bluuebunny/crossref_metadata_2025 huggingface dataset:
Back-EMF Based Rotor Position Estimation for Low Cost PMSM Drive Using Fully Connected Cascade Artificial Neural Networks
Authors: Negri Gabriel H. , Nazário Filipe G. , Oliveira José de , Nied Ademir
Published: February 2018

Permanent Magnet Synchronous Motors (PMSMs) are widely used mainly due to their high torque per volume, high efficiency and low maintenance cost, among other advantages. To perform the vector control on rotor speed and stator currents, the feedback of those variables is necessary, which can be done directly or by estimation. Measuring rotor position and speed directly requires the use of a mechanical device attached to the motor shaft, increasing the drive system volume and its maintenance cost. To overcome such disadvantages, many sensorless methods for speed estimation have been proposed. Among those methods, various strategies based on Artificial Neural Networks (ANNs) can be found. This paper presents a back-electromotive force estimator based on Fully Connected Cascade ANNs (FCC-ANNs). From the estimator, rotor position and speed can be obtained. Simulation and experimental results using automatically generated C code functions for the FCC-ANNs using fixed point notation provided rotor position estimation with simple implementation.
Reconhecimento de Lâmpadas Fluorescentes Empregando o Reator Eletrônico Auto-Oscilante
Authors: Lopes Juliano de P. , Menke Maikel F. , Seidel Álysson R.
Published: February 2018

Neste trabalho é realizado o reconhecimento de lâmpadas fluorescentes tubulares T5 com o reator eletrônico auto-oscilante. A topologia desenvolvida identifica e opera diferentes lâmpadas com sua potência nominal. Um conversor SEPIC é empregado para correção do fator de potência, juntamente com um inversor meia- ponte para alimentar as lâmpadas. A identificação das lâmpadas é realizada com o auxílio de um circuito eletrônico analógico. O circuito de comando auto-oscilante é utilizado para o acionamento dos interruptores dos estágios inversor e de correção do fator de potência. São apresentados resultados experimentais e uma análise dos dados referentes ao atendimento da norma técnica NBR 14418, relativa ao preaquecimento dos eletrodos de lâmpadas fluorescentes T5.
Estimação de Parâmetros e Controle de um Gerador de Indução Duplamente Alimentado Durante a Sincronização com a Rede Elétrica
Authors: Jr. Celso R. Schmidlin , Lima Francisco Kleber de A. , Neto Tobias R. Fernandes , Branco Carlos Gustavo C.
Published: February 2018

O modelo matemático clássico do gerador de indução duplamente alimentado não considera as perdas no núcleo magnético e suplementares. Porém, ele é válido quando o gerador entrega sua potência nominal, o que não ocorre no processo de sincronização, onde o gerador está a vazio. Em geral, os modelos que consideram essas perdas tornam o equacionamento mais complexo. Neste sentido, este artigo propõe que se considerem estas perdas como agrupadas na resistência do rotor, o que mantém as equações da máquina inalteradas. Ainda, apresenta-se um método simplificado para a estimação dos parâmetros do circuito do rotor, os quais são utilizados para sintonizar os controladores de corrente durante o processo de sincronização à rede elétrica. Os resultados de simulação e experimentais confirmam a eficácia da abordagem proposta.
El gasto militar en el Estado de Bolívar 1859-1886
Authors: Pardo Bueno Luis Miguel
Published: February 2018

En el presente artículo, estudio la evolución del gasto militar en el Estado de Bolívar, entre los años de 1859 y 1886, durante los gobiernos del liberalismo radical en los Estados Unidos de Colombia. Para ello, compilé a través de la Gaceta de Bolívar y otros documentos oficiales, los presupuestos públicos anuales del Estado, centrando mi interés en analizar el gasto en el departamento administrativo de la milicia. Mi objetivo principal es mostrar, cómo las políticas del liberalismo radical se enfocaron en la descentralización fiscal y militar, con el fin de fortalecer a los poderes locales, cediéndole a las élites regionales el control y la administración de los recursos del Estado de Bolívar y de su milicia. Para lograr este objetivo, indagué por las formas de financiación de la milicia del Estado y los gastos internos para su funcionamiento, dando cuenta de la escasa partida presupuestal para pagar sueldos, material de guerra, educación y sanidad militar, lo que conllevó a que en la práctica la milicia estatal reclamara de la sociedad a través de recursos privados, las expropiaciones y los empréstitos, los rubros necesarios para su organización y funcionamiento.
Redes sociales, poder político y familia. Un análisis a partir de los Posse Talavera en Tucumán (1830-1870)
Authors: Bolsi Francisco
Published: February 2018

