bluuebunny/crossref_metadata_2025 huggingface dataset:
L’HISTOIRE DE LA PESTE EN EUROPE AU REGARD DE LA PANDEMIE DE COVID19
Authors: Schmitt Jean-Claude
Published: May 2021

La pandémie de Covid 19 à partir de janvier 2020 - depuis la Chine vers le reste de l’Asie, puis l’Europe et l’Afrique, et enfin les deux Amériques -, n’est pas sans rappeler des épidémies du passé, souvent bien plus meurtrières encore, en premier lieu celles de la peste (qui emporta le tiers de la population européenne en 1348). Trois épidémies de peste ont frappé l’Europe à travers l’histoire : la Peste de Justinien (541-770), la Peste Noire (1348-1352, suivie de nombreuses récidives jusqu’en 1720) et la peste de Chine (qui n’a touché en fait que les ports européens et américains, entre 1850 et 1940). La peste, par ses agressions ou ses retraits, a une valeur systémique pour le « long Moyen Âge » qui commence dans l’Antiquité tardive et se poursuit jusqu’au XVIIIe siècle : par ses assauts répétés tout au long de cette période, mais aussi par ses retraits comme entre l’époque de  Charlemagne et le XIVe siècle ; cet âge « sans peste »  correspond à la phase du plus grand essor des campagnes médiévales. Au contraire, quand la peste est de retour entre le XIVe et le XVIIe siècle, elle est un des facteurs décisifs d’une longue stagnation démographique. Jamais la cause véritable de la peste (qu’on attribuait à la corruption de l’air ou à un châtiment de Dieu)  n’a été reconnue tout au long de ces siècles. Pourtant on observe dès la fin du Moyen Âge une progression des conceptions « contagionistes » et non-officielles qui anticipent sur la découverte du bacille de la peste par Alexandre Yersin en 1894, en même temps que du rôle des puces et des rats. La peste a suscité des comportements de toutes natures, qui évoquent parfois les mesures prises aujourd’hui pour freiner ou empêcher la progression de l’épidémie (par exemple la quarantaine). Elle a nourri de nouveaux élans de piété et aussi la recherche de boucs-émissaires dont les communautés juives furent les premières victimes. Sur le plan culturel, elle suscita de brillants témoignages littéraires (tel le Decameron de Giovanni Boccacio), mais on ne peut pas lui attribuer la naissance de l’art macabre, car celui-ci lui est antérieur.
A PESTE DAS BEXIGAS NO BRASIL COLONIAL: TRAGÉDIA HISTÓRICA OU GENOCÍDIO?
Authors: Vainfas Ronaldo
Published: May 2021

O artigo é dedicado ao estudo do impacto da pandemia de varíola na população indígena do litoral brasileiro durante o século XVI. Ele oferece uma comparação entre a disseminação da varíola na América colonial e a da Peste Negra europeia no final da Idade Média. Discute a pandemia de varíola no contexto da colonização ibérica, principalmente a portuguesa. Analisa a hipótese da origem africana da varíola disseminada no Brasil. Também examina as evidências quantitativas sobre a mortalidade indígena, relacionando-a aos procedimentos adotados nas aldeias jesuítas. Por fim, avalia a relevância de conceitos como genocídio ou necropolítica para os estudos sobre a pandemia de varíola no século XVI.
HISTÓRIA, ENSINO E TEMPO PRESENTE: A MEMÓRIA E A FIAÇÃO DO PASSADO
Authors: Silva Fábio
Published: May 2021

O texto aqui apresentado busca discutir a importância da memória para o atual contexto do Ensino de História. Desse modo, essa análise está ancorada na perspectiva de que, apesar de não sermos os únicos fiadores do passado, somos os violadores de memória atravessados pela intenção da verdade, ainda que esta, esteja para nós, singularizada na nossa forma de reinvindicação. Para tanto, buscamos discutir a importância da memória para a compreensão da História no tempo presente. Além disso, tivemos preocupação de analisar também a importância do método para o ensino de História, bem como a praticidade operativa da nossa disciplina, utilizando para isso, o samba como possibilidade de fonte para nossa operatividade.
A New Family of Hybrid Conjugate Gradient Methods for Unconstrained Optimization
Authors: Adeleke Olawale Joshua , Ezugwu Absalom El-Shamir , Osinuga Idowu Ademola
Published: May 2021

The conjugate gradient method is a very efficient iterative technique for solving large-scale unconstrainedoptimization problems. Motivated by recent modifications of some variants of the method and construction of hybrid methods, this study proposed four hybrid methods that are globally convergent as well as computationally efficient. The approach adopted for constructing the hybrid methods entails projecting ten recently modified conjugate gradient methods. Each of the hybrid methods is shown to satisfy the descent property independent of any line search technique and globally convergent under the influence of strong Wolfe line search. Results obtained from numerical implementation of these methods and performance profiling show that the methods are very competitive with well-known traditional methods.
Nonsmooth Vector Optimization Problem Involving Second-Order Semipseudo, Semiquasi Cone-Convex Functions
Authors: Sharma Sunila , Yadav Priyanka
Published: May 2021

