bluuebunny/crossref_metadata_2025 huggingface dataset:
Model-independent Exoplanet Transit Spectroscopy
Authors: Aronson Erik , Piskunov Nikolai
Published: April 2018

We propose a new data analysis method for obtaining transmission spectra of exoplanet atmospheres and brightness variation across the stellar disk from transit observations. The new method is capable of recovering exoplanet atmosphere absorption spectra and stellar specific intensities without relying on theoretical models of stars and planets. We simultaneously fit both stellar specific intensity and planetary radius directly to transit light curves. This allows stellar models to be removed from the data analysis. Furthermore, we use a data quality weighted filtering technique to achieve an optimal trade-off between spectral resolution and reconstruction fidelity homogenizing the signal-to-noise ratio across the wavelength range. Such an approach is more efficient than conventional data binning onto a low-resolution wavelength grid. We demonstrate that our analysis is capable of reproducing results achieved by using an explicit quadratic limb-darkening equation and that the filtering technique helps eliminate spurious spectral features in regions with strong telluric absorption. The method is applied to the VLT FORS2 observations of the exoplanets GJ 1214 b and WASP-49 b, and our results are in agreement with previous studies. Comparisons between obtained stellar specific intensity and numerical models indicates that the method is capable of accurately reconstructing the specific intensity. The proposed method enables more robust characterization of exoplanetary atmospheres by separating derivation of planetary transmission and stellar specific intensity spectra (that is model-independent) from chemical and physical interpretation.
Tidal Deformability from GW170817 as a Direct Probe of the Neutron Star Radius
Authors: Raithel Carolyn A. , Özel Feryal , Psaltis Dimitrios
Published: April 2018

Gravitational waves from the coalescence of two neutron stars were recently detected for the first time by the LIGO–Virgo Collaboration, in event GW170817. This detection placed an upper limit on the effective tidal deformability of the two neutron stars and tightly constrained the chirp mass of the system. We report here on a new simplification that arises in the effective tidal deformability of the binary, when the chirp mass is specified. We find that, in this case, the effective tidal deformability of the binary is surprisingly independent of the component masses of the individual neutron stars, and instead depends primarily on the ratio of the chirp mass to the neutron star radius. Thus, a measurement of the effective tidal deformability can be used to directly measure the neutron star radius. We find that the upper limit on the effective tidal deformability from GW170817 implies that the radius cannot be larger than ∼13 km, at the 90% level, independent of the assumed masses for the component stars. The result can be applied generally, to probe the stellar radii in any neutron star–neutron star merger with a measured chirp mass. The approximate mass independence disappears for neutron star–black hole mergers. Finally, we discuss a Bayesian inference of the equation of state that uses the measured chirp mass and tidal deformability from GW170817 combined with nuclear and astrophysical priors and discuss possible statistical biases in this inference.
Prevalence and Predictors of Depression after Stroke - Results from a Prospective Study
Authors: Vojtikiv-Samoilovska Danijela , Arsovska Anita
Published: April 2018

BACKGROUND: A depression following a stroke (Post Stoke Depression-PSD) is the most common complication of a stroke that has a negative effect on the result after the stroke. A better definition of the risk factors of the disease will provide for better prediction and treatment.AIM: To research identification of the risk factors for PSD, typical for the Macedonian population, which will help in early prediction, timely diagnosis and treatment of the disease?MATERIAL AND METHODS: We carried out a prospective study in order to determine the prevalence and the risk factors of PSD in 100 patients treated at the hospital in Tetovo. The severity, localisation and the functional outcome of the stroke have been examined as potential risk factors for discharge and after 5 months. The symptoms of depression were quantified using the Hamilton Depression Rating Scale (HAM-d).RESULTS: On discharge, 81% of the patients were diagnosed with PSD, and 67% had PSD after 5 months. A statistically significant codependence of p < 0.05 was registered between PSD and the level of functional dependence for activities of daily living (ADL); PSD and the severity of the stroke; and PSD and the level of disability on both examinations. In most patients with PSD, an ischemic stroke in the right middle cerebral artery has been diagnosed; the percentage difference between the other localisations is statistically significant (p = 0.0436; p = 0.0002).CONCLUSION: There is an increased risk of PSD for immobile patients, those incapable of activities of daily living (ADL), with ischemic stroke in the right middle cerebral artery. A PSD screening and additional studies for better prediction are required.
Tueurs, ibitero et notabilités génocidaires au Rwanda (Kigali, avril 1994)
Authors: Piton Florent
Published: April 2018

