bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of gaseous species in group-III nitride growth
Authors: Karpov S. Yu. , Makarov Yu. N. , Ramm M. S.
Published: August 2016

A quasi-thermodynamic model accounting for kinetics of molecular nitrogen evaporation is applied to simulate the growth of binary and ternary group-III nitrides using atomic group-III elements and molecular ammonia as the sources. The values of the molecular nitrogen evaporation coefficients from the surface of GaN and AlN necessary for the simulation are extracted from experiments on free evaporation of the crystals in vacuum, while for InN only estimates are available. The growth process of AlN and InN is studied by analyzing the composition of the desorbed vapor species that are thought to influence the native defect formation in group-III nitrides. Different channels of desorption from the surfaces of group-III nitrides (related either to group-III atoms or to their hydrides) are compared. Specific features of the growth processes under the metal-rich and N-rich conditions are analyzed. The developed approach is extended to study the growth of the ternary compounds GaInN and AlGaN. The growth rate of ternary compounds versus temperature shows a two-drop behavior corresponding to the rapid increase of the respective group-III atom desorption. The effect is accompanied by a corresponding stepwise change in the solid phase composition. Factors retarding the growth of ternary compounds — the miscibility gap related to internal strain accumulated in the solid phase due to the lattice mismatch of binary constituents, and the extra liquid phase formation during growth — are discussed with respect to GaInN.
PEMBE-Growth of Gallium Nitride on (0001) Sapphire: A comparison to MOCVD grown GaN
Authors: Angerer H. , Ambacher O. , Dimitrov R. , Metzger Th. , Rieger W. , Stutzmann M.
Published: August 2016

Thin films of GaN on c-plane sapphire were grown by plasma-enhanced molecular beam epitaxy (PEMBE). The influence of different growth conditions on the quality of the epitaxial layers was studied by x-ray diffraction (XRD), atomic force microscopy (AFM) and Hall measurements. For low deposition temperatures, the growth of a thin buffer layer of AlN results in a decrease of the XRD rocking curve full width at half maximum (FWHM) but also in poorer quality in electronic and optical properties. Samples of 3μm thickness with 570 arcsec FWHM in the XRD rocking curve, a near band gap PL-emission FWHM at 5 K of 7 meV, charge carrier densities of ne = 2 × 1017 cm−3, and Hall mobilities of 270 cm2/Vs at 300 K were grown without a buffer layer. A comparison of the morphology and XRD rocking curves with those of GaN films deposited by metalorganic chemical vapour deposition (MOCVD) shows that the two methods have different growth mechanisms.
Luminescence and Reflectivity of GaN/sapphire grown by MOVPE, GSMBE and HVPE
Authors: Leroux M. , Beaumont B. , Grandjean N. , Pierre Gibart  , Massies J. , Faurie J. P.
Published: August 2016

This work presents an optical characterization by luminescence and reflectivity of GaN layers grown on sapphire using MOVPE, HVPE and GSMBE. Well resolved optical spectra are obtained for each growth technique. The luminescence of Mg doped MOVPE grown GaN is also studied. A Mg acceptor optical depth of ~ 260 meV is obtained.
Theoretical Model for Analysis and Optimization of Group III-Nitrides Growth by Molecular Beam Epitaxy
Authors: Averyanova M. V. , Karpov S. Yu. , Makarov Yu. N. , Przhevalskii I. N. , Ramm M. S. , Talalaev R. A.
Published: August 2016

A theoretical model which accounts for a physisorption precursor of molecular nitrogen is proposed for the analysis of group III-nitride growth by molecular beam epitaxy (MBE). The kinetics of nitrogen evaporation are found to be an essential factor influencing the MBE growth process of group III-nitrides. The high thermal stability of nitrides is explained to be related to the desorption kinetics resulting in a low value of the evaporation coefficient. The values of the evaporation coefficients as functions of temperature are extracted from the experimental Langmuir evaporation data of GaN and AlN. Using the revised thermodynamic properties of the group III-nitrides, and the obtained values of the evaporation coefficient, the process parameter dependent growth rate and transition to extra liquid phase formation during the GaN MBE are calculated. The theoretical results are compared to the available experimental data.
Initial Growth Prismatic Domains in Cyclotron Assisted MBE of GaN/SiC
Authors: Vermaut Philippe , Ruterana P. , Nouet G. , Salvador A. , Morkoç H.
Published: August 2016

In N-rich growth conditions, prismatic domains were formed in the initial stage of a cyclotron assisted MBE of GaN over 6H-SiC (0001). They exhibit {10 0} facets and are either voids or amorphous phase. Their density is of a few 109 cm−2 and they are located in a 50 nm layer closest to the substrate surface.
Dothideomycetes of forest plants communities of the heath zone of Ukraine
Authors: Korolyova O.
Published: August 2016