Recently, Suneja et al. [26] introduced new classes of second-order cone-(η; ξ)-convex functions along with theirgeneralizations and used them to prove second-order Karush–Kuhn–Tucker (KKT) type optimality conditions and duality results for the vector optimization problem involving first-order differentiable and second-order directionally differentiable functions. In this paper, we move one step ahead and study a nonsmooth vector optimization problem wherein the functions involved are first and second-order directionally differentiable. We introduce new classes of nonsmooth second-order cone-semipseudoconvex and nonsmooth second-order cone-semiquasiconvex functions in terms of second-order directional derivatives. Second-order KKT type sufficient optimality conditions and duality results for the same problem are proved using these functions.
GJB2: Frequency of the Less Common Variants in a Sample of the Portuguese Population
Authors: Reis Cláudia Sousa , Santos Ana Cristina , Barros Henrique , Fernandes Susana , Moura Carla Pinto
Published: May 2021

Introduction: Sequence variants in the GJB2 gene account for up to 50% of cases of non-syndromic sensorineural hearing loss in the Caucasian population. In this study, we report the frequency of the less common variants of the GJB2 gene in a Portuguese sample and compare these frequencies with those of a group of hearing-impaired patients.Material and Methods: In order to select the less common GJB2 variants, 147 hearing-impaired patients followed in Centro Hospitalar Universitário de São João were evaluated. Afterwards, the presence of those variants was tested in 360 individuals from Generation 21.Results: The patient assessment enabled the selection of 11 GJB2 variants. Of those, 10 were investigated in Generation 21 participants, with only four being detected, in heterozygosity: p.Phe83Leu, p.Arg127His, p.Val153Ile and p.Asn206Ser, with the allelic frequencies (95% confidence interval) of 0.14% (0.01% - 0.87%), 0.28% (0.01% - 1.08%), 0.97% (0.43% - 2.04%) and 0.14% (0.01% - 0.88%), respectively. Two variants, p.Val37Ile and p.Val95Met, were more frequent in the patients’ group with statistical significance.Discussion: Our results allow for the p.Arg127His and p.Val153Ile variants to comply with polymorphism criteria and support the pathogenicity of p.Val37Ile and p.Val95Met variants. Moreover, two cases of moderate hearing loss were explained by the p.Val37Ile/p. Asn206Ser genotype, substantiating both the pathogenicity of such variants and the hypothesis that compound heterozygosity with p.Ans206Ser is associated with mild-moderate genotypes.Conclusion: Understanding the role of the variants is essential in order to provide genetic counselling to patients and their families. We explored a set of uncommon GJB2 variants that comprised 12% of the hearing-impaired patients in this study, supporting the relevance of their description.
Nível de informação e conhecimento sobre políticas de inclusão no ensino superior
Authors: Teixeira Cauê Ferreira , Pires André
Published: May 2021

A proposta desse artigo é identificar se as informações sobre as políticas de inclusão no Ensino Superior estão efetivamente chegando àqueles que constituem seu público alvo, ou seja, os jovens que estão concluindo o ensino básico nas escolas públicas e/ou que fazem parte de grupos étnico-raciais minoritários. Assim, partindo desse questionamento, apresentamos no presente trabalho informações a respeito do nível de informações e de conhecimentos de estudantes de terceiro ano de ensino médio de uma escola pública e outra privada do município de Limeira-SP sobre as políticas de ação afirmativa. Os dados, obtidos por meio de questões incluídas em um questionário socioeconômico respondido por noventa e três estudantes (quarenta e oito na escola pública, quarenta e cinco na escola privada) e em entrevistas semi-estruturadas realizadas com cinco desses estudantes (três na escola pública, dois na escola privada), revelam que os estudantes da escola privada, embora não estejam no horizonte de contemplação de tais políticas, possuem um nível de informação mais elevado a respeito das mesmas, enquanto entre os estudantes da escola pública, que se incluem no grupo de possíveis beneficiários, o nível de desconhecimento e desinformação mostra-se bastante elevado. Sob essa perspectiva, chama a atenção o fato de que somente um estudante da escola pública assinalou conhecer e saber explicar o funcionamento das políticas de ação afirmativa. Essas constatações denotam a importância e a urgência de que sejam elaboradas estratégias mais eficazes de divulgação e explanação de tais políticas para esses estudantes, que compõem justamente seu público alvo.
Cartografias de cinema
Authors: Girardi Gisele , Pereira Ernandes de Oliveira , Aguiar Mayara Perinni de
Published: May 2021

