bluuebunny/crossref_metadata_2025 huggingface dataset:
Efeito do Tempo de Ensilagem sobre a composição química, perfil Fermentativo e Estabilidade Aeróbia de Silagens de Milho (Zea mays)
Authors: De Almeida Araújo Cleyton , Santos Ana Paula Maia dos , Monteiro Carolina Corrêa de Figueiredo , Lima Deneson Oliveira , Torres André Marques , Santos Caio Vinícios Silva dos , Monteiro Samylle Evelyn dos Santos , Silva Juliana Jesus da
Published: February 2020

A silagem de milho é amplamente utilizada, devido a sua qualidade nutricional, produção de matéria seca por ha-1 e bom padrão fermentativo. Objetivou-se avaliar o efeito do tempo de ensilagem sobre o padrão fermentativo, qualidade nutricional, perdas e estabilidade aeróbia de silagens de milho (Zea mays). Empregou-se um delineamento experimental inteiramente casualizado, com quatro tratamentos (0; 12; 24 e 48h para ensilagem após o corte da forrageira) e cinco repetições. Após 30 dias de fermentação foram determinadas as perdas por efluentes, perdas por gases e recuperação de matéria seca. Para o ensaio de estabilidade, foram retiradas aproximadamente 2kg de silagem de cada unidade experimental e adicionadas em recipientes plásticos com capacidade de 4 litros, foram aferidas a temperatura (intervalo de 2 horas), pH e condutividade elétrica (intervalo de 6 horas) Realizou-se a determinação de nitrogênio amoniacal, capacidade tamponante e dióxido de carbono. A composição química-bromatologica, avaliou-se os teores de matéria seca, matéria mineral, extrato etéreo, proteína bruta, matéria orgânica, fibra em detergente neutro e ácido, carboidratos totais, carboidratos não fibrosos, proteína insolúvel em detergente neutro e ácido e hemicelulose. Todos os resultados foram submetidos a teste de regressão a 5% de probabilidade. O período de ensilagem não influenciou as perdas fermentativas para as perdas por gases e recuperação de matéria seca. O padrão químico da silagem não teve alteração para o teor de proteína bruta com médias de 84,60g; 78,26g; 82,58g e 74,22g, respectivamente para os tratamentos 0h; 12h; 24h e 48h. O tempo de ensilagem após o corte altera a dinâmica de produção de carbono, aumenta o teor de nitrogênio amoniacal, reduz a capacidade tamponante e diminui a estabilidade da silagem.
Análise dos resultados da logística reversa no setor sucroalcooleiro: um estudo de caso em uma usina do estado de Alagoas, Brasil
Authors: Lins Luana Natali dos Santos , Loureiro Sara Christina Lima , Santos Diego da Guia
Published: February 2020

RESUMO: A logística reversa é um tema que vem se destacando ao longo dos anos quando se trata de práticas operacionais e responsabilidade ambiental. Dessa forma, o presente estudo tem como objetivo analisar os resultados da prática da logística reversa realizada pelo setor sucroalcooleiro no estado de Alagoas por meio das operações de uma usina. Para tanto, foi realizado um estudo de caso em uma usina do estado, onde, por meio de uma entrevista com gestores e análise de documentos, foi possível identificar a importância de tais ações às operações da empresa. Constatou-se como resultado que a usina analisada vem se destacando com a reutilização de bagaço da cana-de-açúcar para a produção de energia, torta de filtro e vinhaça, tornando esse um diferencial competitivo perante os concorrentes.  Observou-se ainda que tais práticas auxiliam no processo de gestão à medida que otimizam o sistema produtivo e impactam na redução de custos.

PALAVRAS-CHAVE: Logística Reversa, Compostagem, Responsabilidade Ambiental.
Consumer Price Effects of Joining the European Economic and Monetary Union: Modeling the Post-accession Price Adjustment of Greece
Authors: Ahmed Rushdi
Published: February 2020

This study shows how the Consumer Price Index of Greece is affected by joining the European Economic and Monetary Union. The post-accession price adjustment of Greece is also modeled. The research design employed in the study consists of descriptive statistics, chi-square test and regression analysis. The accession of Greece to the European Economic and Monetary Union (EMU) in 2001 and the introduction of the euro in 2002 were followed by a sharp upward shift of the consumer price level. This increase in consumer price level has given birth to a widely held hypothesis that claims that the accession of Greece to the EMU has caused a structural increase in the consumer price level. In this study this hypothesis is tested and rejected. There was no substantial evidence of such an effect of the aftermath of joining the EMU. However, there was strong evidence of structural breaks in the Greek consumer price equilibrium and of the presence of a non-linear price adjustment model. This study addresses the adjustment behavior of the consumer price level, and finds that the shift in prices after the accession to EMU is normal equilibrium restoring adjustments.
Espectroscopia de impedancia eléctrica en cáncer invasivo del cuello uterino en mujeres de Caldas (Colombia), 2008-2009
Authors: Olarte-Echeverri Germán , Aristizábal-Botero William , Osorio-G. Gloria Fátima , Rojas-Díaz Jerónimo
Published: February 2020