À partir du rapport d’une organisation non gouvernementale rwandaise réalisé peu après la fin du génocide des Tutsi, cet article interroge la constitution et l’organisation des bandes de tueurs (ibitero). Il s’intéresse en particulier au massacre de la paroisse de Gikondo à Kigali le 9 avril 1994. Si les génocidaires viennent de toutes les catégories de la population, miroir en cela d’une « société ordinaire », il y a néanmoins des jeux de pouvoir au sein des bandes. Il existe des notabilités génocidaires qui ne reproduisent pas nécessairement les hiérarchies sociales et politiques antérieures : l’opportunisme politique, la conviction idéologique et l’inventivité meurtrière sont à la fois des motivations et des ressources mobilisées par les « tueurs de grand renom ».
Le mouvement transhumaniste
Authors: Damour Franck
Published: April 2018

Le transhumanisme est un courant d’idées qui prône une transformation de l’être humain par la mise en œuvre de nouvelles technologies, dans des visées d’augmentation des capacités humaines et de prolongation importante de la vie. Né en Californie en 1988, il a diffusé ses thématiques dans le monde entier. S’il est l’objet de nombreuses études philosophiques, éthiques, théologiques, politiques, sociologiques, il a peu suscité de recherches proprement historiques, notamment de son mouvement. Or l’histoire du mouvement permet de mieux cerner ce qu’est le transhumanisme – entre controverse, mouvance et mouvement – et ce qui constitue sa structure idéologique. Une telle approche s’appuie sur la confrontation des publications, des traces numériques du mouvement et des trajectoires de ses membres.
Terracotta Figurines and the Acrolithic Statues of Demeter and Kore from Morgantina
Authors: Maniscalco Laura
Published: April 2018

Archaic figurines of women holding a dove recovered from in and around the Thesmophorion of S. Francesco Bisconti at Morgantina (Sicily) can be associated with a fragmentary terracotta throne now in Vienna. It is possible that this throne was made for one or both of the famous acrolithic sculptures that represented the goddesses Demeter and Kore, from the same sanctuary. The strong East Greek influence on Sicilian archaic sculpture is noted, as well as the possibility that the acrolithic group and the throne may have been made locally with the participation of itinerant artists. Both the throne and the acrolithic sculptures may represent a built, rather than a glyptic, approach to sculpture making, which would anticipate the achievements of the Classical period in chryselephantine sculpture on a much larger scale.
Due mostre a Catania: un’occasione per avvicinare i ragazzi al mondo dell’archeologia
Authors: Pautasso Antonella
Published: April 2018

È stata inaugurata il 16 giugno 2017 la mostra archeologica Katane tra mito e rito. Testimonianze cultuali di Catania greca e la mostra didattica Le terrecotte greche. Per chi? Perché? Come? nei locali della ex Manifattura Tabacchi di Catania, futura sede del Museo Interdisciplinare.
Impact of Violence in Movies on Juvenile Delinquency
Authors: Saeed Naima , Rehman Tansif Ur , Usmani Mehmood Ahmed
Published: April 2018

Studies encompassing media-effects are a prime subject for social science scholars worldwide. The dilemma lies in the very fact that in Pakistan this issue of great significance has not been paid proper attention. Juvenile delinquency is one of the major issues that cause a great hindrance in the social progress of any society. It not only creates anxiety and aggression in youth, but also turns productive humans into a destructive force against family, society and nation. This research endeavors to discover the consequences of violence in movies with respect to Pakistani youth and uncovering a connection between subjection to such type of content and consequently criminal propensities. Publicized research has examined media effects with a variety of consequences; this research has empirical evidence that exhibits the very fact that violence in the media causes delinquency, thus promoting criminal behavior, especially within the context of Pakistani society.
Query Expansion Using Medical Information Extraction for Improving Information Retrieval in French Medical Domain
Authors: Ghoulam Aicha , Barigou Fatiha , Belalem Ghalem , Meziane Farid
Published: April 2018

This article describes how many users' queries contain references to named entities, and this is particularly true in the medical field. Doctors express their information needs using medical entities as they are element rich with information that helps better target relevant documents. At the same time, many resources have been recognized as a large container of medical entities and relationships between them such as clinical reports; which are medical texts written by doctors. In this article, the authors present a query expansion method that uses medical entities and their semantic relations in the query context based on an external resource in OWL. The goal of this method is to evaluate the effectiveness of an information retrieval system to support doctors in accessing easily relevant information. Experiments on a collection of real clinical reports show that their approach reveals interesting improvements in precision, recall and MAP in medical information retrieval.
Identifying Customer Satisfaction
Authors: Tsironis Loukas K.
Published: April 2018

The purpose of this article is to increase the customer service level by expanding the method of application used by the mystery customer (MC) to resolve practical and concrete problems concerning the status of chain stores. The survival of organisations can often be dependent on their customer service level; therefore, there is an immediate need to form a permanent measurement to act as an indicator of that performance. This article concerns the application of MC methods in order to observe the level of quality service in a large retail network in Greece. Based on a quantitative methodology, the research seeks to utilize information concerning the retail operations performance and the factors that influence the evaluation. The results suggested an explicit determination of the factors of satisfied customers through the application of MC method. Action diagrams used as a performance-importance map indicate strong and weak points in terms of criteria and define the required improvement efforts. MC data showed the points or issues that service activities performance is likely to cause dissatisfaction and enables proactive measures to be taken on employee performance and classifies the improvement areas that determined by the analysis and used as a benchmarking tool.
Expanding Bloom's Two-Sigma Tutoring Theory Using Intelligent Agents
Authors: Hall Jr. Owen P.
Published: April 2018

