humana integral. Por isso mesmo, constituiu-se, ao longo do tempo, como síntese das relações sociais em que esteve inserida. No século XXI, disputa-se a hegemonia econômica, política e cultural sobre esse nível de ensino, interesses sociais burgueses perpassam os projetos educativos realizados nas Instituições de Ensino Superior (IES), coerentemente alinhados ao atual estágio de desenvolvimento capitalista: o financeiro. As discussões postas para debate na obra objeto desta resenha – Da universidade à commoditycidade: ou de como e quando, se a educação/formação é sacrificada no altar do mercado, o futuro da universidade se situaria em algum lugar do passado –, de autoria de Lucídio Bianchetti e Valdemar Sguissardi, situam o leitor quanto ao projeto de classe burguês que a domina, materializado nas formas mercantis que a atingem.
Formação profissional e CTS
Authors: Silva Sidney Reinaldo da , Fernandes Rodrigo Rafael
Published: March 2019

Este texto faz uma abordagem dos princípios da formação profissional dos Institutos federais (IFs) e sua correlação com a abordagem Ciência Tecnologia e Sociedade (CTS). Seu objetivo foi mostrar como os IFS contribuem para pensar a formação profissional na perspectiva CTS, isto é, de forma socialmente engajada. A partir de uma apresentação crítica do campo CTS e do tipo de formação profissional a ele associado, foram indicadas as bases ético-políticas da educação no IFs retomando o documento relativo a suas concepções e diretrizes e a lei de sua criação, a Lei nº 11.892. Mostra-se que os Ifs se apresentam como um espaço privilegiado para a formação CTS, podendo ser ocasião para a associação dessa com uma concepção de formação profissional de trabalhadores, pesquisadores e cidadãos capazes de intervir nos processos de decisão pública envolvendo ciência tecnologia.
Educação superior como bem público
Authors: Scoz Emanuella
Published: March 2019

Este texto é uma resenha crítica da obra de Marco Antonio Rodrigues intitulada Educação Superior como bem público, que evidencia o atual curso do ensino superior no mundo. Nesta obra o autor constrói uma crítica saudosista do ensino superior atual e suas vertentes mercantis, lembrando os conceitos humanistas e libertários contidos no tratado de Córdoba de 1918, e na Conferência Mundial do Ensino Superior de 1998. Análise construída para o evento de comemoração dos 25 anos de criação da AUGM , em setembro de 2016, ao qual o autor foi convidado a escrever pontuando projeções para o futuro da educação superior como um bem público analisando os aspectos positivos e negativos do passado.
A Reforma de Córdoba de 1918
Authors: Hayashi Marcelo Innocentini , Hayashi Maria Cristina Piumbato Innocentini
Published: March 2019

No marco do centenário da Reforma de Córdoba, este estudo investigou como se configura a produção científica sobre a reforma universitária e apresenta um balanço das pesquisas que analisaram desde o significado desse movimento ocorrido na Argentina em 1918, até seus e impactos e projeção futura no contexto das universidades da América Latina e do Caribe. O estudo exploratório e descritivo está consolidado em um estado de conhecimento que tomou como objeto de estudo artigos científicos (n=90) disponíveis em bases de dados de acesso aberto publicados em periódicos científicos (n=47) de diferentes países (n=13) no período entre 1978 e 2018. A metodologia adotada combinou a análise bibliométrica e análise de conteúdo e os procedimentos metodológicos foram desenvolvidos nas seguintes etapas: coleta e registro dos dados em uma planilha eletrônica; leitura dos textos completos dos artigos; estabelecimento de categorias de análise; descrição, síntese e análise dos dados. Os artigos foram categorizados em dois grupos: aqueles que abordaram o contexto histórico social e político da Reforma, os princípios do Manifesto Liminar e seus impactos nas universidades argentinas (n=51), e os que focalizaram o legado do pensamento reformista enquanto momento de ruptura e continuidade na história das universidades latino-americanas (n=39). Em seguida foram estabelecidas subcategorias temáticas e as mais frequentes foram: autonomia e extensão universitárias, intelectuais, estudantes e movimento estudantil. Poucos estudos problematizaram questões como gênero, teologia política no movimento reformista, e oposição à Reforma Universitária.
Water-Based Drill-In Fluid Optimization Using Polyelectrolyte Complex Nanoparticles as a Fluid Loss Additive
Authors: Whatley Lucas , Barati Reza , Kessler Zach , Tsau Jyun-Syung
Published: March 2019