The species composition of class Dothideomycetes in the forest plants communities of the steppe zone of Ukraine has been studied. It includes 43 species from 26 genera, 20 families, 6 orders from 2 subclasses and group Incertae sedis. In the taxonomic structure of the investigated species composition it was established predominance of the subclass Pleosporomycetidae, of the order Pleosporales, the families Leptosphaeriaceae, Lophiostomataceae and Mycosphaerellaceae, and also genus Leptosphaeria. We have established the ecological structure of mycobiota and consortial connections with 33 species of plants from 25 genera 11 families. In the ecological structure it was marked the dominance of saprotrophs and xylotrophs. We analyzed the characteristics of habitat distribution of species in communities 3 types of vegetation. A comparison of the taxonomic spectra of Dothideomycetes of forest and steppe communities of the heath zone has been performed.
Methodology to Study Behavioral Aggression Due to the Impact of Television Programs
Authors: Havrylets Yurii , Rizun Volodymyr , Tukaiev Sergii , Makarchuk Mykola
Published: August 2016

The problem of violence on television and its impact on behavioural aggression of the audience occupies a leading position in media effects studies. The main objective of the study was to explore the available methodology used by scientists in the United States and in the European Union to explore the behavioural aggression due to the impact of television programs. Through the classification of findings of the television-induced aggression empirical studies, the methodological framework of the main research methods in this field was formulated. This structure contains two basic types of research methods. First one studies the media-induced aggressive behaviour (using observation and fixing of aggression acts); second one explores the media impact on viewers’ aggressive inclinations. The latter type of techniques does not deal with the behaviour, but only with the ability to act aggressively, and with its help the researcher can only make inference about the likelihood of aggressive actions in the future. Thus, an empirical study of aggressive behaviour is in many aspects more complicated, but this approach allows obtaining more statistically significant data. Instead of that, evaluating aggressive inclinations enables accumulating a large amount of raw (unprocessed) data in faster and easier way. Results / findings. The first attempt was made to systemize all the methods of the TV-induced aggression studies, used by the U.S. and the EU scientists in their respective explorations. Special emphasis was made on the usage of the psycho-physiological measurements in the experimental research of the TV violence impact. It was found that due to the lack of sufficient veracity in the estimation of the impact of long-term media effects, the methods of fixing the short-term effects prevail in the majority of respective studies. Our further studies in this respect will be concentrated on the problematic of formation of aggressive tendencies under the influence of television programs in the long run.
Visual-test and Sorption-spectrophotometric Determination of Melamine in Biological Objects
Authors: Zaporozhets Olga , Smyk Natalia , Rudakova Daria
Published: August 2016

Melamine may have toxic effects on humans and animals. It is well known that melamine accumulates in the body and causes reproductive damages, forms bladder or kidney stones, which can lead to bladder cancer. Trace amounts of melamine at ppm levels may occur in certain food commodities due to its migration from melamine-containing disposable tableware plastics. It was intentionally adulterated to milk products to show a false increase in protein concentration. Considering these facts there is a need for establishing sensitive and reliable methods of melamine determination. As uncostly, rapid and selective melamine detection methods are highly required, the hyphenated sorption-spectrophotometric and visual test methods seem to be perspective candidates.

In the present work the optimal conditions of sorption concentration of melamine from aqueous solutions ontо the silica gel surface were studied. The calibration graph for the sorption-spectrophotometric method is linear in 0.02 – 9.8 μmol.L-1 mg L-1 melamine concentration range. Proposed method allows naked-eye monitoring of biological samples.
About the system of rehabilitation of preterm infants within walking distance
Authors: Surenkova Inga N , Suslova Galina A , Skoromets Anna P
Published: August 2016

During last five years there was increasing preterm infants, these children were born with a gestational age of 26 weeks and weighing 800 g, with severe combined pathology. Preterm infants came to the nearest polyclinics after the first stage of rehabilitation in hospitals. There are many questions how and when specialists should begin rehabilitation of such children. Specialists observes that is required an integrated approach to the rehabilitation of premature babies by analyzing the development of these children. Considering that children’s polyclinic allows monitoring children till 18 years of age, there is a possibility of observing and assisting these children during longer period. It is also very essential to realize that without an adequate intensive nursery care the negative consequences become irreversible for premature infants. Birth of a premature infant is a severe psychological stress for both parents. Often without completely realizing it, the family begins to live in conditions of high emotional stress. The department of medical rehabilitation must operate with the parents of a premature baby, in order to help them adapting to the new conditions of life. The task of differentiated medical and psychological rehabilitation can be fulfilled only by the district polyclinic in which the child will be observed until the age of 18. In the article considered features of modern rehabilitation of preterm infants in the in ambulatory-polyclinic service.
PET - diagnostics of cognitive impairment in patients with parkinson’s disease
Authors: Lytaev Sergey A , Susin Daniil S
Published: August 2016