This article describes how management education is engaged in significant programmatic reforms in response to the business community's call for web-savvy, problem-solving graduates. Web-based intelligent tutors provide a readily accessible vehicle for enhancing business students' learning performance as well as prepare them for the rigors of the global marketplace. A primary goal of these AI-based systems is to approach Bloom's two-sigma learning performance standard. Bloom found that average students tutored one-to-one with mastery learning techniques performed two standard deviations better than students who learned via conventional teaching methods. Intelligent tutors can also be used to identify students at risk, to formulate appropriate intervention plans, and to support team learning. The purpose of this article is to highlight the growing potential for using intelligent tutors to enhance student and team learning opportunities and outcomes and to outline strategies for implementing this revolutionary process throughout the management education community of practice.
Citizens' Use of the Internet and Public Service Delivery
Authors: Zhu Qinfeng , Skoric Marko M , Peng Tai-Quan
Published: April 2018

This article examines citizens' use of the Internet as a popular feedback mechanism, and argues that it can help improve institutional performance. Specifically, it assesses the relationship between Internet penetration rate and public service delivery across 31 first-level administrative divisions in People's Republic of China from 1997 to 2014. A hierarchical linear modelling was conducted using secondary data released by the National Bureau of Statistics and the China Internet Network Information Centre. The result shows a positive relationship between Internet penetration rate and public service delivery when controlling for GDP per capita and education level. The positive relationship increases over time in general. The implications of Internet use for performance-based legitimacy and its impact on political change (or stability) in the authoritarian context are further discussed.
A Quantitative Structure-Property Relationship Study of the Adsorption of Amino Acids on Kaolinite Surfaces
Authors: Ou Yu Heng , Chang Len , Chang Chia Ming
Published: April 2018

This article describes how the adsorption behaviors of various kinds of amino acids onto kaolinite surfaces were investigated by the quantum-chemical calculations and the quantitative structure-property relationships (QSPR). The QSPR results revealed that both adsorption energies of amino acids on tetrahedral Si-O and octahedral Al-O surfaces were mainly affected by the chemical potential and the negative of maximum negative charges of amino acids, which represent the electron flow and the hydrogen bonding between adsorbent-adsorbate interactions. The dispersion and polarization play a minor role in the amino acids adsorption on tetrahedral Si-O and octahedral Al-O surfaces, respectively.
An Integrated QFD-TOPSIS Approach for Supplier Selection Under Fuzzy Environment
Authors: Rahpeyma Bentolhoda , Zarei Mahnaz
Published: April 2018

This article describes how supplier selection is a multi-index problem which affects the efficiency of the whole supply chain in both manufacturing and service industries. Considering the importance of selecting effective suppliers, this article aims to integrate two well-known techniques, Quality Function Deployment (QFD) and The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) in order to evaluate suppliers and rank them based on their merits. In order to handle the inherent uncertainty in the process of experts' judgments, fuzzy logic is involved in the methodology applied in this study. The validity of the utilized integrated approach is demonstrated through conducting a case study in the detergent manufacturing industry in Iran.
Risks Related to Lean Six Sigma Deployment and Sustainment Risks
Authors: Galli Brian J.
Published: April 2018

Lean Six Sigma is a set of tools utilized by organizations to reduce cost and waste. There are risks associated with deploying and sustaining Six Sigma. The risks are different at each stage of the process. To ensure success, these risks must be identified and mitigated. From an organizational standpoint, companies need to understand the differences between Lean Six Sigma deployment and sustainment. The risk factors discussed in this article are leadership, human resource, and project selection. Since Lean Six Sigma is a project-based approach, many tools offered by the Project Management Institute (PMI) can be utilized to complement DMAIC structure. Since risks in improper management are inherent, using project management and Lean Six Sigma tools together is beneficial. This research attempts to identify and analyze the different risks associated with deploying and sustaining Lean Six Sigma. This article presents recommendations based on an analysis of collected information.
Does National Culture Have Any Impact on E-Government Usage?
Authors: Merhi Mohammad I.
Published: April 2018

The motivation of this article was the lack of empirical evidence regarding the relationship between culture and actual usage of ICTs/e-government. By using Hofstede's cultural framework, this article explains the influence of national culture on e-government usage across countries controlled by socio-economic factors, specifically, GDP and literacy rate. Data was collected from reputable organizations such as World Bank databases and Hofstede's website. Ordinary least square and truncated regression are used to test the hypotheses presented in this article. Results indicate that nearly all Hofstede's cultural dimensions and e-government usage are significantly related. In particular, this article indicates that the usage of e-government is higher in nations that score low in power distance, uncertainty avoidance, individualism and masculinity.
Quality Control of eLearning Research Design
Authors: Abdelaziz Hamdy Ahmed
Published: April 2018