It is well known within the industry that conventional drilling fluids can damage the well's producing zone. Damage mechanisms occur due to leakage of drilling fluid into the formation even after the formation of a filter cake. This filtrate contains entrained particulates that can enter the pore spaces of the rock and restrict flow through the pore throats resulting in reduced permeability during production. Cleaner drill-in fluids with low solids content have been developed for use when drilling through a producing zone in an attempt to mitigate the extent of damage caused by leak-off. These fluids should not only provide excellent fluid loss prevention, but also exhibit the rheological characteristics needed to perform the traditional functions of conventional fluids. Even though these fluids reduce the amount of particulates entering the formation by containing less solids, the filtrate that is still able to flow through the filter cake can be equally as damaging. Reduction of filtrate volumes can be further achieved by introducing nanoparticles to bridge across the nano-sized gaps within the filter cake. This research focuses on the application of polyelectrolyte complex nanoparticles (PECNP) as a fluid loss additive to further enhance the filter cake filtration properties of a general drill-in fluid. A baseline fluid is formulated consisting of a sodium chloride brine, biopolymers for rheology and fluid loss purposes, and calcium carbonate as a density and bridging agent. The ratio and pH of polyelectrolytes were optimized in order to create stable PECNPs for this system. Different dilutions of PECNPs were added and tested in a static fluid loss setup, where filtrate volumes were compared to determine the best system of 1/8th diluted nanoparticles. The chosen system was then taken to be tested in the dynamic fluid loss setup "Quasimodo" where fluid loss volumes were successfully reduced and wall building coefficients lowered. Analysis of cleanup curves after testing revealed that the PECNP drill-in fluid was less damaging to the core permeability than when the baseline fluid was used.
Evaluation of Silica Matrix Ion Effects on Barite Scale Inhibitors
Authors: Zhao Yue , M. Sriyarathne H. Dushanee , Harouaka Khadouja , Paudyal Samridhdi , Ko Saebom , Dai Chong , Lu Alex Yi-Tsung , Deng Guannan , Wang Xin , Kan Amy T , Tomson Mason
Published: March 2019

Silica is ubiquitous in oil and gas production water because of quartz and clay dissolution from rock formations. Furthermore, the produced water from unconventional production often contains high Ca2+, Mg2+ and Fe2+ concentrations. These common cations, especially iron, can form aqueous or surface complexes with silica and affect the nucleation inhibition of other scales such as barite. Thus, it is important to investigate the silica matrix ion effects on barite scale inhibitors efficiency to evaluate inhibitor compatibility with silica and common cations in produced waters.

In this study, experimental conditions were varied from 50 mg/L to 160 mg/L SiO2 in the presence of Ca2+ (1,000 and 16,000 mg/L), Mg2+ (2,000 mg/L) and Fe2+ (10 mg/L) at 70°C and neutral pH conditions, all with a background of 1 M NaCl. Our laser scattering apparatus was used to study the effect of silica matrix ions on barite nucleation inhibition [Yan et al., 2015]. For the experiments with redox-sensitive cations (such as Fe2+), a novel anoxic apparatus along with laser scattering apparatus was used. Phosphonate, carboxylate and sulfonate inhibitors were tested. All inhibitors tolerated the experimental conditions with silica. The inhibition efficiency of phosphonate inhibitor DTPMP was impaired by high Ca2+ and Mg2+, and the addition of silica would not affect this result. The polycarboxylic acid inhibitor PPCA tolerated high Ca2+ and Mg2+ conditions, and adding silica did not have influence on this behavior. The polymeric inhibitors, such as PVS and PPCA, also tolerated the experimental conditions with Fe2+ and Fe-silica. Fe2+ significantly impaired the inhibition performance of DTPMP. This may be due to the formation of an Fe(II)-DTPMP precipitate. The detrimental effect of Fe2+ on DTPMP could be reduced, to some extent, by adding silica, which might be due to the formation of Fe-silica complex and the reduction of Fe2+ impact on phosphonate.
A High Temperature and Salt Resistance Supramolecular Thickening System
Authors: Ma Yingxian , Ma Leyao , Guo Jianchun , Lai Jie , Zhou Han , Li Jia
Published: March 2019

