bluuebunny/crossref_metadata_2025 huggingface dataset:
Cryptic speciation in allotetraploids: Lessons from the Botrychium matricariifolium complex
Authors: Williams Evelyn W. , Farrar Donald R. , Henson Don
Published: April 2016

PREMISE OF THE STUDY:

Cryptic species are a challenge for botanists and taxonomists. To improve species delineation in the genus Botrychium (Ophioglossaceae), which includes multiple instances of allotetraploid speciation, we examined a cryptic species complex using genetics and morphology.

METHODS:

We sampled species in the B. matricariifolium complex, concentrating on the Upper Peninsula of Michigan and including multiple proposed morphospecies. We analyzed over 1500 samples using 10 enzyme systems, measured 42 quantitative and qualitative morphological characters for over 650 individuals, and analyzed 145 samples using AFLPs. We tested for diagnostic enzymes in the morphospecies and calculated the correlation between morphological and genetic distances to determine whether putatively distinct morphotypes warrant taxonomic recognition.

KEY RESULTS:

Allozyme allelic variation corresponded loosely to some morphotypes of B. matricariifolium, but with lower genetic distinction among them than found between B. matricariifolium and B. michiganense. Botrychium michiganense contains unique alleles, indicating a different hybrid origin from that of B. matricariifolium and supporting its status as a genetically distinct species.

CONCLUSIONS:

We showed that B. acuminatum morphology and genetics are accommodated taxonomically within B. matricariifolium; B. matricariifolium and B. michiganense likely represent hybridization events between related species; and morphotypes within B. matricariifolium likely represent repeated hybridization events between the same two parental species. These hybridizations have resulted in the array of morphotypes observed by field botanists. By helping to identify diagnostic morphological characters, genetic analyses also help us understand and resolve morphological variation observed in the field.
Endemism in the moss flora of North America
Authors: Carter Benjamin E. , Shaw Blanka , Shaw A. Jonathan
Published: April 2016

PREMISE OF THE STUDY:

Identifying regions of high endemism is a critical step toward understanding the mechanisms underlying diversification and establishing conservation priorities. Here, we identified regions of high moss endemism across North America. We also identified lineages that contribute disproportionately to endemism and document the progress of efforts to inventory the endemic flora.

METHODS:

To understand the documentation of endemic moss diversity in North America, we tabulated species publication dates to document the progress of species discovery across the continent. We analyzed herbarium specimen data and distribution data from the Flora of North America project to delineate major regions of moss endemism. Finally, we surveyed the literature to assess the importance of intercontinental vs. within‐continent diversification for generating endemic species.

KEY RESULTS:

Three primary regions of endemism were identified and two of these were further divided into a total of nine subregions. Overall endemic richness has two peaks, one in northern California and the Pacific Northwest, and the other in the southern Appalachians. Description of new endemic species has risen steeply over the last few decades, especially in western North America. Among the few studies documenting sister species relationships of endemics, recent diversification appears to have played a larger role in western North America, than in the east.

CONCLUSIONS:

Our understanding of bryophyte endemism continues to grow rapidly. Large continent‐wide data sets confirm early views on hotspots of endemic bryophyte richness and indicate a high rate of ongoing species discovery in North America.
Unconventional application of the Mitsunobu reaction: Selective flavonolignan dehydration yielding hydnocarpins
Authors: Huang Guozheng , Schramm Simon , Heilmann Jörg , Biedermann David , Křen Vladimír , Decker Michael
Published: April 2016

Various Mitsunobu conditions were investigated for a series of flavonolignans (silybin A, silybin B, isosilybin A, and silychristin A) to achieve either selective esterification in position C-23 or dehydration in a one-pot reaction yielding the biologically important enantiomers of hydnocarpin D, hydnocarpin and isohydnocarpin, respectively. This represents the only one-pot semi-synthetic method to access these flavonolignans in high yields.
Disciplines of Political Philosophy and Political Science: Antagonism, Cooperation or Indiference?
Authors: Stoškus Mindaugas
Published: April 2016

