bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variabilidade climática para o município de Patos, Paraíba, Brasil
Authors: Menezes Hudson Ellen Alencar , Medeiros Raimundo Mainar de , Santos José Lucas Guilherme , Lima Tiago Silva 
Published: March 2017

<p>O trabalho tem como objetivo avaliar as variabilidades climáticas no município de Patos – PB, enfocando tais variações como um meio para compreender futuras mudanças. Para realização deste trabalho utilizou-se dados de temperatura máxima do ar, umidade relativa do ar e totais pluviométricos mensais e anuais no período de 1994 a 2012, da Estação Meteorológica do INMET na cidade de Patos. Como resultado pode-se afirmar que a temperatura do ar máxima anual demonstrou grande variação entre o período estudado, a temperatura máxima absoluta foi incrementada de 7% e a temperatura mínima absoluta sofreu uma redução de 10, podendo acarretar vários problemas socioeconômico, bem como, para a saúde humana. A partir dos dados, verifica-se, também, que a umidade relativa do ar está sendo incrementado ao longo da série estudada, fato que pode estar relacionado com o aumento da temperatura e consequentemente com uma maior evaporação das águas. Sobre os totais pluviométricos anuais, nota-se que os valores estão aumentando gradativamente, sendo que esse aumento pode estar relacionado com o aumento da temperatura, que faz com que se tenha uma maior evaporação e consequentemente uma maior precipitação.</p><p align="center"><strong>Climate variability for Patos city, Paraíba state, Brazil</strong><strong></strong></p><p><strong>Abstract: </strong>The study aims to assess climate variability in Patos – PB city, focusing on such variations as a means to understand future changes. For this work we used maximum air temperature data, relative humidity and total monthly and annual rainfall from 1994 to 2012, the INMET Meteorological Station in Patos city. As a result one can be said that the temperature of maximum annual air showed great variation between the study period, the absolute maximum temperature was increased from 7% and the absolute minimum temperature was reduced by 10, which may cause various socio-economic problems as well as to human health. From the data, it appears also that the relative air humidity being incremented along the series studied, which can be related to the temperature rise and consequently with a greater evaporation of water. On the annual rainfall totals, note that the values are gradually increasing, and this increase may be related to the temperature increase, which makes it has a higher evaporation and hence greater rainfall. <strong></strong></p>
Probabilidades para pressão atmosférica no município de Mossoró-RN
Authors: Sousa R. P. , De Assis J. P. , Batista B. D. O. , Lima T. S. , Pereira K. E. V. 
Published: March 2017

<p>Objetivou-se elaborar uma tabela de probabilidades da ocorrência de valores mensais da pressão atmosférica em milibar, para Mossoró, RN, Brasil, a partir dos registros diários das pressões atmosféricas obtidas na Estação Meteorológica da Universidade Federal Rural do Semi-Árido em Mossoró, RN, referentes a uma série histórica de trinta e oito anos (1970-2007). A pressão atmosférica mensal em milibar foi estimada utilizando o modelo da distribuição densidade de probabilidade normal, para os níveis de 1% a 95% de probabilidade. Tendo-se em conta os resultados dos testes de aderência a 10% de probabilidade e utilizando-se o Logaritmo da Máxima Verossimilhança, pode-se concluir pela adequabilidade do processo de construção da Tabela de probabilidades, e que esta representa importante subsídio no planejamento das atividades agropecuárias na região, tirando o máximo proveito dos seus benefícios e evitando os seus efeitos danosos.</p><p class="Default" align="center"><strong><em>Probability table for atmospheric pressure </em></strong> <strong><em>in city of Mossoró-RN</em></strong><strong><em></em></strong></p><p><strong>Abstract</strong><strong>: </strong>The aim of this study was to develop a table of probabilities of occurrence of monthly values of atmospheric pressure in millibars, to Natal, RN, Brazil, from the daily records of atmospheric pressures obtained at the Meteorological Station of the Federal Rural University of the Semi-Arid in Mossley, RN, referring to a historical series thirty-eight-years (1970-2007). The atmospheric pressure in millibars monthly was estimated using the model distribution normal probability density to levels of 1% to 95% probability. Try into account the results of the compliance tests at 10% probability and using the logarithm of Maximum Likelihood, we can conclude the suitability of the construction of the table of probabilities, and that this is an important benefit in the planning of agricultural activities in the region, making the most its benefits and avoid its harmful effects.</p><p><strong> </strong></p>
Deconstructing Good Teaching: Views of Consumers of Teaching
Authors: Nabaho Lazarus 
Published: March 2017