Este artículo se propone analizar las redes sociales, el poder político de la élite tucumana, a partir del estudio de la familia Posse Talavera entre 1830-1870. Se utilizaron como fuentes la sección Administrativa de Hacienda, la Sección Judicial Civil, la Sección Protocolos pertenecientes al Archivo Histórico de Tucumán, información que se complementó con la producción bibliográfica sobre el período en estudio. La hipótesis que se planteo fue que la familia Posse Talavera a partir de vínculos formales –alianzas matrimoniales– e informales –relaciones de lealtad y reciprocidad– constituyó una red social y de poder que le permitió situarse en la escena de la política provincial en la  década de 1860 y acumular un patrimonio significativo a partir de las actividades económicas que desarrollaron. Estos vínculos trascendieron la esfera local y regional en consonancia con la construcción del Estado Moderno en la Argentina.
Guerra, Estado y Revolución Militar en la América española durante los siglos XVI y XVII
Authors: Velásquez Arango Juan José
Published: February 2018

Este artículo restituye la biografía de Lorenzo Barcala, un pardo nacido a ines del siglo XVIII en Mendoza (en ese contexto capital de la Provincia de Cuyo) que se destacó en el cuerpo de cívicos pardos de esa ciudad y en otros cuerpos armados entre 1814 y 1835. A través del caso de Barcala busca explorar la movilidad social de soldados de origen africano incorporados a fuerzas militares durante la guerra de independencia y las guerras civiles en la actual República Argentina, partiendo de la hipótesis de que esa participación favoreció su integración y ascenso social. En este marco, el trabajo historiográico interpela y pone en relación fuentes documentales heterogéneas que permiten reconstruir acontecimientos biográicos y las analiza desde una perspectiva cualitativa que focaliza en el actor y sus prácticas y procura situar la trayectoria de Barcala en la historia social de la población negra de Mendoza. A favor de esa idea, el recurso biográico revela aquí estrategias de manumisión y coniguración de la familia de Barcala, evalúa la incidencia del prest en el acceso a la propiedad, y vislumbra en los compromisos económicos del coronel el alcance de sus relaciones y prestigio social.
Movilidad social de afromestizos movilizados por la independencia y las guerras civiles en el Río de la Plata. Lorenzo Barcala (1795-1835)e la Plata. Lorenzo Barcala (1795-1835)
Authors: Morales Orlando Gabriel , Caballero Luis César
Published: February 2018

Este artículo restituye la biografía de Lorenzo Barcala, un pardo nacido a ines del siglo XVIII en Mendoza (en ese contexto capital de la Provincia de Cuyo) que se destacó en el cuerpo de cívicos pardos de esa ciudad y en otros cuerpos armados entre 1814 y 1835. A través del caso de Barcala busca explorar la movilidad social de soldados de origen africano incorporados a fuerzas militares durante la guerra de independencia y las guerras civiles en la actual República Argentina, partiendo de la hipótesis de que esa participación favoreció su integración y ascenso social. En este marco, el trabajo historiográico interpela y pone en relación fuentes documentales heterogéneas que permiten reconstruir acontecimientos biográicos y las analiza desde una perspectiva cualitativa que focaliza en el actor y sus prácticas y procura situar la trayectoria de Barcala en la historia social de la población negra de Mendoza. A favor de esa idea, el recurso biográico revela aquí estrategias de manumisión y coniguración de la familia de Barcala, evalúa la incidencia del prest en el acceso a la propiedad, y vislumbra en los compromisos económicos del coronel el alcance de sus relaciones y prestigio social.
Educación infantil y oficio de maestra-jardinera, Medellín-Colombia: 1915-1930
Authors: Martinez Velasco Miguel Angel
Published: February 2018

El artículo tiene como propósito analizar históricamente la producción de un saber escolar que permitió la educación de los párvulos y la formación de la maestra-jardinera al interior del Colegio María Auxiliadora de Medellín, a partir de la apropiación de Pestalozzi, Fröebel y Montessori. Metodológicamente se empleó el enfoque histórico de la práctica pedagógica y como método algunas herramientas arqueogenealógicas. El contenido del texto se desarrolla en tres momentos: el primero analiza la emergencia de la maestrajardinera, el segundo da cuenta de la institucionalización de la enseñanza infantil como el primer nivel de instrucción y un tercer momento reescribe los discursos y prácticas para llevar a cabo la educación infantil y la formación de la maestrajardinera. Se presentan como resultados las tensiones de saberpoder que acontecieron en el marco de la pedagogía católica, los saberes para educar a los párvulos y la configuración  de la cátedra de pedagogía infantil para la formación de la maestra-jardinera. Como conclusiones se exponen algunos usos de la experiencia educativa del kindergarten salesiano en el presente, recurriendo a la noción de memoria activa del saber pedagógico que permita, hacia futuro, llevar a cabo la reconceptualización de la educación inicial.
Rutas de circulación e intercambio de sal en la provincia de Tunja, segunda mitad del siglo XVI
Authors: Acuña Rodríguez Blanca Ofelia
Published: February 2018

