bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comprehensive Analysis of Borehole Stability with Temperature, Swelling, and Pore Pressure Change for Layered and Orthotropic Formations
Authors: Kaneshima Takuma , Bai Fuqiao , Morita Nobuo 
Published: March 2021

Abstract
Borehole stability depends on various parameters such as rock strength, rock deformations, in-situ stress, borehole trajectory, shale swelling, pore pressure change due to osmosis, overbalance mud weight and temperature. The objective of this work is to construct analytical and numerical equations to predict borehole failure including all these parameters, and to comprehensively propose a methodology to improve the borehole stability.
Analytical solutions are developed for inclined wells with respect to in-situ stress, shale swelling, pore pressure change due to osmosis, overbalance mud weight and temperature. A numerical model is developed for 3D inclined wells with orthotropic formation and layered formation. Using the analytical and the numerical models, stress state around inclined wells are evaluated. The breakout angle is predicted based on Mohr-Coulomb, Mogi, Lade and Drucker-Prager failure theories. Polar diagrams of mud weights are compared to judge the effect of each parameter and the magnitude predicted by the different failure theories.
Shale swelling and pore pressure change due to osmosis are the most difficult to estimate among above-mentioned parameters. The laboratory measured swelling of cores obtained from various formations showed that the magnitude to induce breakouts caused by swelling was the largest comparing with other parameters. Therefore, when shale stability problems occur, we need to estimate the magnitude of shale swelling and osmosis due to water potential difference. Then, to overcome the shale stability problem, we evaluated the sensitivity of human controllable parameters on borehole stability. The parameters which can be controlled by drilling engineers are overbalance, type of mud, borehole temperature and borehole trajectory. If the shale swelling is small, the borehole stability is improved by the mud weight. However, from the swelling tests from the cores of Nankai-Trough, we estimated unless we used a swelling inhibitor to reduce the swelling less than 0.1%, the well was not possible to drill through. Actually, the well was abandoned due to instability after trying side track several times.
Unlike previous works, this paper uses all important parameters (swelling, temperature, pore pressure, orthotropic formation, layered formation) to estimate the stresses around inclined wells with the same formation conditions for quantitative analysis. Failure analysis include Mohr, Mogi, Lade and Drucker-Prager. Finally, the polar diagrams of critical mud weight are used to judge whether we can choose well trajectory, orientation with respect to bedding planes, mud weight, shale inhibitor, and temperature to stabilize the borehole.
Game Changing Cementless Annular Isolation Improving Economical Returns in Deep Water Wells
Authors: Bledou Manfred , Caillon Didier , Groschaus Benjamin , Viger Guillaume , Singh Harpal , Bagal Joseph , Hallaire Maximilien , Onadeko Olugbenga , Hazel Paul , Vasquez Ricardo , Wallach Mathieu , Fürstnow Mette 
Published: March 2021

Abstract
This paper will discuss a game-changing and innovative technology that enabled cementless annular isolation (liner to borehole) across the reservoir, removing the risk of previous experienced cost and time overrun from complex cement operations and securing the full economical return on the wells. The technology has been deployed in four Moho North Albian wells, drilled through a complex reservoir with highly laminated lithology requiring efficient zonal isolation for both acid treatment and water shut off.
During the earlier field development, many cementing challenges were encountered that increased risk and cost and the ability to deliver effective isolation across the reservoir. Poor isolation leads to poor matrix acid stimulation, higher skin and a higher risk of water production. To address this the operator sponsored an industry challenge to achieve reservoir isolation with cost and risk reduction and to deliver overall efficiency gains. Through dialogue between the Operator and a leading service provider in Open Hole Zonal Isolation, a solution was identified that would effectively replace the cement across the reservoir with a metal expandable annular sealing system.
Time for delivery was a key driver to meet the drilling schedule and materialize the cost and risk reductions on the remaining wells. A scope of work was completed that included extensive qualification, manufacture and field deployment. The solution has proven to deliver benefits that address several fundamental aspects which were associated with the cemented liners: Substantial reduction in risk and cost associated with drilling the extended rat hole (shoe track) into the highly pressurized water zone (+/- 100mMD)Removed the risk and cost for the additional run to under ream the 6 ½″ hole to 7 ¼″ (low-ROP)Provided more certainty for zonal isolation whilst delivering effective acid stimulation and maintaining the low skin values.
The technology has many different applications within wells where conventional cement is challenged beyond its capabilities and inherently not fit for purpose, due to factors such as well trajectory, hole geometry, reservoir uncertainty, downhole environment (pressure, Temp, ECD) etc. Within these environments, the technology developed for Moho North adds a proven solution to the Operators toolbox, a technology that is already finding alternate applications and planned deployments.
Compatibility Between API Equations and Design Limits Plots for Ellipse and Circle of Plasticity
Authors: Romero Juan Manuel , Aasen Jan Aage 
Published: March 2021

