bluuebunny/crossref_metadata_2025 huggingface dataset:
Un témoin privilégié de l’art paléolithique dans le Bassin parisien : le galet gravé d’Étiolles (Essonne)
Authors: Fritz Carole , Tosello Gilles
Published: April 2016

La découverte d’une pierre gravée sur le site magdalénien de plein air d’Étiolles (Essonne) est un fait exceptionnel, car les témoignages d’art paléolithique sont rares dans le Bassin parisien. Le bloc de calcaire dur se présente comme un gros galet (3 kilogrammes), choisi pour ses qualités propices à la gravure. Il était placé sous une dalle qui ceinturait le foyer D71-1 daté par le 14C (12315 ± 75 BP). Sur le recto, un cheval, de style très naturaliste, semble couché sur le flanc, l’oeil clos et la bouche ouverte. Deux signes en blessures marquent le corps. Ce cheval est suivi d’un humain composite de sexe féminin, qui semble le menacer. Sur le verso, on observe deux rennes et un cheval de facture plus sommaire. Les figures, notamment les chevaux, présentent des particularités graphiques dont il reste à évaluer l’importance dans l’aire magdalénienne septentrionale. En effet, il est difficile, avec deux spécimens, de parler de «style » local. La comparaison des équidés d’Étiolles avec les rares figures connues dans le Bassin parisien (Cepoy, Pincevent ou Boutigny) n’apporte pas d’élément marquant. Ces pièces montrent surtout que le cheval jouait un rôle thématique privilégié dans l’art de la fin du Paléolithique régional. La localisation du galet sur le bord d’un foyer peut indiquer une relation avec le feu, qui semble moins évidente que pour d’autres pierres gravées, notamment celles découvertes dans les sites du Sud-Ouest européen. En revanche, les éléments de comparaison sont à chercher dans l’art des provinces méridionales. Les gravures d’Étiolles apportent de nouveaux exemples d’analogies sur de longues distances, d’autant plus intéressantes qu’elles se placent à une période où l’unité symbolique du Magdalénien paraît se fissurer. En effet, autour de 12000 BP, les groupes aquitains, jusqu’alors fortement liés à leurs homologues des Pyrénées et des Cantabres, se singularisent : leurs productions symboliques (par exemple les figurations féminines stylisées) indiquent une orientation des réseaux d’échanges non plus vers le sud-ouest mais vers le nord et l’est, c’est-à-dire le Bassin parisien, les plaines de Belgique et d’Allemagne. La découverte d’Étiolles, certes isolée, serait donc l’un des derniers indices témoignant d’une persistance de ces liens ancestraux entre les groupes d’un bout à l’autre de l’aire magdalénienne. L’association de caractères humains et animaux sur la créature composite, le choix d’espèces qui constituaient le gibier de prédilection orientent l’interprétation vers la sphère de la chasse ; en paraphrasant C. Lévi-Strauss (1980, p. 93), faut-il penser que pour les hommes d’alors, le renne et le cheval «bons à manger » étaient tout aussi «bons à penser » ?
Guiry-en-Vexin, la « Ferme Duport » (Val d’Oise), une allée sépulcrale fondée au Néolithique récent
Authors: Pariat Jean-Gabriel
Published: April 2016

L’allée sépulcrale de la «Ferme Duport » à Guiry-en-Vexin (Val-d’Oise) a été fouillée dans les années soixante. La documentation qui en émane a été exploitée à de nombreuses reprises, et récemment en 2006 par le Service départemental d’archéologie du Val-d’Oise. La confrontation des contributions existantes, à laquelle s’ajoutent de nouvelles analyses, permet d’affiner les interprétations relatives à la chronologie et au fonctionnement de ce gisement, semble-t-il fondé à la fin du IVe millénaire av. J.-C. Bien que la durée totale de l’utilisation de ce caveau demeure inconnue, des éléments du rituel funéraire du Néolithique récent transparaissent : inhumations en position repliée, réduction de squelette, etc. Ces caractéristiques, peu communes en Bassin parisien, enrichissent la connaissance des pratiques funéraires des sociétés de la fin du IVe millénaire av. J.-C.
Les objets du Bronze moyen récemment découverts à Chalonnes-sur-Loire (Maine-et-Loire). Analyse typologique, environnement culturel et naturel
Authors: Gabillot Maréva , Simon-Millot Rolande , Petit Christophe
Published: April 2016