A través de este texto se pretende dar a conocer cómo las rutas de circulación de sal en la Provincia de Tunja contribuyeron a configurar un gran espacio económico, que integró a las provincias de Santa Fe, Pamplona y Tunja en el Nuevo Reino de Granada, durante el siglo XVI. Se partió de una reflexión historiográfica relacionada con la circulación y el comercio de la sal, los medios de transporte y las rutas usadas por los indígenas y los españoles; a partir de las cuales se consolidó un espacio económico mediado por la producción y distribución de la sal, que convirtió a la provincia de Tunja en un eje articulador de relaciones entre los sitios productores de sal en la provincia de Santa Fe y los consumidores de las provincias de Tunja y Pamplona. Esta articulación regional facilitó tanto la circulación de productos de distintos pisos térmicos, como la integración de un amplio territorio colonial. Esto debido a que la localización de Tunja como lugar de paso y conexión entre las Provincias de Santafé, Pamplona y los Llanos de San Juan, hizo de esta ciudad y sus términos un atractivo para el asentamiento hispano, a la vez que generó, durante la segunda mitad del siglo XVI, la posibilidad para que se organizaran en toda la Provincia de Tunja, sitios de aposento, venta y reventa de productos importados de España y productos de la tierra, para el sustento y abastecimiento de las necesidades básicas, y de esta forma sacar provecho de las producciones locales como la sal, el hayo, el algodón, las mantas y otros productos.
Engineered Nutshell Particles for Wellbore Strengthening
Authors: Chellappah Kuhan , Aston Mark , Maltby Tony , Savari Sharath , Whitfill Donald L.
Published: February 2018

Drilling fluid designs for wellbore strengthening have been improved through the development of engineered nutshell (ENS) products, which have replaced conventional marble for the larger particle sizes. Marble particles greater than ~400 microns are difficult to maintain in circulation due to their high tendency to grind down and settling out of suspension. Previous work has shown nut shell material to have the potential to overcome these issues. Additional laboratory results are presented which show ENS to have a low impact on mud rheology, and it is also resistant to swelling. There is some evidence for particle agglomeration but this has been found to be manageable in the field. A rigsite procedure for consistently monitoring and maintaining the size and concentration is introduced. The procedure also enables quantification of attrition rates. Two successful case studies are presented. In the first study, the introduction of ENS decreased the required material addition rates for maintenance from 60 to 17 sacks per hour. In the second case study, the corresponding decrease was from 110 to 30 sacks per hour. Furthermore, rigsite slot testing showed an improved sealing performance with ENS. These benefits are expected to become increasingly important as reservoirs become more depleted over time.
Investigation of Fracture Reopening Pressure in Wellbore Strengthening
Authors: Zhong Ruizhi , Miska Stefan , Yu Mengjiao , Ozbayoglu Evren , Takach Nicholas
Published: February 2018

Lost circulation is one of the most costly drilling issues and a major contributor of non-productive time. Wellbore strengthening has been successfully applied to reduce the associated cost and increased the wellbore stability in the industry over the past two decades. It is of critical importance to accurately predict the extra drilling mud weight after wellbore strengthening. However, previous research assumed fixed boundary conditions and only considered the stress intensity factor in the calculation of fracture reopening pressure (FROP). The change of pressure boundary on the fracture surfaces was ignored, which may overestimate the FROP. This paper employed a dislocation-based fracture model to determine the FROP in wellbore strengthening. The proposed model is compared with finite element simulation. An excellent match is obtained for the fracture profile and a clear inflection point can be observed between the plugged zone and unplugged zone. We present how wellbore pressure can change the pressure boundary in the model. Thus, the FROP calculation should be modified with the consideration of fracture plug width.

Results show that the fracture plugged zone pressure can affect the fracture profile. Specifically, lower fracture plugged zone pressure results in higher FROP. Thus, better wellbore strengthening can be achieved in the depleted sections during drilling. On the other hand, the fracture plug width plays an important role in determining FROP. With a fixed fracture plug location, larger fracture plug width can lead to higher FROP. However, there exists a critical fracture plug width for the maximum FROP, which is the value predicted by the previous research. The study reveals the importance of fracture plugged zone pressure and fracture plug width for FROP in wellbore strengthening. The model is useful for the design of wellbore strengthening materials (WSM), which are critical to achieve the best wellbore strengthening effects.
A Comprehensive Real-Time Data Analysis Tool for Fluid Gains and Losses
Authors: Andia P. , Sant R. V. , Whiteley N.
Published: February 2018

This paper describes a comprehensive approach to aid the monitoring and trending of wellbore fluid gains and losses during well construction drilling and completion operations. A software tool was built that is able to integrate real-time data with algorithms to provide early warning indicators for potential well control and lost circulation events. The focus is primarily on amalgamating relevant formation evaluation data, drilling and circulating parameters as well as pre-drill or real-time pore pressure and fracture gradient analyses.