The present article aimed at developing a research methodology to ensure quality control of eLearning field research design and production. The idea of the present research was to investigate effective and ineffective practices in eLearning field. The analysis of a sample of researches and studies (n = 200), conducted in the field of eLearning and Blended Learning in the Arab states revealed that the vast majority of eLearning researches and studies (70%) were stereotypical. Therefore, the researcher developed a list of indicators that ensure quality control of eLearning researches design. A new methodology to design and produce eLearning research is proposed. The proposed methodology contains four stages: Identify Investigate, Prototype, and Produce. Implementation of these stages required the adoption of a tetrad dialogue during the course of answering the six patterns of question: what, who, when, where, how, and why. In addition, the adoption of this new method may support producing adaptive and innovative eLearning research with high level of quality.
Reducing Hydrogen Embrittlement Risk of Steel Bolting in Seawater Environment with Nickel-Cobalt Electroplating
Authors: Rosas Omar , Burk James D. , Garcia Oscar , Hernandez Jose , Girault Carlos
Published: April 2018

Amongst all the several threats derived from corrosion in bolting in marine environments, hydrogen embrittlement is perhaps one of the most dreaded. Hydrogen embrittlement is a form of environmentally assisted cracking (EAC) where hydrogen generated from different sources penetrates inside the basematerial and makes it more fragile. This paper addresses the severity of the environment and the influence of different metallic coatings on the amount of hydrogen present in the base substrate steel bolting. From laboratory generated data, environmental severity and risk of hydrogen embrittlement are estimated and correlated to actual field performance from the literature. This investigation relates the interplay of environment, stress, and materials.

The metallic coatings evaluated in this investigation are: Zinc, Zinc-Nickel, and Nickel-Cobalt ASTM B994, the two formers are typical coatings currently used in bolting in Oil and Gas, the latter is a novel material with offshore applications including subsea environments. Cracking resistance of the AISI 4130/4140 and 4340 also specified as ASTM A193 B7/B7M, L7/L7M and L43 studs or bolts and ASTM A194 nuts, all referred to as bolting, is characterized in terms of the variation in environmental severity. The environmental severity is measured by both, Devanathan–Stachurski cell technique to measure the amount of hydrogen absorbed into the steels substrate across the coatings, and the use of Tafel scans of the coatings and a Pourbaix diagram to measure Ecorr and amount of hydrogen generated. From these results, the metallic plated coatings are ranked as to environmental severity relative to each other.

The results showed an outstanding performance of the Nickel-Cobalt coating compared to the sacrificial coatings. Sacrificial coatings produced large amounts of hydrogen in the cathodic reaction and allowed its penetration to the base-material; Nickel-Cobalt did not produce hydrogen at OCP and the permeation was much lower than in the other materials under cathodic charging conditions. The results of mechanical testing showed that Nickel-Cobalt is not affected by the cathodic charging whilst the tested sacrificial coatings reduce their mechanical resistance in a 50%; these results mean that hydrogen permeation into Nickel-Cobalt is negligible, even after being subject to high cathodic charging. Nickel-Cobalt alloy ASTM B994 is proposed as the emerging technology for carbon and high strength steel bolts to be used in marine environment and subsea where failure is not an option.

The results from this effort have an outstanding relevance in offshore and subsea deep-water drilling and production equipment that depends on high strength carbon and low allow steels. This work addresses failures caused by hydrogen embrittlement that have been documented by the American Petroleum Institute (API) and the Bureau of Safety and Environmental Enforcement (BSEE).
SS: HPHT Technology Verification, Validation, and Regulatory Requirements: HPHT Riser Technology Challenges
Authors: Dincal Selcuk , Reagen Daniel , Saglar Nuri
Published: April 2018

Operators are looking to drill and develop deep-water wells with pressures over 15,000 psi and temperatures exceeding 300°F. Designing for high pressure, high temperature (HPHT) conditions present a number of engineering challenges, which can push conventional subsea technology designs to their limits. Therefore, there is a need to understand the feasibility of riser systems in these conditions and consequently to close any potential gaps between the current qualified technology and the outlined project specifications for a number of key riser components.

For conventional reservoirs, the merits of using wet tree and dry tree systems are well understood after years of design, fabrication, installation and operating experience. For HPHT riser applications, various design challenges exist with respect to the technology readiness of various riser system components of a wet or dry tree system development.

Key riser design issues and technology challenges, applicable to wet and dry tree HPHT systems, are addressed in this paper.