Among a set of objects accidentally discovered in 2003 at Chalonnessur-Loire (Maine-et-Loire, France), a Middle Bronze Age hoard has been identified. The other objects, including a triangular side scraper, are dated from the Late Bronze Age and will be studied later. These eleven Middle Bronze Age objects (called “ the Belvédère set” in this paper) are two fragments of chisels, a fragment of the handle of another flanged tool, a fragment of the handle of a flanged axe belonging to an eastern type (Porcieu-Amblagneu or Langquaid or some variants), two fluted flanged axes with a rare lateral pattern, two simple undecorated bracelets, and three pieces of bracelets of the Drône type. They were all well prepared after casting. Some of them were strongly used and then thrown away. The fluted flanged axes are nearly new and could still be useful. In total they represent a stock of 1 kg of metal. The objets belong to two functional categories, tools and jewellery. The chronological analysis allows us to date them to the Bronze B2 ; they belong to both the Atlantic and Eastern cultural spheres. This association is quite frequent in the Atlantic sphere, but the Chalonnes-sur-Loire set differs from several points of view : these objects show evidence of cultural links between the lower Loire valley and both the Channel and the North Alpine arc and they are much more fragmented than other hoards associating jewellery and tools. Another set of objects discovered at the same place in 1901 (called “ the Pierre-Cou set”) presents several chronological and cultural similarities with the Belvédère set. It consist of three axes including one fluted flanged axe, eighteen bracelets including two of the Drône type, amber beads and a spearhead. Both sets of objects, Belvédère and Pierre-Cou, constitute a conventional so-called mixed hoard, a type of hoard identified in the 1950s by Wolfgang Kimmig. We can thus propose that the Belvédère set is only part of a bigger hoard of the Middle Bronze Age mixed type. The Chalonnes-sur-Loire hoard would be then one of the most western Middle Bronze Age mixed hoards. This hoard (or hoards) was located in a particular place, from the point of view of the natural environment. The objects were discovered in the middle of an island formed by two branches of the Loire which forms a bend at this place. Tin and copper mineralisations are found in the close neighbourhood of the discoveries. These natural patterns, observed for several other Bronze Age hoards in Europe, seem to be significant social factors.
La loi générale de protection de l'environnement de l'Uruguay
Authors: J. Cousillas Marcelo
Published: April 2016

Mettant en œuvre l'article 47 de la constitution de la République qui a proclamé la protection de l'environnement d'intérêt général, la loi du 28 novembre 2000 est la première loi-cadre sur l'environnement de l'Uruguay. L'article passe en revue les principales dispositions ainsi introduites.
Après l'Erika : la prévention de la pollution des mers par le renforcement de la sécurité maritime en Europe (Erika I)
Authors: Roche Catherine
Published: April 2016

Le naufrage de l'Erika a encore une fois amené les instances internationales, communautaires et nationales à renforcer les dispositions en vigueur pour prévenir de telles catastrophes. La France, particulièrement touchée par les derniers accidents, est de nouveau à l'origine des nouvelles réglementations communautaires. Celles-ci ont pour objet de prévenir les pollutions accidentelles et volontaires, en complétant les conventions adoptées par l'Organisation maritime internationale. Les pouvoirs de l'Etat du port devraient, en conséquence, être renforcés de même que les obligations pesant sur l'Etat du pavillon.
A few‐gene plastid phylogenetic framework for mycoheterotrophic monocots
Authors: Lam Vivienne K.Y. , Merckx Vincent S.F.T. , Graham Sean W.
Published: April 2016

PREMISE OF THE STUDY:

Few‐gene studies with broad taxon sampling have provided major insights into phylogeny and underpin plant classification. However, they have typically excluded heterotrophic plants because of loss, pseudogenization, or rapid evolution of plastid genes. Here we performed a phylogenetic survey of three commonly retained plastid genes to assess their utility in placing mycoheterotrophs.

METHODS:

We surveyed accD, clpP, and matK for 34 taxa from seven monocot families that include full mycoheterotrophs and a broad sampling of photosynthetic taxa. After screening for weak contaminants, we conducted phylogenetic analyses and characterized among‐lineage rate variation.

KEY RESULTS:

Likelihood analyses strongly supported local placements of fully mycoheterotrophic taxa for Corsiaceae, Iridaceae, Orchidaceae, and Petrosaviaceae, in positions consistent with other studies. Depression of likelihood bootstrap support values near mycoheterotrophic clades was alleviated when each mycoheterotrophic family was considered separately. Triuridaceae (Sciaphila) monophyly was recovered in a partitioned likelihood analysis, and the family then placed as sister to Cyclanthaceae‐Pandanaceae. Burmanniaceae placed in Dioscoreales with weak to strong support depending on analysis details, and we inferred a plastid‐based phylogeny for the family. Thismiaceae species may retain a plastid genome, based on accD retention. The inferred position of Thismiaceae is unstable, but was close to Taccaceae (Dioscoreales) in some analyses.

CONCLUSIONS:

Long branches/elevated substitution rates, missing genes, and occasional contaminants are challenges for plastid‐based phylogenetic inference with full mycoheterotrophs. However, most mycoheterotrophs can be readily integrated into the broad picture of plant phylogeny using several plastid genes and broad taxonomic sampling.
Comparison of the interactions of daunorubicin in a free form and attached to single-walled carbon nanotubes with model lipid membranes
Authors: Matyszewska Dorota
Published: April 2016