Traditionally, Parkinson’s disease is associated with a deficit of dopaminergic system, manifested in the extrapyramidal motor disorders. In addition, the disease is characterized by a wide variety of not movement disorders. For example, the spectrum of autonomic, mental, cognitive and sensory symptoms is presented. Cognitive impairment, including mild cognitive impairment and dementia in Parkinson’s disease are among the most common disorders are not motor. The purpose of this study was aimed to investigate the relationship of early cognitive impairment and rate of glucose metabolism in different parts of the brain in patients with Parkinson’s disease. Positron emission tomography (PET) with fluorodeoxyglucose synthesis in patients suffering from Parkinson’s disease was performed. Study group consisted of patients (31 persons, age 41-77 years). Patients have passed inpatient and/or outpatient treatment at the clinic of the Institute of Human Brain of the Russian Academy of Sciences. The control group (15 persons) consisted of patients of similar age group without cognitive impairment. To estimate the rate of glucose metabolism was used an original technique of the Institute of Human Brain. Immediately prior to the intravenous administration of radiopharmaceutical [18F]-deoxyglucose was synthesized. Psychological testing consisted of a clinical interview, observation, survey, test, as described in a brief assessment of mental status (MMSE) and the battery frontal dysfunction (BFD). The study found that when the initial cognitive impairment observed pattern of changes in the rate of metabolism of glucose, characteristic of patients with severe cognitive impairment in Parkinson’s disease. This fact leads to the assumption of a high validity of the test battery frontal dysfunction for early diagnosis of cognitive impairment in Parkinson’s disease.
Global Challenges in Democratic Local Governance of the African States
Authors: Okeke Remi Chukwudi , Agu Sylvia Uchenna
Published: August 2016

Local governments in many parts of Africa are yet to be fully accepted as important levels of government (by political actors at the central and sub-central levels). This gives rise to the contradictory scenario whereby such political actors at the central and sub-central levels remain the apostles of centralization on one hand and exponents of democracy as a model of national government on the other hand. Nigeria is the most populous African country. And this marginalization of the local government in the democratic process is prevalent in Nigeria. Invariably, the pervasive effect of this condition, as it negatively affects the availability of dividends of democracy to the African citizen, is worrisome. In the meantime, the continent of Europe is perceived in the study as having possibly taken local government understanding to a model level of local self-governance, through its European Charter of Local Self-Government. Europe is thus, seen in this study as a region in the lead in situating the local government paradigm, within its proper democratic context. The theoretical framework of deliberative democracy is adopted in the study to engage African states to embrace local self-governance as a critical component of democratization.
Civil Society Groups (CSGs) and the Democratisation Process in Nigeria, 1960-2007
Authors: Falode Adewunmi James
Published: August 2016

This paper analyses the significant role the civil society groups (CSGs) played in the democratisation process in Nigeria between 1960 and 2007. The paper discovers that the CSGs made use of the conceptual mechanism in the democratisation process of Nigeria. The conceptual mechanism allowed the CSGs to inject such important concepts as accountability, rule of law, democracy, transparency, human rights and due process into the democratisation process between 1960 and 2007. These concepts were used to tackle some of the major democratization challenges, such as corruption, religious crisis and governance that confronted Nigeria between 1960 and 2007. By using the historical methodology, the paper analyses the crucial role the CSGs played in both the civilian and military administrations thatgoverned Nigeria between 1960 and 2007. The central thrust of the paper is to show how the CSGs contributed to the enthronement of democracy and democratic practices in Nigeria.
Lexis and Mood as Markers of Feminist Ideology in Tunde Kelani’s Arugba and Ma’ami
Authors: Akinmameji Oluwayemisi Olusola
Published: August 2016

Although the negative representation of women in Nollywood movies is worrisome to scholars, they have done little as regards exploring the feminist linguistic analysis of these movies. Studies have focused on the misrepresentations of women with emphasis on the literary perspectives. This paper attempts a lexical and sentential analysis of feminist ideology of two Nollywood movies. The study adopted Norman Fairclough’s model of Critical Discourse Analysis to explain way linguistic are used to instantiate feminist ideology in the movies. Arugba and Maami produced by Tunde Kelani were purposively sampled because of the gender issues in them. Though some movies merely project women as witches and sex slaves, these two movies stand out among those that project the strengths of womanhood. The movies attempt to correct the negative impression about women. Linguistic features such as the lexical indices and mood system are examined. Larger scale features such as allusion and simile are also explored. The study suggests that despite the rot in the value system of the present day Nigeria, there are still women who pass for the ideal. Also, it was discovered that women can determine their fate regardless of what roles the society gives them and could survive even under the worst patriarchy. Beyond their weaknesses, women are necessary to maintain tranquility in the home and the larger society. This paper recommends that movie stakeholders should give responsible roles to women and women should be sensitive and alive to their responsibilities as regulators of the social political Nigerian entity.
Sons do Silêncio: Relações entre o Paradigma da Teo-política do Alto Império Romano e o Conceito de Violência Simbólica em Bourdieu
Authors: Guerra Danilo Dourado
Published: August 2016

