bluuebunny/crossref_metadata_2025_split huggingface dataset:
CBHP MPD Assisted Casing Drilling: A Novel MPD Solution Combining Two Drilling Technologies, Planned and Executed on Otherwise Not Drillable Multiple Directional Wells in North America
Authors: Nauduri Sagar , Parker Martyn , Nabiyev Akram , Sampley Eddy , Kirstein Lenord , Morris Jason , Wilkinson Matthew , Buckner Jason 
Published: March 2019

Abstract
A novel drilling solution, ‘Constant Bottomhole Pressure (CBHP) Managed Pressure Drilling (MPD) assisted Casing Drilling operation', was designed, planned and successfully executed for different operators on multiple directional wells in North America. These wells were otherwise not drillable either conventionally or with CBHP MPD using conventional drillpipe-BHA; and over the last few decades several operators tried and failed to reach the Target Depth (TD) on multiple occasions when drilling some of these formations.
One operator drilled in formations prone to severe faulting/fracturing and with very high permeability, while a different operator drilled through multiple weak zones interbedded with over-pressured and highly conductive regions. Both scenarios resulted in similar issues with fluid displacement, tripping/surge and swab, kicks and losses, running casing and cementing. The generic CBHP MPD solution with a conventional drillpipe-BHA even with ‘Anchor Point' CBHP MPD and its variations was not successful in either of these scenarios in drilling to the TD.
As demonstrated using case histories, the success in these projects was a result of combining two technologies – ‘CBHP MPD' and ‘Casing Drilling'. Pre-planning, understanding formation constraints, training, and having knowledgeable and experienced people involved, enabled safe and successful execution of CBHP MPD assisted Casing Drilling on these projects and helped CBHP MPD develop and reach new horizons.
Nitrogen Cap Drilling A Managed Pressure Drilling Alternative for Highly Fractured Carbonate Reservoir
Authors: Podust Alexey , Starkey Craig , Wood Jeff , Cameron Gareth 
Published: March 2019

Abstract
Nitrogen Cap Drilling (NCD) is a technique developed by Tengizchevroil (TCO) that enables drilling a highly fractured reservoir under conditions where more conventional pressurized mud cap drilling techniques are not viable. NCD is an extension of the closed hole circulating drilling (CHCD) technique (Ref SPE Paper # 79850) previously developed and used extensively by TCO for drilling a highly fractured carbonate reservoir where severe loss circulation is encountered and incurable.
CHCD is a pressurized mud cap drilling technique that relies on the ability to fill the well with a fluid density lighter than the reservoir pressure gradient in order to maintain communication with the reservoir pressure. Once the reservoir pressure gradient drops below the density of the lightest fluid available, the well will no longer support a full column of fluid to surface and an alternate drilling method must be employed.
TCO has developed NCD as a response to this operating reality in the Tengiz field. The NCD technique involves filling the annulus with a heavier than reservoir pressure gradient fluid once severe lost returns are encountered. The annulus fluid level does not reach the surface, and the resulting air gap is pressurized with nitrogen gas. This nitrogen "cap" is contained under the Rotating Control Device (RCD) which allows for maintaining pressure communication with the formation. Well status is continuously monitored by tracking the wellhead pressure and measuring the annulus fluid level. The bottom hole pressure is balanced by manipulating the composition of the annular fluid column and controlling the wellhead pressure.
In 2017, TCO conducted successful field trials and demonstrated that NCD is a viable technique to enable the continuation of the low reservoir pressure drilling program in Tengiz. TCO has since adopted NCD as the standard technique in wells where CHCD is not technically viable or operationally preferable. This paper will describe NCD technique development, equipment, procedures, operational implementation, and key learnings to date.
Influx Management Envelope: Limits Redefinition and Parametric Sensitivity Analysis Based on Data and Lessons Learned from Offshore Applications
Authors: Gabaldon Oscar , Gonzalez Romar A , Bacon William , Brand Patrick 
Published: March 2019