The aim of this article is to discuss the development of the relation between political philosophy and political science. The main causes and possible perspectives of that development are elaborated. There are explored philosophical ideas which influenced the emergence of political science, the process of its institutionalisation and the relation between political science and political philosophy. The analysis of the process of institutionalisation aims at identification of the main causes of the conflict between two disciplines. The culmination of that conflict occured at sixth decade of twentieth century and was named “The Behavioral Revolution”. The sharp antagonism lasted nearly two decates and when it came to an end the relation between political philosophy and political science became stable though ambiguous.
Moral Perception, Cognition, and Dialogue
Authors: Strahovnik Vojko
Published: April 2016

The aim of the paper is to analyse the concept of moral perception. Moral perception gets characterized as a distinctive, non-inferential moral response to concrete situations. In order to relate moral perception with a suitable model of moral cognition the position labelled morphological rationalism is elaborated. Moral judgment follows a dynamical model of reasons, according to which reasons are situated in an agent’s structured morphological background, chromatically illuminating the judgment. The key claim is that such a model is particularly well-suited to accommodate moral perception. From such a perspective some practical implications are elaborated (disagreement, intercultural dialogues).
Online Artistic Activism: Case-Study of Hungarian-Romanian Intercultural Communication
Authors: Horváth Gizela , Bakó Rozália Klára
Published: April 2016

Technical reproduction in general, and photography in particular have changed the status and practices of art. Similarly, the expansion of Web 2.0 interactive spaces presents opportunities and challenges to artistic communities. Present study focuses on artistic activism: socially sensitive artists publish their creation on the internet on its most interactive space – social media. These artworks carry both artistic and social messages. Such practices force us to reinterpret some elements of the classical art paradigm: its autonomy, authorship, uniqueness (as opposed to copies and series), and the social role of art. The analysis is aimed at Hungarian and Romanian online artistic projects from Transylvania region of Romania, relevant as intercultural communication endeavours. Our research question is the way they differ from the traditional artistic paradigm.
Relativity of Visual Communication
Authors: Mutanen Arto
Published: April 2016

Communication is sharing and conveying information. In visual communication especially visual messages have to be formulated and interpreted. The interpretation is relative to a method of information presentation method which is human construction. This holds also in the case of visual languages. The notions of syntax and semantics for visual languages are not so well founded as they are for natural languages. Visual languages are both syntactically and semantically dense. The density is connected to the compositionality of the (pictorial) languages. In the paper Charles Sanders Peirce’s theory of signs will be used in characterizing visual languages. This allows us to relate visual languages to natural languages. The foundation of information presentation methods for visual languages is the logic of perception, but only if perception is understood as propositional perception. This allows us to understand better the relativity of information presentation methods, and hence to evaluate the cultural relativity of visual communication.
ON TESTING THE EQUIVALENCE PRINCIPLE WITH EXTRAGALACTIC BURSTS
Authors: Nusser Adi
Published: April 2016

An interesting test of Einstein’s equivalence principle (EEP) relies on the observed lag in the arrival times of photons emitted from extragalactic transient sources. Attributing the lag between photons of different energies to the gravitational potential of the Milky Way (MW), several authors derive new constraints on deviations from EEP. It is shown here that potential fluctuations from the large-scale structure are at least two orders of magnitude larger than the gravitational potential of the MW. Combined with the larger distances, for sources at redshift

z
≳
0.5

the rms of the contribution from these fluctuations exceeds the MW by more than four orders of magnitude. We provide actual constraints for several objects based on a statistical calculation of the large-scale fluctuations in the standard ΛCDM cosmological model.
COLD CO GAS IN THE DISK OF THE YOUNG ERUPTIVE STAR EX LUP
Authors: Kóspál Á. , Ábrahám P. , Csengeri T. , Gorti U. , Henning Th. , Moór A. , Semenov D. A. , Szűcs L. , Güsten R.
Published: April 2016

EX Lupi-type objects (EXors) form a sub-class of T Tauri stars, defined by sudden sporadic flare-ups of 1–5 mag at optical wavelengths. These eruptions are attributed to enhanced mass accretion from the circumstellar disk to the star, and may constitute important events in shaping the structure of the inner disk and the forming planetary system. Although disk properties must play a fundamental role in driving the outbursts, they are surprisingly poorly known. In order to characterize the dust and gas components of EXor disks, here we report on observations of the 12CO J = 3−2 and 4–3 lines, and the 13CO 3–2 line in EX Lup, the prototype of the EXor class. We reproduce the observed line fluxes and profiles with a line radiative transfer model and compare the obtained parameters with corresponding ones of other T Tauri disks.
DISCOVERY OF MOLECULAR HYDROGEN IN SN 1987A
Authors: Fransson Claes , Larsson Josefin , Spyromilio Jason , Leibundgut Bruno , McCray Richard , Jerkstrand Anders
Published: April 2016