Abstract
This paper presents a methodology to superimpose the American Petroleum Institute (API TR 5C3 2018) uniaxial and triaxial limits on tubular design limits plots. Complications due to a recent change of axis are resolved, producing practical design limits plots that avoid the horizontal shift of the API vertical limits, currently done by the industry. The commonly used slanted ellipse is compared against an adaptation of the circle of plasticity in the form of a horizontal ellipse, showing the convenience of this last one with examples.
After the new collapse formulation was made part of the main body of standard API TR 5C3 (2018), the horizontal axis on the standard industry well tubular design limits plot changed. The present study evaluates this redefinition of the horizontal axis. One consequence of this modification is a difficulty plotting the API tension and compression limits. The API horizontal limits (uniaxial burst and collapse) are found to be independent of load case, while the API vertical design limits (uniaxial tension and compression) are dependent on inside and outside tubular pressures. The approaches used by commercial software and industry publications to solve this challenge are reviewed. A new design methodology is developed to link API uniaxial limits to the triaxial theory.
The main objective of the study is to establish a mathematical relationship between API tubular design limits and the von Mises triaxial theory (API TR 5C3 2018). A methodology that allows plotting the API uniaxial force limits on the design limit plot is developed. The study also shows that the results obtained from the industry standard slanted ellipse are identical to those obtained from the horizontal ellipse and circle. One important difference is that the slanted ellipse is based on zero axial stress datum while the horizontal ellipse/circle uses neutral axial stress datum. The horizontal ellipse/circle is well suited for calculations involving buckling, it is compatible with the information used in field operations and its formulations are less complicated than the tilted ellipse. Therefore, attention is called to it.
Analysis and Evaluation of Problematic Hazard Elements in Drilling through Collapse Features, A Case from Challenging Drilling in Persian Gulf
Authors: Salehi Ehsan , Daneshkhah Vahid , Hosseini Shoar Behnam 
Published: March 2021

Abstract
Complete mud loss is a severe costly drilling problem which increases drilling time and makes wells challenging to control. Such situation was encountered during drilling of three wells from a platform in an offshore field in Persian Gulf. This unexpected problem occurred while other wells from this platform were drilled and completed according to the routine plan. Further investigations using 3D seismic data showed that, these wells had penetrated through a massive collapse feature causing extended drilling times. Buried collapse features are developed as result of karstification due to dissolution of carbonate rocks. Although karstification may be evaluated as a disturbing parameter of reservoir properties, the most critical concern about this phenomenon is difficulties in forecasting drilling mud weight due to highly unpredictable fluid transmissibility. Collapse feature has different viscoelastic properties from its surrounding sediments, therefore, it generates different seismic responses in terms of amplitude and frequency. This aspect was utilized for identification of encountered collapse feature where, a practical semi-automated approach based on seismic derived multi-attributes cubes and neural network analysis was taken. Once a sinkhole cube was generated based on the above approach, geobody of the collapse feature was extracted. Results then were thoroughly validated by mud loss intervals at wells. Close investigation of the sinkhole cube revealed that seven collapse features exist in the area of study in which, problematic wells pass through one of them. It was discovered that all collapse features are interconnected with deep-seated faults which acted as hydrocarbon migration conduit. This incident obviously emphasizes role of geohazards analysis before any offshore drilling, even in a developed field with several number of wells. As experienced, a significant part of well non-productive time can be avoided if an integrated multi-disciplinary approach is taken. The authors will describe an effective proactive approach towards geohazards and present lessons learned in the case presented to address unexpected geo-drilling incidents.
Top-Hole Technology Overcomes Challenging Sand-Based Seabed Conditions and Enables Record Drilling Performance in an Offshore Exploration Well
Authors: Cardenas Camilo , Hansen Hans Erik , Hanssen Sigvald , Blikra Harald , Mathis Wolfgang , Holen Ole Kristian , Kort Arjen , Zhang Youhu 
Published: March 2021