In this work the interactions of an anticancer drug daunorubicin (DNR) with model thiolipid layers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE) were investigated using Langmuir technique. The results obtained for a free drug were compared with the results recorded for DNR attached to SWCNTs as potential drug carrier. Langmuir studies of mixed DPPTE–SWCNTs-DNR monolayers showed that even at the highest investigated content of the nanotubes in the monolayer, the changes in the properties of DPPTE model membranes were not as significant as in case of the incorporation of a free drug, which resulted in a significant increase in the area per molecule and fluidization of the thiolipid layer. The presence of SWCNTs-DNR in the DPPTE monolayer at the air–water interface did not change the organization of the lipid molecules to such extent as the free drug, which may be explained by different types of interactions playing crucial role in these two types of systems. In the case of the interactions of free DNR the electrostatic attraction between positively charged drug and negatively charged DPPTE monolayer play the most important role, while in the case of SWCNTs-DNR adducts the hydrophobic interactions between nanotubes and acyl chains of the lipid seem to be prevailing. Electrochemical studies performed for supported model membranes containing the drug delivered in the two investigated forms revealed that the surface concentration of the drug-nanotube adduct in supported monolayers is comparable to the reported surface concentration of the free DNR incorporated into DPPTE monolayers on gold electrodes. Therefore, it may be concluded that the application of carbon nanotubes as potential DNR carrier allows for the incorporation of comparable amount of the drug into model membranes with simultaneous decrease in the negative changes in the membrane structure and organization, which is an important aspect in terms of side effects of the drug.
DETECTING IONOSPHERIC ANOMALIES ASSOCIATED WITH THREE JAPAN MIYAKO EARTHQUAKES TO SHOW THEIR CORRELATIONS AND ASSOCIATED EARTHQUAKE-INDUCED TSUNAMIS
Authors: Jyh-Woei Lin
Published: April 2016

This study employed two-dimensional principal component analysis (2DPCA) for the detection of anomalies in the two-dimensional ionospheric total electron content (TEC) associated with Japan three earthquakes and earthquake-induced tsunamis. From 04:40 to 04:50 (UTC) on February 15th, first TEC precursor was detected over the epicentre of the 16 February quake with the duration time of at least 10 minutes. A weak TEC anomaly associated with an earthquake-induced tsunami was also detected from 23:15 to 23:20 (UTC) on 16 February with the duration time of at least 5 minutes. An additional earthquake (Mw = 6.3) occurred in Miyako in the vicinity of the first earthquake. Second TEC precursor to the 20 February Miyako earthquake was recorded over the epicentre between 10:20 and 10:30 (UTC) on 19 February with the duration time of at least 10 minutes. A supplemental earthquake occurred (Mw = 6.1) as well in Miyako in the vicinity of the first earthquake. A TEC precursor to the 21 February Miyako earthquake was recorded over the epicentre between 04:15 and 04:25 (UTC) on 20 February with the duration time of at least 10 minutes. The three Miyako earthquakes presented similar anomalies and duration time in the TEC fluctuations, due largely to similarities in the magnitudes of the largest principal eigenvalues and the close proximity of the epicentres. Our results led to the reasonable confirmation that the very weak TEC anomaly following the Miyako earthquake on 16 February was associated with the earthquake-induced tsunami. 2DPCA is a useful mathematical tool for the monitoring of anomalous ionospheric fluctuations for use in the early warning of weak tsunamis.
FIELD TESTS OF ASTROMETRIC SUBSYSTEM
Authors: Zariņš Ansis , Haritonova Diāna , Rubans Augusts , Silabriedis Gunārs , Zvirgzds Jānis
Published: April 2016

The paper presents results of astrometric subsystem’s functionality tests for space object laser ranging and astrometric position determination device, which is under construction in the Institute of Geodesy and Geoinformatics (GGI) of the University of Latvia. Properties of hardware performance for astrometric image acquisition were evaluated and optimal parameters have been selected. Software for image processing and calculation of instrument orientation was tested and adjustments have been made for real-time operation support. Object tracking properties were evaluated, and mount error model parameters were calculated, using test measurements.
Scientific Realism versus Antirealism in Science Education
Authors: Park Seungbae
Published: April 2016

Scientific realists believe both what a scientific theory says about observables and unobservables. In contrast, scientific antirealists believe what a scientific theory says about observables, but not about unobservables. I argue that scientific realism is a more useful doctrine than scientific antirealism in science classrooms. If science teachers are antirealists, they are caught in Moore’s paradox when they help their students grasp the content of a scientific theory, and when they explain a phenomenon in terms of a scientific theory. Teachers ask questions to their students to check whether they have grasped the content of a scientific theory. If the students are antirealists, they are also caught in Moore’s paradox when they respond positively to their teachers’ questions, and when they explain a phenomenon in terms of a scientific theory. Finally, neither teachers nor students can understand phenomena in terms of scientific theories, if they are antirealists.
Les différents troubles visuels chez le jeune enfant
Authors: Bursztyn Joseph
Published: April 2016

L’ophtalmologiste doit participer au bien d’un enfant. Il peut aider au diagnostic mais doit surtout apprécier les capacités visuelles et l’intégrité du globe oculaire. Son rôle ne doit pas s’arrêter au bilan, il doit être actif, en traitant, compensant, équipant, opérant, rééduquant les anomalies. Enfin, il ne doit pas oublier que l’œil évolue comme l’enfant. Le suivi doit s’adapter au bilan initial et être réévalué.
Ergothérapie et vision : un regard sur la vie quotidienne
Authors: Lefévère-Renard Gwenaëlle , Vauvillé Chagnard Barbara
Published: April 2016