Este texto deriva do projeto “Nas telas da escola: cinema e professores de Geografia”, da Rede Internacional de Pesquisas “Imagens, Geografias e Educação”, que buscou diagnosticar práticas de docentes de Geografia com cinema e, a partir daí, estudar elementos que pudessem contribuir com a regulamentação da Lei 13006/14. Nele buscamos pistas para compreender se a cultura visual cartográfica, presente na formação dos docentes de Geografia da escola, se manifesta nas escolhas das obras cinematográficas usadas como recursos imagéticos nas aulas de Geografia. Para tanto, identificamos e sistematizamos diferentes abordagens dos estudos sobre as conexões entre cartografia e cinema, constituindo um arcabouço acerca do impulso de mapeamento e detalhando a abordagem de Castro (2015) que distingue  formas cartográficas ou expressões cinematográficas do impulso de mapeamento: os panoramas, as vistas aéreas e atlas.  Selecionamos os três filmes nacionais mais citados como primeira menção por docentes participantes da pesquisa, de diferentes gêneros, a saber, “Central do Brasil”, “Encontro com Milton Santos: o mundo global visto do lado de cá” e “Ilha das Flores”, que foram analisados à luz das expressões cinematográficas do impulso de mapeamento. Concluímos que é possível que o impulso de mapeamento influencie as  escolhas das obras a serem usadas por professores e professoras de Geografia em sala de aula, indicando a força da cultura visual da cartografia, o que pode induzir ao uso de imagens clichês que limitam os estudantes a pensar o espaço a partir de outras possibilidades.
Breeding Potential of Maize Germplasm Line GEMS-0067 for High Amylose Proportion
Authors: Han Nan , Li Wanchen , Xie Chuanxiao , Fu Fengling
Published: May 2021

Maize varieties with high amylose proportion are more valuable for starch industry. The SBEⅡb gene encodes one of the starch branching isozymes (SBEⅠ, SBEⅡa, and SBEⅡb). Its recessive mutant amylose-extender (ae/sbe2b) decreases the total activities of SBEs and increases amylose proportion up to 60%. Here, the breeding potential of introduced germplasm line GEMS-0067 was evaluated by genotyping and phenotyping. The deletion of the ninth exon of the SBEⅡb gene, high amylose proportion, and the typical irregular granules suggested that this germplasm line was derived from the same resource of high amylose line AE11. The gelatinization and thermal properties, and degree of polymerization of starch chain showed its advantages used for high amylose breeding. However, the negative correlation between amylose proportion and starch content, as well as ker-nel filling characteristics should be overcome during breeding process.
Accurate Drilling Data Interpretations Brought Significant Values to a Major Drilling Project
Authors: Rashid Faisal , Al Saadi Hamdan Mohamed , Duivala Shahid Yakubbhai , Butt Steve , Al Mansoori Sultan , Mughal Muhammad Idrees
Published: May 2021

With the launch of a mega drilling project in the Middle East, the drilling data during the execution stage was collected in two formats; Low-Frequency Data and High-Frequency Data. This paper explains the effective utilization of data in the performance enhancement scheme. The paper also demonstrates the combination of Low-frequency and High-frequency data can reveal the many secrets of the drilling operations and can open the many sides of drilling operations for improvements.

Low-Frequency data was entered manually at the rig-site using an improved coding system to identify the activities start and end times. High-Frequency data was collected through real-time transmission from the different data streaming services at the rig-site. Both data forms were collected simultaneously using stringent rules and close follow-ups to make sure that data collection was free of any reporting mistakes and gaps. Later, the collected data was extracted for different types of analyses and interpretations.

Low-frequency data was studied in a novel way to get the best analytical and critical outcome to make sure that the right areas for improvements were identified and actions were implemented for enhanced performance. Improved operations coding system helped the team to categorize the operations and failures in an effective way to set new standards in data analysis. More than 100 different types of analyses using the best data analysis technique, such as trailing average, normalization, trends, etc., were conducted based on the information collected during the execution phase, and many new KPIs were established with challenging milestones to be achieved in the prescribed period. High-Frequency data was split into different sets of KPIs to identify the multiple Invisible Lost Time (ILT) areas to boost the operational efficiency. Various performance enhancement schemes were developed based on High-frequency data. As a result, these schemes were proven to enhance the performance of the mega drilling project.

This paper discusses the novel methods of drilling data analysis based on low and high-frequency data and shows the effectiveness of the data presented in a standardized format over a period. It deliberates how the teams were challenged to enhance the performance. Such detailed data analysis will bring valuable information for the industry to utilize the conventional database in modernized ways to get the best outcomes from the data analysis results.
Reduced Well Construction Time with Accurate Geostopping in Harsh Drilling Conditions: Case Study from Kuwait
Authors: Saleh Khaled , Al-Khudari Abdulaziz Bader , Al-Najdi Amer , Al-Azmi Mejbel Saad , Al-Otaibi Fahad Barrak , Joshi Girija Kumar , Abdulkarim Anar , Farhi Nadir , Nouh Walid , Clarion Benjamin
Published: May 2021

Traditionally, 12.25-in. hole sections in the Jurassic formations were planned to be drilled with mud weight (MW) of 20 ppg and solids content of 45%. The planned drilling would use a rotary assembly from the Hith formation, crossing several zones in which mud losses or gains were likely. The casing would then be set in the thin shale base of the Gotnia formation. A minor inaccuracy in casing setting depth could often lead to well-control issues.

Pore pressure drops severely below the shale base and requires a MW of 15 ppg. Passing this shale base can lead to severe losses and potential abandonment of the well. An anhydrite marker is located approximately 50 ft above the shale base. To reduce risk, the operator would normally drill to this marker at a rate of penetration (ROP) of 20-30 ft/hr, then decrease the ROP to 2 ft/hr. While slowly drilling the last part of the section, penetration would be stopped every few feet to circulate bottoms-up to receive samples confirming the shale base; this process requires an additional 24 hours of rig time.