For a wet tree development, HPHT conditions require the use of thick wall pipes driven by burst sizing requirements, which in turn will lead to challenges associated with fabrication of pipes, pipe welding and inspection as well as meeting applicable sour service requirements. Furthermore, design of riser hang-off systems of wet tree applications is a critical area that requires consideration. The use of High-Integrity Pressure Protection Systems (HIPPS) to overcome HPHT obstacles is also discussed in this paper.

The use of high strength steel pipe with threaded mechanical connections provides a weight benefit for a dry tree system. However, the qualification of connectors is required and is expected to be a critical activity. In addition, the dry tree system has many other sealing surfaces and connections subject to HPHT loads at the surface and subsea wellhead locations, each of which presents their own design and qualification challenges.
A Multi-Disciplinary Approach to Select the Optimum Infill-Well Location for Efficient Reservoir Management of a Mature Field
Authors: Bose S. , Alzahabi A. , Balasubramanian S. , Chen P. , Thakur G. C.
Published: April 2018

A Multi-Disciplinary Approach (MDA), combining geological characterization, various reservoir property data and production behavior of offset wells, was applied to an unconsolidated sand reservoir to review proposed drilling locations and recommend an optimal well location for improved recovery and effective Reservoir Management (RM). This paper presents a case study where integrated subsurface analysis saved reservoir damage and multi-million dollars in drilling expense, by avoiding a previously approved horizontal well location and selecting an appropriate drilling location.

Seismic amplitude anomalies were investigated by integrating with well-cross-sections along the neighboring wells. Geological and petrophysical information, such as, structure maps, log character, reservoir thickness, sand distribution, NTG, porosity, hydrocarbon pore volume, proximity to gas cap or water zone, and fluid-flow conduits, were analyzed to characterize the reservoir zone, which is contributing to well production.

Interference among the wells was studied in detail for an optimal development strategy. Bubble maps (based on cumulative production plot), well performance analysis, distance between wells and reserve evaluation based on field data were investigated to arrive at an informed decision regarding infill location. In addition, the well history and reservoir characterization were reviewed in detail and integrated with the production analysis.

Integrated analyses using the geological maps and production data showed that higher production correlates directly to the higher pore volume and permeability areas of the maps. The results included show that rock quality is as important as the hydrocarbon saturations in contributing to the production of the field. The reservoir quality maps, fluid contacts, and fault framework helped significantly to identify the higher risks associated with the proposed location. It was recommended to not drill at this high-risk location, contributing to a significant saving of multi-million dollars in Capex. The significant savings in Capex made from the recommendation to not drill the high risk location was helpful to plan a replacement drilling location based on integrated subsurface analysis.
Optimizing Existing Subsea Assets for Respudding of Wells: Step-Over Jumper
Authors: Mercer T. , Williams J. , Roberts J. , Robichaux S. , Flakes K.
Published: April 2018

In the current market, operators are exploring the potential opportunities to optimize the production of existing assets. The goal was to tie a respudded well into existing field architecture, with minimum equipment, time, and cost. The operator respudded a cluster manifold well approximately 50 meters from the tie-in manifold. At roughly twice the distance of the existing well jumper, this approach posed a challenge for a traditional vertical in-plane jumper.

A study was completed to compare a few traditional approaches. The options considered werea 50-meter-long jumper able to reach from existing manifold to the new subsea treea tie-in skid with a flow loop supported by a mud mat and two approximately 25-meter-long jumpersa tie-in skid with a flow loop supported by the abandoned wellhead from the replaced treea step-over jumper (SOJ) supported by a suction pilea SOJ supported by the abandoned wellhead.

Evaluation concluded that the last option was the most cost-effective solution, with 60% capex savings when compared with the SOJ with a suction pile. The benefit of using the SOJ is that the vessel size can be significantly reduced while minimizing the amount of subsea hardware on the seafloor. Essentially, the SOJ works as an extension of the production jumper. First, the production fluid travels from the subsea tree into a conventional jumper. Then, the production fluid travels through the SOJ, where one end of the SOJ is supported by the abandoned subsea wellhead. Finally, the production fluid travels into the manifold. The SOJ is similar to a conventional half-"M"-shape jumper, which has one outboard hub (connector) at each end. The SOJ, however, replaces one of the connectors with an inboard hub and a step-over module (SOM). The SOM provides a firm connection and an inboard hub interface to connect a conventional jumper. The firm connection is accomplished by landing and attaching the SOM to the plugged and abandoned wellhead. Then, a conventional 25-meter half-"M"-shaped vertical jumper is installed between the tree and the SOM to make the final tie-in to the new respudded well.

This is an opportunity for operators to utilize their existing subsea architecture to accomplish cost-saving ventures in their brownfield assets. The SOJ is an efficient solution that allows tie-ins to respudded wells that are farther away from the core field architecture.
Comparison of ASME and BS-EN Codes on Design by Analysis for Subsea Pipeline Components
Authors: Farahani Kasra , Vosooghi Navid
Published: April 2018

Design by Analysis (DBA) based on nonlinear finite element analysis provides an efficient method to design subsea pipeline components. This approach is widely used in oil and gas industry for subsea pipeline components design and pressure vessels. In contrast to linear analysis and stress linearization/categorization, the nonlinear finite element analysis approach provides a more accurate and efficient design route. The design codes encourage the use of the nonlinear analysis approach especially for components with complex geometry.