Both CO and SiO have been observed at early and late phases in SN 1987A. H2 was predicted to form at roughly the same time as these molecules, but was not detected at early epochs. Here, we report the detection of NIR lines from H2 at 2.12 and

2.40

μ
m

in VLT/SINFONI spectra obtained between days 6489 and 10,120. The emission is concentrated to the core of the SN in contrast to Hα and approximately coincides with the [Si i]/[Fe ii] emission detected previously in the ejecta. Different excitation mechanisms and power sources of the emission are discussed. From the nearly constant H2 luminosities, we favor excitation resulting from the

44

Ti

decay.
NuSTAR AND SWIFT OBSERVATIONS OF THE VERY HIGH STATE IN GX 339-4: WEIGHING THE BLACK HOLE WITH X-RAYS
Authors: Parker M. L. , Tomsick J. A. , Kennea J. A. , Miller J. M. , Harrison F. A. , Barret D. , Boggs S. E. , Christensen F. E. , Craig W. W. , Fabian A. C. , Fürst F. , Grinberg V. , Hailey C. J. , Romano P. , Stern D. , Walton D. J. , Zhang W. W.
Published: April 2016

We present results from spectral fitting of the very high state of GX 339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of

a
=

0.95

−
0.08

+
0.02

and inclination of 30° ± 1° (statistical errors). These values agree well with previous results from reflection modeling. With the exceptional sensitivity of NuSTAR at the high-energy side of the disk spectrum, we are able to constrain multiple physical parameters simultaneously using continuum fitting. By using the constraints from reflection as input for the continuum fitting method, we invert the conventional fitting procedure to estimate the mass and distance of GX 339-4 using just the X-ray spectrum, finding a mass of

9.0

−
1.2

+
1.6

M

⊙

and distance of 8.4 ± 0.9 kpc (statistical errors).
CHROMOSPHERIC MODELS AND THE OXYGEN ABUNDANCE IN GIANT STARS
Authors: Dupree A. K. , Avrett E. H. , Kurucz R. L.
Published: April 2016

Realistic stellar atmospheric models of two typical metal-poor giant stars in Omega Centauri, which include a chromosphere (CHR), influence the formation of optical lines of O i: the forbidden lines (λ6300, λ6363) and the infrared triplet (λλ7771−7775). One-dimensional semi-empirical non-local thermodynamic equilibrium (LTE) models are constructed based on observed Balmer lines. A full non-LTE formulation is applied for evaluating the line strengths of O i, including photoionization by the Lyman continuum and photoexcitation by Lyα and Lyβ. Chromospheric models (CHR) yield forbidden oxygen transitions that are stronger than those in radiative/convective equilibrium (RCE) models. The triplet oxygen lines from high levels also appear stronger than those produced in an RCE model. The inferred oxygen abundance from realistic CHR models for these two stars is decreased by factors of ∼3 as compared to values derived from RCE models. A lower oxygen abundance suggests that intermediate-mass AGB stars contribute to the observed abundance pattern in globular clusters. A change in the oxygen abundance of metal-poor field giants could affect models of deep mixing episodes on the red giant branch. Changes in the oxygen abundance can impact other abundance determinations that are critical to astrophysics, including chemical tagging techniques and galactic chemical evolution.
THE ACCRETION DISK WIND IN THE BLACK HOLE GRS 1915+105
Authors: Miller J. M. , Raymond J. , Fabian A. C. , Gallo E. , Kaastra J. , Kallman T. , King A. L. , Proga D. , Reynolds C. S. , Zoghbi A.
Published: April 2016

We report on a 120 ks Chandra/HETG spectrum of the black hole GRS 1915+105. The observation was made during an extended and bright soft state in 2015 June. An extremely rich disk wind absorption spectrum is detected, similar to that observed at lower sensitivity in 2007. The very high resolution of the third-order spectrum reveals four components to the disk wind in the Fe K band alone; the fastest has a blueshift of

v
=
0.03
c

. Broadened re-emission from the wind is also detected in the first-order spectrum, giving rise to clear accretion disk P Cygni profiles. Dynamical modeling of the re-emission spectrum gives wind launching radii of

r
≃

10

2
−
4

GM

/

c

2

. Wind density values of

n
≃

10

13
−
16

cm

−
3

are then required by the ionization parameter formalism. The small launching radii, high density values, and inferred high mass outflow rates signal a role for magnetic driving. With simple, reasonable assumptions, the wind properties constrain the magnitude of the emergent magnetic field to be