After reaching the casing point, the operator would pull out of the hole to pick up logging-while-drilling (LWD) tools to perform a wiping run. This logging, however, is frequently cancelled because of wellbore stability issues, resulting in the loss of important formation-evaluation data across this interval.

A new solution has been developed, comprising drilling with a rotary assembly to the final anhydrite marker, then pulling the string out of hole to pick up LWD triple-combo and sonic tools, with a conventional gamma ray sensor placed only 6 ft from the bit. The remaining part of the section would then be drilled at 7-10 ft/hr until the gamma-ray tool detected the shale base, thereby determining the casing depth. In addition, it was planned to re-log the previously drilled interval.

This solution prevented the well from potential abandonment and reduced drilling time. It also secured critical formation evaluation data for exploration and future field development.

The engineered drilling solution was tried for the first time in these formation sequences within a harsh drilling and logging environment. The option of rotary steerable services with an at-bit GR sensor was not considered because of the high cost.
Effect of Casing Couplings to Frictional Pressure Losses While Setting Casing a Step Change
Authors: Eren Tuna , Merey Sukru , Polat Can
Published: May 2021

All wells require casing strings so that the planned operations can proceed. Ensuring a good quality casing set is vitally important. When conducting the calculations for frictional pressure losses the casing couplings are not taken into consideration. In API calculation methodologies for drill pipe the effect of tool joints is not taken into calculation. However, the small clearance between the casing coupling and the hole size is definitely creating an additional frictional pressure drop in comparison to the calculated which under normal circumstances taken into account the nominal casing outer diameter (OD).

In this study the effect of casing couplings is taken into consideration when calculating the annular frictional pressure losses to drive the Equivalent Circulating Density (ECD). The generally accepted frictional pressure loss equations are used for a variety of casing running scenarios. The methodology that is introduced in this research study is a step change for automation in drilling operations.

The findings are used to compare with the conditions during which the effect of casing couplings is not taken into consideration. The general findings indicate that annular frictional pressure losses are very critical for all wells but especially for the wells with narrow drilling margins.

This research study reveals that annular frictional pressure losses are very critical for the successful casing running operations not only during circulations through the casing string but also at the time of the cementing of the same. The introduced methodology that takes into consideration of casing couplings can be used for automation in drilling operations.
Drilling in Slips: Strategies to Measure the Invisible Lost Time, Technical Limits Definition, Using Standard Analytics and Machine Learning Algorithms
Authors: Mora Silvia , Martinez Damian
Published: May 2021

Drilling is probably the most critical, complex, and costly operation in the oil and gas industry and unfortunately, errors made during the activities related are very expensive. Therefore, inefficient drilling activities such as connection duration outside of optimal times can have a considerable financial impact, so there is always a need to improve drilling efficiency.

It is for this fact, that the measure of different behaviors and the duration of the drilling activities represent a significant opportunity in order to maximize the cost saving per well or campaign. Reducing the cost impact and maximizing the drilling efficiency are defined by the way used to calculate the perfect well time by the technical limit, non-productive time (NPT), and invisible lost time (ILT), in an operating company drilling plan.

Different approaches to measure the invisible lost time that could be present in the in slips activity on the drilling operation are compared. Results show the differences between multiple techniques applied in real environments coming from a cloud platform.

The methodologies implemented are based on the following scenarios, the first one use a combination of a custom technical limit based on technical experience, the historical data limit using standard measures (mean, average, quartiles, standard deviation, etc.), and a depth range variable (phases) differentiation, initial, intermediate, and final hole sizes is used.

A complexity comparison uses the rig stand and phase footage variables for base line (count and duration) definition per phase, the non-productive time activities exclusion and data replace techniques mixing with an out of standard time detection in slips behavior (motor assemblies, bit replacing, bottom hole assembly (BHA), etc.) using standard and machine learning mechanisms. A final methodology implements an in slip ILT by technical limit definition using machine learning.

The results using the same data set (set of wells) and coming from the different methods has been evaluated according to the total invisible lost time calculated per phase, percentage of activities evaluated with invisible lost time per phase and the variation of ILT considering the activities defining the technical limit. Finally, the potential implementation by any operator can be evaluated for these methodologies according to their specific requirements.

This analysis creates a guideline to operating companies about multiple techniques to calculate ILT, some using innovative procedures applied on machine learning models.
Automated Well Control: From Automated Detection to Automated Shut-In
Authors: Atchison Bryan Wade
Published: May 2021

Objectives

April 2010 in the Gulf of Mexico and January 2017 in Oklahoma brought into sharp focus what can happen if the oil and gas industry gets well control wrong: 16 fatalities, significant environmental damage, loss of assets and reputation. Each year we have multiple blowouts and several fatality events due to a loss of well control. The oil and gas industry can improve from a personnel safety, environmental and reputation perspective. The Automation of Well Control will bring a significant step change in the area of Process Safety forwells. It prevents blowouts, reduces all influx volumes, minimising kicktolerance volumes and reducingcasing and well costs.