L’ergothérapie s’adresse à des personnes en situations de handicap dans le but de maintenir ou de développer leur potentiel d’indépendance et d’autonomie personnelle, sociale, scolaire ou professionnelle. Cette discipline ne se focalise pas seulement sur la personne et ses troubles mais aussi sur l’impact de son environnement et de ses habitudes de vie. Pour l’enfant porteur de troubles visuels au sens large, c’est une charnière entre le travail des orthoptistes et ophtalmologistes – professionnels de la vision – et la vie quotidienne telle que la vivent l’enfant, ses parents, ses éducateurs et enseignants. L’ergothérapeute réalise des évaluations en analysant les activités de l’enfant dans ses lieux de vie mais aussi au moyen de tests normés et étalonnés. Ses interventions sont à la fois rééducatives et réadaptatives : la rééducation tente pour chaque enfant d’augmenter ses potentialités et la réadaptation a pour but de réduire l’impact parfois défavorable de l’environnement physique et humain. Clarisse, Juliette et Corentin sont trois enfants qui ont bénéficié de l’accompagnement d’un ergothérapeute à un moment de leur enfance, pour des rééducations, conseils, adaptations ou installations, toujours en lien avec leur entourage et leur environnement.
Une vie posthume. Maurice Halbwachs et la sociologie française (1945-2015)
Authors: Hirsch Thomas
Published: April 2016

Tenu par ses contemporains pour un disciple à la fois convaincu et conquérant d’Émile Durkheim, le souvenir de Maurice Halbwachs a connu depuis sa mort trois périodes nettement distinctes, épousant le rythme de son actualité éditoriale : d’abord, de 1945 à 1955, une tentative de sauvetage qui, selon des modalités diverses, tente de le distinguer de l’« école sociologique française » pour mieux l’acclimater aux orientations nouvelles d’une sociologie en train de se réinventer ; ensuite, entre 1964 et 1976, un partage entre reconduction des lectures de l’après-guerre et réinscription historique dans le sillage d’É. Durkheim ; enfin, depuis le tournant des années 1990, et à l’aune de l’engouement pour la notion de mémoire collective, une nouvelle logique de distinction tentant de justifier l’exceptionnalité de ses recherches. La vie posthume de M. Halbwachs retracée ici permet autant d’interroger les schèmes de lecture qui informent le regard porté sur son œuvre que de questionner les contraintes qui pèsent sur l’écriture de sa propre histoire par la sociologie française.
Un modèle hiérarchique de l’artiste et de l’expertise
Authors: Bessy Christian
Published: April 2016

Dans cet ouvrage, Bernard Lahire propose une analyse générale de la sacralisation de l’art et des artistes, en partant des opérations d’attribution et d’authentification. Dans un premier temps, nous précisons la posture analytique de l’auteur sur la question de l’authenticité des œuvres d’art et des procédures d’authentification. Cette posture est fondée sur la puissance performative des experts et donc sur une forme de rapport hiérarchique entre experts et profanes. Dans un deuxième temps, nous rentrons dans l’histoire singulière du tableau de Nicolas Poussin représentant La fuite en Égypte afin de montrer les enjeux des différentes épreuves d’attribution, en particulier au regard des rapports de domination se logeant dans le pouvoir d’imposition des experts. Dans un troisième temps, nous présentons une discussion critique de l’ouvrage à partir d’un modèle plus horizontal de l’expertise et des rapports entre les artistes et leurs admirateurs, fondés sur des rapports d’initiation.
Technological competition: a path towards commoditization or differentiation? Some evidence from a comparison of e-book readers
Authors: Benghozi Pierre-Jean , Salvador Elisa
Published: April 2016

La concurrence par la technologie est au cœur des dynamiques compétitives du numérique. Elle se traduit par des stratégies industrielles articulant innovations de rupture et innovations répétées et façonnant progressivement, au fil d’étapes successives, la configuration des offres, la structure des marchés et l’organisation des filières industrielles. Ces trajectoires technologiques résultent de tensions entre deux objectifs contradictoires : se spécialiser sur des systèmes propriétaires pour mieux maîtriser une base de clients, ou s’inscrire dans des standards partagés pour pouvoir adresser l’ensemble du marché. Dans un cas, la succession d’innovations consolide une concurrence entre écosystèmes propriétaires et exclusifs ; dans l’autre cas, les perspectives d’innovation et de création de valeur s’ouvrent plus largement à tous les acteurs des filières car elles s’appuient sur des supports technologiques « commoditisés ». Le marché des liseuses offre une illustration emblématique de ces enjeux qui se jouent, dans la concurrence technologique, entre fournisseurs de terminaux, plateformes numérique et éditeurs.
Wearable Technologies in Academic Information Search
Authors: Gibson Robert
Published: April 2016

Wearable technologies and appliances are making inroads into a variety of consumer and commercial applications, including leisure and entertainment, health care, and gaming. A natural evolution of the technology is in academe where faculty and students have begun exploring the possibilities of the technology in a variety of settings, most visibly in libraries where the process of seeking information using such devices holds significant promise. This chapter provides an inventory of the state of wearable technology, its challenges, its possibilities, and how it might be used in academe, including a study regarding the ability to access common library indexes using two wearable appliances: Google Glass and a smart watch.
Decommissioning Process Optimization Methodology
Authors: Siems G. L.
Published: April 2016