Abstract
The Influx Management Envelope (IME) assists in identifying influx conditions which could compromise the primary well barrier and fluid handling capacity on surface. IME boundaries are influenced by changes in parameters such as mud weight, wellbore depth and geometry, pump rate, surface pressure, etc. Thus, any changes to these parameters will change the acceptable influx volume and intensity for Dynamic Influx Management. It is, therefore, critical to understand how changes in each of these variables affect IME limits so that its validity can be established within parameter ranges, rather than only for discrete values.
This work presents an in-depth discussion of how IME limits are determined, with both detailed philosophical and practical guidance on methods to calculate the surface and subsurface limits. Recent deepwater applications of the IME are used to represent baselines for presenting methods of calculating IME limits, including a basic single bubble approach, through to the most robust approach of including transient, multiphase simulations. Parameter sensitivity analyses are performed to determine reasonable ranges for which an IME is valid, with the goal of understanding the required IME update frequency during operation.
Utilization of Managed Pressure Drilling in Deep High Pressure High Temperature Gas Wells
Authors: Moid Farrukh , Ghamdi Ahmed A. , Nutaifi AbdulRahman M. , Utaibi Abdullah A. 
Published: March 2019

Abstract
Drilling in high pressure high temperature (HPHT) deep gas reservoirs, with multiple shallow different pressure horizons, requires special techniques which include application of Managed Pressure Drilling (MPD), revising casing setting depths, improving casing strength, and refining mud design. This paper focuses on application of MPD in HPHT gas wells and also describes briefly other techniques which can improve drilling performance and reduce non-productive time.
Road to Success in MPD - Vaca Muerta Case History
Authors: Bulant Ezequiel , Gabaldon Oscar , Bedoya Jorge 
Published: March 2019

Abstract
Challenging drilling operations in the Vaca Muerta unconventional shale gas play have prompted operators to implement innovative drilling techniques to improve drillability and operational efficiency. Significant benefits have been reported by utilizing Managed Pressure Drilling (MPD), Underbalanced Drilling (UBD), and/or drilling with casing; however, challenges still exist, due to a variety of reasons. The heterogeneity found from field to field and within fields has resulted in wells with significant events, some resulting in loss of the well, even on the same pad where a previous well has been drilled uneventfully.
Arguably, the most successful non-conventional drilling technique being incrementally used in the area is MPD, often combined with UBD, particularly in gas wells. As with any new technology implementation, there is a learning curve which can be accelerated by translating learnings from successful experiences.
Three key components for a successful implementation on MPD are still building a collective experience in the Vaca Muerta play. Firstly, the equipment and associated technology is the key enabler for physically perform the operations safely and efficiently.
The second component is a ‘soft’ framework consisting of a robust layered approach including overarching standard policies, the MPD strategy for implementation in the specific project, conceptual and detailed procedures, and specific work instructions.
Lastly, the human component is a group of competent personnel, whom, at their specific responsibility level, understand the ‘soft’ framework, and knows how to operate the hardware to implement the technology so that objectives are met.
The potential of the technology is limited to the weakest of these three components. A strong combination of any two of them, not complemented by the third one, will most likely result in a partial success at best, if not a complete failure at worst.
The operator had recently three major events in wells being drilled with MPD, which resulted in the loss of the wells. After implementing a training program on MPD/UBD, which emphasized the human factor and understanding of the equipment, the ‘soft’ framework of strategy, procedures and project management, the safety and efficiency during operations has increased significantly. This resulted in a better handling of events related to bottom hole pressure control without a single well loss event to the date of writing this document, approximately nine months of continuous operations. The other mainstay of this process has been the flexibility to adapt the application of the methodology based on the well challenges encountered.
Applying complexity theory to model the operation of clinical trials in human communities
Authors: Berg Machteld van den , Ogutu Bernhards , Sewankambo Nelson K , Merten Sonja , Biller-Andorno Nikola , Tanner Marcel 
Published: March 2019

Abstract
Background

When a vaccine clinical trial enters a human community two independent systems merge into one system with various levels if interdependence. This system exhibits non-linearity and unpredictability, creating challenges for the research team. In this study we explore the researcher experience during clinical trials in human communities, through the lens of complexity theory.