Resumo: o século I traz consigo um conteúdo historiográfico significativo envolvendo as relações de poder e de dominação operadas pelo Império romano diante das comunidades do mundo mediterrâneo. Nesse breve estudo pretender-se-á analisar a relação entre a violência simbólica e o paradigma da teo-política do Império dos Césares. Guardadas as políticas de interpretação que sustentam criminalizações e heroísmo exacerbados, isso é o que de forma parcial e fragmentária analisaremos nesse texto. Palavras-chave: Violência simbólica. Teo-política. Poder. Império Romano.
Тенденции развития государственно-частного партнерства
Authors: Крюкова Екатерина Леонидовна , Лемьева Ирина Витальевна
Published: August 2016

Статья посвящена обзору современных тенденций государственно-частного партнерства (ГЧП). Актуальность темы статьи определена тем, что по расчетам Всемирного банка 10% увеличение финансовых вложений в инфраструктуру обеспечивает 1% рост экономики. В результате анализа законодательства в сфере ГЧП, научной литературы и статистических данных были выявлены пять тенденций развития ГЧП в России.
Взаимодействия государства, бизнеса и образовательных организаций в рамках государственно-частного партнерства
Authors: Бакшеева Анна Дмитриевна
Published: August 2016

В статье представлено исследование существующих трактовок государственно-частного партнерства применительно к различным сферам экономики. Рассмотрено ГЧП в сфере высшего образования. Проанализировано взаимодействие государства и бизнеса при целевой подготовке кадров.
Insect Repellent Properties of Melaleuca alternifolia
Authors: Bin Edris Mohamad Adib , Yusuff Mamat Awang Soh , Shahzad Aslam Muhammad , Syarhabil Ahmad Muhammad ,   School of Bioprocess Engineering, Universiti Malaysia Perlis, Kompleks Pusat Pengajian Jejawi 3, 02600 Arau, Perlis, Malaysia.,   School of Bioprocess Engineering, Universiti Malaysia Perlis, Kompleks Pusat Pengajian Jejawi 3, 02600 Arau, Perlis, Malaysia.,   School of Bioprocess Engineering, Universiti Malaysia Perlis, Kompleks Pusat Pengajian Jejawi 3, 02600 Arau, Perlis, Malaysia.,   School of Bioprocess Engineering, Universiti Malaysia Perlis, Kompleks Pusat Pengajian Jejawi 3, 02600 Arau, Perlis, Malaysia.
Published: August 2016

The aim of this study is to compare the use of plant-based insect repellents that are environment friendly with the use of insect repellents based on chemical substances which can be harmful to the environment and human health. The plant studied here is “tea tree”; its scientific name isMelaleuca alternifolia. Essential oil from this plant is extracted by steam distillation method. Based on the previous research, tea tree oil has antimicrobial, antifungal, anti-inflammatory, and insect repellent properties. Some experiments were done on tea tree oil to determine its insect repellent properties and the suitable concentration that can be used to make sure its repelling effect is optimum. The purpose of this determination is to avoid its harmful effect on humans because it can be toxic if it is used at high concentration. The results showed that tea tree oil repelledTribolium castaneum. Furthermore, the toxicity assays also gave positive result where the tea tree oil has toxic properties againstSolenopsis invicta. The lethal dose (LD) of tea tree oil to kill 50% of a group ofS. invictais 23.52 μL/mL. This LD50 is determined by using the arithmetic method of Karber. Broadly, the results showed thatM. alternifoliahas insect repellent properties and shows toxicity against certain insects.
Electrochemical Behavior and Determination of Chlorogenic Acid Based on Carbon Nanotubes Modified Screen-Printed Electrode
Authors: Ma Xiao-Yan , Yang Hong-Qiao , Xiong Hua-Bing , Li Xiao-Fen , Gao Jing-Ting , Gao Yun-Tao
Published: August 2016

In this paper, carbon nanotubes modified screen-printed electrode (CNTs/SPE) was prepared and the CNTs/SPE was employed for the electrochemical determination of antioxidant substance Chlorogenic acids (CGAs). A pair of well-defined redox peak of CGA was observed at the CNTs/SPE in 0.10 mol∙L-1 acetic acid-sodium acetate buffer (pH 6.2) and electrode process is adsorption-controlled. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) method for the determination of CGA were proposed based on the CNTs/SPE. Under the optimal conditions, the proposed method exhibited linear ranges from 4.73×10-7 to 4.45×10-5 mol∙L-1, the linear regression equation was Ipa(µA) = 4.1993 C (mol∙L-1)+1.1039 (r = 0.9976) and the detection limit for CGA could reach 3.25×10-6 mol∙L-1. The recovery of matrine was 94.74~106.65% (RSD = 2.92%) in coffe beans. The proposed method is quick, sensitive, reliable, and can be used for the determination of CGA.
Natural Language Processing Techniques on Oil and Gas Drilling Data
Authors: Antoniak M. , Dalgliesh J. , Verkruyse M. , Lo J.
Published: August 2016