The over 4,500 idle wells and 783 idle structures in the U.S. federal waters of the Outer Continental Shelf at the beginning of 2011 were increasing the risk of contamination to the environment as these assets aged, while at the same time the cost to decommission these assets was on the rise. During the hurricane seasons of 2005 and 2008 over 175 structures and 1,000 wells were damaged or toppled to the sea floor by wind and storm surge that further exposed the risk, increased the cost of decommissioning and made underwriting the repair or replacement of these assets no longer affordable to many operators.

Renewed pressure on operators to decommission idle infrastructure sooner rather than later was brought forth by the issuance of new guidelines by regulators in the form of a Notice to Lessee. These new guidelines now require operators to decommission idle wells and supporting structures as soon as possible, but no later than 5 years after they become no longer useful for producing oil and gas in paying quantities.

With the cost of decommissioning and regulatory pressure increasing, many operators began seeking new and better decommissioning methods that could get more work done, safely and at a lower cost. Employing the newest technologies, a new, optimized decommissioning methodology was made possible. The size and capabilities of a newly designed and constructed 335 class self-elevating, self-propelled, marine vessel (liftboat) allowed a departure from the traditional method of performing decommissioning work-steps sequentially, one-after-the-other, to a new method of performing the majority of work-steps concurrently in just one spread mobilization.

The new concurrent model was utilized over a 30-month period and demonstrated that not only did the new liftboat perform as proposed, use of the new model resulted in a 140% more wells and structures being removed over the number expected to have been removed using traditional methods. The actual spend to execute the total work scope was reduced by one-third (33%) and, most importantly, the excellent safety performance achieved by the single, consistent team of specialty workers was recognized with the presentation of the 2013 Safety-in-Seas Award by the National Ocean Industries Association (NOIA).
Fluid Characterization with LWD Resistivity and Capture Cross Section Enhances Understanding of Horizontal Well Production – A Case Study in a Siliciclastic Brownfield
Authors: Liu Ruiying , Li Qiang , Li Ting , Liu Yanmei , Lu Zhongyuan , Yu Gang , Guo Xinyong , Yang Chuan
Published: April 2016

In this case study, we examine oil wells in a brownfield, where water production is a major concern. The target reservoirs consist of several thin sandstone beds with excellent lateral extension. As a result, the operator generally chooses to produce from long horizontal sections. In order to better understand production and make informed decision about future development plans, it is critical for the operator to accurately characterize fluids in the field through well logging. The challenge in formation evaluation lies in the uncertainty in formation salinity, because the injected water makes formation water salinity highly variable. In such environments, saturation equations that rely on a good knowledge of the water salinity, such as resistivity-based equations (Archie) or ther mal neutron capture cross section (Sigma), cannot fully capture the variability in fluids distribution in the reservoir. The problem is further complicated by low-resistivity-pay, where the resistivity contrast between water and pay zones is quite small.

A recently proposed workflow can solve for water salinity at each depth level by simultaneously inverting for water saturation (Sw) and water resistivity (Rw) from resistivity and Sigma logs. This method does not require a priori knowledge of water salinity. One can further compute an irreducible water saturation (Swi) from lithological dry weights, which in turn are derived from geochemical logs. The amount of water that's movable in the pore space is then given by Sw – Swi. We can use Sw – Swi as a qualitative indicator of water floods distribution and use it to understand fluids production of horizontal wells and design the next phase of development to target bypassed hydrocarbon.

In this report, we studied the LWD logs and production history of 3 horizontal wells in a brownfield, where formation salinity is highly variable. It is found that water production is directly related to Sw – Swi. We also show that resistivity-based saturation equations can give misleading interpretation of the fluid type due to variable salinity. Adding Sigma into the interpretation model accounts for salinity changes and gives results that are consistent with production history.
Insights from CFD Validation of a Jackup Rig
Authors: Barczak Nicholas A. , Reifsnyder Jefferey D. , Mobbs Charles B.
Published: April 2016

The authors performed a computational fluid dynamics (CFD) analysis of a self-elevating mobile offshore drilling unit (SE MODU) as a replacement for wind tunnel testing. The authors utilized an unsteady RANS method to model wind forces on an SE MODU for a variety of wind headings. The simulation produced force and moment data for individual structural components of the SE MODU. The final data set presented sufficient information to calculate overturning moments of the SE MODU in a range of wind conditions.

This paper discusses several techniques developed for the SE MODU analysis: meshing of disparate structural scales, accurate simulation of large intricate structures, and accurate description of dynamic effects. The paper presents methodology for calculation of a center of effort that correctly relates vector force to vector moment in all three dimensions. The authors demonstrate that center of effort was not appropriate to dynamic flow situations; direct moment coefficients were more suitable.

As part of the validation process, CFD analysis was performed on a similar SE MODU design and compared to existing wind tunnel results. This paper compared forces and moments in all three axes for multiple wind headings. The CFD analysis compared very well with wind tunnel results, showing only a 10% difference from the experiment.