B
≃

10

3
−
4

G if the wind is driven via magnetohydrodynamic (MHD) pressure from within the disk and

B
≃

10

4
−
5

G if the wind is driven by magnetocentrifugal acceleration. The MHD estimates are below upper limits predicted by the canonical α-disk model. We discuss these results in terms of fundamental disk physics and black hole accretion modes.
Enhancing Retention of Future Information Professionals Using Attitude Inoculation
Authors: Fagnot Isabelle , Stanton Jeffrey
Published: April 2016

Les prévisions d’emploi dans le domaine des Systèmes d’Information (SI) varient au fil du temps, mais les employeurs évoquent souvent le fossé entre les besoins de l’entreprise et le manque de personnes qualifiées sur le marché du travail. Ce constat soulève la question de savoir comment les étudiants prennent leur décision de poursuivre ou non un diplôme dans un domaine donné au vu des informations disponibles sur un secteur particulier du marché de l’emploi. L’objectif principal de cet article est de comprendre si et comment des messages d’inoculation pourraient aider les étudiants à maintenir leurs attitudes positives pré-existantes envers les caractéristiques des professions des technologies de l’information; d’explorer les raisons pour lesquelles certains choisissent de poursuivre des études dans le domaine des systèmes d’information et de suggérer des solutions pour accroître le nombre de ceux qui choisissent ce domaine professionnel. Ce projet de recherche utilise la Théorie de l’Inoculation. Les hypothèses posées ont été testées par une expérimentation de terrain. La première hypothèse teste la résistance au changement pour les participants qui reçoivent un message d’inoculation avant un message persuasif au sujet du domaine professionnel des systèmes d’information. Les deux autres hypothèses testent la résistance au changement sur la base du genre des participants et de leur programme d’études. Plusieurs résultats significatifs ont été mis en évidence. Les groupes qui ont été inoculés ont présenté une plus grande résistance au changement. Un déclin plus faible de la résistance a été observé pour les participants du groupe de traitement; les participants des groupes de contrôle ont été plus affectés par le message persuasif que les participants qui avaient reçu l’inoculation. Toutefois, l’étude n’a pas montré de différence significative basée sur le genre ou le domaine d’études. Ces résultats permettent de mieux adapter la communication envers les futurs professionnels de l’information.
Une lecture structurationniste des pratiques de management de projet SI
Authors: Bia Figueiredo Marie , Morley Chantal
Published: April 2016

Dans les travaux sur le management de projet, les normes sont généralement considérées comme extérieures aux acteurs. Or, elles n’ont de réalité que si elles sont mises en pratique par les acteurs des projets. En même temps, ces derniers disposent d’une capacité d’action leur permettant d’agir sur les normes mises en actes. Pour comprendre comment les normes de management de projet sont énactées et structurent les pratiques des projets, nous avons mené une étude de cas au sein d’un grand programme informatique. Le corpus a été analysé en utilisant une approche structurationniste qui permet d’étudier les pratiques de management sur un projet comme simultanément structurées par les normes énactées, mais aussi comme participant à la production de ces normes. Nous avons également repéré des pratiques sociomatérielles dans nos résultats. D’un point de vue empirique, la recherche apporte une contribution aux connaissances encore limitées sur la conduite des projets SI dans un environnement fortement normalisé. En outre, elle propose une grille de lecture alternative à celles qui dominent aujourd’hui dans la littérature sur la réalité des pratiques face aux normes, ainsi qu’une approche méthodologique pour les étudier. Son originalité principale est de mettre en évidence une construction circulaire des systèmes sociaux que représentent les projets, basée sur la réflexivité des acteurs et leur capacité transformatrice.
Le management amont et aval des droits de propriété intellectuelle au sein des écosystèmes-plateformes naissants
Authors: Attour Amel , Ayerbe Cécile
Published: April 2016