<p>Literature attests to limited systematic inquiry into students’ conceptions of good teaching in higher education. Resultantly, there have been calls for engaging students in construing what makes good university teaching and in developing a richer conception of teaching excellence. This interpretivist study that is based on views of final year university students from six academic disciplines investigated students’ conceptions of good teaching at Makerere University in Uganda. Students conceived good teaching as being student-centred, demonstrating strong subject and pedagogical knowledge, being approachable, being responsive, being organised, and being able to communicate well. Most of the conceptions of good teaching hinge on what the teacher does (the means) rather than affording high quality student learning (an end). It can therefore been concluded that good teaching is a multi-dimensional construct that defies a single definition and cannot be assured and assessed using a single indicator.</p>
Improved Primary Cement Jobs and Mitigation of Sustained Casing Pressure through the Use of Foamed Spacer Design Technology
Authors: Kumar Animesh , Gillies James , Mehra Rohit , Pardeshi Mahendra , Wilke Andrew , Li Jason 
Published: March 2017

Abstract
This paper covers the development, field testing and execution of a foamed spacer fluid on a conventional oil/gas block in India. It discusses the equipment and processes necessary to apply this technology of foamed spacer in production casing and the advantages of its application.
Sustained Casing Pressure (SCP) is one of the major challenges in many wells. This pressure resulting from poor zonal isolation by primary cement jobs represents a safety hazard, can influence production rates and in a worst case could compromise the structural integrity of the well. One cause of SCP in the wells was determined to be incomplete removal of drill cuttings and mud resulting in poor cement bonding. This results in micro-annulus/channeling within the annular cement sheath, thus allowing shallow formation gas to percolate to surface resulting in SCP.
The primary cement job for production casings is critical to the success of a well completion. In many instances, the use of conventional spacer technology has not managed to produce a good cement bond. This paper discusses how a foamed spacer system can be designed and used to increase mud removal and improve the quality of the cement job.
Foaming the spacer drastically increases its ability to effectively displace drilling mud and drill cuttings. This is achieved as a result of high annular velocity present even in large washed-out hole. The foamed spacer also typically has a higher yield point (YP) which helps in proper mud removal. In addition, foaming will increase the volume of the spacer, and extra volume allows longer contact time.
This paper highlights a case study for the application of foam spacer and documents the lessons learned. Job execution of foamed spacer is the basis for further improvement and implementation of foam technology for cement system as well. The paper also illustrates advanced laboratory tests done, such as effect of foam cement on skin damage, foam stability tests at downhole conditions, permeability tests, etc.
A Real-Time Well-Site Based Surveillance and Optimization Platform for Drilling: Technology, Basic Workflows and Field Results
Authors: Payette G. S. , Spivey B. J. , Wang L. , Bailey J. R. , Sanderson D. , Kong R. , Pawson M. , Eddy A. 
Published: March 2017

Abstract
We describe recent technology advances, basic workflows and field trial results for a real-time well-site based surveillance and optimization software platform for drilling. The system integrates with existing infrastructures available at a typical rig-site and may be deployed in the driller's cabin to enable real-time decisions by drilling personnel. The platform leverages as input one-second real-time surface data (obtained from sensors instrumented on surface equipment and available at most well sites). The platform provides surveillance capabilities, trending analysis tools, and controllable drilling parameter recommendations to improve drilling performance by enhancing decision-making at the well-site.
The platform supports active drilling parameter management by encouraging regular drill-off tests. Understandings obtained from these tests allow the system to provide real-time information on performance trends and drilling dysfunctions through various displays which aid in the drilling optimization process. We describe recent technology enhancements to the system which leverage adaptive response surface technologies that map out performance and dysfunction for the controllable drilling parameters as drill-off tests are performed. The system allows users to view performance maps for a variety of system outputs including Mechanical Specific Energy, Rate of Penetration, stick-slip severity, and Depth of Cut, as well as combinations of these outputs. The performance maps give precedence to "new" data and adapt as the bit wears and/or new formations are encountered and are leveraged to provide controllable drilling parameter recommendations to the driller.
We present examples from recent field applications of the system which demonstrate the value of real-time well-site based drilling optimization and parameter management leveraging surface data. We provide examples where the software was able to provide operation personnel with the confidence to increase Weight on Bit beyond "field rules" to enable faster drilling operations as compared with offsets. We provide additional examples highlighting how active surveillance and parameter management using the system's recommendations and response surface maps was able to produce multiple record bit runs in mature fields. We also discuss workflows enabled by the system and efforts taken to enhance field personnel uptake by working to address the human machine interaction aspect of the platform during software development.
The Value of High-Definition Wellbore Surveys in an Arctic Land Environment
Authors: Bevzenko Vladimir , Chatar Crispin , Gorichka Marian , Kuznetsov Aleksey , Abzalov Zarif 
Published: March 2017

