bluuebunny/crossref_metadata_2025 huggingface dataset:
A project of nation
Authors: Pimentel Mariana Barroso de Almeida , Chaguri Mariana Miggiolaro
Published: March 2019

This research project has as purpose to investigate the political-ideological imbrication of the relationship between the public and private in the educational sphere, based on the performance of the Unibanco Institute and the Itaú Social Foundation in the public policies for High School in Brazil. Based on the documentary analysis of the diagnoses and prescriptions produced by the same regarding the educational problem, supported on the bibliographical production available about the entanglement between the private sector and the public sphere, this research seeks to relate and understand the latest changes occurred in such politics.
Desenvolvimento e análise das características de micropartículas de polissacarídeos incorporando extrato de Arrabidaea chica para aplicação na terapia de lesões em tecidos cartilaginosos
Authors: Pereira Mariana Borges , Moraes Angela Maria , Westin Cecília B.
Published: March 2019

Neste trabalho foi realizada a preparação de micropartículas de alginato utilizando cloreto de estrôncio como agente reticulante e variando-se os parâmetros concentração de alginato e agitação, buscando-se obter micropartículas com morfologia e tamanhos ideais para aplicação in vivo por injeção intra-articular. Pôde-se inferir que a concentração de 3,5% e a agitação com rotação de 2.000 rpm propiciaram micropartículas com características adequadas para a proposta. Além disso, incorporou-se extrato da planta Arrabidaea chica nas micropartículas nas proporções de 5, 10 e 15% em relação a massa polimérica total, alcançando-se uma eficiência de incorporação máxima de 79%.
Fatores associados à adesão e à descontinuidade ao "Projeto Cesta Verde", vertente do programa de aquisição de alimentos (PAA) de Limeira, SP
Authors: Grilo Mariana Fagundes , Oliveira Julicristie Machado de , Frizo Bárbara Lellis de Sá
Published: March 2019

O "Projeto Cesta Verde", vertente do PAA em Limeira, SP, provia cestas de alimentos produzidos localmente à famílias em condição de vulnerabilidade social. O estudo com cartáter descritivo indicou que a maioria dessas famílias se encontravam em situação de Insegurança Alimentar e Nutricional (IAN) e que os alimentos fornecidos pelo projeto contribuiam para a melhoria dos hábitos alimentares. A descontinuidade no projeto pelos beneficiários pode ser explicada por fatores de âmbito individual dos participantes e do âmbito de gestão da política pública.
Hierarchically structured and bifunctional core-shell rare earth nanoparticles
Authors: Morais Amanda Justino de , Sigoli Fernando Aparecido , Mazali Italo Odone , Ferreira Flávia de Sousa
Published: March 2019

Hierarchically nanostructured core@shell systems of NaGdF4:Er:Yb@NaYF4:Yb@NaYF4:Tb:Yb and NaYF4:Tb:Yb@NaYF4:Yb@NaGdF4:Er:Yb composition were synthesized to investigate the influence of composition and crystalline structure on the efficiency of the upconversion emission (UC). The main goal is the preparation of magneto-luminescent systems for a possible application in biological media. Information on the crystalline phase, particle morphologies and the upconversion emission spectra were obtained using: X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Luminescence Spectroscopy (LS).
Implementação de simulador de marcha humana baseado no modelo biomecânico
Authors: Chen Mariana Onofre , Rosario Joao Mauricio
Published: March 2019

Exoesqueletos são dispositivos mecatrônicos integrados ao corpo humano, que se destinam a mapear e/ou ampliar suas funções motoras interagindo de forma física e cognitiva com o usuário. Visando a aplicação de exoesqueletos, esse projeto propunha a modelagem de um sistema que representasse o funcionamento de membros inferiores, com o estudo, compreensão e simulação do comportamento biomecânico da marcha e sua possível aplicação em protótipo utilizando componentes robóticos e hardware de supervisão e controle.
Influence of stirring velocity and current density on electrodeposition of Zn-Fe-Mo alloys
Authors: Hori Mariana Sayuri , Neto Ambrosio Florencio de Almeida , Costa Josiel Martins
Published: March 2019

This work realized varied electrodeposition experiments to obtain Zn-Fe-Mo alloys submitted to different operation conditions. Studies of electrodeposition and characterization were realized to evaluate the current density and catodic rotation influence on the coatings.
As competências necessárias para a atuação do pianista colaborador de coro
Authors: Borges Mariana Villas Bôas , Mendes Adriana do Nascimento Araujo
Published: March 2019

Este projeto de iniciação científica teve como proposta estudar as competências necessárias para a atuação do pianista colaborador inserido na atividade coral. Teve como objetivo principal investigar as espeficidades técnicas exigidas para este tipo de profissional. Como procedimento metodológico, foi realizada uma pesquisa bibliográfica e documental, apoiada nos autores Freire (2011) e Ribeiro (2003), para detectar se a proposta curricular do Curso de Piano Erudito e Popular da Universidade Estadual de Campinas (Unicamp) proporciona a formação do pianista que irá atuar como colaborador.
Estudo epidemiológico descritivo do ZIKA Vírus na região metropolitana de Campinas, casos de microcefalia e avaliação do sistema de vigilância epidemiológica em relação aos seus diagnósticos diferencias - sarampo e rubéola
Authors: Figueira Mariane , Kemp Brigina
Published: March 2019