In order to build a comprehensive real-time data analysis tool for managing the fluid in the well, three groups of parameters were identified as essential for monitoring: surface fluid flows and volumes, surface and downhole drilling parameters and formation properties, and gas events in the wellbore and at the surface. Eight capabilities were created to aid the monitoring of the identified key parameters. These capabilities depend on a number of integrated algorithms and displays that operate within a realtime data platform and were designed to utilize measurements in real-time as well as relevant well construction information. The primary aim is to provide a medium for visualization of events and informative trends, along with alerts when parameters fall outside specified thresholds. Presenting this collated information in real-time provides shared awareness of fluid gain/loss risks and events to personnel that work in a real-time monitoring center as well as to offshore and onshore operation teams. The software tool was developed and tested over three years and trialed in two wells with offshore and onshore operations personnel. It is now being deployed and used by technical specialists that work in a real-time monitoring center and operation support teams in the office.
Nanocellulose and Biopolymer Blends for High-Performance Water-Based Drilling Fluids
Authors: Hall Lee J. , Deville Jay P. , Santos Catherine M. , Rojas Orlando J. , Araujo Carlos Salas
Published: February 2018

Water-based drilling fluids are an economical and environmentally appealing option for wellbore construction. Both conventional and high-performance varieties of water-based systems typically use biopolymers to provide viscosity, suspend solids, and control fluid loss in the wellbore. Some examples include both naturally occurring biomaterials produced by plants or bacteria (e.g., starch, guar, xanthan) as well as their chemically modified analogues. However, new materials that could help improve efficiency, rate of penetration (ROP), or high-pressure/high-temperature (HP/HT) performance are necessary to expand the use of economical water-based systems in increasingly demanding conditions. Recently identified nanostructured biomaterials, such as nanocellulose, have been observed to have outstanding mechanical, structuring, and thermal properties and are known to be potent viscosifiers at low concentrations. This paper discusses a study that investigates the performance of water-based fluids by either replacing or augmenting their common oilfield biopolymers with cellulose nanofibrils (CNFs).

In this study, CNFs produced from technical-grade kraft pulp were mixed in aqueous dispersions with commercial biopolymer viscosifiers, such as xanthan and guar gum. Measurements were made of rheology, dispersion stability, CNF/biopolymer interaction, and filtration behavior as they relate to desirable fluid properties. Unexpected synergies were discovered when the CNFs were blended with secondary biopolymers. Increases or decreases observed in system viscosity were dependent upon the type of biopolymer mixed with nanocellulose but independent of the mass balance of the ingredients. In some mixtures, lower biopolymer concentrations increased viscosity within mixed systems while other mixtures decreased viscosity with increased concentrations.

The implications of these unusual findings suggest that performance efficiency can be tailored simply by mixing CNFs with biopolymers that are already used extensively in water-based fluids, allowing an operation to use less material. This discovery can enable a new method to maintain drilling fluid properties during drilling operations with the added benefit of increased temperature stability.

By modifying the surface of CNFs with secondary biopolymers, a wide range of fluid behaviors were achieved through changes in surface chemistry, surface morphology, and gel-network formation. Such nanocellulose fluid systems could serve as a renewable, nontoxic, and potentially cheaper alternative to synthetic polymers in high-performance, water-based fluids with the added benefit of controlling and helping to improve fluid properties using a mixture with common oilfield biopolymers.
Active Mud Line Pumping, Design, Testing and Future Possibilities in Rig Design
Authors: Hong Young Wan , van Kuilenburg Robert
Published: February 2018

The drilling industry is continuously improving drilling efficiency and safety. Precise control of the downhole pressures and knowledge of fluid flows is an essential element in any drilling improvement project. To obtain real time fluid flow data in drilling operations Coriolis flow meters are more and more used. However Coriolis flow meters are expensive, prone to be blocked by cuttings and handle multiphase and gas entrained fluids poorly.

To mitigate the problems associated with Coriolis flow meters, Noble Drilling and selected 3rd party vendors teamed up to design and test a test skid to prove the performance of a surface based active mud line pumping system. Active mud pumping systems could be a key component for future drilling rig designs and improve performance of current rig designs.

The active mud line pumping system is a pumping system to transfer drilling mud laden with cuttings using pumps from the gumbo box to the shakers. This allows detecting well bore problems such as kicks and loss of circulation with minimum time delay. By adding weight sensors, fluid density can be determined and if installed in the active mud tanks full flow-in / flow out data can be obtained. Active mud line pumping systems do not rely on gravity driven flow for moving fluid. This allows more efficient rig designs with improved safety features as well.

A key design feature of the active mud line pumping system is that it uses components that are already used on drilling rigs. This will facilitate efficient operation and maintenance by normal rig crews.