We prepared physically linked allyl alcohol polymer/polyacrylamide double network hydrogels via one-pot strategy. These double network supermolecular fracturing fluids were found to have a better viscosity at high temperature compared to the conventional polyacrylamide systems. After testing with a rheometer, the fluid viscosity could stay 320 mPa s at 150 °C under 170/s shear rate. With NMR and FT-IR results' help, we determined that abundant polar groups of chains were still free, which could complex ions to keep, even enhance the chain stability. Thus, these double network systems showed excellent salt resistance with the non-covalent interactions and physical entanglements, and the viscosity of the allyl alcohol polymer/polyacrylamide system did not drop but increase. The viscosity in high salinity could increase nearly 40 % compared with the initial situation. Overall, the novel fracturing fluid system could maintain a high viscosity and better rheological properties under high salinity and showed excellent high-temperature stability, to make up the lack of fracturing fluid at this stage. It is expected to potential fluid issues caused by low water quality and harsh downhole temperatures were resolved or mitigated.
Out with the Old: Developing a New Test Methodology for Paraffin Wax Dispersion and Inhibition Testing
Authors: Miller Amanda , Smith Rashod , Dufresne Brad , Mahmoudkhani Amir
Published: March 2019

Traditional test methods to evaluate dispersion and inhibition of paraffin wax, which are mainly based on wax gelation and deposition, often fail to distinguish and differentiate between classes of chemistries at a reasonable resolution. Recommended products based on such lab screenings sometimes have a difficult time proving success in the field. The rush for oil production from unconventional shale plays in North America create a need for quick and elaborate testing to effectively evaluate new products for prevention and remediation of known paraffin wax issues. This paper will present a progress made in this area.

For our studies a model oil system was used, which consists of field wax deposit dissolved in kerosene. Testing with a model oil allowed us to focus on the chemistries that are effective against paraffin chains known to cause issues. Several different testing conditions were used to push the ability of the chemistries to function. Light scattering was used to monitor transition from turbidity to sedimentation of paraffin wax from bulk solution under static or dynamic conditions. A total of twelve compounds from three classes of polymers and three classes of surfactants were used in treatment of these oil systems.

With this new lab testing methodology, we have been able to discover new insights on the chemistries used for paraffin wax dispersion and inhibition. In contrast to methods which only measure the end point, light scattering and transmission methodology provides system details at time intervals of 30 sec or higher. The method also allowed us to differentiate chemistries based on their impact on the separation index and sedimentation rate of targeted paraffin chains under stressed conditions by forced precipitation. It was found that certain classes of chemistries are more suited for dispersion and inhibition of waxy condensates once system passed the critical point, while others fail over time. This new approach is fast and versatile and must be used as part of a suite of lab and field screenings for product development and recommendation.

New methodology based on light scattering and transmission of oil systems can provide details not seen before on colloidal stability or instability of waxy crudes under stressed conditions. The method gives an even greater insight to how different chemistries function to mitigate known paraffin issues. Quantitative and reproducible data are obtained allowing faster screening of various chemistries and enhancing product development for new and aging fields.
Internal Viscoelastic Surfactant Breakers from In-Situ Oligomerization
Authors: Daeffler Christopher , Perroni Dominic , Makarychev-Mikhailov Sergey , Mirakyan Andrey
Published: March 2019

Viscoelastic surfactants (VES) are important gelling agents in well stimulation treatments. Proper job design requires that the additives create the desired viscosity for effective proppant or gravel pack sand transport. Post-stimulation production enhancement partially relies on the thoroughness of gelling agent destruction or removal, known as "breaking" the gel. VES gels are non-damaging and do not create a filter cake, and thus are prone to high leak-off. The leak-off fluid potentially has a high zero-shear viscosity and can be challenging to remove from the formation. We propose a breaker system that comprises a monomer and radical initiator that will travel into to the formation with the VES gel. The resulting polymer will disrupt the worm-like micelles of the VES, creating spherical micelles and reducing the viscosity of the fluid. The breaker system presented here is operable at 200 °F. Rheology measurements show that the VES fluid with monomer and initiator has reduced viscosity and becomes less shear-thinning. Optical transmission and backscattering measurements show that the presence of breaker does not greatly accelerate proppant settling. The reduced viscosity would not adversely affect proppant transport. Core flow experiments compared retained permeability of cores treated with VES and VES with reacted monomer and initiator. The core flushed with broken fluid possessed a retained permeability of 79%, while the unmodified VES left only 44% retained permeability.
Production Chemistry Issues and Solutions Associated with Chemical EOR
Authors: Graham Gordon M. , Frigo Dario M.
Published: March 2019