O Zika Virus foi detectado no Brasil em 2015. A região metropolitana de Campinas também foi atingida. Casos de Microcefalia também foram notificados em Campinas. Logo, o presente estudo tem como objetivo geral fazer um estudo epidemiológico descritivo da ocorrência do ZIKAV na região metropolitana de Campinas (RMC).Os resultados encontrados foram 963 casos de ZIKAV notificados entre os anos de 2014 e 2016, sendo 535 confirmados. O município de Campinas foi o que mais houve registro de casos confirmados (467 casos), significando um Coeficiente de Incidência (CI) de 39,49/100.000 hab.). O sexo com maior número de casos foi o feminino, na idade fértil de 16 a 48 anos, com maior percentual de casos (69%). Foram 509 casos confirmados considerados como autóctone e 15 como importado.Referente aos caos de microcefalia, foi observado um aumento de de 7 casos,nos primeiros anos para 157, nos anos de 2014 a 2017. Conclui se que a RMC foi atingida pelo vírus, sendo Campinas, o de maior risco. Com relação à microcefalia, nota-se um aumento de casos nesta região.
Reforma universitária de Córdoba
Authors: Aguiar Jórissa Danilla Nascimento , Rojas Gonzalo Ádrian
Published: March 2019

Ao celebrar o centenário da Reforma Universitária que aconteceu em 1918 em Córdoba, na Argentina, trazemos ao debate a importância de estudar essa experiência de rebelião contra a hierarquia universitária, ao passo que destacamos também sua atualidade, principalmente no que diz respeito à necessidade de democratização da universidade e sua vinculação a classe trabalhadora e setores populares. Objetivamos contribuir para que essa experiência seja conhecida pela ampla maioria dos estudantes no Brasil, indicando também sua relevância para (re)construir um novo movimento estudantil numa perspectiva emancipadora. Para isso, realizamos uma revisão histórico-bibliográfica sobre o que propunha e o que significou a referida reforma em termos de autonomia e democratização, e que assinalou o nascimento de uma nova geração latino-americana, provocando agitações posteriores em outros países do subcontinente. Ressaltamos que essa experiência evidencia o papel ativo do movimento estudantil enquanto ator social na promoção de mudanças sociais pautadas por uma orientação inerente à luta de classes e na concretude da construção de um projeto que vislumbra uma nova hegemonia na sociedade. Como conclusões, destacamos a atualidade da luta pela democratização e o objetivo de vincular a universidade aos problemas da sociedade, terreno fértil para o desenvolvimento de uma educação emancipadora e popular.
A importância da Reforma de Córdoba para o contexto acadêmico latino-americano
Authors: Pereira Elisabete Monteiro da Aguiar
Published: March 2019

O artigo apresenta os contextos social, político, econômico e educacional do movimento de Córdoba de 1918, cujo centenário se comemora em 2018. Analisa esses contextos no seu desenvolvimento histórico como bastidores da eclosão da reforma de Córdoba e publicação do documento conhecido como Manifesto Liminar, ou documento da Reforma Universitária de Córdoba. O ponto central do artigo é o de analisar a importância que o movimento teve naquele tempo e as razões da sua influência permanente nos movimentos estudantis nestas dez décadas de existência, em vários países da América Latina, tornando-se um importante legado para os estudantes e um igualmente importante chamado para a organização particular de um universidade latino-americana com olhar para suas específicas questões sociais, culturais e educacionais.
Sobre los factores de diferenciación de la diversidad rural y las opciones de su clasificación: ensayo metodológico en la provincia de Málaga
Authors: Larrubia Vargas Remedios , Navarro Rodríguez Susana Rosa , Natera Rivas Juan José
Published: March 2019

El objetivo de este trabajo es elaborar una propuesta para medir la diversidad del medio rural. Dada las limitaciones de los indicadores simples se recurre a la técnica del análisis multivariante. Como una primera experiencia el procedimiento propuesto se aplica en el espacio rural de la provincia de Málaga. La clasificación de los indicadores mediante componentes principales ha identificado tres factores como nuevas variables que explican la diversidad rural: “transformación productiva”, buen status demográfico”, “dinamismo local”. A partir de este análisis se ha derivado dos tipologías, una estadística (análisis clúster) y otra directa que han permitido clasificar el territorio en ocho niveles de ruralidad. Concluyéndose que ambas tipologías describen acertadamente las diferencias básicas del medio rural en la provincia, por la relevancia y pertinencia de los mencionados factores.
Engineered Vesicles for the Controlled Release of Chemical Additives and Application for Enhanced Oil Well Cement Integrity
Authors: Contreras Elizabeth Q. , Johnson Kenneth D. , Rasner Diana , Thaemlitz Carl J.
Published: March 2019

Encapsulation-based systems are of interest in the oil and gas industry in applications such as chemical additive preservation, small molecule release, particle delivery, and self-sealing materials. Many methods are used to encapsulate relevant chemical additives for the controlled release of contents like polymeric vesicles, inorganic shells, and mesoporous materials. Here a novel system for the controlled release of encapsulated cargo that utilizes engineered features of permeable polymeric shell walls is shown.