The testing shows that by using Tesla pumps it is possible to transfer heavy cuttings laden drilling fluids accurately without degradation of the cuttings. Valuable insights were gained at start/stop performance and flow measurements. Future testing will focus on improving the kick detection control loops and extending the modeling of the systems for future rig designs.
Perf-and-Wash Cement Placement Technique as a Cost-Effective Solution for Permanent Abandonment of a Well with Multiple Permeable Zones: A Case Study from North Sea, UK
Authors: Joneja Galen , Nafikova Svetlana , Reid James , Rublevskyi Anton , Salazar Jose
Published: February 2018

The job objective in a UK North Sea field was to permanently abandon a well that had poor cement bonding behind the casing across the intended isolation intervals. The challenge was to provide lateral isolation across two separate intervals in the most efficient way possible. Two "perf-and-wash" operations were executed successfully during the well abandonment. The deeper barrier envelope was validated by tagging and pressure testing the plug. The shallower section had been logged prior to the operation and, on completion of the perf-and-wash job, the plug was drilled out to allow for relogging, which indicated more than 76% of the perforated interval had circumferential coverage. After the bond log results were confirmed, a further cement plug was set across the shallow interval by conventional methods and verified by tagging and pressure testing. This paper outlines the detailed design preparations and presents both case histories where these steps were implemented successfully.
A New Workflow for Estimating Bit Wear and Monitoring Drilling Efficiency in Real Time During Drilling Operations
Authors: Millan Ekaterina , Ringer Maurice
Published: February 2018

This paper presents a new workflow for monitoring drilling efficiency in real time during drilling operations. Based on a bit-rock interaction model, the new workflow provides parameter estimations, such as bit wear and in-situ rock strength, obtained from typical real-time drilling measurements. The model can be used to predict rate of penetration (ROP) ahead of the bit, optimize drilling operating parameters, and determine the potential benefits of tripping out to change the bit.

The new approach presented here was initially tested in a laboratory-based drilling rig. Once these tests confirmed the theory, the technique was then validated on several operations to monitor and optimize drilling efficiency.

The workflow presented in this paper is a powerful method for monitoring real-time drilling efficiency through estimating bit wear, in-situ rock strength, and future ROP. This new method uses a novel approach that combines time-based and depth-based drilling data and innovative data processing algorithms to further constrain and enhance these estimated parameters. The new method is totally automatic and has been shown to facilitate optimizing drilling efficiency in real time.
Drilling Analysis Using Big Data has been Misused and Abused
Authors: Maidla Eric , Maidla William , Rigg John , Crumrine Michael , Wolf-Zoellner Philipp
Published: February 2018

The authors have been contacted by many people in the industry lately that are incorrectly utilizing big data to produce correlations that attempt to identify operational "sweet spots". This paper will show examples and address the need to add several steps to big data before any meaningful correlation results can be obtained, mainly understanding (and this is not a comprehensive list):

- The sensors involved and their limitations;

- The errors in the placement of these sensors (e.g. hook load sensor on the deadline);

- The frequency of the data and how this impacts the analysis (some companies provide 10-second data);

- The quality of the data itself;

- The appropriate filtering of data to ensure apples-to-apples comparisons;

- The rig state must be known

- Understanding of the physics involved.
A Practical Method to Monitor Wellbore Strengthening Particle Concentration
Authors: Alberty Mark , Yao Ziheng
Published: February 2018

The StressCage methodology of wellbore strengthening uses sized particles to bridge and seal induced fractures, increasing fracture resistance in permeable formations. The size distribution of the particles, or fracture prevention material (FPM), that are added to the mud is engineered to ensure correctly sized particles enter and bridge the induced fracture before it grows beyond its designed width and length. A minimum concentration of FPM is determined through a physics-based numerical calculation to derive a mud formulation based on the particle size distribution (PSD) and density of the selected mud additives. This minimum concentration and particle size distribution of FPM must be maintained at all times that the wellbore pressure exceeds the fracture gradient or previously generated fracture resistance of the formation in order to prevent the failure of the StressCage and the subsequent loss of wellbore integrity.

A number of methods have been used to monitor FPM concentration in the mud. Most methods sample the mud returning from the well before arriving at the mud shakers, pass the collected mud sample through stacked sieves, remove the liquid mud coating the particulates using either centrifuges or drying ovens, and weigh the resulting residue to determine the return concentration. These methods can be inadequate and difficult to implement due to the requirement of specialized equipment on the rig (ovens, laser PSD, centrifuges, etc.), the need for additional personnel to conduct the mud monitoring activities on the rig, and the significant delay in obtaining the results. The lag time for results in deepwater wells can be 5 to 10 hours, depending on the time required to circulate the mud up the well and dry the samples. This delay can prevent operators from detecting when FPM concentration decreases to below the minimum required for drilling depleted sands.

A simple and fast method has been developed that requires minimal special equipment. A reference sample is collected from a reserve mud pit carefully prepared with the target minimum FPM concentration. The mud is then run though a set of selected stacked sieves. The reference tare weights of the wet FPM collected in each sieve are used as a reference for monitoring the active system. The reference wet FPM weight is compared to mud samples collected from the suction pit of the active system as the well progresses. The difference in the weight observations is then used to determine appropriate additions to maintain or exceed the minimum requirements.
Flexible, Self-Healing Cement Eliminates Sustained Casing Pressure in Denver-Julesburg Basin Unconventional Wells
Authors: Langley M. , Cleveland M. , Eulberg J. , Hudson M.
Published: February 2018

The oil and gas industry has operated in Denver Julesburg (DJ) basin for many decades. Currently in the basin, increasing population density and wellbore complexity have resulted in a heightened visibility of long-term well integrity. Failure can lead to future liabilities, loss of public trust, and a revoked right to operate. Operators must demonstrate commitment to well integrity to continue operating in the basin, yet many still report sustained casing pressure (SCP) on a significant portion of wells. Because SCP corresponds to the open communication of fluids to surface, it is a direct metric of well integrity failure. Regulations require operators to report and remediate instances of SCP on all wells. On average, clients experience one well with SCP for every five drilled.