Chemical EOR is an increasingly employed approach used to enhance oil recovery by combining changes in fluids mobility, macroscopic sweep, interfacial tension, etc. to essentially improve, or extend the economic life of a water flood. It includes flooding with polymer, surfactant, alkaline/surfactant, alkaline-surfactant-polymer (ASP), CO2 and / or other miscible gases which is often combined with waterflood (e.g., CO2 WAG) etc. However, the improved oil recovery is often accompanied by physical and chemical changes in the produced fluids that cause many production-chemistry (PC)-related challenges when fluids subsequently arrive in the production system, including exacerbation of scale and naphthenates deposition, carboxylate deposits associated with injected polymer, enhanced corrosion and separation issues, etc. Understanding and predicting the production chemistry challenges at producers are further complicated by chemical changes as the fluids propagate through the reservoir such as reaction with reservoir formation minerals, chemical retention, chemical degradation and hydrolysis, etc. More importantly the implications for the production system and processing facilities are not always accounted for and proactively managed.

The paper evaluates the main chemical changes that occur in the system for each EOR approach –– and shows how these changes, including in situ reservoir reactions and the stability/instability of the EOR packages themselves can exacerbate a range of PC-related challenges especially when considering the likely production of up to three different fluids: formation water, the EOR flood medium and any previous flood water from previous secondary recovery

The paper includes modelling results, laboratory results to validate model predictions as well as examples from field case studies to illustrate the impact of the chemical changes referred to above. Specific highlights include the impact of the use of either high- or low-pH EOR fluids on scale control, corrosion control and asphaltenes control; for scale it examines both inhibitor performance per se as well as retention onto rock during squeeze treatment. Also illustrated are the risk of carboxylate-based deposit derived from polymer flood, and the phenomenon of carboxylate-based solids and soaps, which can exacerbate the separation of an already highly challenging system.

The overall conclusion is that chemical EOR can have significant impact on PC and that these should not just be considered at the design stage and not just for the injection system but also to take into account the impact these may have on production wells following breakthrough of flood waters, showing that essentially each new or exacerbated PC issues can be predicted or at least anticipated with the required degree of confidence before implementation of EOR.
Innovative Acidizing Solutions for Severely Damaged Clay-Rich Sandstone Reservoir with Gravel Pack Completions in Offshore Myanmar
Authors: Kim DongKyoon , Bae Youngwoo , Liu Hai
Published: March 2019

Acid stimulation in sandstone reservoirs containing significant amount of clays can end up with undesired results due to unexpected reactions between stimulation fluids and formation clays. This paper demonstrates how heavily damaged clay-rich sandstone reservoir completed with cased hole gravel pack (CHGP) in offshore Myanmar can be successfully established for commercial production with organic clay acid stimulation treatment. The formation is laminated dirty sand with very high clay content (up to 30%) and large gross height (>100m MD). Production logging results showed only a small portion of perforated intervals contributing to production. Thus, an appropriate stimulation treatment is required to unlock well potential and prevent screen failures from concentrated flow through a small interval.

Given high clay content as well as presence of acid sensitive clays, conventional treatments using HCl as preflush and hydrofluoric (HF) acids as main fluids would result in potential damages from secondary and tertiary reactions. Furthermore, undissolved clays in the critical matrix left over from the treatment would potentially migrate and plug the pore throat. The new acid system was designed to generate small amount of HF in-situ (∼0.1%) at any given time with total strength of 1% HF, which would greatly minimize second and tertiary reactions and also permits acids travel deeper into the formation. Furthermore, the reaction products would react with the clays and physically "welding" the undissolved clays to the surface of the pore spaces permanently and prevent them from migration.