When placing cement, a multitude of additives in large quantities are needed to meet a variety of functional needs that are suitable for the many diverse wellbore conditions. However, using large amounts of certain additives could have adverse effects which can destabilize the slurry at surface conditions. Using vesicles, cement additives are delivered without requiring modification. In this way, the possibilities of formulations comprised of a number of vesicles with various encapsulants lends to significant advancements in cementing. Applications in cement design is demonstrated from measurements obtained using the consistometer as well as testing from oilfield equipment.

Experimental results show that a basic cement slurry design responds to the release of an encapsulant by the measure of change in viscosity and thickening times at two different temperatures at 3,000 psi. For example, the thickening time of a slurry can be controlled with the delayed release of an accelerant, at ambient pressure. With an increase in temperature up to 100 °F and 300 °F, the encapsulated additive is squeezed at a higher diffusion rate, resulting in a faster thickening time. In all cases, the vesicles are observed to remain intact within the set cement and contribute significantly to the mechanical properties of set cement. Vesicle dual performance stems from unique characteristics, such as an aqueous core, wall thickness and permeability, chemical composition, and mechanical integrity of the shell wall. Here, the shell walls are engineered with high molecular weight polymeric material that upon release of the encapsulated chemical additives, the emptied vesicles continue to impart beneficial mechanical properties to the set cement, such as compression strength.
Characterization of Type and Maturity of Organic Matter in Source Rock by In-situ Electrical Heating and Temperature Transient Analysis
Authors: Lee Kyung Jae
Published: March 2019

Reliable estimation of organic matter characteristics is essential in drilling decisions, source rock evaluation, and unconventional reservoir production. Their measurement is based on experiments after core sampling, which is time-consuming and economically challenging. In this study, we present a new approach to evaluate the characteristics of organic matter in source and reservoir rocks by in-situ electrical heating and temperature transient analysis under in-situ conditions.

The new approach is based on inverse modeling, which monitors in-situ heater temperature during electrical heating and machine learning technologies. Thermal method of electrical heating is applied for the in-situ pyrolysis, to figure out the characteristics of organic matter—kerogen volume fraction and activation energy of decomposition reaction. The heater temperature acts as an indicator of type and maturity of kerogen, since it is affected by the bulk thermal conductivity of formation, which is a function of dynamically changing rock-and-pore composition by kerogen decomposition. A full-physics simulation model of in-situ kerogen pyrolysis is used to generate output data of electrical heater temperature, which is the input data of learning-based models. Minimal simplification of physical and chemical phenomena in the full-physics simulation model, which describes the multicomponent-multiphase-nonisothermal systems involving kinetic reactions, gives the confidence of synthetic output data of heater temperature.

Full-physics simulation model computes system responses under unknown and uncertain input parameters, which determine the reactivity of kerogen pyrolysis. The full-physics simulation model generates the sets of heater temperature transient data while heating with constant heat flux, in the 300 different simulated source rocks containing Types 1, 2, and 3 kerogens with various organic matter content and activation energies. Based on the set of heater temperature transient data as input parameters, Artificial Neural Network (ANN) is employed to generate a black box model to estimate the unknown organic matter content and activation energy. Developed ANN data-driven model shows better performance in estimating unknown parameters, in Types 2 and 3 kerogens with wide ranges of activation energies than Type 1 kerogen with a narrow range of activation energy. Support Vector Machines (SVM) method, which categorizes data into multiple classes by using hyperplanes, is applied to classify the heater temperature transient data into different types of kerogens and shows good performance in classification.

The new characterization technology of in-situ organic matter in source rocks presented in this study provides reliable information of types and maturity of organic matter, without experiments after core sampling. It is expected to enable the realistic evaluation of source rocks under subsurface conditions, by resolving technical and economic challenges.
Development of Scale Squeeze Enhancement Technology via Application of Metal Nanoparticles Coupled with Polymer Scale Inhibitors
Authors: Guraieb Paula , Tomson Ross , Littlehales Ian
Published: March 2019

Polymeric scale inhibitors used for scale squeeze treatments to control downhole inorganic scale don't perform well when pumped into the reservoir due to the poor adsorption properties on the rock surface. However polymeric inhibitors are more temperature stable than phosphonates and have higher tolerance to elevated cation compositions in the water. Therefore, a new chemistry composed of metal nanoparticles coupled with a polymeric scale inhibitor was developed to improve the squeeze life.

The use of nanoparticles in the oilfield has increased in recent years; this development shows how nanoparticles can be used to increased surface area and retention of scale inhibitor in the reservoir. Metal nanoparticles were selected because of their low environmental toxicity and low formation damage potential during injection and flowback.

A fast and efficient synthesis method was developed to create a novel chemistry that couples nanoparticles with polymeric inhibitors to produce a product that it was hoped would have excellent squeeze properties in multiple rock permeabilities and compositions.