As a primary well barrier element, the cement sheath is vital to well integrity improvement. Enhanced placement techniques of conventional cements failed to prevent SCP, confirming that failure is derived from post-placement dynamic conditions. The solution must account for pressure and temperature stresses, preventing and mitigating mechanical failures throughout the well life cycle. A flexible and self-healing cement design provides a twofold response that is ideal for wells in areas, such as the DJ basin, with SCP risk.

Mechanical properties are optimized based on the results of a mathematical stress model. Although Portland-based cement systems can be optimized to sustain higher levels of dynamic stresses, it is impossible to avoid a mechanical failure entirely. Therefore, a self-healing function is a critical secondary feature. The self-healing mechanism is designed to activate upon contact with an invading hydrocarbon and can be formulated for any type of hydrocarbon, from high gravity oil to dry gas.

Flexible and self-healing cement has been successfully designed and implemented on approximately 250 wells in the DJ basin with a reduction to 2% instances of SCP. Elimination of SCP provides confidence in long-term well integrity, which is essential to continued operation in the basin.
Breaking the Performance/Cost Paradigm in Drill Pipe Connections in Extended Reach Drilling
Authors: Plessis Guillaume , Muradov Andrei , Wright Chuck , Morgan Dan , Dugas Jeremy , White Brennan , Daley Dallas
Published: February 2018

Various generations of double-shouldered drill pipe connections have been developed in the past 30 to 40 years with performance as a primary driver. The objective was to bring improvements in torque and hydraulics to satisfy drillers' needs. The record extended reach drilling (ERD) wells could not have been delivered without these technological advancements. The driver for these developments was solely on improved performances, with limited focus on cost, as these technologies were so enabling that the associated costs were deemed acceptable.

When these same connections started to be used on land rigs to deliver wells in a factory drilling fashion, where cost control is of higher importance, the cost of maintaining these premium connections started to become more apparent. It, therefore, became obvious that a different approach was needed to meet the combined need for performance, as well as a lower cost of ownership post acquisition.

A comprehensive two-year research and development (R&D) program was carried out to evaluate various design options. After the research was conducted, a design was chosen that allows better control of stress inside the connection. This allows users to benefit from other design features besides the torque and hydraulics of a streamlined connection. The R&D program included numeric simulation and mechanical lab testing. More specific elements of the design allowed more tolerance related to field damage of the connection, less material loss on repairs, and more importantly, a ruggedness so that the connection can remain in the field longer rather than needing to be repaired so often.

The final stage of qualification was a field trial at the manufacturer's test rig facility. A post field trial inspection confirmed the improved serviceability and ruggedness, qualifying the connection for commercial release.

The 4th generation double-shouldered connection was first put to task in the Permian basin. A rental string was dispatched to a land rig and used to drill the longest and fastest lateral in the area. The tapered 5½ in. by 5 in. drill pipe string, which comes with tool joints of a similar size (this of 5 in. drill pipe), drilled the well and saved two days off the estimated drilling plan. Subsequently, more strings have been deployed, and more data shall be gathered in this paper to demonstrate the low repair rate.

A new approach has been used to design a connection that performs at high torque levels but also demonstrates improved serviceability and a ruggedness approaching that of an API rotary shoulder connection.
Rapid Development of Real-Time Drilling Analytics System
Authors: Cao Dingzhou , Loesel Chad , Paranji Sanjay
Published: February 2018

This paper serves to provide a technical overview of the Real-Time Drilling (RTD) analytics system currently developed and deployed. It also serves to share practices used in managing the RTD analytics project which have resulted in the efficient delivery of work products. By employing the novel and agile development approach on the RTD project, the design to production time has been faster and has cost much less compared to a more traditional multi-year effort and cost intensive RTD development project. Within three months, for proof of concept (PoC) purpose, an RTD analytics system with two analytics modules was built from scratch and placed online in production. This real-time decision-support tool has been fully accepted by the operations team and has become a powerful tool for daily well operations. After eleven months as this paper was drafted, this system has four analytic modules online for production and three analytic modules under development; it is expected that more new modules will be added to the system on a regular basis.
A New Approach to Characterize Dynamic Drilling Fluids Invasion Profiles in Application to Near-Wellbore Strengthening Effect
Authors: Ezeakacha Chinedum Peter , Salehi Saeed , Bi Hongfeng
Published: February 2018

Mud cake evolution and plastering have been identified as important wellbore strengthening mechanisms. They serve to reduce losses through pore throats and fractures, while impeding the growth of induced fractures. Recent experimental and analytical studies have also revealed the complexities in drilling fluids’ invasion profiles and mud cake buildup. These complexities arise from the changing wellbore conditions observed in an actual field scenario. It is important to investigate the effects of these conditions on drilling fluid invasion for near-wellbore strengthening application.