Method

A system has been developedwhich enables Automated Well Control whilst in drilling mode. Pre-determined influx rates, agreed by the operator and drilling contractor, and input by the driller are established. Once the system detects the influx, it performs a series of operations by taking control of the drilling rig equipment. The drill string is spaced out, top drive and mud pumps are stopped, and the BOP is closed. All of this occurs without the driller doing anything; however, he can intervene at any moment. Thissystem is designed as an aid to the driller and does not remove his responsibility.

Results

The Automated Well Control system has been tested on drilling simulators with real drillers. Comparisons tests have shown that the technology enables shut-in times faster than conventional human interface methods, with influx volumes typically 10-20% of those experienced during manual shut-in. Additionally, a full Field Trial using a traditional rigdemonstrated the effectiveness of the system, proving up the functionality under different operational requirements. The system can now be applied to any type of rig worldwide. Over 50 potential modules have been identified. Planned developments forthe system include circulatingout the kick automatically, shut-in for tripping, circulating, cementing and in-flow testing. It provides assurance for afast, safe and effective shut-in.A full Technology Qualification process has been used for this technology.

Innovative Technology

Over the past 20 years, technology advancements associated with simulators and cyber-rigs have enabled new technologies to be developed. One of these technologies is Automated Well Control.

It is believed that this innovative system will enable a step change in the performance ofprocess safety forwell control, dramaticallyreducing major accident hazards, thereby saving millions of dollars per well, reducing environmental impact and preventing loss of life.
A Unique Engineering Approach in Horizontal Drilling Through Unconsolidated Formations to Minimize Time and Cost Using High-Build-Rate Rotary Steerable Systems in Sultanate of Oman
Authors: Omara Ahmed , Alba Hector , Al Yarroby Faisal , Al Abri Ahmed , Al Habsi Riyad
Published: May 2021

Drilling horizontal wells with a high dogleg severity (DLS) of 10–16 deg/30 m is the approach that one operator in Oman adopted to drill the buildup section. The 8½-in section used to be drilled with a conventional motor BHA, which took around 4 days to complete. Due to the high DLS, it was required to slide at least 80% of the time. This led to a slow drilling rate, hole cleaning issues, and difficulties running the 7-in liner afterward. For a step change to happen, a full directional drilling system had to be reengineered with an extensive study of the BHA and well design. The objective was to reduce the total drilling time in the 8½-in BUS, improve the borehole quality, and reduce flat time.

Traditional rotary steerable systems (RSS) are limited with their steering capabilities. A hybrid, high-build-rate RSS with push- and point-the-bit features offers the capabilities of achieving a DLS of up to 17 deg/30 m as it is independent of outside formation. Implementing the new approach eliminated the long sliding intervals and poor borehole cleaning caused by limited surface rotation with the motor BHA. The system was modeled using finite element drilling dynamics simulation software, with multiple bits and drillstring configurations to optimize the directional results. In addition, compressive study of the mud properties enabled drilling the section safely throughout Nahr Umar shale. Later, the same system was coupled with a high-torque motor, and the results showed an even better performance, which the operator plans to consider in the future to enhance the drilling rate.

The use of a hybrid RSS system with a specific bit built for the application has proven its success as an integrated engineered drilling solution. It reduced the 8½-in section drilling time by 50% with improved borehole quality and delivered an overall ROP that is approximately three times what a motor BHA would have delivered. The improvement is a result of the use of PDC over TCI bits and the elimination of slide drilling. In addition, full rotation and elimination of micro-DLS resulted in smoother liner running operation. While drilling, the 100% rotational steering improved the overall hole cleaning, and the modified mud properties and additives helped eliminate the wiper trips performed previously prior to reaching the reservoir section. The success of this integrated system led the operator to replace all the motors in the entire field.

This paper emphasizes the impact of new technology together with effective well engineering in drilling efficiency. With current industry focus on cost control, high-DLS RSS technology introduces new savings when used in the right application. This particular case is very common across the industry and proves the many advantages of integrated engineering projects.
A Rotational Continuous-Circulation Tool RCCT for Decreasing Non-Productive Time NPT and Mitigating Drilling Operational Risk
Authors: Alshalan Meshari Mansour , Alshaarawi Amjad O. , Alhamed Haytham H. , Aljohar Abdulwahab S.
Published: May 2021

This work presents how a Rotational Continuous-Circulation Tool (RCCT) can decrease non-productive time and mitigate risks in the oil and gas drilling operations. The proposed tool provides almost continuous rotation of the drill-string and continuous circulation of drilling mud during the making/breaking of drill-pipe connections. Continuous rotation minimizes the stationary time during the connection. Thus, the risk of static contact between the wall of the formation and drill string (which can cause a differentially stuck drill-pipe) is reduced. This is one aspect by which non-productive time (NPT) is reduced, and the potential of encountering a differentially stuck pipe incident is mitigated. Continuous circulation enhances the hole cleaning efficiency. Rather than gravitating or being suspended, drilling cuttings continue to be removed to surface during connections with continuous circulation. As a result, the risk of having a mechanical stuck pipe incident (e.g., Pack-off) is prevented. In addition, maintaining continuous circulation eliminates down-hole pressure fluctuations. This reduces the risk of hole stability issues, and also enables navigation through zones with tight drilling pressure window. The proposed tool has been trial-tested twice to demonstrate its compatibility with the current drilling rigs/practices. Further trial tests are planned to demonstrate the added value of the tool.
A Statistical Machine Learning Model to Predict Equivalent Circulation Density ECD while Drilling, Based on Principal Components Analysis PCA
Authors: AlSaihati Ahmed , Elkatatny Salaheldin , Gamal Hani , Abdulraheem Abdulazeez
Published: May 2021

Mathematical equations, based on conservation of mass and momentum, are used to determine the ECD at different depths in the wellbore. However, such equations do not consider important factors that have a influence on the ECD such as: (i) bottom hole temperature, (ii) pipe rotation and eccentricity, and (iii) wellbore roughness. Thus, discrepancy between the calculated ECDs and actual ones has been reported in the literature.