Cet article analyse les effets du management des droits de propriété intellectuelle (DPI) associés aux connaissances amont et aval dans le développement des systèmes complexes que sont les écosystèmes-plateformes naissants. Caractérisés par l’absence d’acteur orchestrateur, ces écosystèmes-plateformes sont d’emblée inscrits dans une logique d’innovation inter-organisationnelle autour de la plateforme technologique qui en structure l’existence. En montrant à l’appui du cas Nice Futur Campus (NFCampus), comment le management amont et aval des DPI contribue à la naissance des écosystèmes-plateformes du Near Field Communication (NFC), cet article propose plusieurs contributions théoriques, à la fois sur les écosystèmes naissants (très peu investis par la littérature sur les écosystèmes-plateformes) et sur les travaux relatifs à l’innovation ouverte. Ces contributions sont relatives au rôle structurant des DPI dans l’émergence d’un écosystème, à l’articulation des connaissances tacites et explicites dans son développement et au degré d’ouverture de sa plateforme technologique. L’article éclaire en outre les praticiens comme les acteurs publics locaux sur la manière dont les DPI sont susceptibles de favoriser ou freiner l’industrialisation des nombreuses expérimentations en cours, inscrites dans le domaine du NFC ou qui émanent plus généralement d’un écosystème-plateforme sans acteur orchestrateur.
Purpose, Scope, and Technical Considerations of Wearable Technologies
Authors: Mehdi Mehtab , Alharby Abdulrahman
Published: April 2016

The purpose of this chapter is to concentrate on the technical considerations of wearable technologies. Approximately 50% of this chapter will be based on technical considerations while 30% is based on study areas, universities, degrees, and other information related to wearable technologies. For new readers of wearable technologies, we begin with a brief history and cover the scope of the field. The remaining 20% of the chapter covers useful information for interested readers of wearable technology.
Health and Fitness Wearables
Authors: Butler Mike S. , Luebbers Paul E.
Published: April 2016

Health and fitness wearable technology has been around for about 45 years. The most common wearables initially included heart rate monitors, pedometers, and GPS systems. While most of these were initially available as stand-alone devices, many are now available in combination devices such as fitness trackers and smart watches. Health and fitness wearables are used in a wide variety of situations including sports, athletics, personal health, fitness, education, and medical settings. A brief history of each wearable is provided, basic functions are explained, selected research is presented, and potential future developments are discussed. Some information is provided regarding current models and features.
Wearables and People with Disabilities
Authors: Paris Damara Goff , Miller Katrina R.
Published: April 2016

Assistive technology including wearables, have a positive impact towards changing the lives of people with disabilities. Advances in glass, electronics, sensors, and a wide range of digital devices are substantially improving how people with disabilities (PWD) navigate the world, and allow greater possibilities for PWD who are competing in today's job market. This chapter explores the following topics related to disabilities: Historical developments changing the lives of people with physical and sensory disabilities, laws pertaining to technology access, technological advances in wearables for individuals who are deaf, blind, paralyzed, or other mobility and speech impairments, socio-cultural and vocational implications of wearables for individuals who are deaf, deaf-blind or speech impaired, and the applications needed for wearables to meet the on-the-job demands.
The ScavengAR Hunt
Authors: Watanabe Daniel
Published: April 2016

This chapter explains the design and execution of a pre-service teacher training case study using Augmented Reality (AR), Quick Response (QR) codes, and social media mobile applications installed on iPads. The ScavengAR Hunt activity centered on a story narrative inspired by works of fine art using trigger images from the AR mobile application ARART® and incorporated elements of the board game Clue®. Pre-service teachers in the study were divided into groups of 4-6 and assigned specific, individual roles related to a mobile application used in the ScavengAR Hunt, and completed specific tasks while exploring the campus of a midwestern university. The research monitored the groups in real-time through reports submitted on Twitter and responses from QR code scans. The ScavengAR Hunt served as a model for designing a mobile learning activity incorporating multiple mobile applications.
Microseismic Monitoring Improves Hydraulic Fracturing Diagnostic and Optimizes Field Development in Western Desert, Egypt
Authors: Salah Mohamed , Bereak Ahmed , Gabry Mohamed A. , Batmaz Taner , El-Sebaee Mohamed , Swedan Ahmed , Abdel-Halim Amro
Published: April 2016