The project revealed several advantages of CFD over traditional wind tunnels in this application. The insights from CFD showed the contribution of each structural component to overturning moment, and results revealed significant elements of overturning moment not considered by the current industry standards. CFD analysis required a similar level of effort as a wind tunnel test but produced far more detailed knowledge.
Probabilistic Analyses for Lateral Buckling of Pipe-in-Pipe Systems
Authors: Gitahy Leonardo , Charnaux Carlos , Manso Daniel , Roberts Graeme
Published: April 2016

In order to meet the growing demand for oil production in even deeper waters, new technologies have been developed, making the exploration of such fields possible. A system used as an alternative for the control of extreme operating conditions (high temperatures and pressures) of such exploration fields is the pipe-in-pipe system. This kind of system is extensively used in offshore applications in which exceptional thermal insulation capability is required, preventing hydrate/wax formation and maintaining the production temperature up to the arrival facilities.

However, extreme operating conditions can cause the system to experience thermomechanical buckling, which can lead to a structural failure of the system. In order to control these thermomechanical loads and ensure that pipeline is within a safe operating margin, the potential buckling formation locations need to be assessed and may need to be mitigated. The key point in the thermomechanical design of offshore pipelines is to define whether the buckling phenomena should be controlled or not. The optimal solution may often involve addressing natural imperfections whilst establishing the required engineered mitigation measures.

Design assumptions such as the pipeline as-laid lateral Out-Of-Straightness (OOS) and the pipe-soil interaction parameters are common input data uncertainties existent during design of HP/HT offshore pipeline systems. A robust design should be impervious to variations in the values of these design parameters, considering values that lie within reasonable and feasible limits, such that the project can proceed with reasonable certainty and within sensible cost limits. In this scenario full of uncertainties, reliability analysis has been implemented in the thermomechanical design of offshore pipeline systems. The purpose of reliability analysis is to reduce the design conservatism by quantifying the probability of failure associated with the pipeline system.

This paper presents a novel and viable proposal for conducting probabilistic analysis associated with lateral buckling of a full length pipe-in-pipe system, through the application of detailed finite element analysis. The information contained in the paper can be used as guidance for future reliability evaluations of offshore pipeline systems.
Normalized Modulus Reduction and Material Damping Ratio Curves for Bay of Campeche Sand
Authors: Taboada Victor M. , Dantal Vishal , Roque Diego Cruz , Lopez Francisco Flores , Nabor Procoro Barrera
Published: April 2016

Predictive equations for estimating normalized shear modulus and material damping ratio of sand are presented in this paper. The equations are based on a modified hyperbolic model and a statistical analysis of existing isotropically consolidated resonant column and strain-controlled cyclic direct simple shear test results for 252 specimens obtained from the Bay of Campeche. Two independent modified hyperbolic relationships are fitted to model stiffness (G/Gmax)-strain using two parameters and material damping ratio-strain curves using four parameters. Variables used in the equation for normalized shear modulus are: confining pressure; shear-strain amplitude; a reference strain, defined as the shear strain at which the shear modulus has reduced to 0.5Gmax, and a curvature parameter which controls the rate of modulus reduction, such as the model suggested by Darendeli (2001). The equation for damping ratio D, is expressed in terms of the reference strain, defined as the shear strain for a 50% increase in material damping ratio (i.e. D/Dmax = 0.5), a curvature parameter which controls the rate of material damping ratio increase, the minimum material damping ratio Dmin, and the maximum material damping ratio Dmax, similar to the equation suggested by Gonzalez and Romo (2011). It is found that the Bay of Campeche sand exhibit more linear response and lower damping ratio than other sands reported in the literature. The uncertainties associated with the predictive equations are quantified. A case study is provided to illustrate an application of the predictive equations to seismic response analysis and the importance of considering confining stress. The predictive equations of normalized shear modulus reduction G/Gmax and Damping ratio curves are easy to apply in practice, and are useful in the analysis of granular strata and offshore structures subjected to earthquake loading when site specific laboratory testing is not available.
Removing Marine Growth Using an ROV with Cavitation Technology
Authors: Restivo Andrew , Brune Michael
Published: April 2016

Marine growth on the submerged hull of a floating offshore installation can prevent the effective inspection of external hull plating, weld, and coating. Subsequently, several countries throughout the world have established regulations addressing inspection and maintenance of structures in their offshore waters. Marine growth removal using high-pressure water is very common in the industry, but high-pressure water can easily damage and strip away anti-fouling coating. This smooth, slippery, and low-friction coating is what prevents organism growth from attaching to a subsea surface.

The objective of this project was to develop the technology necessary to remove marine growth from offshore structures using an ROV-operated system employing controlled cavitation erosion without damaging the anti-fouling coating. An ROV-mounted skid fitted a custom cavitation nozzle has been developed to perform this work.

A detailed quality test plan was created to analyze the system for subsea use for an operator in Angola. The primary goals of the Cavitation Water Jet System (CWJ) test plan were threefold:

Determine, for all nozzle sets operating at their rated pressure and flow, the optimum standoff distance, attack angle, and traverse rate necessary to remove simulated marine fouling without damaging the underlying coatings.