Core flood experiments were conducted on intact core under onshore Permian conditions of temperature pressure and brine composition as well as conditions simulating an offshore conventional field (results will be reported separately). The experimental results will be presented to show the extended squeeze lifetime of the new product in comparison to a traditional polymeric scale inhibitor retained by adsorption and also will give insight into the mechanisms by which the nanoparticle/scale inhibitor enhances squeeze life, both by increased adsorption as well as prolonging release of scale inhibitor.

The product developed is able to significantly increase the squeeze life of polymeric scale inhibitors by up to 10x depending on the minimum inhibitor concentration required. The retention of the inhibitor into the rock is significantly increased, while the release is controlled at above minimum effective concentration for extended periods. The theoretic explanation for this is a metal-inhibitor bond, proprietary to the product that allows for continuous release of inhibitor into the solution, without release from the rock. Traditional squeeze returns have a Freundlich isotherm, this product also follows a similar return curve, however does not suffer from the high concentration release at the beginning of the treatment flowback.

These results show that nanoparticles can be used in the oilfield to enhance existing scale inhibitors as well as create new combination products that can improve performance. Use on nanoparticles in the oilfield is an evolving topic that has significant room to grow and expand into multiple areas of oilfield chemistry. This study showcases the application of nanoparticles to enhance performance of polymeric scale inhibitors for squeeze application while maintaining a cost effective product that is environmental responsible.
Performance Comparison of Novel Chemical Agents in Improving Oil Recovery from Tight Sands Through Spontaneous Imbibition
Authors: Huang Hai , Babadagli Tayfun , Chen Xin , Li Huazhou
Published: March 2019

Tight sands are abundant in nanopores leading to a high capillary pressure and normally a low fluid injectivity. As such, spontaneous imbibition might be an effective mechanism for improving oil recovery from tight sands after fracturing. The chemical agents added to the injected water can alter the interfacial properties, which could help further enhance the oil recovery by spontaneous imbibition. This study explores the possibility of using novel chemicals to enhance oil recovery from tight sands via spontaneous imbibition. We experimentally examine the effects of more than ten different chemical agents on spontaneous imbibition, including a cationic surfactant (C12TAB), two anionic surfactants (O242 and O342), an ionic liquid (BMMIM BF4), a high pH solution (NaBO2), and a series of house-made deep eutectic solvents (DES3-7, 9, 11 and 14). Experimental results indicate that the ionic liquid and cationic surfactant used in this study are detrimental to spontaneous imbibition and decrease the oil recovery from tight sands. The high pH NaBO2 solution does not demonstrate significant effect on improving oil recovery, even though it significantly reduces oil-water interfacial tension (IFT). The anionic surfactants (O242 and O342) are effective in enhancing oil recovery from tight sands through oil-water IFT reduction and emulsification effects. The DESs drive the rock surface to be more water-wet and a specific formulation (DES9) leads to much improvement on oil recovery under counter-current imbibition condition. This preliminary study would provide some knowledge about how to optimize the selection of chemicals for improving oil recovery from tight reservoirs.
Insight of New Eco-Friendly Acidizing Corrosion Inhibitor: Structure and Inhibition of the Indolizine Derivatives
Authors: Yang Zhen , Wang Yefei , Wang Renzhuo , Chen Wuhua , Ding Mingchen , Zhan Fengtao , Hou Baofeng
Published: March 2019

Propargyl alcohol, at great expense and with high toxicity, is often used as an essential synergistic component of corrosion inhibitors for acidizing; however, in our recent work, a novel indolizine derivative was found to exhibit effective protection performance without the synergism of propargyl alcohol. These indolizine derivatives were easily prepared from quinoline, pyridine, and several halide compounds via 1,3-dipolar cycloaddition reaction. The derivative could prohibit the corrosion of metal at an extremely low concentration and fulfills the requirements of increasingly stringent environmental standards. The inhibition performance of the indolizine derivatives to N80 steel was investigated in 15 wt.% HCl and 20 wt.% HCl by weight loss measurements, potentiodynamic polarization method (Tafel curves), and electrochemical impedance spectroscopy (EIS).

In the absence of propargyl alcohol, when the dosage of indolizine derivatives in 15 wt.% HCl is 0.1 wt.%, the inhibition efficiency of N80 steel increases to approximately 99% at 90 °C. The indolizine derivative shows a superior anti-corrosion performance at a much lower concentration than that of benzyl quinolinium chloride (BQC, a commonly used compound in current acidizing corrosion inhibitors), which serves as the precursor to indolizine derivatives. More importantly, these protective indolizine compounds behave better than the synergistic inhibitor propargyl alcohol. The reinforced active adsorption groups in indolizine derivatives could provide extra adsorption sites and fasten the inhibitive molecule to the steel surface, thus augmenting the protective effect. Here, a new inhibitive indolizine derivative is presented as an acidizing inhibitor that may also offer a low-pollution technique for corrosion prevention.
Novel Laser-Hydrothermal Apparatus for Nucleation and Inhibition Study of Scale Minerals at Temperatures up to 250°C
Authors: Deng Guannan , Kan Amy T. , Zhang Fangfu , Lu Alex Y. , Tomson Mason B.
Published: March 2019

In this work a new laser-hydrothermal apparatus is designed to evaluate nucleation of scale minerals at temperature up to 250°C, its reliability is proven by measuring induction time data of barite from 90°C to 250°C at various Saturation index (SI) values, with the objective that such a design would contribute to the scale-related research at extreme temperature.