Recent advances in search, machine learning, and natural language processing have made it possible to extract structured information from free text, providing a new and largely untapped source of insights for well and reservoir planning. However, there are major challenges involved in applying these techniques to data that is messy and/or lacking a labeled training set; we cover some of the methods in which these problems can be overcome. We present a method to compare the distribution of hypothesized and realized risks to oil wells described in two datasets that contain free-text descriptions of risks. We treat one dataset as a training set for a logistic regression classifier, and then use this classifier to label in the events in the other, out-of-domain dataset. To adjust for differences between the datasets, we rebalance the training set and supplement it with labeled instances automatically extracted from the test set. These simple domain adaptation techniques allow us to achieve an average F1 score of 0.84 on the out-of-domain test set.
Drawdown Control: A Platform for Safeguarding and Optimising Production
Authors: Calvert Patrick
Published: August 2016

Since the inception of Intelligent Energy over a decade ago, there has been a gradual transition from the collection and visualization of large data sets through to the intelligent analysis and interpretation of data. A recent drive towards automation has evolved from the desire to streamline ongoing activities, reduce exposure to human error and continuously position operations at the optimum operating point.

Attempts to automate the optimization process, whether through closed loop optimization or multi-variable control, have largely focused on the facilities. This approach has merit when production is on plateau, as the rates will typically be constrained by the processing capacity of the facilities. As production declines, the handling capacity of the facilities becomes less of a burden and the deliverability of the well stock gains prominence. Productivity is now constrained by well uptime along with the health of the completion.

Adequate control of the drawdown can have a positive impact on both the health of the completion and on the uptime of the well. For weak wells, the well must be beaned up at a certain rate to prevent liquid loading. Control of the drawdown is therefore paramount in ensuring a successful restart. For wells that cut water or free gas and transect multiple reservoir layers, the drawdown will drive coning and promote cross flow. As both are detrimental to production, overall productivity is driven by the ability to control and optimise the drawdown. Finally, if the rock is poorly consolidated, rapid fluctuations in the drawdown can have a detrimental impact on the rate of sand production, screen erosion and skin growth.

Within this paper, the value of controlling the drawdown will be presented along with a control solution that has proved effective at controlling the drawdown during start-up, continuous production and ramp down to within 5 psi.
Collaborative IE Inside and Across Functional Silos - A Software Solution that Really Works
Authors: Fjellheim R. , Lohne H. P. , Sivertsen S. , Sølvberg A. , Thorsen T.
Published: August 2016

Intelligent Energy solutions have been successfully adopted by many operators with documented benefits. Still challenges remain, such as weak cross-discipline collaboration, sub-optimal decision making, and an inability to effectively learn from experience. Hence, enterprise IE - achieving better collaboration across discipline silos - remains an important challenge. "Top down" ways of obtaining enterprise IE include co-locating function teams, integrated planning, business process management, and information management and standardization.

In this contribution we describe a pragmatic "bottom up" software solution that supports collaborative IE on an enterprise level, serving both departmental functional silos and their need to coordinate with other parts of the organization (both onshore and offshore). The solution builds on well proven enterprise social media technology, augmented with a carefully designed set of integrated collaboration tools. The latter include case management, information sharing, document management, task and workflow support, Outlook/Lync integration, decision support, and more.

The solution was successfully deployed at the onshore operations center of a major North Sea field. We provide details and experience from rollouts in three separate but interlinked areas:

– Monitoring the condition of offshore gas turbines and supporting maintenance decisions – Supervising drilling operations, logging and following up well interventions – Managing and optimizing production from a large multi-well field

In each case we describe how the IE solution supports the natural way of working of the involved personnel, making their work day more productive and enjoyable. We also describe how the solution enables improved coordination on a practical level across functions, e.g. when maintenance decisions need to be coordinated with production plans. Finally, we assess operational and business related benefits of the IE solution, and discuss possible future extensions of our work.
Real Time Decision Making - Incorporating Dynamic Risk Management
Authors: Hartigan Andrew , Thrasher Darryl , Adlam Robin
Published: August 2016

This paper introduces Dynamic Risk Modeling and reports on a 2016 proof-of-concept demonstration of the emergent capability. While Dynamic Risk modeling can apply in any high risk environment, the demonstration focuses on the High Pressure, High Temperature (HPHT) drilling environment and uses 2010 Macondo cumulative risk as a demonstration scenario.

Dynamic Risk Modeling integrates the effect of human decisions with technical conditions; it enables three evolutionary capabilities in risk management: The awareness of cumulative and current risk based on input from multiple points and times of originThe quantitative insight of the coupling effect of multiple hazards when barriers or controls change conditions or failThe incorporation of real-time data into risk awareness, management and decisions

The paper demonstrates enhancement of the digital oilfield by applying real-time data to predictive decision making. The model receives continuous well data, processes it through the model with other environmental and human factors, and translates it into real-time risk awareness and insight.