Determine the reaction forces generated from the lance and rotary head when operating at their rated pressure and flow rate. Since the rotary head can be fitted with two nozzle types operating at 8000 PSI @ 15 GPM and 5500 PSI @ 21 GPM respectively, the rotational speed for both was measured.

Determine the performance of system at different water depths.

 

The system passed quality tests and inspection, and was successfully used for FPSO hull cleaning in Angola in 2014-2015.
FLNG Projects Economics Improvement Based on Reliability Assessment
Authors: Benyessaad Olivier , Forte De Souza Karina , Le Diagon Vincent , Rocha Gustavo
Published: April 2016

With about 30 FLNG projects in planning, appraisal or FEED stage, the offshore industry is now diving in a new era. Even if the current oil price crisis is massively impacting new projects, gas projects remain a priority as it is considered by most of the energy analysts as the energy of the future for both, economical & environmental reasons. As no feedback is currently available, most of the operators are now looking towards the first units to be on stream to valid economic models based on unstable assumptions. This paper aims at demonstrating how reliability techniques such as RAM assessment can allow operators to adjust their economic model, ensure optimum return on investment and design reliable and safe installations. By using straight from concept stage of an FLNG project an adapted RAM tool coupled with an efficient RAM assessment based on experienced people, it will be possible to ensure design has been conducted effictively with respect to production performance and maintenance & repair strategy. Later on, by incorporating on a regular basis operational data comining from industy return on experience, companies will be able capitalize properly they experience and re-use it for future projects.

The paper will first give an overview of the (F)LNG market outlining the main challenges. Then, based on recent projects, it will detail the reliability methodology applied to ensure the profitability of such innovative installations. This section will focus on the key parameters and assumptions to be considered in order to assess production availability of the full FLNG installation in the most appropriate manner. Finally, after having pointed out the ins and outs of these analyses, a case study will be developed to quantify the benefit of the proposed approach.
Online Asset Integrity Management and Operational Optimisation Through Online Integrity Monitoring
Authors: Wallace Gary , Champlin Tom
Published: April 2016

This paper will focus on monitoring the integrity of fixed equipment in oil and gas production assets. The insight gained from a real time understanding of asset integrity enables enhanced evidence based operational decision making to improve safety and profitability. A case study and lessons learned from the use of online integrity monitoring systems will be given for upstream facilities.
Integrity Management Services for Floating Units from Design to Decommissioning
Authors: Boutrot Jonathan , Legregeois Nicolas
Published: April 2016

By reviewing the process of Asset Integrity Management applied from the design phase, continued through the in-service life and obsolescence considerations for decommissioning, this paper presents a view of managing the safety and operational efficiency of floating structures.

The paper will go through the presentation of a didactic process ensuring the Asset Integrity of the structure in answering a few questions:

How to ensure a correct knowledge of the offshore facilities' condition?

What are the main degradation processes threatening the facilities?

What will be the response of a facility to the main threats over the years?

How to implement a cost-effective Inspection Strategy?

 

Answers to those questions will involve various services embedded into a global Integrity Management process such as CFD and hydrodynamics, structural FEM calculations, condition monitoring, Risk-Based Inspection strategy and 3D geometric models for visualization and reporting.

Established at design phase and updated during the in-service life of the Unit, this global Asset Integrity process for the structure will support and optimize the inspection programme based on risk considerations by focusing on the most critical elements to the safety.

Besides an OPEX cost reduction by optimizing the inspection efforts, the engineering services that are parts of the Asset Integrity Management are fully embedded into that global process. This brings another cut in costs by saving time and thus cost when performing engineering analysis.
A New Method to Design and Optimize the ICD for Horizontal Wells
Authors: Shi Hongfu , Zhou Haiyan , Hu Yong , He Yifan , Fu Rong , Ren Bo
Published: April 2016

QHD oilfield in Bohai Bay, China, is characterized by conventional heavy oil (average viscosity 150cp under reservoir conditions) with excellent reservoir quality (up to 30% porosity and 1-2D permeability) and strong aquifer. Horizontal and multilateral wells are widely used in QHD and most wells were standard completion. After 13 years of development, many wells show sharp production decline and rapid water cut increase. What's more, water breakthrough in several wells is much earlier than prediction. The high mobility ratio, hell-toe effect, bottom water, permeability heterogeneity and sand are contributed to reduced ultimate recovery and well life.

The use of ICD (inflow control device) is becoming more and more prevalent as it can delay the water break through and significantly improve the economic life of a well. This is especially important for offshore fields where well intervention is difficult and expensive. Therefore, ICD technique is proposed to address the above production problem while prolonging production life (BREKKE K, 1997).

In this paper, I discuss the feasibility of ICD for horizontal wells in heavy oil reservoir of offshore field. First, I analyze the actuality of the offshore heavy oil with strong bottom water in Bohai Bay and the reason of bottom water coning. Secondly, I discuss the feasibility of ICD for horizontal wells in heavy oil reservoir of offshore field. Finally, a new method is established to design the additional pressure of ICD. The method is compared to the uniform liquid method; what's more, a numerical model is developed to validate the new method. The production performance of the first ICD wells was discussed to provide evidence on its effectiveness and robustness. This has provided valuable data prior to well drilling and the final optimization of ICD.