To achieve this goal, some dynamic wellbore conditions which are close-to-real field conditions were simulated in a controlled laboratory setup. The following conditions were investigated: rotary speed, temperature, type of lost circulation material (LCM), concentration of LCM, differential pressure, eccentricity, rock permeability, and fracture width. In the experimental setup, the geometry of the shaft that simulates drill pipe rotation allowed for mud cake evolution and plastering around the inner diameter of the thick-walled cylindrical porous media. Water-based mud (WBM) recipes were formulated for different porous media types. The rheological profile for each mud recipe was investigated for operating temperature limit. Dynamic drilling fluid invasion experiments were conducted with thick-walled cylindrical Buff Berea sandstone, Upper Grey sandstone, and fracture slots with varying widths.

The results indicate that temperature, rock permeability, fracture width, and LCM type and concentration are the most influential factors that control dynamic fluid invasion profiles. Increase in granular LCM concentration at elevated temperature is not completely effective in reducing pore-scale fluid invasion. Spurt invasion, rock porosity, permeability, and fracture width are important determinants of mud cake evolution. Increase in fiber LCM concentration showed effective mud cake evolution in the fracture slots. The results from testing mud cake stability revealed mud cake rupturing on three experiments out of the nine that were performed. The novelty in this approach is the use of thick-walled cylindrical cores and fracture slots to profile dynamic fluid invasion of different fluid recipes. Pressure, temperature, and pipe rotation were combined to simulate wellbore conditions under which fluid loss, cake growth, and plastering occur. This approach can be used in drilling fluid design for minimizing fluid loss, cost, and selection of operating conditions.
Unconventional Drilling in the New Mexico Delaware Basin Case History
Authors: Willis John , Tellez Diego , Neel Randy , Caraway Greg , Adam Derek , Rodriguez John
Published: February 2018

The drilling practices, well designs, and experiences from drilling 179 unconventional horizontal wells drilled from 2012 through late 2017, in the New Mexico Delaware Basin, are presented.

Geological conditions addressed include high-pressure flows, lost circulation, salt and anhydrite, and drilling effects. Successful practices covered include casing design and setting depths, bits, rotary steerable systems (RSS), rig specifications, pad layout, and others. Mud systems discussed include brine, mixed-metal hydroxide, invert and direct emulsions. The benefit of rotary steerable drilling assemblies is discussed. Techniques to predict, prevent, and mitigate the effect of downhole vibrations are addressed, including bit and bottom-hole-assembly design, and operating practices.

Overall drilling speed was increased by 149% (measured as feet-per-day) during the period from 2012 to 2017 through the practices that are covered. During the same period, average lateral lengths increased from approximately 3,000 ft in 2016 to approximately 7,000 ft in 2017, with 10,000 ft laterals common. Rig capabilities, pad layout, casing designs, drilling fluids, drilling dynamics practices, and other designs improved significantly in the past 3 years. A methodical approach to vibrations has proven to be critical to consistent performance. Direct emulsion mud has shown promising results as a low-density fluid with salt-saturated water phase. Casing designs were optimized to eliminate strings in some cases, and to reduce hole sizes in other cases. Rig modifications were required to support long laterals and larger drill pipe sizes.

The economic success of New Mexico unconventional developments is heavily dependent on minimizing well cost. It is a difficult area requiring complex optimization.
Wellbore Instability Prediction Using Adaptive Analytics and Empirical Mode Decomposition
Authors: Lin Abraham , Alali Mohammed , Almasmoom Salahaldeen , Samuel Robello
Published: February 2018

Wellbore stability is one determining factor to the success of drilling operations. A multitude of wellbore stability issues may still be encountered, despite all previous knowledge and experience, when drilling a certain formation. However, the use of the large amount of data collected during drilling can provide valuable insight. This collected data, in combination with artificial intelligence models, can be used to predict wellbore stability in new drilling operations. Because wellbore stability is such a common and expensive issue to the industry, many papers in the literature have presented a multitude of techniques and algorithms to predict wellbore stability. The predictions made in the literature have all provided relatively good accuracy; the most common methods that have been presented include the use of multivariate statistics, linear methods, and artificial neural networks.