This paper aims to explore how artificial intelligence (AI) and machine learning (ML) could provide real-time accurate prediction of the ECD, to have more insight and management of wellbore downhole conditions. For this purpose, a supervised ML algorithm, support vector machine (SVM), based on principal components analysis (PCA), was developed.

Actual field data of Well-1 including drilling surface parameters and ECDs, measured by downhole sensors, were collected to develop a classical SVM model. The dataset was split with an 80/20 training-testing data ratio. Sensitivity analysis with different SVM parameters such as regularization parameter C, gamma, kernel type (linear, radial basis function "RBF") was performed. The performance of the model was assessed in terms of root mean square error (RMSE) and coefficient of determination (R2). Afterward, PCA was applied to the dataset of Well-1 to develop an SVM model using the transformed dataset in PCA space. The performance of the model while using different numbers of principal components was evaluated.

The results showed that the classical SVM with the linear kernel predicted the ECD with RMSE of 0.53 and R2 of 0.97 in the training set, while RMSE and R2 were 0.56 and 0.97 respectively in the testing set. The PCA-based SVM model, with the linear kernel and four principal components (93.53% variation of the dataset), predicted the ECD with RMSE 0.79 and R2 of 0.95 in the testing set.
First Deployment of Motorized Casing Reamer Shoe in Abu Dhabi Offshore
Authors: Biyanni Hanifan Mayo , Al Ameri Suhail Mohammed , Couzigou Erwan , Gohel Prashant , De Barros Adelson Jose Calleia , Alhammadi Yousef Ahmed , Al-Marzouqi Adel , Al Ameri Fahed Salem , Hathaway Neil , Kerr Edward
Published: May 2021

The paper will describe a novel approach of deploying casing through a problematic open hole. It involves a drillable hydraulic motorized casing reamer shoe that can rotate freely without aid of pumping, but once resistance is encountered, pump pressure can then be applied to engage the drive mechanism inside the tool. Thus it will turn into a high-speed reaming shoe that delivers sufficient reaming action.

A market research was done to find a quick intermediate solution to tackle difficulty in deploying casing down to section TD. A turbine based motorized reamer shoe was then selected to encounter the challenge with some risk mitigation in place.

The first deployment was run in the well where it was identified as a challenging well context and had experienced casing being held up in the first run. Despite the fact that a wiper trip has smoothened the hole condition, the parameters that were captured during the running, the finger printing, the cementing job, and the drilling out of the shoe had ticked some boxes to evaluate the suitability of the technology implementation in the field. Moreover, the lessons learned from the first run itself has also led to further testing and modification of the tool design/setup itself.

The detailed analysis and operation feedback from casing running job and subsequent operation will be beneficial to provide other operators in assessing the minimum requirement and suitability of this technology utilization to overcome the drilling challenge.
Staged-Fracturing Completion Technology for the Ultra Deep-Hpht High Inclination Well in the Keshen Gas Field: a Case Study
Authors: Wang Kelin , Wang Yan , Liu Hongtao , He Xinxing , Liu Shuang , Shan Feng , Jiang TianHong , Bu Lulu , Ding Liangliang
Published: May 2021

Keshen No. 10 gas reservoir has a large amount of resources, but the geological structure is complex, and three sets of faults are developed in the upper formation. Four vertical wells had been drilled in the last ten years, and only one well was drilled successfully. To develop the gas field, a high inclination well KSX was designed to avoid the faults. The final well depth is 7060m, maximum inclination was 76.6°, reservoir pressure was 103MPa, reservoir temperature was 154 °C, effective reservoir thickness was 115.5m, and the production casing was 7 3/4 inch with 5 inch liner. The staged-fracturing was designed to achieve a high production rate, and it was a major challenge for completion design and operation.

To meet the requirement of staged fracturing, the different completion technology including bridge plug isolation, packer isolation and temporary plugging of perforated intervals were evaluated, and the combination of packer isolation and temporary plugging was finally chosen. Based on the casing program, 7 3/4 inch + 5 inch double packer combination was chosen preferably. Also, systematic analysis was conducted for the past failure case of double packer fracturing in the HPHT well, and it was clear that excessive axial force was the key factor of packer failure. Therefore, expansion joint was set between the packers to relieve the axial force on the packer during the fracturing. In addition, the soluble ball was chosen to open the sliding sleeve to conduct the next interval fracturing operation.