Upper Baharyia formation is a common reservoir in the Western Desert of Egypt. It is characterized as a heterogeneous reservoir with low sand quality and shale interbeds that make hydraulic fracturing a mandatory technique to economically develop these marginal fields. The continuous economic field development requires an efficient application of hydraulic fracturing, which, in turn, requires understanding fracture propagation paths and the area of pay affected by the fracture treatment to optimize well spacing and placement and determining the best injection pattern for optimizing sweep efficiency. To optimize the fracture design, a microseismic monitoring technique was implemented for the first time in Khalda concession, Western Desert of Egypt to diagnose the hydraulic fracture and improve field development strategies. Two hydraulically fractured wells were monitored in an attempt to assess the fracture propagation and perform fracture model calibration to develop a predictive tool for hydraulic fracture design and to indicate the fracture growth as the fractures are being created by rock failure.

The objectives of this fracture mapping were to (1) measure fracture geometry (height, length and azimuth) and (2) provide immediate information that could be used on offset spacing and azimuth strategy associated with future wells. The results of microseismic fracture mapping are being integrated with the planned stimulation model, mini-frac data, stress profile and geological information shall be combined to calibrate the fracturing model for future fracturing campaigns in Upper Baharyia formation.
Statistical Rock-Property Estimates from Inverted Impedances and Rock-Physics Modeling
Authors: Spikes Kyle T.
Published: April 2016

This work provides an example of a technique to estimate reservoir properties from inverted seismic impedances. High-quality seismic data has made inversion of that data for elastic properties reliable. Petrophysical and elastic properties from well-log data, along with a rock-physics model, explain the relationships among the elastic properties and the reservoir properties of interest. However, ambiguity and non-uniqueness are present in those relationships. The inversion of seismic data for P-impedance (IP) and S-impedance (IS) requires pre-stack seismic data, and a particular algorithm to combine low-frequency information. The inversion provides IP and IS for every time sample at each CDP. A calibrated rock-physics model translates seismic-scale impedances to reservoir properties. The calibration of the model typically is done using well-log curve information around the interval of interest. This paper demonstrates the seismic inversion routine and the subsequent mapping of the inverted impedances to rock properties using data from the Marco Polo field. The rock-physics model chosen was the soft-sand model because of the geological trends identified from well data and the interpretation of the depositional environment. In addition, the well-log data indicated the presence of five facies, including a gas-sand, oil-sand, two brine-sands, and shale facies. A Bayesian classification technique mapped the seismic impedances to the most likely facies. A statistical technique was necessary to account for the non-unique relationships among the elastic and reservoir properties. The results are realizations of the most likely facies. Probabilistic estimates of porosity and saturation for the hydrocarbon-bearing facies came from joint conditional distributions of IP and the ratio of P- to S-velocity (VP/VS). Maps of the probabilities contain the associated uncertainty in each results. Limitations to this technique are three-fold. First is that the relationship is non-unique between impedances and the rock properties, whereby one value of impedance relates to different combinations of rock properties. Second, the resolution of the seismic data is the resolution of the rock properties. Third, the rock-property estimates have errors in them due to errors in the rock physics model, errors in the inverted data, and errors in the match between the data and the model.
Evolution in Reliability of High-Speed Mud Pulse Telemetry
Authors: Emmerich W. , Greten A. , Brahim I. Ben , Akimov O.
Published: April 2016

Mud pulse telemetry (MPT) is the leading real-time data transmission technology in the oil industry to deliver answers while drilling. New logging-while-drilling (LWD) tools produce increasing amounts of data that has to be transmitted to the surface. To avoid a compromise between rate of penetration (ROP) and log density, the real-time data rate has to increase. This is particularly true when demanding mud environments create demanding transmission conditions for MPT. As the well depth increases, it affects the mud density and mud plastic viscosity, making the situation even more challenging.

This paper describes evolutionary changes to a MPT system. The system uses a special training sequence (TS) that is regularly sent by a shear valve pulser. Surface controls detect the TS and use it to tune, automatically, adaptive filters. These filters respond to the current channel conditions, enabling reliable physical data rates of 10bit/s and greater. To avoid decreasing the decoding quality due to non-optimal filters that have been calculated during pressure/flow disturbed transmission, the system automatically tests the performance of all filter sets. Afterwards, the coefficients are saved into a database with additional information. This empowers the field service engineer to perform a quick look at the database and maintain high decoding quality.