The demonstration of Dynamic Risk Modeling is applied to the Deepwater Horizon drilling environment in April, 2010 to show how a real-time representation of current and cumulative risk could have aided decision makers with critical information and insight.
Big Data Analytics for Prognostic Foresight
Authors: von Plate Moritz
Published: August 2016

Objectives/Scope

With the rise of big data analytics in petroleum engineering, a plethora of data collectors, sensors, transmission devices, and software tools is entering our lives at the personal and professional levels. Data is extracted, transferred, processed, and utilized - be it from wearable devices, refrigerators, or motorcycles. It also spans areas such as public facilities, transportation networks, and major industrial assets.

In the sphere of petroleum asset management data analytics is certainly not a new concept. For decades, equipment condition data has been explored and exploited. Internal data networks, repositories, and historians, along with the condition monitoring, predictive diagnostics, and performance optimization applications show a long tradition of utilizing data to gain useful insight.

Methods, Procedures, Process

Current asset management technologies can identify what is going on, where, why there are challenges, and how they can be resolved. Yet, new prognostic analytics emphasizes data-driven forecasts addressing "when" questions, such as "When will my compressor have a malfunction?". Presently, such forecasts have no real proxy in petroleum asset management. The questions "When will my bearing fail?", "When is my last chance for plant revision?", and "When will turbine replacement be cheaper than refurbishment?" are widely asked but rarely answered.

Results, Observations, Conclusions

We will review herein which major challenges prognostics faces in the petroleum industry sphere, how they are currently being resolved, and what benefits can be achieved. We present, in addition, a detailed example of an application of prognostics in a petrochemical manufacturing plant. Condition and process data of a cracked gas compressor is utilized to generate remaining useful life distributions and future malfunction risk profiles. The main objective of the operator is to reduce both downtime and maintenance costs.
Smart Oilfield Safety Net: An Integrated System for Prediction of Asset Integrity Opportunities
Authors: Killen N. , House R. , Sankur V. , Thigpen B. , Chelmis C. , Prasanna V. K. , Neumann U. , Raghavendra R. , Yao K. , You S. , Ershaghi I.
Published: August 2016

We present an integrated system that automatically collects historical and current data from heterogeneous sources, performs analytics to identify telltale signatures of Loss of Containment (LOC) events, and makes asset behavior predictions as an asset ages. Our semantically enhanced system of record stores and manages heterogeneous data introduced by a variety of collection mechanisms and frequencies, and also captures subject matter knowledge and experience to automate LOC prevention decision making. Analytics provide a "learning by example" platform; LOC patterns can be quickly identified even in new facilities by utilizing other facilities LOC facts. Machine learning techniques coupled with rule-based systems and advanced visualization environments can not only determine an asset’s health, but also minimize labor intensive and error prone data comprehension and decision-making.
Reservoir Uncertainty Analysis: The Trends from Probability to Algorithms and Machine Learning
Authors: Ani Maureen , Oluyemi Gbenga , Petrovski Andrei , Rezaei-Gomari Sina
Published: August 2016

For over fifty years, reservoir development around the world has covered different reservoir types and environments with vast technology, expertise and a growing variety of approaches. However, the predominant challenge from which a myriad of other field development issues arise has been on how to accurately characterise reservoir parameters because the obtained results are largely associated with uncertainties due to subsurface geological complexities.

This paper focuses on the evolving advances and current practices in reservoir uncertainty modelling and gives insight into the future trends. This work critically examines the foremost statistical reservoir uncertainty analysis approaches, the current probabilistic and stochastic uncertainty modelling workflows which are typically based on various numerical models, and the very recent development of embedding some artificial intelligence algorithms (which include genetic algorithms, artificial neural networks, Bayesian networks amongst others) in reservoir uncertainty modelling, which now points to a future of using more sophisticated machine learning systems for achieving reservoir models and parameters with higher confidence.

These evolving trends and approaches are discussed in more detail in this paper; with an in-depth analysis of the associated workflows, fundamental principles, strengths, weaknesses, robustness and economics of each approach. Also, reconciliation between the statistical, probabilistic, stochastic and artificial intelligence methods present a deep insight into the prospects of using artificial intelligence for optimising the modelling of reservoir uncertainties beyond the capabilities of conventional methods. Thus saving time and cost by quantifying the uncertainties in reservoir properties as well as regenerating new best-fit reservoir attributes using the robust uncertainty analysis networks and the pattern-recognition ability of machine learning networks.

Hence, this paper presents a comprehensive review of the various uncertainty analysis methods, and also analyses the confidence of artificial intelligence applications which are increasingly pushing the frontiers to improved uncertainty modelling.
Data to Language - Leveraging Software to Understanding and Communicate Well Integrity Risk Throughout the Organisation
Authors: Mundie Gavin , Wilson Sean
Published: August 2016

It is inevitable that during a wells life cycle there will be failures or degradation that introduce risk. By applying process safety principles, there are three questions that an operator should ask themselves:Do we understand what could go wrong?What systems remain to prevent this happening?Are we getting the right information to assure us that these systems are working effectively?

In terms of well integrity management, questions one and two are dealt with in major accident hazard reviews, leading to well designs that ensure there are adequate barriers between the hazards in the well and the environment.