Background solution (e.g. 1m NaCl) in a borosilicate glass bottle was placed inside a hydrothermal reactor. GC oven was used for temperature control and a modified Nd-Fe-B magnetic stirrer under the oven was used for stirring. A PFA tubing was selected to be the part with contact with solution for corrosion control. Using a 0.5 ml sample loop in two separate 6-ways switch valves, Ba2+ and SO42-concentrated solutions were simultaneously injected into a background solution. After supersaturation was initiated, a laser beam penetrated through the sight glasses installed on the both sides of the reactor to record the turbidity change during the nucleation process.

Induction time (tind) of Saturation index (SI) values from 0.34 to 1.02 was measured at temperatures from 90°C to 250°C. Data correlates well with data from previous laser test at 90°C in a regular beaker experiment. The induction time (tind), that is, how fast a supersaturated solution induces nucleation and crystal growth to form detectable turbidity, decrease with temperature at a fixed SI value. For example, tind of 93 minutes at 150°C decreases to about 2 minutes at 250°C under the the same SI value of 0.65, indicating that increasing temperature facilitates the nucleation process at certain supersaturation levels. This temperature impact can be attributed both by thermodynamics and kinectic aspects.
Impact of Temperature on Fluid-Rock Interactions During CO2 Injection in Depleted Limestone Aquifers: Laboratory and Modelling Studies
Authors: Azuddin Farhana Jaafar , Davis Ivan , Singleton Mike , Geiger Sebastian , Mackay Eric , Silva Duarte
Published: March 2019

When CO2 is injected into an aquifer, the injected CO2 is generally colder than the reservoir rock; this results in thermal gradients along the flow path. The temperature variation has an impact on CO2 solubility and the kinetics of any mineral reactions. Core flood experiments and associated reactive transport simulations were conducted to analyse thermal effects during CO2 injection in a dolomitic limestone aquifer and to quantify how CO2 solubility and mineral reactivity are affected.

The experiments were conducted by injecting acidified brine into an Edwards Limestone core sample. A back pressure of 400 psi and injection rates of 30 mL/hr and 300 mL/hr were used. A range of temperatures from 21 °C to 70 °C were examined. Changes in the outlet fluid composition and changes in porosity and permeability were analysed. A compositional simulation model was used to further analyse the experiments. The simulations were history-matched to the experimental data by changing the reactive surface area and the kinetic rate parameter. The calibrated model was then used to test the sensitivity to CO2 injection rate and temperature.

The impact of temperature on CO2-induced mineral reactions was observed from changes in mineral volume, porosity and permeability. The reaction rate constants estimated from the outlet solution concentrations are much lower than existing data for individual minerals. The estimated specific surface areas for carbonate minerals are in reasonable agreement with published values. The numerical investigations showed that at the lower temperatures, despite the reaction rates being slower, the solubility of the minerals was higher, and so as a result of these competing effects, moderately elevated calcium and magnesium concentrations were observed in the effluent. At higher temperatures, the solubilities of the minerals were lower, but now the reactions rates were higher, so similar effluent concentrations could be achieved. However, at higher flow rates, characterized by a lower Damköhler number, the residence times were shorter, and so lower effluent concentrations were observed. Additionally, the solubilities of calcite and dolomite varied to different extents with temperature, and so the calcium to magnesium molar ratio in the effluent brine increased with increasing temperature.

The change in mineral composition during CO2 injection varies between the near well zone and the deeper reservoir. Near the well where the temperatures will be lower, solubilities are elevated, but the kinetic reaction rates and residence times will be lower, somewhat limiting dissolution. Deeper in the aquifer the solubilities will be reduced and residence times will be longer, enabling an equilibrium to be established. Modelling is thus required to connect these flow regimes.
Scale Prediction and Mineral Solubility Under HPHT Conditions
Authors: Nichols David , Goodwin Neil , Graham Gordon , Frigo Dario
Published: March 2019

Accurate scale prediction modelling is only possible when reliable mineral solubility data are available under the required conditions. It is recognised that the relative paucity of high pressure, high temperature (HPHT) solubility data can result in inaccurate predictions as current models extrapolate from data obtained under more conventional conditions. This paper describes the generation of additional fundamental solubility data under HPHT conditions and comparison of the obtained values with several existing models.

A purpose-built laboratory test rig capable of making mineral solubility measurements up to 250 °C (480 °F) and up to 30,000 psi has been used in this work. Experimental solubility data have been generated for calcium sulphate at different temperatures and the methodology has been investigated to ensure that equilibrium conditions have been reached. In this work, barium sulphate solubility data have also been generated at conditions up to 200 °C (390 °F) and 19,000 psi. Notably, the solubilities have been determined in the presence of relatively high concentrations of additional ions, e.g., calcium, as it was recognised that available data were limited for more oilfield-representative brine compositions from HPHT reservoirs. The data generated were also compared against solubility predictions for a range of industry models to assess their accuracy in these circumstances.