Sophisticated changes to the TS and to the surface algorithms have significantly improved the automated detection rate of the TS search. Compared to offset runs in challenging fields, decoding quality and reliability have improved. The introduction of higher automation levels enables field personnel to deliver more answers to the operator, and provide multifaceted bottomhole assemblies with many LWD services. By eliminating the tradeoff between ROP and log density through higher data rates in MPT, the overall cost of drilling wells decreases without compromising safety.
Asset Integrity Monitoring for Sand Erosion on an Offshore Gas Production Platform
Authors: Fuggle Tom
Published: April 2016

Abrasive sand in the produced fluid can eat away at metal at an astonishing rate and monitoring pipe wall thickness in high risk areas and adjusting the flow of gas to minimise erosion can make a tremendous difference in preserving the integrity of the asset whilst maximising production rates.

Typically, acoustic sand detectors are used to detect periods of high sand production and production is throttled to avoid erosion of pipework during these periods. However, this approach does not directly measure the erosion impact - loss of metal and resulting loss of integrity of the piping systems.

An integrity monitoring system is introduced that ensures that accurate and up-to-date information about the impact of sand production on metalwork is available. The monitoring system brings significant benefits in cost reduction, production maximisation, safety and reliability – all ultimately improving the profitability of the production asset.

In the case study presented, the producer was able to increase production of an unmanned platform in the Caribbean Sea by 12% resulting in a payback period of several days. The data is used to detect and optimise control of erosion issues early. Non-intrusive, battery-operated, wireless integrity monitoring systems are ideal for inaccessible locations such as offshore assets, where the costs and safety risks of access to the fixed equipment for any kind of manual inspection are high.
Gas-Driven Power Generation System: The Niger Delta Contribution to the Nigerian National Grid
Authors: Idachaba Francis Enejo
Published: April 2016

Nigeria ranks as the country with the 7th largest proven reserves of gas globally but currently focuses on the exploration of its oil with little economic use of its gas. The gas is either exported as Liquefied Natural Gas or flared by the oil and gas majors. The government has attempted to minimize the flaring by putting legislations to compel the International Oil Companies (IOCs) to stop the flaring and also encourage the utilization of the gas for electricity generation but the main challenge with this approach has been in the high cost associated with the compression and storage of the gas and the risks of vandalism associated with pipeline transport of the gas. This paper presents an approach for increasing the utilization of the gas for power generation by minimizing the risks associated with vandalization. The Niger Delta which has the bulk of the reserves can become the power generation hub of the country where all the gas driven power generation is done and fed to the national grid through a network of transformers and power lines. This configuration will eliminate the need for long pipelines while enabling the deployment of monitoring technologies on the short lines and also minimize the storage capacity required as the gas produced will be utilized by the generators. It also provides an opportunity for public Privat participation in the power supply sector. This system will ultimately improve the power supply availability in the country.
Advancements in Extreme Pressure Rotary Sealing
Authors: Dietle Lannie , Richie Aaron
Published: April 2016

Polymeric rotary seals used in various oilfield equipment face challenging demands, including rotation for extended periods of time while sealing high differential pressure (?P). Such seals are typically mounted in a housing and compressed radially against a rotatable shaft, and prevent fluid from escaping through the clearance between the shaft and housing.

One of the damage mechanisms that limits seal life is extrusion. High ?P forces seal material to extrude into the shaft-to-housing clearance. Factors such as shaft defection and runout overstress the extruded material, causing pieces to break away. Another damage mechanism is the accelerated adhesive wear that occurs when the PV (pressure times velocity) capacity of the seal material is exceeded for conventional rotary seals, or as hydrodynamic rotary seals transition toward boundary lubrication. In static sealing, extrusion is minimized by reducing shaft-to-housing clearance. In rotary sealing, the clearance has to be large enough to accommodate shaft deflection, runout, etc. Failure to provide adequate clearance results in heavily loaded metal-to-metal contact that damages the shaft, the seal, and the housing.

This paper describes an innovative sealing arrangement that dramatically increases the PV capability of rotary seals, and summarizes key results from an extensive laboratory test program. Test conditions that were varied include shaft diameter, velocity, ?P, temperature, seal material, and lubricant. In the most extreme tests, each seal was exposed to a ?P of 7,500 psi and a velocity of 240 ft/minute for 1,000 hours, and survived in excellent condition. Potential applications for the new technology include rotating control devices (RCDs), washpipe assemblies, cementing heads, and hydraulic swivels.