The treatment was designed in three stages: 1) screen and gravel pack cleanup using coiled tubing (CT) jetting; 2) injectivity test; 3) main treatment consisting of acetic acids as preflush, and new acid system as main fluids followed by overflush. A newly designed linear gel containing relative permeability modifier was used for diversions. Two underperforming CHGP wells were treated, and both wells yielded 100% increase in productivity with no fine production observed at the surface.

The success of the campaign owes to the sophisticated engineering workflow which starts from diagnostic of the damage zone and root-cause of the formation damage, followed by detailed analysis of various skin components using radial numerical reservoir modeling for all the reservoir layers that led to a proper treatment strategy and fluid design based on the damage and formation mineralogy as well as comprehensive laboratory tests. This has helped to minimize the risk of the treatment and eventually unlocked the production from the heavily damaged sandstone reservoir.
A Unified Experimental Method and Model for Predicting Scale Inhibition
Authors: Dai Chong , Dai Zhaoyi , Zhang Fangfu , Zhao Yue , Deng Guannan , Harouaka Khadouja , Wang Xin , Lu Yi-Tsung , Paudyal Samiridhdi , Ko Saebom , Gao Shujun , Kan Amy T. , Tomson Mason
Published: March 2019

Scale formation that can hinder continuous oil production is a serious problem in oilfield. Among all common scales, barite and calcite are two of the most important scales. Scale inhibitors have been widely added to prolong the induction time of scales. This study evaluates the methods and previous inhibition models to measure and predict scale formation in the presence of phosphonate and polymer inhibitors under common brine conditions. Turbidity measurement with laser light was used accurately and quickly to measure the induction time, and good reproducibility can be achieved between different sources of inhibitors. By conducting a set of independent inhibition experiments, previous models were evaluated and the demand for model improvement was carefully pointed out. On the basis of these evaluations, new ScaleSoftPizer (SSP) model was proposed by incorporating all available data under various simulated oilfield conditions (4-175°C). The new SSP barite inhibition model was more internally consistent, and the new SSP calcite inhibition model expanded the applicable temperature ranges. The new SSP model was incorporated into SSP 2019. To prove the application of new SSP model, the predicted minimum inhibitor concentrations (MICs) were compared with lab observations and field data, which shows good consistence and improvements. This study improved the prediction of MIC over wide ranges of temperature and inhibitor types, which can significantly reduce the expenses and efforts to solve scale formation problems.
A More Effective Solution to Treat Paraffinic Crude Oil Wells
Authors: Phan T. , Faust M. , Balsamo V. , Champion Nalco
Published: March 2019

Production from highly paraffinic crude oil wells poses unique technical challenges such as poor flowability and paraffin deposition on the production tubing. Paraffin deposition increases the lift load on the pump, reduces pump efficiency, and eventually plugs the pump. To restore the productivity of these wells a common solution is to inject hot oil or hot water at 160°F–200°F to clean the deposits. This process imposes higher operating cost and lost production due to well downtime.

Paraffin inhibitor (PI) and pour point depressant (PPD) have been used to treat paraffinic fluids but are not effective for wells with high water cuts. These wells when treated with PI/PPD still require high cost maintenance such as the hot oil/water jobs and/or well workover. This paper presents a more effective treatment using tailored chemical mixtures to form a water dispersion with the paraffinic oil, thus to increase oil flowability and reduce deposition. A novel test method has been developed to evaluate effectiveness of treatment chemicals on various paraffinic oils based on flowability and cleanliness. The test method has been validated with field trial data from three different wells in the Uinta Basin, Utah and Julesburg Basin, Colorado.

The results of the field trials showed a significant increase in pumping efficiency and crude oil production. Need for hot water application was also reduced or eliminated for the treated wells. Improved oil and produced water quality were also observed. These results demonstrated that the water dispersion-based treatment is a more effective treatment for high paraffin wells with high water cuts.
Role of Surfactant Structures on Surfactant-Rock Adsorption in Various Rock Types
Authors: Wilson Daniel , Poindexter Laurie , Nguyen Thu
Published: March 2019

Adsorption of surfactant onto rock surfaces is dependent upon a number of factors, including characteristics of both the adsorbent and surfactant molecules. Considering that surfactant-based unconventional means to improve oil recovery are strongly dependent on the interaction at the liquid/liquid interface between soluble surfactant solution and crude oil, loss of surfactant to liquid/solid interfaces can create a negative effect for some of these applications in terms of performance and economics.