Abstract
Since 1929, when the first wellbore surveying tool was developed, drillers and geologists have looked on in anticipation as the industry worked persistently at improving the technology. Today, the majority of work is limited to accelerometers, magnetometers, and gyroscopic tools. Surveying in the Arctic is particularly challenging since magnetometers have an inherent error in the physics of the measurement that make them less favorable at high latitudes. Gyroscopic tools are not particularly suited to the drilling environment and are usually run after the drilling process, losing their real-time advantages. Accurate well placement is vital to the success of hydrocarbon production; accurate surveys are required in real time to drill complex 3D wells that penetrate multiple small geological targets and avoid costly risks of drilling out of the production zone. Meanwhile, interest in the Arctic region is growing, in part because of possibilities for resource development, new access to transportation routes, and climate change. Energy companies are certain to be at the forefront of Arctic development and investment.
In the Arctic environment, with the error terms already inflated, an improvement in positional certainty can be a welcomed change. Technology that enables taking surveys continuously with downhole tools while drilling and reprocessing the data in real time give us the opportunity to eliminate errors associated with surveying frequency such as true vertical depth (TVD) error or inaccurate tortuosity. TVD assurance utilizing the high-definition survey technology has been used with several new approaches, for example, to reduce rig time on surveys by increasing the interval between stationary surveys without degradation in positional certainty. This technology also helps in understanding real borehole tortuosity and thus has an influence on drilling optimization and well completion strategy, helping the drilling engineers to create better models, for example, by improving modeling torque and drag.
This paper will discuss the drivers for high-definition surveying in Russian Arctic land drilling, the science of the measurements, and the technology behind this unique method for survey calculations. Case histories will also be discussed in detail before, finally, making some conclusions about the future of this method as it relates to increasing positional certainty.
Quantification of Wellbore Collision Probability by Novel Analytic Methods
Authors: Bang J. 
Published: March 2017

Abstract
Unintentional collision between two wellbores may have serious economic and health-safety-environmental (HSE) consequences. It is therefore important to evaluate the probability of such an event in the well planning phase, and at critical stages during the drilling phase.
A commonly used approach is to analyze the collision probability between two points, one in each wellbore, that are determined from geometric criteria only. This procedure may ignore point pairs with higher collision probabilities, and thereby lead to over-optimistic conclusions. Typically, the results from such methods will be accurate only for simple wellbore geometries such as straight sections and for position uncertainties that are highly symmetrical with respect to the wellbores. More advanced methods that overcome such limitations are impractical for general application because of high conceptual or computational complexity.
This paper proposes novel analytic methods that potentially may overcome these problems. Formulae are derived for two important situations: the direct hit and the unintentional crossing scenarios. In both cases, the spatial region of interest is divided into carefully designed segments, such that the collision probability can be accurately evaluated for each segment. The total collision probability is then found by summing the results over all segments. The main advantage of this approach is that it gives accurate results for arbitrary well geometries and uncertainty ellipsoid orientations.
The algorithms can easily be integrated in existing software for wellbore anti-collision analysis. The paper shows examples of results, which all are in good agreement with control calculations. Compared to existing methods, the proposed methods are therefore believed to represent a significant improvement to quantitative collision probability analysis, for both the wellbore planning and the drilling phases.
Model-Based Control in Managed Pressure Drilling
Authors: Stakvik Jon Åge , Berg Christian , Kaasa Glenn-Ole , Graham Robert , Torrealba Antonio 
Published: March 2017

Abstract
Increased use of Managed Pressure Drilling (MPD) has enabled a significant improvement in drilling operations through the ability to accurately control pressure within a narrow window and by actively managing the annular pressure profile. However, the technology has not yet reached its full potential; well control events involving a gas influx causes two-phase flow in the well and can lead to severe deterioration of pressure control performance. In this study, a robust model-based MPD control system is presented and results from drilling a well in the Umm al-Quwain region in the UAE demonstrate invaluable benefits for both normal operations and during well control events.
Due to its transient nature, drilling has always been a complicated operation and requires highly skilled personnel to achieve the desired pressure control accuracy. The introduction of automated MPD systems tries to implement more robust and safer control over well control operations that were previously manual tasks, however, this is still a challenge since wellbore conditions are constantly changing. This has prompted the need for proactive and model-based control techniques that act in advance to optimize the performance based on measurements and knowledge of the system. The development of this state-of-the-art MPD control system involved detailed validation in a high-fidelity simulator and thorough tests of robustness and performance in a full-scale flow loop with continuous gas injection capabilities, with focus on two-phase flow and gas influx handling.
Results from field operations show that the model-based MPD control system maintains robust performance during planned operations such as connections and drilling ahead. Based on pump flow measurements surface back-pressure or bottom hole pressure are maintained constant during fast pump ramp-down and ramp-up without the use of a back-pressure pump. Usually, MPD control systems require strict procedures on pump ramp speed to maintain constant pressure during transient operation. In this paper, the model-based control system implemented is shown to handle irregular pump flow changes and still maintain constant surface back-pressure or bottom hole pressure. In particular, a simulated pump emergency shutdown is shown where the pumps are stopped in less than 20 seconds. The MPD control system still managed to maintain constant bottom hole pressure by closing the chokes in a controlled manner.
In summary, this paper presents a field implementation of a fully model-based MPD control system that demonstrates its ability to compensate for irregular pump flow changes. Throughout these irregular pump flow changes, the control system maintains constant bottom hole pressure or surface back-pressure. Furthermore, the system demonstrates the ability to maintain the desired pressure control precision in all normal operations and during all unplanned events experienced during the operation.
Improved Through-Christmas-Tree P&A Plug Placement with New Innovative Cementing Methodology
Authors: Olsen M. , Sætre T. , Hanssen R. , Waagen M. , Sirevaag B. , Lindanger C. , Gustafsson J. R. 
Published: March 2017