Objetivo: obtener las curvas de resistividad eléctrica de tejido cervical en presencia de cáncer invasivo del cuello uterino.Metodología: estudio de corte transversal en pacientes con carcinoma invasor del cérvix. Se utilizó un medidor de impedancia de tejido (Electrical Impedance Spectroscopy Mk3.5 single channel system), el cual, mediante una sonda tetrapolar con dos electrodos de corriente y dos de voltaje, permite calcular la impedancia de transferencia de los tejidos.Resultados: se realizaron 102 mediciones y se obtuvieron las curvas de resistividad del tejido cervical en 18 mujeres con edades entre 46 y 72 años (56+/-9, media +/-DS). De esta manera, se encontró que los tejidos presentan una curva de resistividad característica para cáncer invasivo de cérvix con parámetros de resistividad promedio (R0 = 4,35+/-2,26 [Ω-m], media +/-DSy R∞ = 1,41+/-0,57 [Ω-m]). Con estos estimativos se obtuvieron los valores de la resistividad de los líquidos extra e intracelular (R = 4,35+/-2,26 [Ω-m] y S = 2,44+/-1,11 [Ω-m]).Conclusión: la espectroscopia de impedancia eléc trica muestra un patrón diferente en tejidos prove nientes de carcinoma invasor del cérvix en relación con el tejido cervical sano.
Seguridad y actividad de la Solución de Bardana como coadyuvante en el manejo del prúrito vulvovaginal en Colombia. Ensayo clínico fase II
Authors: Canaval Hoover , Bonilla Jairo , Scarpetta Claudia , Martínez Fernando , Orejarena Jaime , Solórzano Diana
Published: February 2020

El prurito genital puede ser la manifestación de problemas alérgicos, infecciones genitales, entidades sistémicas o una reacción primaria. El manejo de este síndrome es un reto para ginecólogos y médicos generales.Objetivo: evaluar la seguridad y actividad de la solución de bardana al 1,2% en aplicaciones externas diarias por 5 días, como coadyuvante en el manejo de las vulvovaginitis para generar alivio del prurito.Metodología: el presente es un ensayo clínico de fase II, multicéntrico, abierto, no comparativo, realizado en pacientes con prurito genital, quienes fueron evaluadas en 14 ciudades colombianas. En el estudio se incluyeron a todas aquellas mujeres mayores de 18 años con prurito genital sin importar su etiología, quienes no hubiesen recibido tratamiento alguno para la vulvovaginitis o la vulvovaginosis en los 30 días previos a su inclusión en el estudio y quienes, además, no hubiesen utilizado ningún producto farmacéutico de manera tópica en los 8 días anteriores al inicio del tratamiento. Asimismo, se excluyeron todas las pacientes en estado de embarazo, con trastornos psíquicos o mentales de difícil control y con antecedentes de alergias a medicamentos. Se evaluó la edad de la paciente, la intensidad del prurito, la presencia de irritación vulvar, leucorrea, los agentes infecciosos asociados con ésta y la tolerancia.Resultados: se incluyeron 154 pacientes de las cuales se excluyeron 2 por no asistir al último control. Al final de los tratamientos, 83,6% de ellas manifestaban no tener prurito o sólo en una intensidad mínima y 11,8% lo referían como leve. El prurito clasificado inicialmente en 30,5% de las mujeres como severo se encontró sólo en 2,6% al segundo día y tan sólo en 1,3% persistía al final de la terapia. Similares resultados se obtuvieron en los subgrupos con infección demostrada por sólo cándida o sólo bacterias.Conclusión: la utilización local complementaria de una solución tópica de bardana en mujeres con prurito genital podría ser una alternativa eficaz de manejo.
Nicolás Rosa, la juventud del crítico
Authors: Podlubne Judith
Published: February 2020

A mediados de los años 1950, el joven Nicolás Rosa colabora en el diario Democracia de la ciudad de Rosario. Estas colaboraciones, compuestas de notas y relatos, marcan su ingreso a la escritura a través del periodismo cultural. El propósito del artículo es caracterizar el corpus de materiales relevados en la búsqueda de archivo, desconocido para los lectores especializados, y examinar la imagen de crítico que se perfila en ellos, a partir de una perspectiva biográfica, es decir, incorporando el proceso biográfico a la escritura del artículo. Esta perspectiva no sólo permite reponer sus autofiguraciones iniciales, sino también, conjeturar en torno a las circunstancias que lo habrían transformado en un crítico barthesiano.
SPECIAL ISSUE: THE BIOGRAPHIC DIMENSION
Authors: Musitano Julia , Surghi Carlos
Published: February 2020