The results obtained for calcium sulphate solubility indicate the importance of validating the test methodology, not just for each mineral, but also under the required temperature and pressure conditions, to verify that equilibrium solubility conditions have been achieved. Barium sulphate solubility increases with the addition of other divalent ions but the extent of the increase is at present not accurately predicted by existing scale prediction models at HPHT conditions. In some cases, the predicted barium sulphate solubility was up to three times greater than the experimentally determined value. It is apparent that there is considerable scope for improvement of scale prediction models under HPHT conditions particularly in complex brine systems and that further fundamental solubility data are required to facilitate this.

This paper provides additional data for mineral solubility under HPHT conditions but, more importantly, shows data for complex brines that are more representative of those produced in oilfields. The work further demonstrates the limitations of existing scale prediction modelling software under HPHT conditions, particularly in the presence of other divalent ions, and illustrates areas where additional data and model development is critical to enable more accurate modelling of scale risk under these conditions.
Experimental Investigation of Particulate Polylactic Acid Diversion in Matrix Acidizing
Authors: Shirley Robert Mark , Hill A. D.
Published: March 2019

Polylactic Acid (PLA) is increasingly used in the oil industry and specifically for diversion in matrix acidizing as evidenced by a number of field cases recently published. The solid polyester is particularly attractive due to its ability to degrade in the presence of water and heat, negating the need for cleanup fluids or complicated procedures. A majority of the analysis on the effectiveness of PLA thus far comprises experiments on artificially created slots, filter cake analysis, and field trials. This paper demonstrates the effect of PLA in wormholes developed by acidizing outcrop cores.

In these experiments, a wormhole is generated in a portion of the core by limiting the amount of acid injected. Next, the PLA is injected into the core using a heavy brine suspension. Finally, more acid is injected until a wormhole breaks through the core. Computer Tomography (CT) scans are taken, and the pressure drop across the core is recorded at each stage. Experiments were conducted for a variety of initial wormhole lengths.

It can be difficult to suspend PLA while injecting it through a core in a way that is benign to the core, acid, and PLA; and in a way that does not add any pressure drop or diversion due to viscosity changes. This paper describes and justifies a suitable method of keeping PLA suspended to allow its use in core flood experiments. The CT scans show that even when the PLA plugs the wormhole, additional acid tends to continue to develop the dominant wormhole. The pressure drop profiles show that the pressure drop due to PLA injection is proportional to the mass of PLA, both in the wormhole and on the core surface. The pressure profiles also show that there is an increased pressure drop due to PLA in the wormhole versus in a filter cake on the surface.

This paper details a new method of visualizing and analyzing the effect of PLA in a multistage acidizing treatment. Empirical correlations are presented for estimating the pressure drop caused by PLA, both as a filter cake on the formation surface and as a filling inside wormholes. The correlations were incorporated in a comprehensive carbonate acidizing model to predict the diversion efficiency of PLA particles. The simulation is verified using published field trials of diversion treatments.
Simulation Study of Scale Management During Hydraulic Fracturing in Unconventional Reservoirs
Authors: Abouie Ali , Sanaei Alireza , Sepehrnoori Kamy
Published: March 2019

Geochemical scale formation and deposition in reservoir is a common problem in upstream oil and gas industry, which results in equipment corrosion, wellbore plugging, and production decline. In unconventional reservoirs, the negative effect of scale formation becomes more pronounced as it can severely damage the conductivity of hydraulic fractures. Hence, it is necessary to predict the effect of scale deposition on fracture conductivity and production performance.

In this work, an integrated reactive-transport simulator is utilized to model geochemical reactions along with transport equations in conventional and unconventional reservoirs considering the damage to the fracture and formation matrix. Hence, a compositional reservoir simulator (UTCOMP), which is integrated with IPhreeqc, is utilized to predict geochemical scale formation in formation matrix and hydraulic fractures. IPhreeqc offers extensive capabilities for modeling geochemical reactions including local thermodynamic equilibrium and kinetics. Based on the amount of scale formation, porosity, permeability, and fracture aperture are modified to determine the production loss. The results suggested that interaction of the formation water/brine and injection water/hydraulic fracturing fluid is the primary cause for scale formation. The physicochemical properties such as pressure, temperature, and pH are the secondary cause affecting scale formation in the reservoir.