Question three is managed by the verification and assurance of the identified barriers and systems that are aligned with corporate or industry performance standards.

This paper suggests a fourth question:

4. Is risk communicated to the relevant people to ensure effective decisions are made, and that the risk is understood and mitigated?

Traditionally, a well failure model approach can be used to optimise the risk assessment process with recommended response times to repair specific failures. However, it does not account for the whole asset and the overall level of risk is posed to the installation. Further, the scoring methodology needs to be understood by a specialist and aligned with the corporate risk matrix used by asset managers.

This paper describes how software systems can be leveraged to provide effective communication in the organisations "language of risk" and helps to visualise the accumulation of risk from wells that are aligned with the corporate matrix. This small step change vastly improves the understanding and communication of well integrity risk throughout the organisation enabling installation management early challenge, better resource utilisation and the monitoring of creeping accumulative change.
A Case Study on Remotely Operated Intelligent Bridge Plugs for Plug and Abandonment Operations
Authors: Arackakudiyil Zac Suresh , Thomson Barry , Førde Carl Henning
Published: August 2016

This paper demonstrates a new method of using remotely operated intelligent bridge plugs to replace conventional plugs, thereby eliminating the need for multiple wireline runs. This reduces operational expenses and eradicates potential health, safety, and environment (HSE) challenges resulting from additional personnel involvement in the pressure control equipment rig up and testing.

Use of traditional plug-and-prong barriers and retrievable bridge plugs is integral in plug and abandonment (P&A) operations. However, multiple wireline runs are required in wells with considerable gas buildup.

The well in this paper had a considerable amount of gas buildup in the annulus that required periodic circulating. Use of an intelligent bridge plug offered the potential to open and close the plug remotely because the plug uses onboard decision-making electronics that monitor well condition. The plug is programmed to either open or close whenever a specified condition (known as a trigger) is detected.

The intelligent bridge plugs allowed the operator to communicate with the tool remotely from the surface using applied pressure commands, and the plugs were opened and closed periodically to circulate the gas buildup out of the annulus. The plugs were later closed remotely to act as a barrier while the christmas tree was removed and the blowout preventer (BOP) was installed. The plugs were finally opened and pulled along with the tubing, saving further wireline runs.

The operator was able to circulate all of the gas buildup in this mature well and continue the P&A operation. The well discussed in the case study used the intelligent plug to remotely open and close nine times. This saved 18 wireline runs in comparison to a conventional retrievable bridge plug. Considerable financial savings were achieved by removing intervention runs, and HSE risks involved with rigging up and running wireline were also eliminated in this case. Because of the benefits provided by using the intelligent plug, the operator plans to perform future P&A operations without mobilizing a wireline unit to the rig.

The industry is beginning to experience an increase in P&A operations. Minimizing costs without sacrificing safety is of utmost importance. The groundbreaking use of remotely operated intelligent bridge plugs for P&A operations could be a timely supplement to existing solutions.
Integration of Petroleum and Reservoir Engineering Workflows in Production Database Management Systems
Authors: Talbot David , Jeffs Paul , Hyde Andrew , Kohok Abhimanyoo , Rossi David
Published: August 2016

The Breagh tight gas field is located in the Southern North Sea and currently delivers gas from 8 wells via a normally unmanned installation (NUI) to a processing facility in Teesside. In the coming years there is scope to install a second NUI and drill an additional nine wells. Platform and onshore sensors deliver high-frequency pressure, temperature, and flow rate data for each well, in addition to key facility data.

The high volume and variable quality of this high frequency and real time data directly affects the way in which daily engineering activities are performed. Originally, the engineering team used conventional methods of data handling, storage and management, including manual manipulation, and spreadsheet computations. This was a time consuming exercise which led to excessive replication of data and a lack of audit trail behind the data used for any analysis.

Allocation of field production to individual wells is a key production engineering workflow. The flow rate data is the prime input for every piece of analysis conducted by the reservoir engineering team; decline curve analysis, rate and pressure transient analysis, material balance and history matching the numerical simulation model. The results of this analysis directly impacts upon routine production strategy & optimisation, workovers, well planning, future development strategy and reserves. The platform Venturi flow meters have proven unreliable throughout the production life of Breagh, leading to the evaluation of several alternative allocation methods, all of which are manual and time intensive.

This paper presents workflows for production data management and production allocation. Various production allocation methods are used and this paper demonstrates the impact of data accuracy on long-term development decisions, and short term interventions due to flow assurance issues. Thereby, the asset team can shift from a reactive, to a proactive position and generate value for the business.
Smart and Automated Workover Candidate Selection
Authors: Zangl Georg , Neuhofer Lisa , Zabel David , Tippel Philipp , Pantazescu Cosmin-Ionut , Krcmarik Vladimir , Krenn Lisa , Hachmöller Barbara
Published: August 2016

A probabilistic expert system assisting workover candidate selection and increasing the technical and economic success rate of workovers, has been developed in cooperation with a major Central-European operator.