En los últimos años, un grupo de colegas de diferentes universidades de Argentina nos nucleamos alrededor de un interés en común: la biografía literaria, sus problemas de forma, sus alcances intelectuales y su gravitación en el campo literario. En las primeras aproximaciones a nuestro objeto, notamos que el interés crítico y teórico por las diversas formas de lo autobiográfico, en las últimas décadas, no tienen comparación con el estudio de la producción biográfica; y comprendimos entonces, que había que dotar a la biografía, en tanto que forma y problema, de la contundencia teórica que la autobiografía había tenido desde la década de 1970. También, observamos que la atención sobre el género de la biografía le pertenecía teórica y críticamente a los discursos historiográficos de las ciencias sociales
ANALISIS LEARNING AND INOVATION SKILLS MAHASISWA PAI MELALUI PENDEKATAN SAINTIFIK DALAM IMPLEMENTASI KETERAMPILAN ABAD 21
Authors: Rusadi Bobi Erno , Widiyanto Rohmat , Lubis Rahmat Rifai
Published: February 2020

The research aims to describe the skill of Islamic education student in developing learning and innovation skills of student through a scientific approach. This study used a qualitative method based on descriptive analytic. The subjects of this research were 20 Islamic education students of Syarif Hidayatullah State Islamic University and North Sumatera State Islamic University who were carrying out practice of teaching in school. The subjects were chosen based on the the purpose of this study, thus the subjects were only students who used a scientific approach. Data collection is done by using interviews, observation, and study documentation. The study was conducted in July to October 2019. The results of this study showed that the ability of Islamic education students to observing aspects 80.63%, questioning aspects 75%, information gathering aspects (experimenting) 65%, reasoning/ associating aspects 78%, and communicating (comunicating) aspects 51.67% . Furthermore, in the average, the overall learning activity was carried out by islamic education teacher prospective students in developing learning and innovation skills with a scientific approach of 70.06% was achieved in a good category.
Perbandingan Metode Regresi Spline Truncated dengan Regresi Linear Sederhana untuk Kasus Harga Saham Perusahaan Pertambangan di Indonesia
Authors: Widodo Edy , Irmayanti Adisti Nurul
Published: February 2020

Saham merupakan surat berharga  yang dapat dibeli dan dijual oleh perorangan atau badan usaha sebagai tanda penyertaan kepemilikan seseorang maupun badan usaha dalam suatu perusahaan atau perseroan. Salah satu saham yang mengalami dampak dari fenomena krisis ekonomi global adalah perusahaan pertambangan. Harga saham dipengaruhi oleh kurs rupiah. Data harga saham dan kurs rupiah masuk ke dalam kategori data longitudinal. Untuk menangani data longitudinal dibutuhkan analisis yang tepat, salah satunya dengan menggunakan pendekatan nonparametrik regresi spline truncated untuk mengetahui bagaimana pengaruh kurs rupiah terhadap harga saham. Model terbaik pada metode ini bergantung pada penentuan titik knot optimal, yaitu titik knot yang memiliki nilai GCV minimum. Model regresi spline truncated terbaik terletak pada orde 2 dengan 3 titik knot untuk PT Adaro Energy Tbk. dan PT Aneka Tambang Tbk., sedangkan untuk PT Indo Tambangraya Megah Tbk. berada pada orde 3 dengan 2 titik knot. Dengan pembanding nilai MAPE, hasil prediksi dengan menggunakan regresi spline truncated lebih baik daripada regresi linear sederhana Adapun nilai MAPE yang dihasilkan adalah 7,81% untuk PT Adaro Energy Tbk., 8,51% untuk PT Aneka Tambang Tbk., dan 12,74% untuk PT Indo Tambangraya Megah Tbk.
Utilization of Family Planning Contraceptives among Women inthe Coastal Area of South Buru District, Maluku, 2017
Authors: Titaley Christiana Rialine , Sallatalohy Ninik
Published: February 2020

Maluku Province is one among provinces in Indonesia with a contraceptive prevalence rate (CPR) lower than the national average. This study aimed toexamine factors associated with the utilization of family planning contraceptives among women of reproductive age living in the coastal area of South BuruDistrict, Maluku, Indonesia. Data were derived from a household health survey conducted in five subdistricts in South Buru, e.g., Namrole, Leksula, Waesama,Kapala Madan and Ambalau Subdistricts on November 2017 by the Faculty of Medicine, Pattimura University in Ambon. Information on contraceptive usewere collected from 390 married women aged 20 - 49 years. Bivariate and multivariate logistic regression analysis were employed to examine the factorsassociated with utilization of family planning contraceptives. This study found a low rate of utilization of family planning contraceptives (38.5%). The odds ofutilization modern contraceptive significantly reduced among women living in Ambalau and Leksula Subdistricts, aged 41 - 49 years, those who intend to havemore number of children, and with a low level of knowledge about family planning contraceptive methods.
Evaluation of Program for Overcoming Intestinal Worm Infections among Children
Authors: Febriyanti Henny , Idris Haerawati
Published: February 2020