During hydraulic fracturing, precipitation of barite and dissolution of calcite are identified to be the main reactions, which occur as a result of interaction between the formation brine, formation mineral composition, and injection water/hydraulic fracturing fluid. Calcite dissolution can increase the matrix porosity and permeability while barite precipitation has an opposite effect. Therefore, the overall effect and final results depend on several parameters such as HFF composition, HFF injection rate, and formation mineral/brine. Based on the fracturing fluid composition and its invasion depth in this study, the effect of barite precipitation was dominant with negative impact on cumulative gas production. The outcome of this study is a comprehensive tool for prediction of scale deposition in the reservoir which can help operators to select optimum fracturing fluid and operating conditions.
The Development and Field Test of High Efficient Foam Unloading Agent Based on Gemini Surfactant and Nanomaterials
Authors: Junwen Wu , Wenfeng Jia , Rusheng Zhang , Xueqi Cen , Haibo Wang , Jun Niu
Published: March 2019

The high efficient foam unloading agent was developed to solve the problem of unloading of liquid loading gas well with high gas temperature, salinity and high concentration of H2S gas and gas condensate. The Gemini anionic surfactant with special comb structure was synthesized as foaming agent molecule, the modified nanoparticles with certain size and degree of hydrophobicity was adopted as solid foam stabilizer, and the fluorocarbon surfactant was designed and synthesised as gas condensate resistance components. The indoor experiment results show that the foam unloading agent showed good foaming and foam stabilizing ability when the temperature is as high as 150°C, salinity is up to 250000 ppm and H2S concentration up to 2000 ppm. Besides, the foam unloading agent present good liquid carrying ability when the volume fraction of gas condensate is as high as 50%. The field test of this foam unloading agent in Longfengshan north 201-XY well shows that, the average gas production increased from 7256 m3/day to 11329 m3/day, increased by 56%, the average differential pressure between tubing and casing dropped from 2.66 MPa to 2.38 MPa, fell by 10.5%, both liquid yield and gas production are obvious, which prove that the foam unloading agent can meet the demand of drainage gas recovery for high content gas condensate gas field.
Surfactant-Inhibited Barium Sulphate Nanoparticles for Use in Drilling or Completion Fluids
Authors: Whyte John Morrison
Published: March 2019

The benefits of a nanoparticle-weighted fluid are numerous, allowing the possibility of high-density drilling fluids, a true alternative to expensive heavy brines, barite-weighted reservoir drill-in fluids and the virtual elimination of barite sag. By using a branched carboxylic acid, rather than a linear molecule as a crystal growth inhibitor during precipitation, true nano-scale dispersions have been achieved that are stable in water, with no detectable agglomeration and that are self-dispersing after drying. This paper proposes that greater steric hindrance and smaller particle sizes are achieved by utilising branched, or chair-like carboxylic acids, rather than the long-chain molecules more commonly used. The use of FTIR, XRD, DLS and SSNRM have been combined to demonstrate that inhibitor concentration is the dominant effect in preventing crystal growth but does not account for particle growth retardation alone.

Spherical nanoparticles with a dispersed ZAvg of 16nm and low contact areas have been created. They produce dispersions with a density of 2.27g/cm3. These dispersions display no detectable ‘sag’ after 428 days in suspension suggesting that colloidal stabilisation has been achieved. This paper also demonstrates that further decreases in particle diameter are possible through a combination of mechanical shear during precipitation and pH modification after precipitation has ceased. An optimum pH post-precipitation of 10.4 is close to that targeted by many water-based reservoir drill-in fluids, further highlighting the possibility of surfactant-inhibited barium sulphate nanoparticles as a density agent for drilling fluids. Using pH to modify the PSD of the nanoparticle dispersions strongly suggests that the dispersions can be tuned to one suitable for the intended operation. The growth inhibitors used during precipitation are low-cost and non-toxic and enable the dry particles to disperse to comparable PSDs after drying to their precipitated values. The technology allows the creation of a high-density brine replacement fluid, presenting a significant cost saving over an alternative such as caesium formate in some applications

Previous research on barium sulphate nanoparticles [3] succeeded via the adsorption of long-chain carboxylic acids. We have shown that shorter, branched carboxylic acids - a new approach - are more effective and in significantly lower concentrations. This paper has found that a rigid, chair-like molecule provides an equivalent particle size distribution at an ultra-low adsorption level.
The Impact of H2S on Carbonate Scaling Risk. A Field Case Study
Authors: Ness Giulia , Sorbie Ken , Lugo Nancy , Kelly Caroline
Published: March 2019

The effects of H2S on system integrity, sulphide scaling potential and health and safety in oil and gas production is well recognized and understood. However, as part of a wider study on pH dependent scale predictions, the authors have identified an additional challenge associated with the presence and/or development of H2S in reservoirs containing carbonates: higher H2S concentration reflects in higher calcium carbonate scaling potential. The intention of this work is to demonstrate the impact of H2S using a real field case scenario and investigate how the variability in water cut, aqueous phase composition, CO2 and H2S concentration can impact the well carbonate scaling potential and ultimately its productivity.

To model pH dependent scales correctly, it is necessary to integrate PVT calculations with the aqueous phase thermodynamic mineral scaling calculations. This has been extensively discussed in previous publications by the authors. For this work, a commercial integrated PVT and scale prediction software package was used to determine the scale prediction profile from reservoir to the first stage of topside separation. In addition, to investigate the impact of PVT on the final results, a second PVT software employing a different equation of state (EOS) is used and the results obtained from this calculations are coupled with the same aqueous phase model using the Heriot-Watt scale prediction workflow.