Abstract
When the production of a platform well is no longer profitable, two options are available—either perform permanent plug and abandonment (P&A) or reuse the slot by plugging the original well and sidetracking. P&A requires setting barrier elements in the wellbore to prevent hydrocarbon migration between potential flow zones and to the surface. In most cases, it is financially beneficial to perform as much of this work as possible during an intervention phase before rig operations begin, thus saving rig operating expenses.
Most conventional barriers are balanced cement plugs, and setting a cement plug requires a drilling rig to handle the workstring through which the cement is placed, crew, and associated equipment [e.g., blowout preventer (BOP)]. However, the rig time spent performing P&A could be used more productively, such as drilling and completing new wellbores. An operating and a service company developed a method for setting the primary P&A cement plug toward the reservoir without a drilling rig. The cement is set through the Christmas tree using a specialized wireline-set packer as a base and wiper plugs installed on a specialized spool piece to isolate the cement and indicate completion of the job. This paper explains the method and equipment and presents three case studies from the Norwegian sector of the North Sea.
CFD Modelling of Observed Cuttings Transport in Oil-Based and Water-Based Drilling Fluids
Authors: Sayindla Sneha , Lund Bjørnar , Ytrehus Jan David , Saasen Arild 
Published: March 2017

Abstract
Cuttings transport has been a topic of research for many years. It has been observed that drilling fluids with similar properties according to the API standard can have significantly different behaviour with respect to the efficiency of cuttings transport. Oil based drilling fluids have been considered to be superior to water based drilling fluids when it comes to the hole cleaning, even if the fluid properties are equal as measured in accordance with API specifications. Despite this well-known fact, very limited studies are available in the literature to address this issue. Experimental studies with various oil-based drilling fluids and water-based drilling fluids were conducted in a 10m long flow loop under identical and controlled conditions. Further to understand the physics behind the observed differences in the cuttings transport efficiency, we have developed an Eulerian-Eulerian multiphase computational fluid dynamics (CFD) model using commercial software ANSYS FLUENT. Experimental values from the flow loop experiments are compared with the CFD model results. CFD model helps to fill the gap in the results, which could not be obtained using experiments. The experimental results confirm that the annular frictional pressure loss in a fully eccentric annulus are significantly lesser than the values predicted by using models available in the literature for concentric annulus. CFD model includes realistic conditions like eccentric annulus and flow velocities. CFD model is used to conduct simulations for a wide range of parameters and the obtained results will be used to develop improved correlations for the prediction of cuttings transport.
Improving the Structural Integrity and Sealability of Float Valves With Optimized Float Bore Design
Authors: Holcomb Spenser R. , Gokhale Samit , Lee Kang 
Published: March 2017

Abstract
In many instances subs and stabilizers are bored to be used with a float valve in a box connection facing up-hole rather than down-hole. Sometimes the requirements for float bore depth, which are derived for a "box-down" float bore, are not sufficient to ensure the proper sealing of the float valve within the float bore in this "box-up" configuration. Additionally, regardless of float bore orientation, there is a chance that the float bore depth requirement can be long enough that the float bore runs into the pin connection of the sub on which it is machined. This can result in high stress in the float bore which could lead to fatigue cracks and a reduced load capacity of the tool due to a decrease in cross sectional area.
This paper details the design methodology used to ensure the proper sealing of float valves used in box-up float bores. Finite element analysis (FEA) was conducted to determine the distance from the back of the float bore to the shoulder of the pin connection necessary to substantially reduce the stress experienced as a result of connection make-up forces.
The new design methodology ensures proper sealability of float valves and structural integrity of the tool. New requirements based on this methodology have been implemented by various manufacturers and vendors with successful results.
A case study is provided which describes how a gap in current industry accepted inspection practices led to a sub with a float bore that was machined long enough to reach the shoulder of the pin connection to be overlooked. This led to the failure of the sub downhole. The paper provides a reasoned approach to new criteria needed for float bore design and makes the case for the standardization of float valves.