This study; therefore, focuses on investigating the adsorption mechanism of surfactants onto sandstone and limestone reservoir media. Besides quantifying how much surfactant is adsorbed, emphasis specifically on the effect of surfactant parameters on the adsorption capacity was evaluated. Although literature well documents that mineralogy, temperature, pH, inclusion of other chemicals, and salinity all play strong roles on the adsorption capacity of surfactants on a solid surface; all of these parameters, with exception of mineralogy, were maintained as constants for this work.

Anionic alcohol propoxy sulfate, nonionic alcohol ethoxylate, and ether carboxylate surfactants were studied. Academic focus for this effort was placed on surfactant parameters being evaluated including the structure of the surfactant hydrophilic head group and the surfactant hydrophobic tail. The number of mechanisms involved in surfactant loss from aqueous solutions to assorted porous media adds to the complexity of this phenomenon. Experimental results show that various surfactant parameters affect the adsorption differently based on their interaction with different adsorbents. An increase in hydrophobicity appears to increase surfactant adsorption. This was observed through a number of different mechanisms including increasing percent of propylene oxide (PO) and increasing degree of hydrophobe branching of the surfactants. Conversely, increasing carbon chain length and keeping the percent of PO more constant appeared to show a general decrease in adsorption trend with alcohol propoxy sulfate and a discernible decrease in adsorption in sandstone versus limestone mineralogy. It was also observed that varying ratios of propylene oxide and ethylene oxide extensions to alcohol alkoxy sulfate molecules will have an influence on surfactant adsorption.

Surfactant properties provide information on the type and mechanism of interactions involving surfactant molecules at the solid/liquid interface and their efficiency as surface-active agents. The findings from this study can be used to improve understanding on how the role of different surfactant parameters may affect surfactant adsorption. This will help lead to enhancements in designing surfactant molecular structures that in turn minimize adsorption to rock surfaces, while maintaining desired fluid performance for effective oil recovery.
What Can We Learn from Analysis of Field Asphaltenes Deposits? Enhancing Product Development Through Knowledge-Based Field-to-Lab-to-Field Approach
Authors: Da Silva de Aguiar Janaina Izabel , Pimentel Porto Mazzeo Cláudia , Garan Ron , Punase Abhishek , Razavi Syed , Mahmoudkhani Amir
Published: March 2019

Recent studies revealed that solids from lab-generated deposits often exhibit compositional differences from those of field deposits, pointing to a more complex fouling process in field operations. The objective of this work was to understand and apply knowledge from field deposit characteristics in order to design and conduct laboratory experiments which yield solid deposits with comparable compositional fingerprints. This approach allows a more objective and reliable product development and recommendation strategy to be adopted for increased success in the field applications. First, oil and deposit samples from an offshore field was characterized. Second, samples of the asphaltenes extracted from oil (AEO) and from the deposit (AED) were characterized based on solubility using an Accelerated Solubility Test (AST). A customized Asphaltene Dynamic Deposition Loop (ADDL) was used in this study to simulate the precipitation and deposition of asphaltenes from the crude oil. Crude oil used in the tests was from the same well where the deposits were collected. ADDL tests were conducted at high temperature and pressure and the composition of the collected deposit from this test was compared with the deposits from the field. At last, Light Scattering Technique (LST) was applied to screen asphaltene inhibitors (AI). Four candidate chemistries were tested on LST. To confirm the efficiency, the high performer was tested on ADDL under dynamic conditions. Deposits collected from the ADDL were characterized and results showed a high degree of similarity to the field deposit. AI1 was evaluated by ADDL and it decreased the deposition in the filters by 60% and 84% at 1000 ppm. This product was selected to be tested in the field and a plant trial is ongoing.
Effect of Fluid Loss Polymers Architecture on Cement Slurry Rheology : Impact of Adsorption and Microstructure
Authors: Cadix Arnaud , Molinie Vincent , Wilson James
Published: March 2019

Several polymer technologies are commonly used as fluid loss control additives. Working mechanisms were studied by Plank et al. (Plank et al. 2009) and most of the time these can be classified into 2 categories: adsorbing polymers and pore plugging "microgel" like systems. In addition, these polymers have a strong influence on the cement slurry rheology and are also often expected to play a role on cement particle suspension, cement sheath homogeneity and to prevent settling.