Abstract
Top hole construction is a critical part of any well design, especially for subsea wells. It is considered to be the foundation for the well, and it is crucial for ensuring well integrity. Uncertainties and conditions of the seabed and top layers could compromise the stability of the chosen solution. This paper describes the first implementation of the conductor anchor node (CAN®) technology in sand-based conditions and demonstrates its positive impact on the drilling performance for an offshore exploration well in the North Sea.
The main challenges identified in the top-hole design for this well were the presence of boulders down to 65 m below the seabed, and hard soil that consisted mainly of very dense sand and high strength sandy-clay layers. Different solutions were evaluated using a risk-based approach, looking to optimize operational performance and decrease the environmental footprint. A technology which consists of a pre-installed short conductor within a CAN was chosen. This solution enabled the operator to establish a competent well foundation above the boulder interval and increase operational efficiency by reducing the critical rig time. However, the CAN technology had not been deployed in this type of soil previously. Thus, the feasibility of its installation became one of the main milestones of the project. This was made possible due to a set of contingencies and modifications that were the result of a strategic collaboration among the parties involved.
The CAN was successfully installed by a crane vessel before the rig arrived at location, and the set of contingencies and modifications mentioned in this paper were decisive to ensure it reached the required penetration depth. Furthermore, this paper demonstrates that the CAN technology was crucial for the project to achieve top performance results and become one of the fastest exploration wells drilled in the Norwegian basin. This solution reduced uncertainties related to the conductor cementing, load and fatigue capacities, and deep surface casing cement. Improvement in the drilling performance is determined by estimating the decrease in drilling time, materials and consumables. Those results are then used to perform a cost comparison which demonstrates that the CAN technology reduced the top-hole construction cost significantly on this offshore well. In addition, the reduction in the well environmental footprint is quantified, and its contributions to the projects health and safety goals are highlighted.
Derivation to Calculate Pipe Collapse Performance using a Combined Loading Equivalent Grade Accounting for Axial Stress, Internal Pressure, Bending and Torsion
Authors: Besse Jean-Guillaume 
Published: March 2021

Abstract
This paper proposes a new analytical derivation to incorporate bending and torsion into collapse calculation, further pushing the already existing approach of combined loading equivalent grade proposed in API TR 5C3 (2019) Clause 8.4.6 Eq. (42) for axial stress and internal pressure (identical to ISO TR 10400 Clause 8.4.7) used to calculate a differential collapse pressure.
This new derivation is also based on Hencky-von Mises maximum distortion criterion. The interest of developing such combined loading equivalent grade is to enable the use of the four collapse types described in Clause 8 i.e., Yield Strength, Plastic, Transition and Elastic. The formulae are adapted to a closed-form equation similar to current Eq. (42), enabling pipe collapse performance calculation. Newly derived formulae are checked against a size governed by yield strength collapse to verify consistency. The restrictions regarding collapse performance under compression are discussed.
New Triaxial Connection Safety Factor for Tubular Design
Authors: Goodman Malcolm A 
Published: March 2021