Prevalence of intestinal worm infection in generall is extremely high in Indonesia among the poor population with poor sanitation. One of the government programs to address this problem is the distribution of medicines to prevent intestinal worm infections. However, the coverage of the achievement for this program is still low in several areas of public health centers in Palembang. Therefore, this study was conducted to evaluate the efficacy of the national program for preventing intestinal worm infections. The qualitative research design used evaluation model approach Context, Input, Process, and Product (CIPP) model. This study was conducted in one of health centers in Palembang City. The informants were selected using purposive sampling method. Data collection was done via in-depth interviews, document reviews, and observations. Descriptive content analysis was used to examine and process the collected data. Results showed that, from situational factor, the program is held by the government because of the high prevalence of intestinal worm infection. The study found the input component, limited staff that handles this program. There were limited facilities for the extension of the infrastructure. In the process component, the distribution of the drug albendazole was not optimal in all elementary schools. Four elementary schools did not receive albendazole. This study demonstrated that the implementation of the program was not optimal
Entomological Index and Home Environment Contribution­ ­to Dengue Hemorrhagic Fever in Mataram City, Indonesia
Authors: Satoto Tri Baskoro Tunggul , Pascawati Nur Alvira , Wibawa Tri , Frutos Roger , Maguin Sylvie , Mulyawan I Kadek , Wardana Ali
Published: February 2020

Indonesia is a member of Southeast Asia Regional Office (SEARO) ranked the first in dengue hemorrhagic fever (DHF) problem based on incidence rate (IR)and case fatality rate (CFR). Several provinces in Indonesia experience an outbreak, one of which is the Mataram City in West Nusa Tenggara Province.Mataram City is an endemic area of DHF because the DHF cases are always found in three consecutive years with the number of cases that fluctuate andtend to increase. This study aimed to obtain factors that could be used to improve early warning systems in controlling DHF. This study used a case controldesign with a ratio of 1:1 to 180 house holds. The results showed that home environmental factors, such as no ceiling, indoor and outdoor temperature thathad the potential for breeding places for mosquitoes, no wire net in ventilation, low lighting and high humidity, related to DHF transmission. Vector distibutionwith entomology index showed that the existence of larvae, eggs and mosquitoes played a role in dengue transmission. The dominant factors affecting the transmission of dengue in Mataram City are the condition of the ceiling and the existence of mosquito eggs in the house.
Tres personajes en busca del lugar perdido
Authors: Vera Chaparro Vanessa
Published: February 2020

Los geniecillos dominicales (1964), Conversación en La Catedral (1969) y Los verdes años del billar (1986) son novelasprotagonizadas por jóvenes personajes, cuyas acciones se llevan a cabo en una sociedad peruana sometida porla dictadura militar. Ludo Totem, Santiago Zavala y Ricardo Yáñez experimentan una crisis individual como consecuenciade la ruptura que establecen con su lugar de origen (familia, clase social, círculos sociales). Nos interesaaquí determinar y analizar los factores de dicho distanciamiento y el efecto que ejerce sobre el proceso formativo deestos. Para ello, el esquema tripartito que propone Edward Said (2004): filiación, filiación problemática y afiliación, funcionarácomo el marco teórico de nuestro estudio. Con su ayuda, demostraremos que estos personajes son agentestrastocados por una violencia pública que se internaliza en los espacios privados que habitan para desfigurarlos e inclusodesaparecerlos.
Validation of Error Models – A Key Component of Risk Mitigation in Wellbore Collision Challenges
Authors: Ali Tarig , Ledroz Adrián , Weston John , Allen William
Published: February 2020

The estimation of wellbore position uncertainty, sometimes referred to as error modelling, is of vital importance when considering the safety and efficiency of the drilling process, particularly in crowded fields with tight spacing between wells. New survey tools employing new technology, new principles and sophisticated data processing techniques become available every year with different accuracy claims. The dependability of the error models and whether they properly represent the uncertainties of a given survey system, new or old, is not easy to judge. This paper describes a simple method to support the validation process of uncertainty models.

Multiple surveys of different type are often available for the same well with some degree of overlap for different wellbore sections. For example, the well might have been drilled using magnetic MWD data and later a drop gyro might have been run to reduce the positional uncertainty or to validate the magnetic data. Overlapping surveys can be compared, and the difference can be gauged against the claimed uncertainty models using the relative instrument performance model (RIP) test and the Chi-square test.

Analysis of several wells with different trajectories and more than 100 overlapping surveys has allowed a major oil company to build confidence and accept the uncertainty models claimed by one service company. This has allowed the oil company to implement the service company IPM (Instrument Performance Model) files without having necessarily to understand in great detail how the survey systems operate, how they are calibrated or quality controlled. Using the right models allows optimal planning of wells and survey programs, and reduces the risks of a collision while at the same time permitting wells to be drilled in congested fields.

The paper describes a simple approach for validating uncertainty models for survey tools. The tests used for the validation are available in most well planning software programs and can be completed by personnel without the necessary expertise required to understand the subtleties of all the survey tools involved in the process.
Downhole Attitude-Hold Controller Leads to Automatic Steering of Directional Wells with Improved Accuracy and Reduced Tortuosity
Authors: Zalluhoglu Umut , Tilley Jim , Zhang Wei , Grable Jeff
Published: February 2020

This paper illustrates the performance of a precise attitude-hold control feature enabled for a new-generation rotary steerable system (RSS) via an intelligent downhole navigation and control system. State-of-the-art downhole navigation sensors and a high-bandwidth pad actuation system are combined with advanced signal processing and control algorithms to ensure tight directional control of RSS along vertical, tangent, and lateral sections, maximizing the pay-zone contact for hydrocarbon extraction.