The scope of this paper is to investigate the impact of several types of fluid loss polymers on cement slurry stability. Then, an effort is made to correlate the working mechanism of the fluid loss additive with cement slurry rheological behavior and its ability to prevent segregation or settling.

On top of conventional tests on fluid loss and flow rheology, refined evaluations of the rheological behavior are performed in oscillatory rheometry at very-low strain. This technique allows some insight into the microscopic interactions at stake in cement slurries. In particular a "yield stress model" is applied to formulated oil well cement slurries at 90°C providing additional insight on the impact of adsorbing or non-adsorbing polymers.

From this study it can be confirmed that adsorbing polymers have a strong impact on rheological properties with a surprisingly lower yield stress combined with improved slurry stability. On the other hand non adsorbing polymers of either linear or μgel form have a very limited impact on slurry yield stress and a variable impact on slurry stability through either viscosification of the interstitial fluid for linear polymers or enhanced settling hindrance from μgels.
Experimental Study on the Synthesis and Interfacial Properties of Oligomeric Silicone Surfactant
Authors: Jie Zhang , Xu Xianguang , Wang Lihui , Li long , Zhang Die , Zhao Zhiliang , Wang Shuangwei
Published: March 2019

Severe formation damage is induced by the invasion of working fluid and the subsequent water blocking. Surface modification by surfactant adsorption can change the wettability of the rock surface to enhance the removal efficiency of reservoir fluid and reduce the water blockage damage. Therefore, surfactant shows a good potential applicant in condense reservoir. In the current paper, an oligomeric silicone surfactant (OSSF) containing sulfonic acid groups is synthesized to improve the water flowback effect.

The critical micelle concentration (CMC) is determined by equilibrium surface tension. Micelle can be formed above the CMC and its size and distribution increase with the concentration. At the same time, the surface tension increases with the aging temperature but decreases with the adding of inorganic salt. The OSSF adsorption through solid-liquid surface can change the surface chemical composition and transfer the wettability of reservoir from water-wet to gas-wet by decreasing the surface energy. Increasing temperature leads to the change in the adsorption isotherm from Langmuir type (L-type) to "double plateau" type (LS- type). Quantum chemistry study shows that the adsorbed layer of OSSF can reduce the adhesive force of CH4 and H2O on the pore surface of cores. The OSSF can also decease the initial foaming volume and stability in induction period and accelerating period of sodium dodecyl benzene sulfonate (SDBS).

It is found that the surface tension of OSSF increases with aging temperature but decreases with the adding of inorganic salts.The OSSF has positive effect on wettability reversal to water-wet reservoir by adsorption on solid-liquid interface. The results indicate OSSF adsorption layer can change surface chemical composition and exhibit lower interface energy than that of the cores. The presence of NaCl can decrease foaming volume and improve foam stability of OSSF. At the same time, OSSF can decease the initial foaming volume and stability in induction period and accelerating period of sodium dodecyl benzene sulfonate (SDBS).
Roles of the Hydrophobic Tail Groups on the Properties of CO2-Switchable Surfactants
Authors: Hou Qingfeng , Wu Qi , Xu Yan , Zheng Xiaobo , Zhao Yujun , Wang Yuanyuan , Guo Donghong , Xu Xingguang
Published: March 2019