In this paper, the Design by Analysis approach of ASME VIII D2 and BS-EN-13445-3 using nonlinear finite element method are compared and discussed. These two codes are widely used standards for design of pipeline components and pressure vessels. The philosophy of both codes is limit state involving load and resistance factors. In this paper, emphasis is given to component design in ultra-deep water condition and its significant effect on design during operational cyclic loads. For comparison purpose, a subsea inline Tee is designed to both codes and subsequently the design outcomes are compared and discussed.
The Process to Provide Effective Decision-Support and Realise Value – Implementing a Global Well Integrity Management Software System
Authors: Smith C. J. B. , Lorwongngam A. , Crabtree A. R. , Smith L. , Lunt G.
Published: April 2018

After spending four years in a close partnership, an independent E&P operator and a services company collaborated in rolling out a progressive well integrity management methodology across operations in West Africa, North Sea, Gulf of Mexico and onshore USA (conventional and shale) has been delivered using a software framework.

This paper describes the process of how the software was configured and adapted to meet the demands of varied well operations and well production types, while also supporting an objective to deliver a standardized view of well integrity across the organization. The incorporation of consistent practices to support the operator's integrity program, including those laid out in ISO 16530-2[1], "Well integrity for the operational phase," is described. This includes a description of the implementation and the value gained from the incorporation of a well failure model (well failure action matrix) that determines and ranks risk to provide decision-making support for potential well intervention.

Furthermore, this paper discusses the practical challenges of implementing a system of this type and the steps taken to ensure the system was incorporated into the operating plan across a diverse portfolio of well types and operating environments.

The implementation project and its results are described, exploring the key factors that contributed towards its success, including user case examples. The paper discusses future areas that may add further value to the safe operation, reliability and the integrity of the operator's assets.
Data Driven Virtual Sensors for Riser Prognostic Integrity Management
Authors: Sundararaman S. , Thethi R. , Hill M.
Published: April 2018

In-field riser strain or motion monitoring provides direct indication of riser fatigue and strength performance for prognostic integrity management. However, direct riser monitoring in the field has been limited in offshore developments to date with respect to its use as a standard on every floating platform and on every riser system attached to the vessel. This is due to the high perceived capital or operational costs of direct subsea monitoring when deployed on every riser to reliably monitor over the entire service life. Furthermore, monitoring devices are typically installed at practical locations, which may not be at fatigue critical areas. A lack of known response in service can result in qualitative inspection planning, conservative fatigue predictions and reduced asset utilization.

Data-driven virtual sensors provide an innovative solution for life of field riser monitoring and predictive inspection planning. The virtual sensor is a machine learning model that calculates stresses in the time domain at the fatigue hot spots and at high stress locations along the riser. The sensor is driven by platform motions and environmental loads that are typically measured in the field. It allows calculation of fatigue in near real-time using time synchronous data. The virtual sensor system can be integrated with a topside or centralized data platform.

The vision for the virtual sensor is to train a machine learning model initially with finite element global riser analysis data and subsequently with full scale field data from the riser in service. Data aggregation from a term and deployment limited riser monitoring system is employed to capture system-specific response. This hybrid strategy results in low cost virtual sensors for life of field riser monitoring.

This paper describes the motivation, methodology, validation and applications for riser virtual sensors. A framework for the development of a riser system machine learning model is described. Global response data is obtained from a vertical top tensioned riser operating in a water depth of 5,000 ft. Fatigue predictions are compared against the fatigue damage calculated from finite element analysis data.
Geohazard Monitoring – Mind Mapping the Complexity
Authors: Strout James M. , Vanneste Maarten , Forsberg Carl Fredrik , Cauquil Eric , Unterseh Stephan , Byrd Daniel
Published: April 2018

Future exploration and production areas may well lie in complex settings where various geohazards can play a role over the lifetime of the field development. The complexity of this is daunting: it is necessary to understand the fundamental geological drivers, address operational conditions for monitoring and instrumentation (including feasibility), the vulnerabilities at stake, and the range of physical parameters that can – or cannot – be measured.

A versatile and generic strategy for assessing and managing geohazards for the operational lifetime of the field is necessary, and this strategy should be applicable to as wide a scope of geohazards as possible. This complexity has been functionally and graphically represented in a series of interactive mind maps, providing a generic framework for geohazard assessment and management, which through the inclusion of site relevant details may be reduced to site-specific tools for geohazard applications.