During the completion operation, wellbore treatment, packer centralization and the other auxiliary measures were taken, completion string was successfully run in the expected depth, and the packer setting was also normal. During the fracturing operation, the target intervals were divided into two zones by both soluble ball and packers, the fiber temporary plugging of perforated intervals were completed in each zone, and the temporary pressure was up to 7 MPa. The total injection fluid volume 2562m3, total sand volume 159m3, maximum flow rate 6.55 m3/min, maximum pump pressure 118.5MPa. After fracturing operation, the production rate 740,000 m3/d was obtained with wellhead flow pressure 75MPa, and the rate was 2.6 times larger than the vertical well.
Stems as Natural, Green, Non-Toxic Corrosion Inhibitors
Authors: Ng Jun Hong Clarence , Almubarak Tariq , Nasr-El-Din Hisham A.
Published: May 2021

Corrosion during acid treatments causes severe damage to the tubulars and downhole equipment. Consequently, this leads to an increase in expenditure to maintain well production rates and well integrity. NACE estimates the cost of corrosion costs to be roughly 1.372 billion USD annually to the industry, making corrosion control extremely important. Therefore, corrosion inhibitors must be included in any acid treatment formulation. This work aims to develop environmentally friendly and non-toxic corrosion inhibitors that can work in the harsh oilfield conditions. Samples of 10 different stems were tested as sources of potential corrosion inhibitors.

To determine the inhibition effectiveness of the different samples, N-80 coupons were exposed to 15 wt% HCl solutions at temperatures between 77-200 °F with 2 wt% of each sample for 6 hours. In addition, a control solution containing no corrosion inhibitor was used to establish a corrosion rate for a base case.

At a concentration of 2 wt%, sample 1, 2, and 3 were found to perform the best, exhibiting 94.4% to 99.9% corrosion inhibition efficiency at 77°F. Sample 8 was observed to perform the worst with a corrosion inhibition efficiency of 57.3%. At 150°F, the corrosion rate of sample 1 was found to be 0.0275 lb/ft2, while that of sample 2 was 0.0171 lb/ft2. At this temperature, sample 3 did not perform well, exhibiting a corrosion rate of 0.155 lb/ft2 and thus was not tested at higher temperatures. At 200°F, the addition of a corrosion inhibitor intensifier resulted in a corrosion rate of 0.0136 lb/ft2 for sample 1 and 0.00878 lb/ft2 for sample 2. These results show that a naturally occurring, green, non-toxic corrosion inhibitor can be developed from these stems and can comfortably pass the industry requirement for low carbon steel.

Currently used corrosion inhibitors are associated with environmental concerns and severe health risks. Recent developments in corrosion inhibition technology successfully tackled the environmental concerns, but still faces issues with toxicity and performance at high temperatures. The results in this work share two new naturally occurring, green, non-toxic, high-temperature stable corrosion inhibitors that can be developed from stems and can successfully protect the tubular during acid treatments.
Unlocking Oman's Tight Gas Potential using State-of-the-Art Underbalanced Coiled Tubing Drilling Technologies
Authors: Lynn Stephen , Manoharan Sumith , Barkat Souhaibe , Al-Ruzeiqi Saleh , Terras Yan , Kindi Ahmed , Khaldi Saud , Sibani Ahmed , Ajmi Hussain , Ruqaishi Abdullah
Published: May 2021

With the large amount of tight gas reserves remaining in Oman, new innovative techniques and methods to unlock these reserves have become imperative for the future economic success and stability of the country.

Among the various technologies considered, the concept of underbalanced coiled tubing drilling (UBCTD) was introduced. In order to address the harsh downhole challenges such as high temperatures, deep burial depths, under pressured reservoirs, abrasive and hard sands and logistical constraints; a fully integrated well delivery solution was developed jointly by the operator and energy service company.

In accordance with this strategy, best in class downhole drilling tools, a state-of-the-art fully automated coiled tubing drilling unit together with technical and project management experts were deployed. Application specific solutions to the challenging subsurface conditions included utilization of underbalanced drilling (UBD) techniques, deployment of high temperature drilling assemblies, fit-for-purpose bit drive mechanism and a robust integrated management system. All of the above was achieved whilst ensuring the safety of all personnel during the project and reducing carbon emissions through a flare minimization strategy and diesel consumption reduction initiatives.

Over the course of the pilot campaign, reservoir exposure per well was doubled, average penetration rate compared to conventional rotary drilling was more than tripled and incremental production improvements of up to 230% were observed. This paper discusses the challenges faced and the solutions implemented during this three well pilot campaign.
Drilling Efficiency Benchmarking Tool: Developing A Drilling Performance Measure Combining Data Science and Statistical Approach
Authors: Bimastianto Paulinus , AlSaadi Hamdan , Khambete Shreepad , Cotten Michael , Couzigou Erwan , Al-Marzouqi Adel , Chevallier Bertrand , Qadir Ahsan , Pausin Wiliem
Published: May 2021

Majority of organizations endeavor to reduce operating costs and improve operational efficiencies. The concept of Mechanical Specific Energy (MSE) has long been implemented in the industry to improve drilling performance. The Drilling Real time Operations Center (RTOC) has taken the concept of MSE beyond its traditional approach by developing a Drilling Performance Measure combining data science and statistics to benchmark drilling efficiency.