Abstract
The API equation for internal leak of API connections is uniaxial since it ignores axial force and external backup pressure. ISO 13679 for qualification of premium connections is biaxial at best. It includes tension/compression but ignores backup pressure for both internal and external leak tests. For tubular design, this paper introduces a new fully triaxial safety factor for threaded connections with dependence on thread shear and hydrostatic pressure. Hydrostatic behavior is modelled with the Mean Normal Stress, and thread shear behavior is modelled with the shear component of the von Mises Stress. A Leak Line for use like the pipe body ellipse is proposed for quick leak assessment. Leak ratings are presented for an example case of 7-in. 35-ppf N80 LTC. The new triaxial safety factor with two connection constants applies to all types of threaded connections, including tubing, casing, and drill pipe, so long as the two constants are evaluated with appropriate but simple physical tests.
Culture and Coronavirus Disease Statistics Public Health Through the Lens of Hofstede’s Cultural Dimensions, A Multiple Regression Analysis
Authors: Wang Jiali , Bandera Cesar , Yan Zhipeng 
Published: March 2021

Abstract
Background Hofstede’s Culture Dimensions (HCD) are the most prevalent metrics with which social scientists distinguish cultural differences between countries. In this study, we examine the relationships between HCD and the COVID-19 pandemic. In particular, we investigate how differences in COVID-19 infection, death and recovery between countries correlate with differences in individualism (IDV), indulgence (IVR) and power distance index (PDI).Method We use multiple linear regressions to interpret statistical and economic significances. Results IDV is found to be significantly associated with death rate and recovery rate globally, while IVR and PDI do not seem to be significantly relevant. None of the three dimensions are significantly related to the global infection rate. Conclusions These results have implications for the design of public health campaigns on preventing COVID-19 infection and compliance with vaccination campaigns. Some practical strategies have been proposed for public health officials to help mitigate COVID 19 spread.
Mechanical Properties of Group Iv Single-walled Nanotubes: A Finite Element Approach Based on the Density Functional Theory
Authors: Dastmard Mohammad , Ansari Reza , Rouhi Saeed 
Published: March 2021

Abstract
In this article, the density functional theory is applied to investigate the mechanical properties of single-walled nanotubes of group IV of periodic table including carbon nanotube, silicon nanotube, germanium nanotube and stanene nanotube. (10,10) armchair nanotube is selected for the investigation. By establishing a link between potential energy expressions in the molecular and structural mechanics, a finite element approach is proposed for modeling the nanotubes. In the proposed model, the nanotubes are considered as an assemblage of beam elements. Young’s modulus of the nanotubes is computed by the proposed finite element model. Young's modulus of carbon, silicon, germanium, and tin nanotubes are obtained as 1029, 159.82, 83.23 and 18.15 GPa respectively, using the density functional theory. Also, the finite element approach gives the values as 1090, 154.67, 85.2 and 82.6 GPa respectively. It is shown that the finite element model can predict the results of the density functional theory with a good accuracy.
Identification of Tumor Necrosis Factor-Alpha (Tnf-α) Inhibitor in Rheumatoid Arthritis Using Network Pharmacology and Molecular Docking
Authors: Yu Jun , Zhou Peng 
Published: March 2021

Abstract
Background: This study aimed to investigate the molecular mechanism of Radix Paeoniae Alba (White peony, WP) in treating rheumatoid arthritis (RA) and tumor necrosis factor-alpha (TNF-α) inhibitor (TNFi) by using network pharmacology and molecular docking. Methods: In this study, the ingredient of WP and the potential targets of RA were obtained from the Traditional Chinese Medicine Systematic Pharmacology Database, GeneCard and OMIM databases, respectively. Establishment of RA-WP potential target genes interaction network using STRING database. Network maps of WP-RA-potential target genes network was constructed using Cytoscape software. gene ontology (GO), and biological pathway (KEGG) pathway enrichment analysis were used to further explore the RA mechanism and therapeutic effects of WP. Using molecular docking technology to analyze the optimal effective components from WP to docking with TNF-α. Results: 13 active ingredients and 71 target genes were screened from WP, 49 of which intersect with RA target genes and are considered as potential therapeutic targets.Network pharmacological analysis showed that the WP active ingredients of mairin, DPHCD, (+)-catechin, beta-sitosterol, paeoniflorin, sitosterol, and kaempferol showed better correlation with RA target genes such as PGR, PTGS1, PTGS2, NR3C2, TNFSF15, CHRM2. The signaling pathways of the active ingredients for the treatment of RA are TNF-α signaling pathway, toll-like receptor signaling pathway, cell apoptosis, interleukin-17 signaling pathway, C-type lectin receptor signaling pathway, mitogen-associated-protein kinase, etc. Molecular docking results suggest that mairin was the most appropriate natural TNFi.Conclusions: Our findings provide the essential role and basis, for further studies into the molecular mechanisms of WP and TNFi development in RA.
A Machine Learning Method Based on the Combination of Nonlinear and Texture Features to Diagnose Malignant Melanoma From Dermoscopic Images
Authors: Ghahfarrokhi Sepehr Salem , Khodadadi Hamed 
Published: March 2021