The intelligent downhole navigation and control system blends sensors measuring gravitational and magnetic fields surrounding the RSS to track the propagation of the borehole. The sensory measurements are conditioned by a set of advanced signal-processing techniques prior to being fed to the attitude-hold controller. The controller then generates a control signal to minimize both deviation from a reference trajectory and wellbore tortuosity.

Case histories from wells drilled using the automated attitude-hold control feature are presented. The field data include results from vertical, tangent, and lateral sections of wells in various formations from several conventional and unconventional applications. One case suggests significant reduction in generated doglegs upon engaging the attitude-hold controller in a lateral section with a challenging formation. Another case study shows that inclination was maintained within a tight error bound of ±0.1° during a tangent section. An example from a vertical well is also provided, where the vertical-hold control feature was able to hold inclination within 0.1° on average. The ability to tightly lock-in to a desired borehole attitude and to quickly adapt after altering the reference trajectory has proven that the attitude-hold control feature improves wellbore placement accuracy substantially, while minimizing tortuosity.
Simulating Drillstring Postbuckling State and Weight Transfer with Advanced Transient Dynamics Model
Authors: Chen Wei , Shen Yuelin , Chen Rongbing , Zhang Zhengxin , Rawlins Sheldon
Published: February 2020

As the drilling sections become deeper and longer, transferring more weight downhole to improve ROP is the primary concern to the operator. Drillstring buckling is a primary concern when using very aggressive drilling parameters. Buckling is a phenomenon where the drillstring suddenly loses stability as axial compression exceeds a certain threshold. The drillstring first buckles sinusoidally inside the wellbore which is then followed by helical buckling. Buckling leads to accelerated joint wear, tool fatigue failures, and lower drilling efficiency. To better manage the buckling risk, this paper proposes a method of simulating drillstring buckling inception and post-buckling state using an advanced transient dynamics model.

A buckling and post-buckling analysis methodology was developed based on the finite element transient dynamics model. The model captures the enriched physics involved in the buckling phenomenon: the large deformation of buckled drillstring, the strong non-linearity of contact and friction forces, and the dynamically triggered buckling due to drilling rotation. Transient dynamics simulations are conducted for drillstring with the actual well trajectory and rotation speed. Weight on bit (WOB) is ramped up gradually, and the drillstring deformation is monitored to detect the onset of buckling. The post-buckling state is examined to evaluate drilling efficiency and string reliability.

To conduct the model validation, an extended reach drilling (ERD) job was analyzed by the model. A measurement while drilling (MWD) tool was deployed in BHA to measure the downhole weight and torque. The simulation implies the helical buckling occurs in drill-pipe and captures the drilling weight and torque loss due to buckled string. Most existing buckling theories use the analytical equations of critical buckling load, which were normally derived based on the idealized assumptions, such as perfect wellbore shape and uniform tubular geometry, but neglect friction and string rotation. The proposed method simulates the drillstring buckling in the actual field drilling conditions. It gives more realistic predictions of buckling inception load and post-buckling configuration. The transient dynamics model is capable of simulating drillstring whirl and weight lockup under the severe helical buckling. Based on the simulated the post buckling configuration of the string, an automatic interpretation method was proposed to detect the buckling mode and location along the drillstring.

Using the transient dynamics model, the simulation procedure presented in this paper can significantly improve drillstring buckling and post-buckling predictions and help mitigate buckling risk in well planning and execution phases.
Thermodynamic Basis for Brine Density as a Function of Pressure, Temperature and Chemical Composition in Deepwater and XHPHT Environments
Authors: Rahman S. M. , Sathuvalli U. B. , Suryanarayana P. V.
Published: February 2020

In the computation of annular pressure build-up (APB), the pressure-volume-temperature (PVT) response of the annular fluids is of paramount importance. Though the physics of APB is well understood, there is uncertainty in the thermophysical properties of the fluids in the wellbore annuli, especially in the case of brines. Often brines must be used behind the production tieback because of the constraints imposed by the tubing leak and the abandonment leak loads. While custom tests can be performed to determine brine PVT, they can be time consuming and expensive. In this light, our paper presents a method to determine the density of brines from their chemical composition, as a function of pressure and temperature. It compares theoretical predictions with results of tests on brines used in our industry and available test data from the oil and gas and other industries.

In 1987, Kemp and Thomas (1987) used the principles of chemical thermodynamics to develop equations for the density of brines as a function of pressure and temperature and their electrolytic actions. However, their paper contained two (inadvertent, and probably typographical) errors. One of the errors lay in the set of the Debye-Hückel parameters, and the other was contained in the coefficients of the series expansion for the infinite dilution molal volume. Further, they (inadvertently) did not mention the role of a crucial parameter that accounts for the interaction between the ionic constituents of the salt. As a result, nearly a generation of engineers in our industry has been unable to reproduce their valuable results from an important study or apply their technically rigorous results to other brine chemistries.