To extract maximum value from the available database, a workflow was developed to construct a Drilling Efficiency Benchmarking Tool. The different steps will be described for performing the data ingestion, cleansing, selection (offset well selection), methodology of computing the statistical model for MSE baseline per Formations and visualization of the output (charts and logs), to compare the actual MSE with baseline and thereby measuring the performance efficiency.

The offset wells analysis results show that the workflow can construct an MSE baseline using high frequency data in a meaningful way, which is then set as a target envelope and projected through the real-time platform for monitoring and intervention purposes. This implementation of real-time MSE benchmarking helps identify the area of potential improvement, optimize drilling parameters to ultimately improve ROP and minimize lost time. As an analytical tool, it highlights achievable performance for each field and provide insights to consider new Best Practices.
Benefits of Using Continuous Circulation Systems in ERD Wells to Manage ECD, Bottom Hole Pressure and Hole Cleaning
Authors: Petrie Scott William , Doll Rick
Published: May 2021

Continuous Circulation Systems (CCS) have been around since the JIP between Shell, BP, Statoil, BG, Total and Eni in October 2000. Initial reports of these systems demonstrated that while cumbersome, the use of CCS is of benefit to drilling ERD wells. Continuous circulation keeps cuttings moving out of the wellbore, reducing or eliminating the time required to circulate clean any high-angle section before making a drill pipe connection or before tripping out of the hole.

Continuous Circulation over each connection enhances the management of Equivalent Circulating Density(ECD) to control the bottom hole pressure on the well by never switching off the pumps, therefore the wellbore never experiences an Equivalent Static Density(ESD). Through this mechanism, the application of CCS has also been proven to manage bottom hole pressure constantly, which in conjunction with good drilling practices for torque and drag management, are key factors in drilling any Extended Reach Drilling(ERD), Complex or High Pressure/High Temperature (HPHT) well.
High Performance Drilling Onshore Abu Dhabi
Authors: Kuyken Chris Wilhelm , Elkasrawy Mohamed Elsaied , Al Breiki Ali Mubarak Saeed , Elgendy Yahia Abdelfattah Mahmoud , Abdelaal Ahmed Gamal
Published: May 2021

High performance drilling is an approach applied in the drilling of hole sections that are not primarily benefitting from data acquisition except the minimum like gamma ray and directional. Therefore these sections are drilled with high ROP and subsequently cased in support of reducing well costs.

High performance drilling leading to continuous ROP optimization has been proven a key enabler for invisible lost time reduction (ILT), being one of the current regional well delivery challenges. In this paper we explain the approach followed by the team comprising of operator, service provider and equipment provider in reducing the impact of ILT during the actual drilling phase. We learnt that creating a performance culture based on rigorously applying of best practices and the eagerness to continuously improve on past performance as a first strategy and the application of novel directional drilling motor technology as the second resulted in ROP performance records. For example in one field an average ROP record was achieved of 188 ft / hour a 15 % improvement from the previous record.

We learnt that in particular the communication between all parties i.e. the client office, the service provider and the team on the rig was the most important factor in order to create a shared vision on the need to improve the ROP based on the last ROP performance benchmark.

Secondly the latest motor technology and the way of how it gets deployed, available to the team played a major role, and brought the performance level to a new dimension whereby the ROP was targeted to be optimum instead of maximum thereby reducing the risk for NPT related incidents (hole problems, equipment break-down) and repair and maintenance cost becoming cost prohibitive.

This paper is specifically meant to share best practices from the last 10 years with the larger UAE drilling community. It is service provider contribution to provide insights for the new generation drilling engineers and directional drillers in safely pushing the drilling performance to higher levels all the time targeting the ILT in hole making.

The work has proved that a combination of low torque high speed and high torque low speed can successfully performance drill all vertical hole sizes in the UAE on-shore fields either using tri-cone or PDC bits.Figure 1High performance motor
Early Anomaly Detection Model Using Random Forest while Drilling Horizontal Wells with a Real Case Study
Authors: AlSaihati Ahmed , Elkatatny Salaheldin , Mahmoud Ahmed , Abdulraheem Abdulazeez
Published: May 2021

There has been discrepancy between the pre-calculated and actual T&D values, because of the dependence of the model’s predictability on assumed inputs. Therefore, to have a reliable model, the users must adjust the model inputs; mainly friction coefficient in order to match the actual T&D. This, however, can mask downhole conditions such as cutting beds, tight holes and sticking tendencies.

This paper aims to introduce a machine learning model to predict the continuous profile of the surface drilling torque to detect the operational issues in advance. Actual data of Well-1, starting from the time of drilling a 5-7/8-inch horizontal section until one day prior to the stuck pipe event, was used to train and test a random forest (RF) model with an 80/20 split ratio, to predict the surface drilling torque. The input variables for the model are the drilling surface parameters, namely: flow rate, hook load, rate of penetration, rotary speed, standpipe pressure, and weight-on-bit.

The developed model was used to predict the surface drilling torque, which represents the normal trend for the last day leading up to the stuck pipe incident in Well-1. Then the model was integrated with a multivariate metric distance, Mahalanobis, to be used as a classifier to measure how close an actual observation is from the predictive normal trend. Based on a pre-determined threshold, each actual observation was labeled as "NORMAL" or "ANOMAL".