Methods

We conducted in-depth interviews with a total of 11 researchers working on a phase III vaccine clinical trial in Kenya (Registry name: RTS,S ClinicalTrials.gov; Registry number: NCT00866619; Registry date: March 20, 2009). The interviews captured the researcher’s experience of working in a complex adaptive system and were analysed using thematic coding.

Results

Both human communities and clinical trials have the attributes characteristic of complex adaptive systems. Challenges researchers encountered working in this merged system include rumours, suspicion related to blood draws, and misconceptions. The researchers highlighted that a foundation of trust and open communication were foundational blocks to embrace the non-linearity of the system.

Conclusions

We have identified the key role that complexity theory plays in improving clinical trial design. The factors identified by our respondents, as seen through the lens of complexity theory, are integral to informing how clinical trial research can be tailored to the local social setting. Understanding the system (community and trial) as one allowed for the identification of patterns that influence the emergence of the system. This calls for clinical trial design to incorporate iterative practices to better equip research teams to adapt to the emerging behaviour of the system.
Outcome prediction in disorders of consciousness: the role of coma recovery scale revised
Authors: Lucca Lucia Francesca , Lofaro Danilo , Pignolo Loris , Leto Elio , Ursino Maria , Cortese Maria Daniela , Conforti Domenico , Tonin Paolo , cerasa antonio 
Published: March 2019

Abstract
Background: To evaluate the utility of the revised coma remission scale (CRS-r), together with other clinical variables, in predicting emergence from disorders of consciousness (DoC) during intensive rehabilitation care.
Method: Data were retrospectively extracted from the medical records of patients enrolled in a specialized intensive rehabilitation unit. 123 patients in a vegetative state (VS) and 57 in a minimally conscious state (MCS) were included and followed for a period of 8 weeks. Demographical and clinical factors were used as outcome measures. Univariate and multivariate Cox regression models were employed for examining potential predictors for clinical outcome along the time.
Results: VS and MCS groups were matched for demographical and clinical variables (i.e., age, aetiology, tracheostomy and route of feeding). Within 2 months after admission in intensive neurorehabilitation unit, 3.9% were dead, 35.5% had a full recovery of consciousness and 66.7% remained in VS or MCS. Multivariate analysis demonstrated that the best predictor of functional improvement was the CRS-r scores. In particular, patients with values greater than 12 at admission were those with a favourable likelihood of emergence from DoC.
Conclusions: Our study highlights the role of the CRS-r scores for predicting a short-term favorable outcome.
Enabling policy innovations promoting multiple ecosystem benefits: lessons learnt from case studies in the Baltic Sea Region
Authors: Zilans Andis , Schwarz Gerald , Veidemane Kristina , Osbeck Maria , Tonderski Andrzej , Olsson Olle 
Published: March 2019

Abstract
This paper analyses how specific institutional barriers and drivers affect the success of agri-environmental governance and policy innovations in four case study catchments in Germany, Latvia, Poland and Sweden. Possible adaptations of institutional settings are explored, aiming at increased effectiveness of policies and governance in delivering multiple ecosystem benefits along with reduced nutrient emissions and flood management. Factors of success synthesized from existing examples of innovative policy instruments in the EU and further afield are used to identify barriers and opportunities for the implementation of policy innovations in different institutional settings across the Baltic Sea Region (BSR). Key factors of success include close and trusting cooperation in scheme development, utilization of intermediaries in trust building, an active role of civil society and private sector, spatial targeting and coordination of measures, and result-based and long-term approaches. It is concluded that the effectiveness of measures can be increased by (i) adopting a less prescriptive approach to implementation, (ii) strengthening bottom-up participatory stakeholder learning processes, (iii) fostering cross-sectoral planning and funding initiatives, (iv) creating incentives for local collaborative actions, (v) developing cooperative nutrient management initiatives in the BSR and (vi) developing a systematic and coordinated approach to pilot-testing of new concepts and measures.
Assessment of the level of living of the population in Tambov region
Authors: Cheremisina Natalia V. , Veiss Elena V. 
Published: March 2019