In this paper, we return to the basic equations of chemical thermodynamics and the principles of stoichiometry and delineate the inadvertent errors that had crept into in the Kemp and Thomas (1987) study. We then present the rectified equations and reproduce their example with the corrected results. Further, we compare the predictions from the original Kemp and Thomas (1987) work with results from other leading chemical engineering models. Finally, we compare the results of theoretical models with test measurements from the lab and characterize the uncertainty inherent in each model.

In summary, we have identified the error in an elegant and important thermodynamic state equation, and rendered it useful once again, to the industry. Further, we demonstrate its validity with new tests and provide uncertainty bounds.
Helical Pipe Viscometer System for Automated Mud Rheology Measurements
Authors: Gul Sercan , Erge Oney , van Oort Eric
Published: February 2020

Optimum well construction operations require frequent and accurate measurements of drilling fluid properties. Optimized hydraulics, hole cleaning and well control requires proper management and characterization of fluid rheology and density. Currently, the methods by American Petroleum Institute (API) standards are used for drilling fluid property measurements. However, these methods are sporadic, labor-intensive and the data quality is highly dependent on the practicing engineer. These dated methods need to be replaced and improved by an automated, continuous and practical way of measuring and monitoring drilling fluid properties.

In this paper, we introduce a helical-pipe viscometer system for automated mud measurements. An automated flow-loop was constructed to perform experiments with Newtonian and non-Newtonian fluids. Flow tests were conducted in two straight- and two helical-pipe test-sections. Frictional pressure loss data was obtained from each section simultaneously. Flow rate, density and temperature data were obtained using a Coriolis flow meter.

It was observed that the toroidal geometry results in secondary flow due to the centrifugal forces. Therefore, elevated frictional pressure losses and delayed transition to turbulent flow were observed in the experiments from the helical-pipe test-sections. A machine-learning regression model was trained using the results from the experimental data for friction factor predictions by the helical pipe pressure loss measurements. The proposed approach was compared with both the experimental data and other theoretical equations reported in the literature. It was observed that the existing correlations in the literature for non-Newtonian fluids are not accurate for the characterization of Herschel Bulkley fluids. Using the trained machine learning model, an algorithm was developed and tested to prove the applicability of the system for automated rheological property determination. Very good accuracy was observed when comparing helical pipe viscometer measurements with standard API measurements.

Helical pipe viscometers offer distinct advantages over standard pipe viscometers, such as compact size and more versatile frictional pressure loss profiles. They are also of interest for the hydraulic design of coiled tubing and slim-hole operations, where the maximum allowable flow rate is often limited by frictional pressure loss.
Using Model-Based Design for Digital Twins to Predict the Real-Time Performance of Surface Equipment
Authors: Johnson Weston , Rao Samvith
Published: February 2020

A digital twin of the above ground electro-mechanical and control systems for a drilling rig was created using a model-based software. Using a library of pre-built software models, reduced the development time of the digital twin using traditional software development methods from over a year with a team of experts, to less than 4 months for a single developer. In addition to a significant time savings, the resulting simulation was able to predict performance of the top drive, draw works and mud pumps with an error of less than 3% for most conditions.

Physics-based twins were built to describe the physical properties of devices (motors, pumps, bus parameters), including material properties, using pre-built block from libraries. These blocks describe mathematics and dynamics of systems. Using sensor data from 3 sensors (Speed, Torque and Current), 16 motor parameters were estimated and calibrated to field data.
Maximizing Drilling Performance Through the Delaware Basin Brushy Canyon and Interbedded Formations
Authors: Dupriest Fred E. , Noynaert Samuel , Cunningham Tyrell , Rendon Marcus
Published: February 2020

The purpose of this study was to develop a physical understanding of the bit damage that occurs in the Brushy Canyon and Avalon formations in the southern Delaware Basin and to develop practices to mitigate it. The operator had already implemented a programmatic initiative to move the organization toward physics-based, limiter-redesign workflows in order to achieve performance gains in a safe and efficient operation. A significant performance limiter was trips for damaged bits.

Two dominant causes of bit damage were observed. One was tangential overload of the outside cutters, which tends to occur if hard streaks are exited with high WOB and depth of cut (DOC). The second is continuous wear of the outside cutters that occurs if lower WOB is used to avoid the tangential overload. There was no operating window in which any given WOB did not enable one or the other form of damage in 12-1/4″ holes.

An explanation of how the overload may occur is presented along with the results of changes in field practices that were consistent with the concept. The progress that was made was partly due to physics-based training of operations personnel which enabled them to interpret observed behaviors and manage dysfunction more intensely. Some elements of the physics-based workflow and training are also discussed at length because they are integral to the improvements achieved in performance (Dupriest 2005, 2006); particularly the use of a Geologic Roadmap and surveillance of the Baseline MSE.