Switchable surfactants can be reversibly converted between surface active and inactive forms by induced triggers including pH, ozone, ultraviolet light, CO2, N2 and heat. Examples of the CO2 triggered switchable surfactants are guanidines, imidazoles and amidines. In a typical process using CO2 triggered switchable surfactants, an emulsion originating from two immiscible phases is stabilized when CO2 is introduced. Afterwards, the emulsion is flushed by N2 or air, resulting in the destabilization and phase separation. These distinctive properties of the switchable surfactants make them appealing chemicals in the transportation and recovery of the crude oil. N'-alkyl-N, N- dimethylacetamidine bicarbonates, as a CO2-triggered switchable surfactant, has been reported in stabilizing the light crude oil (Lu 2014). However, the influence of hydrophobic tail groups on the properties of CO2-switchable surfactants in the protonation and emulsification has not yet been well elucidated. In this work, a series of acetamidines with differing hydrophobic tail group were synthesized, and the synthesis conditions were optimized. The effect of the hydrophobic tail group on the conductivity and emulsion stability were also investigated in details. All the acetamidines presented an excellent switchable property in the conductivity test. Compared to the surfactant with shorter hydrophobic tail group, the acetamidine bicarbonate with longer hydrophobic tail group presented a faster deprotonation rate during bubbling N2. Shorter hydrophobic tail group was beneficial to the protonation of the acetamidines in the presence of CO2, resulting in the formation of hydrophilic bicarbonates compound. However, these bicarbonates with shorter hydrophobic groups were more difficult in deprotonation during the bubbling N2 stage. To examine the emulsifying ability of N'-alkyl-N,N-dimethylacetamidines with different hydrophobic tail groups, emulsifying experiments were conducted at 30°C using a mixture of oil-water containing as synthesized acetamidines (0.1%wt.). The mixture of dodecane-water formed an emulsion after bubbling CO2. The variation in phase separation should be ascribed to the different length of hydrophobic groups of these acetamidines. This revealed the correlation between tail group carbon numbers and hydrophobicity.
PDEA-Based Amphiphilic Polymer Enables pH-Responsive Emulsions for a Rapid Demulsification
Authors: Hou Qingfeng , Zheng Xiaobo , Guo Donghong , Zhu Youyi , Yang Hui , Xu Xingguang , Wang Yuanyuan , Chen Gang , Hu Guangxin , Wang Jinben
Published: March 2019

Stimuli-responsive emulsions have attracted much attention in diverse fields. However, research on the rapid and effective demulsification based on pH-responsive emulsions has barely been reported, although they are viewed as promising canditates for oil-water separation processes after oil recovery. In the present work, we have successfully synthesized a series of pH-responsive emulsions on the basis of a novel polymer containing amphiphilic and protonated moieties. The properties of these pH-responsive emulsions including stability, morphology microscopy, Zeta potential, and interfacial tension have been extensively investigated. We observed that the prepared oil-in-water emulsion could stay stable for more than 24 h within the pH range of 8-10, while it lost 80-90% of the water in 10-20 min if the pH was adjusted to 2-4. The variation in emulsion stability can be attributed to the protonation of poly [2-(N, N-diethylamino) ethyl methacrylate] (PDEA) residues at low pH values. Accordingly the polymers intend to become more hydrophilic and depart from the oil-water interface, leading to an increased interfacial tension. Furthermore, it was found that the applied polymers aggregated at the oil-water interface and that the morphology of aggregations was strongly affected by the pH values. These proposed polymers enabled the formation of emulsion with a controllable response to the pH stimuli. This work is expected to shed light on the development of stimuli-responsive emulsions and may have significant implications in the fields of oil recovery, waste water treatment, and so forth. For example, due to the high w/o interface activity of surfactants such as heavy alkyl benzene sulfonate (HABS) and petroleum sulfonate, severe emulsion has also been found with the alkali-surfactant-polymer (ASP) produced fluid. Currently, rapid breaking of these emulsion fluid is still a big challenge.
Assessing marine equivalent virtual water supplied by the ocean: a case study of China's coastal areas
Authors: Sun Caizhi , Zhang Mengfei
Published: March 2019

‘Virtual water’ represents water resources consumed by industrial, agricultural, and other human activities. Virtual water flow is significant for coordinating the global water balance, but most current research has focused on land. In this study, marine products or services are introduced into the research framework of virtual water, and the concept of ‘marine equivalent virtual water’ is introduced. The formulas are proposed from three aspects: food, environment, and power generation. The calculation results for China's marine equivalent virtual water content from 2006 to 2015 show a U-shaped characteristic in which different factors change in importance over time. In addition, the marine equivalent virtual water system structure is analyzed and forecasted for China's coastal areas by 2025. Through the changes in the marine equivalent virtual water system entropy, the research area is divided into three development types: equilibrium, orderly, and change. Each area can be targeted to put forward development proposals. The marine equivalent virtual water proposition quantifies the function of the ocean in the supply of freshwater resources. It provides a new perspective for relieving pressure on terrestrial water resources and is of great significance to water resource management and water policy formulation; this concept should be built upon in future research.