Purpose of the study.To assess the standard of living of the population of the Tambov region through statistical methods.Materials and methods.The study used the methods of analysis of the composition and structure, the calculation of absolute and relative indicators of dynamics, average values, comparative analysis, graphical method of analysis, as well as the general theoretical method of analysis of Russian and foreign literary sources. The main information sources for the study were the data from the official website of the Federal State Statistics Service, its territorial office in the Tambov region, as well as the data from the Unified Interdepartmental Statistical Information System. In addition, the works of such authors as R. Zhukov, M. Malkina, N. Zotkina, S. Ignatova, E. Sadovaya, V. Sautkina and others were analyzed.Results.The main results of the study include the following:– Over 6 years (from 2012 to 2017) in the Tambov region, the largest share of the population, namely 23.0% in 2012 and 27.1% in 2017, had an average per capita cash income of 15 to 25 thousand rubles; – In 2012, the average per capita income of a resident of the studied region was most often met for 16,381.5 rubles (fashion value), and in 2017 – 18,561.0 rubles;– In the Tambov region from 2012 to 2017, the average absolute deviation of the studied indicator from the average in Russia is 5434.1 rubles;– The purchasing power of money incomes of the population has decreased for almost all food and non-food products; – The main sources of monetary incomes of the population of the Tambov region in 2017 are the wages of employees and receipts from social benefits (their share in the income structure is more than 20%);– The structure of the budget expenditures of the population of the Tambov region in 2017 is as follows: the purchase of goods and payment for services amounted to 77.5; mandatory payments and fees - 7.7%; real estate purchase - 1.9%; growth of financial assets - 12.9%;– The size of the average per capita monetary income of the population is inversely related to the unemployment rate of the region.Conclusion.In general, summing up the study, we can draw the following conclusion. For a number of indicators characterizing the standard of living of the population of the Tambov region, there is a positive trend, for example, an increase in the average per capita cash income of the population. Another positive trend was found: an inverse relationship between the unemployment rate and average per capita income. However, despite this, in our region it is lower than the average in Russia. Half of the population has incomes less than 17,730 rubles, and the most common income is in the amount of 18,561 rubles, which is significantly lower than the average for the Tambov region.
Combination of Pattern Classifiers Based on Naive Bayes and Fuzzy Integral Method for Biological Signal Applications
Authors: Akbarzadeh Omid , Khosravi Mohammad R. , Shadloo-Jahromi Mehdi 
Published: March 2019

Background:
Achieving the best possible classification accuracy is the main purpose of
each pattern recognition scheme. An interesting area of classifier design is to design for biomedical
signal and image processing.

Materials and Methods:
In the current work, in order to increase recognition accuracy, a theoretical
frame for combination of classifiers is developed. This method uses different pattern representations
to show that a wide range of existing algorithms could be incorporated as the particular
cases of compound classification where all the pattern representations are used jointly to make an
accurate decision.

Results:
The results show that the combination rules developed under the Naive Bayes and Fuzzy
integral method outperforms other classifier combination schemes.

Conclusion:
The performance of different combination schemes has been studied through an experimental
comparison of different classifier combination plans. The dataset used in the article has
been obtained from biological signals.
Robotic Path Planning Using Flower Pollination Algorithm
Authors: Mehta Ishita , Singh Geetika , Gigras Yogita , Dhull Anuradha , Rastogi Priyanka 
Published: March 2019

Background:
Robotic path planning is an important facet of robotics. Its purpose is to
make robots move independently in their work environment from a source to a destination whilst
satisfying certain constraints. Constraint conditions are as follows: avoiding collision with obstacles,
staying as far as possible from the obstacles, traversing the shortest path, taking minimum time,
consuming minimum energy and so on. Hence, the robotic path planning problem is a conditional
constraint optimization problem.