Bits from two wells drilled were pulled green after drilling from the surface casing through the Brushy Canyon. While this is encouraging the results from rig to rig was inconsistent. Bit design needs were identified that should enable higher success, and some of these features are now found in the current market. They were not available at the time of this initiative in 2018.

The nature of the interfacial severity damage varies from the southern to northern end of the Delaware basin, with laminar calcite streaks dominating in the south (the operator's acreage) and nodular chert inclusions occurring in some areas of the north. Both create high loading of a small number of cutter studs and the real time and engineering design practices that limit the interfacial severity damage discussed in this paper may be useful across the basin.
Qualification & Testing of a Powered Wired Drill Pipe Solution
Authors: Silvester Ian , Høgset Tore , Torvund Steinar , Saxena Subodh
Published: February 2020

This paper documents the development, qualification and field test deployment of an electrically powered and wired drill pipe system for use by operators, drillers and service companies in oil & gas drilling operations. Deployment of the technology has the potential for users to power downhole tools from surface and thus reduce or remove downhole batteries / turbines. High-speed bi-directional telemetry over the wired drill pipe can improve realtime communications and downhole measurement quality, while enabling high frequency, surface and downhole data sharing / integration.

The development of the system is centered around: a braided conductor and an insulating materiala robust field replaceable pipe connector systemtransceivers optimized for the transmission characteristics of the system

The novelty of the new drill pipe design is the ability to supply downhole tools with power in addition to bi-directional high-speed data communication telemetry from surface over the same braided and insulated conductor, manufactured into the ID profile of the drillstring. Due to power regulation at surface and matched transceivers, the need for in-string communications repeaters is avoided. In addition, special attention has been paid to the design, robustness and field maintainability of the connector system at each end of the drill pipe.

Qualification of the system in a laboratory environment applied downhole drilling conditions using simulators, highly accelerated life tests ("HALT"), and physical testing on discrete samples, joints and short strings of drill pipe. Transceiver performance, connector make/break cycles and testing of the conductor and insulating layer under tension, bending, torque, pressure, temperature and erosion were all performed. Parallel "real life" runs on testing and commercial drilling rig operations have yielded encouraging early results to validate the qualification laboratory testing. Minimal damage was observed during handling and downhole use on several drilling rigs, indicating that the system has the potential to be handled as regular drillpipe and can be simply integrated into rig operations.

Several iterations in design and testing of the braid and insulating material have proven the viability of new manufacturing techniques and given valuable insight as to the ability of the design to withstand normal drilling conditions of flow, torque, tension, pressure, temperature etc. gained through commercial drilling rig testing. System trials on rig operations have shown that stable downhole power can be delivered whilst communicating with a minimum bit rate of 56Kbit/sec during drilling. A top drive slip-ring assembly at surface and a crossover to a service company BHA downhole have been developed and were used for the drilling trials.
Drillstring Failure Prevention - A Data Driven Approach to Early Washout Detection
Authors: Kuesters Andrea , Mason Colin , Gomes Paulo , Cockburn Colin , Lodhi Huma
Published: February 2020

Drillstring washouts occur when a leak path develops through the drillstring, leading to the loss of pressure integrity. These events often lead to significant non-productive time across the industry, with many operators experiencing multiple events per year across their global operations. Data driven techniques were applied to detect washouts and prevent them developing into twist-offs. Statistical techniques, rules-based logic and machine learning approaches were assessed against various operations where washouts had occurred. The results showed that data driven techniques can provide effective solutions for detecting the onset and development of drillstring washouts.
Wellhead and Conductor Multi-Variate Fatigue Analysis for Old and New Subsea Wells
Authors: Pilisi Nicolas , Lewis David
Published: February 2020

Deepwater wells historically have, and will continue to, push technological limits. Through the years, water depths and well depths have continued to increase. BOP's are now substantially larger than they were 20 years ago and casing string weights have also steadily and substantially increased. Additionally, since the Macondo incident 10 years ago, capping stacks have also been included in the design process. All of these developments have resulted in higher fatigue loads and an evolved conductor design, wellhead design and in some cases, inclusion of the 28″ pipe (secondary conductor) to support the 36″ conductor. But what about older wells? Wells that may need to receive a modern drill-ship for work-over, intervention or abandonment?

The objective of this paper is to answer the question posed and in doing so create an awareness of the ability for historical well designs to receive a modern BOP and capping stack – or not. In answering, this paper presents a case study of fatigue analysis performed on generalized modern and historical designs and their ability to receive a modern subsea BOP and capping stack. This paper examines the need for full and proper multi-variate fatigue analysis of existing and newly installed subsea wellheads and conductor strings for a set of subsea equipment, top of wellbore architecture, met-ocean and soil conditions. In performing this work, soil and metocean data were considered for the Mediterranean Sea, the Gulf of Mexico and West Africa.