However, it is also necessary to acknowledge that a suitable system for a given development will always remain site-specific as it must consider the actual geohazards at the site.
The Underwater Intervention Drone, A New Method for Delivering IRM Services in the Subsea Environment
Authors: Jamieson Jim , Wilson Lee , Sherry Wayne , Main William , Solheimsnes Pål Atle
Published: April 2018

Inspection Repair and Maintenance (IRM) services have traditionally in the subsea environment been vessel based relying on remotely operated vehicles (ROV) or Diver operations. The global industry challenge to reduce costs has driven incremental savings; increasing inspection intervals, optimizing the supply chain and contracting methods. Continuing to identify significant incremental savings is not sustainable in the long-term; a more innovative approach is required that eliminates the need for the support vessel, whilst managing the risk in continued operations. Statoil engaged i-Tech Services, a Subsea 7 company, to investigate and report on the use of an underwater vehicle system concept to deliver a new method of providing field wide IRM services. The concept and investigation named as "Underwater Intervention Drone" (UID®) study.

This paper presents a description of the UID® approach to IRM, the equipment needed and the technologies (both existing and to be developed) required to make this concept operationally feasible. For Statoil, the Snorre Expansion Project (SEP), a future field in the North Sea has been selected as the Pilot for the UID® system. An overview of the specific deployment method and services provided by the infrastructure to support the UID® will also be commented upon.

The UID® is a new way of providing IRM services, driven by Statoil to reduce cost and CO2 emission while maintaining a high level of IRM service capability. The UID® encompasses Statoil's and many of the current industry drivers Cost reduction, Digitisation and reduced Environmental impact.
Digital Well Planning - New Cost Saving Well Construction and Life Cycle Well Integrity Model
Authors: Brechan B. , Dale S. I. , Sangesland S.
Published: April 2018

A new generation software for well construction and maintenance is under development. The working name is Life Cycle Well Integrity Model (LCWIM) as its main focus is to support work with wells and fields from the planning stage to final P&A. LCWIM is a systematization of a fully digitalized software model that can provide many advantages for the industry. This paper focusses on four main objectives: Firstly, reduction of workload and direct human involvement by replacing many tasks in well construction and well integrity engineering by automatization. The goal is to shift the focus of humans towards supervision of computerized processes. Secondly, a modern software architecture should provide a fluent interlink between all stakeholders to provide and share information. A fully digitalized module should reduce repetitive tasks. Building on the architecture and metadata of LCWIM, future digitalization projects in e.g. administrative routines such as invoicing can be linked to establish a work process dominated by computerized events which are supervised by humans. Thirdly, the model will store all relevant data pertaining to a well through its life cycle, providing a potent self-service information hub that is easy to use for all disciplines. Fourthly, the scope of the LCWIM is to improve HSE and significantly reduce non-productive time in three ways: (1) interactive experience transfer, (2) embedding of interactive standards and governing documentation to support planning and operation, (3) elevation of personnel out of direct involvement into a supervisory role to reduce human error.

Access and availability favours a cloud based solution. With increasingly more data and information to process, a modern software will require significant processor capacity that is scalable according to the number of users. By combining the capacity of both servers and local computers, the software can provide advanced calculations and graphical representations at interactive response times.
Alcohol Ethoxylate Nano Surfactant: Surface Tension and Compatibility with Acidizing Additives
Authors: Omar Abdulrahman Bin , Alawani Nadrah , Al Moajil Abdullah , Aldarweesh Sajjad
Published: April 2018

Alcohol ethoxylate-based nanosurfactant was experimentally assessed to be used in HCl acid-based stimulation recipes. The surface tension of the surfactant with different stimulation additives was compared with commonly-used linear and branched alcohol ethoxylate-based surfactants. Nanosurfactant showed the lowest CMC of 2 gpt compared to 3 and 5 gpt for branched and linear alcohol ethoxylate-based surfactants, respectively at 77°F. The Nanosurfactant illustrated the highest performance in lowering the surface tension of water to 17 dynes/cm at 280°F. Spent 20 wt% HCl acid and mutual solvent affected the performance of nanosurfactant by increasing the surface tension at temperatures up to 300°F. Live 20 wt% HCl acid showed insignificant effect on the performance of nanosurfactant. Despite the negative interactions with number of stimulation additives, nanosurfactant showed superior surface tension lowering abilities compared to linear and branched alcohol ethoxylate-based surfactants.
Hebron Platform: Innovative Design and Efficient Execution
Authors: Widianto _ , Chichester Justin , Younan Adel , Khalifa Jameel , Komperla Krishna , Bidne Knut
Published: April 2018

The Hebron platform was successfully installed on the Grand Banks (Offshore Newfoundland and Labrador) in June 2017 with first oil produced in November 2017. It consists of a single shaft concrete Gravity Based Structure (GBS) supporting an integrated drilling and production topsides. The design of the platform was challenged by sub-arctic and extreme metocean conditions which required innovative design and layout approaches for many elements considered routine for typical platforms. This paper highlights the underlying innovative technologies, analytical and design methods as well as the capital-efficient execution strategies employed.
Experimental and Computational Study of Thermodynamic Hydrate Inhibitor Mixing and Displacement in Subsea Jumper
Authors: Lu Haidan , Tracy Noah , Johnson SC , Volk Micheal , Delle-Case Emmanuel , Ozbayoglu Evren M.
Published: April 2018