Methods:
To overcome this problem, the Flower Pollination Algorithm, which is a metaheuristic
approach is employed. The effectiveness of Flower Pollination Algorithm is showcased by using
diverse maps. These maps are composed of several fixed obstacles in different positions, a source
and a target position. Initially, the pollinators carrying pollen (candidate solutions) are at the source
location. Subsequently, the pollinators must pave a way towards the target location while simultaneously
averting any obstacles that are encountered enroute. The pollinators should also do so with the
minimum cost possible in terms of distance. The performance of the algorithm in terms of CPU time
is evaluated. Flower Pollination Algorithm was also compared to the Particle Swarm Optimization
algorithm and Ant Colony Optimization algorithm.

Results:
It was observed that Flower Pollination Algorithm is faster than Particle Swarm Optimization
and Ant Colony Optimization in terms of CPU time for the same number of iterations to find an
optimized solution for robotic path planning.

Conclusion:
The Flower Pollination Algorithm can be effectively applied for solving robotic path
planning problem with static obstacles.
Analysis of High-Efficiency Transformerless Inverter for a Grid-Tied PV Power System with Reactive Power Control
Authors: Ramachandran Selvamathi , Vairavasundaram Indragandhi 
Published: March 2019

Background:
In recent days grid-tied PV power systems play a vital role in the entire energy
system. In a grid –tied PV system Transformerless Inverter (TI) topologies are preferred for its
reduced price, improved efficiency, lightweight etc. Therefore many transformerless topologies have
been proposed and verified with real power injection only. Recently, almost every international
standard has imposed that a specified amount of reactive power should be handled by the grid-tied
PV inverter. According to the standard VDE-AR-N4105, grid-tied PV inverter of power rating below
3.68kVA, should attain Power Factor (PF) from 0.95 leading to 0.95 lagging.

Objective:
To address this issue of grid-tied PV system with reactive power control, in this paper
Fuzzy gain scheduling controller is proposed as a power controller for High Efficiency Transformeless
(HETL) inverter. The performance of the proposed scheme is analyzed and validated with the
comparison of a conventional PI controller based active and reactive power controllers.

Methods:
This paper is with the intention of improvement in the performance of the system, the
FGS controller is anticipated as active and reactive power controllers. In conventional PI controller
gains are constant for any value of the error, which makes error and delay in optimum value of voltage
(Vα and Vß). Hence in this analysis FGS controller tunes PI controller gain with respect to
change in active and reactive power error.

Results:
Comparative performance of PI and FGS based HETL inverter is presented in this paper. It
is noted that for any cases either Pref is constant or variable the FGS reduces ripple than PI based
HETL inverter system. Compare to constant reference power case variable reference case produces
more ripples in both systems.

Conclusion:
From the analysis FGS based HETL inverter in a grid-tied PV based power system
produces the best performance in all aspects such as voltage, active power and reactive power.
Исследование квантовых флуктуаций в Fe-=SUB=-x-=/SUB=-Mn-=SUB=-1-x-=/SUB=-Si с учетом LDA + U + SO-расчетов электронной структуры
Authors: Повзнер А.А. , Нуретдинов Т.М. , Волков А.Г. 
Published: March 2019

AbstractQuantum spin fluctuations are studied in chiral helicoidal Fe_ x Mn_1 – _ x Si ferromagnets on the basis of the direct calculations of the electronic structure. The disappearance of the helicoidal long-range order is shown to be accompanied by the appearance of the crossover of the thermodynamic and quantum transitions with a sharp decrease in the local magnetization and the zero fluctuation amplitude. Suppression of the local magnetization by quantum spin fluctuations leads to the concentration–temperature magnetic transition with the disappearance of the helicoidal short-range order. The calculations of the magnetization of the Fe_ x Mn_1 – _ x Si compositions show that at 0.12 < x < 0.20 the magnetic state in the thermodynamic limit is characterized by the short-range (not long-range) helicoidal order.