The well selected for this study shows productivity issues as well as signs of presence of calcium carbonate scale. However, scale prediction calculations carried out in the past did not show any potential for carbonate scale formation at the given conditions. After rigorously accounting for variations in water cut over time, as well as for increased H2S due to reservoir souring, our work clearly shows a correlation between a gradual loss of well productivity and carbonate scaling potential.

This work clearly demonstrates the impact of H2S on calcium carbonate scaling potential and highlights the importance of correctly modelling CO2 and H2S partitioning in gas/oil/water at the different stages of production, from reservoir to topside separation. Following this study, it has also been possible to offer specific well treatment and testing recommendations to verify the results and try to obtain improvements in production efficiency.

Moreover, the application of our approach to a real field scenario shows how some field findings associated with carbonate scale problems can be explained only by correctly modelling the full three phase system (oil, gas and water). Some aspects of this approach are frequently overlooked and not linked correctly to carbonate scale formation.
Carbonic Acid Resistance of Hydroxyapatite Based Cement
Authors: Srivastava Aman , Ahmed Ramadan , Shah Subhash
Published: March 2019

With the current applications of CO2 in oil wells for enhanced oil recovery (EOR) and sequestration purposes, the dissolution of CO2 in the formation brine and the formation of carbonic acid is a major cause of cement damage. This degradation can lead to non-compliance with the functions of the cement as it changes compressive and shear bond strengths and porosity and permeability of cement. It becomes imperative to understand the degradation mechanism of cement and methods to reduce the damage such as the addition of special additives to improve the resistance of cement against acid attack. Hence, the primary objective of this study is to investigate the effects of hydroxyapatite on cement degradation.

To investigate the impacts of hydroxyapatite additive on oil well cement performance, two Class H cement slurry formulations (baseline/HS and hydroxyapatite containing cement/HHO) were compared after exposure to acidic environments. To evaluate the performance of the formulations, samples were prepared and aged in high-pressure high-temperature (HPHT) autoclave containing 2% brine saturated with mixed gas containing methane and carbon dioxide. Tests were performed at different temperatures (38 to 221°C), pressures (21 to 63 MPa) and CO2 concentrations (10 to 100%). After aging for 14 days at constant pressure and temperature, the samples were recovered and their bond and compressive strength, porosity and permeability were measured and compared with those of unaged samples.

The results demonstrated that adding hydroxyapatite limits carbonation. Baseline samples that do not contain hydroxyapatite carbonated and consequently their compressive strength, porosity, permeability, and shear bond strength significantly changed after aging while hydroxyapatite-containing samples displayed a limited change in their properties. However, hydroxyapatite-containing samples exhibit high permeability due to the formation of microcracks after exposure to carbonic acid at high temperature (221°C). The formation of microcracks could be attributed to thermal retrogression or other phenomena that cause the expansion of the cement.

This article sheds light on the application of hydroxyapatite as a cement additive to improve the carbonic acid resistance of oil well cement. It presents hydroxyapatite containing cement formulation that has acceptable slurry properties for field applications and better carbonic acid resistance compared to conventional cement.
High-efficiency Corrosion Inhibitor for Acidizing: Synthesis, Characterization and Anti-corrosion Performance of Novel Indolizine Derivative
Authors: Wang Yefei , Yang Zhen , Wang Renzhuo , Chen Wuhua , Ding Mingchen , Zhan Fengtao , Hou Baofeng
Published: March 2019

A novel indolizine derivative inhibitor for acidization was introduced. It could exhibit effective corrosion inhibition at a much lower concentration without propargyl alcohol and shows economic and environmental advantages. From quinoline, benzyl chloride, and chloroacetic acid, two indolizine derivatives were prepared under certain conditions. These inhibitive indolizine derivatives were both synthesised from benzyl quinoline chloride (BQC), which one of the conventional quaternary ammonium corrosion inhibitors used for acidising. The target compound was purified and instrumental analysis methods including elemental analysis, high-resolution mass spectrometry (HRMS), and NMR were used to characterise the chemical structure. The inhibition performance of the indolizine derivatives in 15 wt.% HCl, 20 wt.% HCl, and mud acid (12%HCl + 3%HF) for N80 steel was investigated by weight loss measurement, electrochemical method (potentiodynamic polarization and EIS), and SEM surface morphology assessment.

When 0.1 wt.% indolizine derivative was added, the inhibition efficiency of N80 steel in 15 wt.% HCl at 90 °C increased to 98.8 % and 99.1 % respectively without the synergistic effect of propargyl alcohol: however, in terms of BQC, even at a dosage of 1.0 wt.%, the inhibition efficiency of N80 steel only reached 83.3 % under the same conditions. The novel derivative could impart an improved corrosion resistance effect. Compared with BQC, there are more active adsorption sites in the derivative and therefore the inhibitor could be better fastened to the steel surface. The firmly adsorbed inhibitors would thereby prevent the metal surface from making contact with H+ ions and finally increase the inhibitory effect. As a high-efficiency corrosion inhibitor, the novel indolizine derivatives may offer a new strategy for corrosion protection in acidising.