This paper presents two approaches to solve the wellbore instability prediction problem. First, principal component analysis (PCA) and linear discriminant analysis (LDA) are used in an attempt to reduce the dimensionality of the dataset. The results indicate that the dataset dimensionality could not be reduced. Second, nonlinear artificial intelligence models were implemented, including the artificial neural network (ANN), specifically the Bayesian regularization neural network (BRNN), and support vector machine (SVM). After building these two models and checking their accuracy, a new feature was implemented to filter the input data. Empirical mode decomposition (EMD) was adopted, which is commonly used in the field of signal processing to eliminate noise and variation in the data. This study evaluates the effect of EMD on the prediction and classification accuracy for wellbore stability. The study results are promising; by using EMD, accuracy was increased by 15% for both the ANN and the SVM models.
Backward Whirl Testing and Modeling with Realistic Borehole Contacts for Enhanced Drilling Tool Reliability
Authors: Popp Timothy , Stibbe Holger , Heinisch Dennis , Reckmann Hanno , Spanos Pol
Published: February 2018

Drillstring-borehole contact may result in backward whirl: a common and catastrophic phenomenon. To increase BHA (bottom hole assembly) reliability, reduce non-productive time (NPT), and ultimately improve service delivery, an in-house backward whirl testing rig is developed to investigate dynamic loads. Analytical and numerical models elucidate dynamic responses and are validated against backward whirl test results. A 6 ¾-in. BHA is tested in an 8.5 in. borehole using a continuous and discontinuous borehole profile. At a rotary speed of 60 rpm, and using a continuous borehole, lateral acceleration amplitudes range between 20 to 30 g with an RMS value of 3 gRMS. In comparison, a discontinuous profile results in acceleration amplitudes between 40 to 50 g with an RMS value of 7 gRMS. In regard to the discontinuous profile, the response spectrum shows a broader range of frequency content up to 200 Hz while distinct frequency peaks are evident in the spectrum when the continuous profile is used. Results indicate that backward whirl may occur from friction induced contact with different borehole profiles. Further, discontinuous profile yields drastically higher dynamic loads with a broader frequency spectrum than a continuous profile. Furthermore, validated models may serve as useful predictions for the backward whirl phenomenon and the system response. Backward whirl testing of full scale drilling tools with realistic, discontinuous borehole contact, supplemented with validated modeling, is a new approach to understand downhole dynamic events.
Improving Surface WOB Accuracy
Authors: Kyllingstad Åge , Thoresen Karl Erik
Published: February 2018

Weight on bit (WOB) is the axial trust force applied to the bit during drilling. It is one of the most important controllable variables of the drilling process. Still, it is quite rare and very difficult to measure it directly, and we are often left with estimating it indirectly through measurements of the tension at the top of the string, or even at the dead line anchor. This indirect WOB measurement, commonly called surface WOB, is most often calculated as measured off-bottom hook loadminus the actual hookload. This method assumes that the reference string weight is constant and does not change during drilling.

This paper challenges this assumption by discussing a variety of physical effects that can cause the reference hook load to change, during the drilling of a new stand and after a traditional WOB zeroing procedure is carried out. The paper discusses the following effects that can be used for correcting the reference hook load: 1)well bore friction, 2)added weight in air, 3)well inclination, 4)flow induced lift, 5) nozzle jet lift, 6)cuttings in suspension, and 7) back-pressure in managed pressure drilling operations.
Automated Large Data Processing: A Storyboarding Process to Quickly Extract Knowledge from Large Drilling Datasets
Authors: Saini G. , Chan H. , Ashok P. , van Oort E. , Isbell M. R.
Published: February 2018

Substantial volumes of data are collected during modern drilling operations. However, the business value of such data is limited unless it can be analyzed quickly to derive practical knowledge for application on subsequent wells. The sheer quantity and messiness of data can overwhelm oilfield personnel, making it difficult for them to extract value. An automated process is necessary to extract knowledge quickly and efficiently from large datasets. Our team identified a preliminary set of 12 questions with answers that provide immediate knowledge to help improve the drilling of subsequent wells. Each of these ten questions is best answered through a storyboarding process. The process involves the automatic creation of a series of one-page visuals with just the right amount of information on each page to validate the answers to the questions. Standardizing the structure of the data (well-site data, survey data, geology data, well plans, etc.) enables software to rapidly create these visuals and is an important step in the process.

This work describes how the storyboarding process was applied to a dataset of more than 100 gigabytes (GB) from 16 shale wells drilled in North America. Examples of questions that could be quickly answered using the process are: ‘What was the best drilled well on the pad?’ and ‘Did a particular bottom hole assembly (BHA) improve drilling in a particular section of the well?’ Scripts were written in Matlab and Python to automatically process the raw data and generate more than 20 different types of one-page visuals that are well suited to present the answers to such questions. The illustrated information includes insights into BHA performance, wellbore tortuosity and quality, vibrations, weight on bit transfer, and other drilling dynamics. Identifying the relevant KPIs to satisfactorily answer the questions and present exactly the right information from the vast amounts of data was a challenge. This paper documents and describes the concept of storyboarding that uses visuals to answer comprehensive questions. This concept is not yet widely applied in the drilling industry today, but is expected to be quickly adopted by stakeholders interested in drilling performance improvement and cost saving opportunities.