Abstract
Skin cancer affects people of all skin tones, including those with darker complexions. Melanomas are known as the malignant tumors of skin cancer, resulting in an adverse prognosis, responsible for most deaths relating to skin cancer. Early diagnosis and treatment of skin cancer from dermoscopic images can significantly reduce mortality and save lives. Although several Computer-Aided Diagnosis (CAD) systems with satisfactory performance have been introduced in the literature for skin cancer detection, the high false detection rate has made it inevitable to have an expert physician for more examination. In this paper, a CAD system based on machine learning algorithms is provided to classify various skin cancer types. The proposed method uses the Online Region-based Active Contour Model (ORACM) to extract the Region Of Interest (ROI) of skin lesions. This model uses a new binary level set equation and regularization operation such as morphological opening and closing.Additionally, various combinations of different textures and nonlinear features are extracted for the ROI to show the multiple aspects of skin lesions. Several metaheuristic optimization algorithms are used to remove redundant or irrelevant features and reduce the feature space dimension. These are applied to the combination of the extracted features in which, Non-dominated Sorting Genetic Algorithm (NSGA II) as a multi-objective optimization algorithm has the best performance. Furthermore, various machine learning algorithms include K-Nearest Neighbor (KNN), Support Vector Machine (SVM), Fitting neural network (Fit net), Feed-Forward neural network (FF net), and Pattern recognition network (Pat net) are employed for the classification. Accordingly, the best-obtained precision of 99.24% based on five-fold cross-validation is attained by the selected features of texture and nonlinear indices through NSGA II, applying the pattern net classifier. Also, the comparison between this paper's experimental results and other similar works with the same dataset demonstrates the proposed method's efficiency.
Cognitive and Motor Dual Task on Multi-area Brain Activation and Gait Performance in Individuals with Parkinson’s Disease
Authors: Liu Yan-Ci , Yang Yea-Ru , Yeh Nai-Chen , Ku Pei-Hsin , Lu Chia-Feng , Wang Ray-Yau 
Published: March 2021

Abstract
Background In people with Parkinson’s disease (PD), gait performance deteriorating during dual task walking compared to single-task walking has been noted in previous studies. However, the effects of different types of dual task on gait performance and brain activation were still unknown. Methods This study investigated the walking performance changes and multi-area brain activities during cognitive and motor dual task walking in people with PD. Twenty-eight participants with PD were recruited and performed single walking (SW), walking while performing a cognitive task (WCT), and walking while performing a motor task (WMT) at their self-selected speed. Gait performance including walking speed, cadence, stride length, stride time, swing cycle, temporal and spatial variability and dual task cost (DTC) were recorded. Brain activation of the prefrontal cortex (PFC), premotor cortex (PMC), and supplementary motor areas (SMA) were measured by functional near-infrared spectroscopy during walking. Results Results showed the walking performance deteriorated upon performing a secondary task, especially the cognitive task. Also, a higher and sustained activation in PMC and SMA during WCT as compared with WMT and SW in the late phase of walking was found. Moreover, gait performance was negatively correlated with PMC and SMA activity during different walking tasks. Conclusions Individuals with PD demonstrated gait deterioration during dual task walking, especially WCT. The SMA and PMC were further activated in people with PD when performing cognitive dual task walking. Trial registrationTCTR20190118010. Registered 18 January 2019, retrospectively registered.