The risk of gas hydrate formation is one of the major concerns for offshore flow assurance. Solutions of methanol (MeOH) and mono-ethylene-glycol (MEG) are most often employed as thermodynamic inhibitors (THI) to prevent the formation of hydrate plugs. This study involves experimental and modeling work to investigate and compare the suitability and effectiveness of methanol and MEG on inhibiting and displacing the water in jumper type configurations during flushing procedures. Numerical analysis aims to investigate the mixing and displacing mechanisms that occur during jumper flushing to optimize key factors such as the position of the injection port and the flowrate of a required chemical inhibitor.

This paper presents the experimental results with respect to effect of inhibitor type, injection rate, brine salinity and liquid loading. All experiments were carried out in a 3" jumper system at The University of Tulsa. Simulations using 1D transient multiphase flow simulator were conducted to evaluate its capacity to predict the thermodynamic inhibitor dispersion by using the inhibitor tracking module. The 3D computational fluid dynamic (CFD) simulations were performed with the commercial software to help predict the amount and flowrates of chemicals required, and to serve optimizing the location of injection ports. Comparisons were made between the simulation results and experimental data from full fresh water loading jumper displacement tests with MEG and methanol.

From the experiments, several conclusions are drawn. Different dispersion and partitioning mechanisms were observed for methanol and MEG through experiments, especially in the vertical sections and low spots of the jumper. Methanol overriding the water phase at horizontal low spots was captured for the low velocity experimental cases, leaving a large amount of water behind that could result in under-inhibited situations. For the 12% brine tests, less water was displaced for each MEG injection rate, whereas a better mixing of methanol with brine was measured. The 1D and 3D simulations provided reasonable prediction for THI distribution along the jumper after displacement tests, except that neither was able to reproduce methanol overriding the water phase at both low spots. 3D CFD simulations results obtained generally gave better agreement with the results from the experiment.

This study provides a better understanding of the displacement and mixing mechanisms of thermodynamic hydrate inhibitors. It helps operators minimize operational risks, reducing the size of the umbilical and decreasing capital costs related to equipment and chemicals.
The Challenges Facing the Industry in Offshore Facility Decommissioning on the California Coast
Authors: Byrd Robert C. , Smith John B. , Spease Steven J.
Published: April 2018

This paper addresses the challenges of decommissioning oil and gas facilities offshore California, where there are a number of large, deep-water platforms, and decommissioning infrastructure and services are severely lacking. The regulatory process for decommissioning platforms is also very complex and expensive and the prospects for reefing platform jackets are uncertain at best. These circumstances have created a situation that the domestic oil and gas industry has not really faced before, i.e., that the cost risk may not be determinate. This will pose a major challenge to decommissioning project management. The paper addresses the major issues and attempts to put boundaries on the cost risk.
Novel Washpipe-Free ICD Completion With Dissolvable Material
Authors: Corona Georgina , Fripp Michael , Novelen Ryan
Published: April 2018

Completions using inflow control devices (ICDs) help provide balanced production inflow, delay water and gas breakthrough, and extend the productive life of the well. For fluid circulation, displacement, and wash down, an ICD completion typically utilizes a washpipe or inner string to provide flow to the bottom of the screens. However, the use of a washpipe increases operational time, operational risks, and costs. Through the use of dissolvable materials, a washpipe-free ICD completion has been developed for fluid circulation and wellbore displacement.

The dissolution properties of multiple dissolvable materials were experimentally measured with field fluid samples used during running in hole (RIH) and displacement. The degradation rate was characterized at downhole temperatures in terms of both mass loss and volume loss versus time. The dissolvable material was incorporated into a nozzle ICD to help prevent flow between the inner and outer annulus of the tubing. The pressure-holding performance of the ICD with the dissolvable material was measured by means of small-scale testing for pressure integrity, followed by full-scale testing, simulating particular fluid circulation and displacement sequence characteristic of both a Middle East and West Africa application.

Laboratory testing was used to determine dissolution rates of multiple materials at representative temperatures and in various fluids. Small-scale testing demonstrated that the dissolvable material provided pressure sealing integrity within the ICD. The dissolution rate of the dissolvable material within the plugged ICD behaved as predicted in the laboratory tests when subjected to circulation and displacement with the fluids representative of the field application. The washpipe-free ICD completion performance tests indicated that the dissolvable material provides a means for circulation and displacement while maintaining pressure integrity necessary for the successful deployment of the lower completion. The capability to run washpipe-free ICD completions helps reduce operational time and costs, and upon dissolution of the dissolvable plugs, delay gas and water breakthrough through the use of ICDs.