The paper demonstrates the importance of seamless teamwork and coordination between reservoir engineers and project team to deliver superior performance. In a word, this paper is expected to assist well completion decisions for offshore heavy oil reservoir and to spark continue research on ICD.
Macondo and Bardolino: Two Case Studies of the Human Factors of Kick Detection Prior to a Blowout
Authors: St. John M. F.
Published: April 2016

Objectives

The Macondo and Bardolino incidents of 2009 and 2010 had similar beginnings but very different outcomes. While Macondo ended in disaster, Bardolino ended without a spill or injury. This case study of these two incidents analyzes and compares the human factors of detecting an influx or kick for each incident.

Methods

A set of 147 human factors issues involved in kick detection were assessed, first in aggregate, and then in terms of a step by step narrative of each incident. Next, patterns among the human factors were identified by determining which factors tend to cluster together across a set of 43 incidents. Some factors tend to co-occur with other issues.

Results

These clusters of co-occurring issues form two general themes which can be described as a general wariness toward well control versus early engagement and investigation, such as stopping to check for flow. The wariness cluster is more closely associated with shutting in the well early, which is an important objective of safe well control practice. However, a human factors barrier associated with the engagement cluster, considering the possibility of an influx, may have led to the turning point between the Macondo and Bardolino incidents.

Novel information

These analyses point to promising locations to focus attention, both for assessing rigs prior to incidents, during investigations after incidents, and most importantly, for researching and developing new technologies and procedures for minimizing or precluding incidents all together.
CFD Simulation of Current Past Bluff Body at High Reynolds Number
Authors: Ibrahim Ahmed , Huang Chen-Pey , Korpus Richard , Dalton Charles
Published: April 2016

Strong ocean currents flowing past bluff offshore structures such as semisubmersibles and tension-leg platforms (TLP) can instigate large amplitude vortex-induced motion (VIM). This can lead to significant fatigue loads on the mooring system and its attachments. Simulating this problem numerically is of particular interest to the offshore industry in order to determine design loads and to avoid or suppress motion and vibration of the structure. But despite this being a classical flow problem, it remains a major numerical challenge, particularly at high Reynolds numbers where most offshore platforms operate. The difficulty arises from the strong nonlinear nature of the governing Navier-Stokes equations and the unsteady turbulent nature of the physical flow itself.

This study was therefore conducted to identify best practices for using Computational Fluid Dynamics (CFD) to estimate the loads imposed by uniform currents past a stationary bluff body (representing a semisubmersible column). Several Reynolds numbers were chosen to cover the subcritical, transcritical, and supercritical flow regimes. Two Reynolds-Averaged Navier-Stokes (RANS) software packages were used, the open source code OpenFOAM and the commercial code STAR-CCM+.

Verification of the numerical model and validation of results against published experimental test data is presented and the implications discussed. The paper provides several key elements that should be considered when modeling a uniform current past bluff body at high Reynolds number.
Flow Assurance Design Considerations for Umbilical Riser Base Gas Lift System
Authors: McDermott Chris , Ike Shirley , Braniff Martin
Published: April 2016

Riser Base Gas Lift is one of several methods successfully deployed that can enhance production and suppress severe slugging. With few moving parts, it is a solution that can be accommodated into existing infrastructure with minimal upgrades on existing facilities while not being as maintenance intensive as other solutions. The flow assurance design is critical to successful implementation and this paper details this process through the means of a case study.

The case study in question is a three well, deep water subsea tie-back. The subsea system consists of an 8" × 12" pipe-in-pipe round-trip piggable flowline loop which will experience severe terrain slugging. Riser base gas lift had been implemented with success on adjacent fields at this facility; therefore it was again selected for deployment. From a Flow Assurance perspective, design considerations discussed are: Optimum Injection Rate/Operating Range: Flowrate requirements that will effectively mitigate slugging and will not violate any operating constraints.Low Temperature Mitigation: Design against brittle material failure.Erosion Control: Assessment of droplet erosion.Production Chemistry: Design to prevent formation of hydrates/asphaltenes in the production system due to injection of gas.Testing/Benchmarking: Since system design is heavily dependent on the accuracy of simulation modelling, details of equipment flow tests to validate performance are discussed.Recommendations/Support to Operations: Development of standard operating practices associated with gas lift.Execution Issues: Detailing design adaptations to system changes during installation etc.Revalidation: Review of actual operational performance against design intent.

For this field, a novel technological solution of a gas-lift umbilical riser was selected. This configuration provides the best balance of operability, reliability and cost. The operating philosophy uses a fixed subsea orifice /topside choke to control the gas flow (rather than the conventional variable subsea choke). The orifice will regulate the injection rate even as the system pressure varies due to slugging, allowing the umbilical to act as an accumulator that dampens the pressure variations and allows for a larger bandwidth and smoother operation. Ultimately this configuration is envisioned to be less dependent on operator interaction.