In order to streamline and standardize the workover candidate selection process across 240 fields using a corporate-wide software solution, expert knowledge, data analytics and already existing workflows and methods have been integrated. The underlying logic is capable of detecting a comprehensive set of well integrity and deliverability problems for active and shut-in wells.

A problem detection logic based on historic workover performance provides risk, cost and success estimates. Well production gain through proposed workovers is calculated automatically based on reservoir and neighbourhood potential. Reservoir and well performance KPIs and NPV calculations enable flexible ranking of candidates with regard to technical and economic aspects.

This paper describes the applied procedures and methods, like data analytics, machine learning and reasoning tools like Bayesian Belief Networks. The system additionally integrates petroleum engineering and knowledge discovery techniques. The screening logic works as a repeatable and automated process that can be scheduled or be executed on demand. The screening of several thousands of wells takes less than an hour. Hence the process can be executed more often and much quicker, leading to an intensified monitoring of possible business opportunities.

Over the last 2 years, several studies in more than 30 fields - with a total number of 7,600 wells - representing a wide variety of reservoir and well characteristics have been performed. In the course of these studies and in independent blind tests the correct and precise functionality was successfully tested.

The smart and automated workover candidate selection process leads to reduced costs, helps to remove non value adding work through automation and improves the overall workover success.
A Step by Step Approach to Improving Data Quality in Drilling Operations: Field Trials in North America
Authors: Ashok Pradeepkumar , Ambrus Adrian , Ramos Dawson , Lutteringer John , Behounek Michael , Yang Yueheng Lisa , Thetford Taylor , Weaver Terrence
Published: August 2016

Multiple literature studies have indicated that a significant amount of data collected during drilling operations is unreliable. To move towards better data quality, two critical hurdles need to be overcome. First, the case for the value of good data needs to be made, so that resources can be allocated towards improving data quality. Second, a process needs to be established within the operator company to measure and improve the quality of data. This paper is a case study in addressing these challenges. In this work, we focus on eight core surface sensor measurements essential to drilling operations (block position, hook load, rotary speed, rotary torque, pump strokes per minute, flow rate out, standpipe pressure and pit volume) and attempt to assess/improve their quality. The first step involves identifying how much of each measured data deviates from their accepted values. This is most economically accomplished using automated data validation software. Once the root cause is identified, steps can be taken to rectify the problem. Four rigs in North America were identified for this trial conducted over a six-month period. The goal is to establish a data quality improvement loop that continually accesses data, identifies issues, and implements corrective actions. This paper explains this process and how it has been applied to improve the quality of drilling data.
Advanced Decision Support for Deepwater Offshore Drilling Incorporating Insights from Nuclear Power and Aerospace
Authors: Nelson William R.
Published: August 2016

Experience gained from catastrophic events such as Three Mile Island, Challenger, Columbia, and Fukushima has highlighted the critical importance of effective decision making to assess the situation when abnormal conditions are first detected and to formulate an effective response to terminate the event and minimize the consequences. A common thread across these incidents has been the failure to recognize that critical safety barriers have been defeated.

A systematic approach for decision support has been developed using the concept of dynamic barrier management. This approach combines bow tie diagrams from the offshore industry with the success path concept from the nuclear power industry. By combining bow tie diagrams - which provide information about the barriers that can intervene in the progression of an accident, with response trees - which provide information on actions needed to maintain or restore the barriers, a comprehensive, robust approach for dynamic barrier management can be realized.

This paper summarizes lessons learned from major accidents in the nuclear, aerospace, and offshore industries. The dynamic barrier management approach for decision support is described, and experience from offshore drilling and production applications is summarized. Decision support for dynamic barrier management combines effective methods from the nuclear power, aerospace, and offshore industries to form a powerful approach for increasing offshore safety.
How Do We Accelerate Uptake and Fulfill the Value Potential of Intelligent Energy?
Authors: Gilman H. , Lilleng T. , Nordtvedt J. E. , Unneland T.
Published: August 2016

The objective of this paper is to identify ways to accelerate the uptake and fulfill the value potential of Intelligent Energy (IE). The paper is co-authored by a cross-industry group drawn from operators, service provides and product vendors, all of whom have been involved in the IE arena for 10 years or more. We have analyzed the past experience to identify ways in which IE has been successful, and improvements that could be made to add value across a broader scale amid the challenges of today's commercial environment. In this paper, assessments are given on IE implementations to identify practical ways in which we can expand deployment and deliver results more quickly, including the importance of collaboration and competition in the IE domain, and how longer-term business models and new organizational ideas could improve the industry's uptake of IE. We have identified two areas where we believe changes to our approach could deliver significant benefits, through the expanded use of integrated workflows and shared Subject Matter Expert services. We discuss the benefits and challenges of this integrated approach to solution design, work processes, technology, skills and competencies. Field cases from two major operators are given as best practice examples on advanced use of Intelligent Energy in the oil and gas industry.