In evaluating, a sample of well designs from 20 years ago through today was selected and a modern fatigue analysis workflow applied. It shows the engineering methodology for calculating and estimating the remaining fatigue life of existing and newly installed wellheads and conductors following the installation of a modern BOP and capping stack. The paper explores the important role of fatigue analysis and shares identified limitations. It also considers what physical factors may be modified to find an acceptable solution. In doing so, readers should get a sense for where potential issues may lie and consider the question of whether lighter BOP and / or capping stack solutions are a consideration for the future.
Drilling Dynamics Model to Mitigate High Frequency Torsional Oscillation
Authors: Shen Yuelin , Chen Wei , Zhang Zhengxin , Bowler Adam , Jeffryes Benjamin , Chen Zhenyu , Carrasquilla Maria Neves , Smith David , Skoff Greg , Panayirci Huseyin Murat , Arevalo Yezid , Bolchover Paul
Published: February 2020

In recent years, the phenomenon of drill string torsional oscillation at frequencies over 50 Hz has been well documented. This high frequency torsional oscillation (HFTO) creates cyclic fatigue loading on bits and drilling tools within the bottom hole assembly (BHA) and thus limits tool life and drilling performance. However, few models exist which can predict occurrence of HFTO and its severity. To our knowledge; none of these models consider the entire drilling system including the bit-rock interaction, downhole drive(s), BHA design, and surface drilling parameters, and hence there is a need to develop a system model for HFTO mitigation.

A 3D transient drilling dynamics model has been extended to study the severity of HFTO and cyclical loading to drilling tools. The accuracy of the model was validated by theoretical calculation, and high frequency downhole data. An example analysis was conducted to evaluate drilling system design performance in terms of HFTO risks. Good correlation was found between the analysis and field data collected from the Permian Basin.

Advanced models were developed for mud motors and rotary steerable system (RSS) tools. After conducting a full drilling simulation, the drilling system behavior under HFTO can be fully described. Cyclical torque loading of differing magnitudes and frequencies were observed for different BHA components depending on HFTO vibration mode, HFTO severity and BHA design. PDC cutters were subjected to different cyclical loading depending on bit design, formation and HFTO conditions. The mud motor power section was found to undergo high frequency cyclical loading which could accelerate its rubber degradation. Since the failure of PDC cutters and the degradation of mud motor power sections have a critical effect on drilling performance, the importance of mitigating HFTO cannot be underestimated. By evaluating the loading conditions, an optimized drilling system can be selected. Field data has proved the validity of this approach.

The methodology presented in this paper offers a new way for the industry to systematically mitigate HFTO by considering the rock drilled, bit design, mud motor utilized, the mechanics of RSS and other tools in the BHA, as well as drilling parameters. The usage of this approach can reduce premature drilling component failure and improve drilling performance, especially in the high energy drilling applications found in North America Land and other areas.
Managing Lost Circulation in Highly Fractured, Vugular Formations: Engineered Usage of High Fluid Loss Squeeze and Reticulated Foam Lost Circulation Materials
Authors: Savari Sharath , Butcher Jacques , Al-Hulail Mustafa
Published: February 2020

Controlling severe to total lost circulation in naturally fractured/vugular formations has always been challenging, particularly in carbonate formations across the Middle East. For such situations, conventional particulate lost circulation materials (LCMs) might not be effective. An extension to the work presented on a high fluid loss squeeze (HFLS) and reticulated foam LCM that provides further technical justification for making such LCMs more suitable for severe to total losses in uncertain situations is discussed.

Savari et al. (2016) presented laboratory evaluation methodology, test results, and field applications of the subject HFLS and reticulated foam LCM. At the time, laboratory test data were presented for the LCM combination that could seal a laboratory-simulated fracture/slot size of 9,800 microns. For the current work, a similar test setup evaluated the efficiency of this LCM to seal larger openings. An adapter with an opening of 31,700 microns was used, and the combination of HFLS and reticulated foam LCM successfully sealed the opening when tested using an industry standard test setup.

For laboratory-based tests, the combination of HFLS LCM and different-sized reticulated foam LCM was successful in sealing a 31,700 micron opening. An industry standard test setup [permeability plugging apparatus (PPA)] was used to evaluate the LCM. The same LCM combination was mixed in different bases, such as water, diesel, mineral oil, and brines; further, the LCM combination was weighted to determine if the sealing performance was consistent. For the aforementioned variations, the LCM combination was successful in sealing the 31,700 micron opening. The LCM plug was also evaluated for the maximum differential pressure it can withstand in wet conditions and for its compressive strength. Under wet conditions, the plug withheld 4000 psi differential pressure and yielded a compressive strength of approximately 400 to 2,800 psi. The latest test data were generated using industry standard PPA equipment with minor modifications. Hence, this helps provide an opportunity for end users to evaluate such LCMs in their own facilities to qualify and generate technical confidence in the LCM combinations before field application.

The combination of HFLS and reticulated foam LCM can provide a technically efficient alternate to particulate solutions for managing severe to total losses in naturally fractured/vugular formations. Test data presented in this work are a first-of-its-kind reported in the petroleum industry literature for any comparable LCM, which further provides confidence in such LCM combinations and can help reduce well costs related to time and mud.