The new high ?P sealing arrangement is based on three technical advances:

The seal is lined with a plastic having excellent high pressure extrusion resistance.

The seal incorporates an advanced hydrodynamic inlet geometry that is sufficiently aggressive to produce hydrodynamic interfacial lubrication when plastic seal materials are used. Hydrodynamic lubrication with plastic seals significantly increases the PV capability of the seals beyond what is achievable with elastomer seals.

An axially force balanced, radially pressure balanced backup ring having a very small clearance with the shaft is interposed between the rotary seal and the shaft-to-seal housing clearance.

 

The extrusion resistance of the hydrodynamic plastic seal, combined with the axially and radially balanced backup ring, allows this rotary sealing arrangement to reliably operate at ~5 times the PV value of conventional high pressure polymeric seals for durations in excess of 1,000 hours.
StressCage and Frac Pack: Drilling the Conventionally Undrillable Without Creating the Unfraccable
Authors: Rylance M. , Mahadev K.
Published: April 2016

There is little doubt that the success and reliability of frac-pack completions in the Gulf of Mexico has become the yard-stick by which Gulf of Mexico sand control completions are currently measured. Simultaneously, StressCage has become common practice as a method to overcome challenges drilling through depleted zones, in order to cope with complex mud-window constraints for new developments and infill wells. The success of these drilling and completion approaches and their rapid widespread application has resulted in ever more depletion. This has potentially created a vicious circle in terms of drilling the well to desired depth vs. the ability to install a low-skin frac-pack completion.

While these two techniques in isolation represent uniquely optimal solutions to their individual challenges, there is growing evidence that their application within the same wellbore has the potential to create conflicting ideals. The StressCage application is associated with the plugging of small fractures which have been induced in the wellbore wall, thereby increasing the effective fracture gradient, which allows for the drilling of substantial depletion. However, the presence of a range of widely distributed particle sizes in the mud system, as well as increased general solids loading, may result in deep and invasive plugging of the permeable formations and any smaller fractures within the same open-hole sections. When these plugged formations are then the target for subsequent fracturing operations, there is a significant potential to create near wellbore problems that complicate or bring into question the ability to install a frac-pack completion.

This paper will provide a number of examples of the application of StressCage, where resulting frac operations appear to have been hampered or complicated by the use of the StressCage approach and/or associated mud conditions. These examples will provide some evidence of such interactions but, more importantly, demonstrate the contradiction that these two techniques potentially represent. The paper will also outline a scenario resulting from a sand-control lower completion assembly in place, in a new borehole drilled with StressCage method, that could be resistant to any form of frac breakdown (or simple mechanical intervention), and, thereby, compromise the frac and well completion itself.

In addition to the case histories, the paper will outline various engineering approaches that should be considered, including geo-mechanical analysis of well placement, identification of near wellbore issues prior to and during the fracturing operations, careful management of stress caged solids makeup, mud management and frac-pack design in order to avoid or overcome such challenges. All of this helps ensure that we do not create the paradox of being able to drill through the undrillable but then creating the unfraccable as a result.
Functionalized Nanosilicas as Shale Inhibitors in Water-Based Drilling Fluids
Authors: Boul Peter J. , Reddy B. R. , Hillfiger Matt , O'Connell T. Pete , Thaemlitz Carl
Published: April 2016

Water-based mud formulations inclusive of nanosilicas offer the possibility for improved shale inhibition with reduced environmental impact over conventional shale inhibitors. These additives may be effective in maintaining well stability and in preventing equipment problems, such as bit balling, which may be experienced in the absence of good shale inhibition.

A series of different nanosilicas have been tested as shale inhibitors in water-based muds. Differences in shale inhibition are observed depending on the kind of nanosilica that is used. The Nanosilicas described in this article are tested in fresh water and sea water to determine their applicability in both on-shore and off-shore scenarios. In sea water, nanosilica muds appear to be more powerful inhibitors than silicate/KCl muds. The data presented in this report indicate that a nanosilica mud achieves less shale erosion in sea water than a conventional silicate/KCl mud. This increased performance of nanosilica is accompanied with greater ease in handling the lower pH fluid (which can range from pH 8.5 to 10.0) compared to silicate muds which often exceed pH 12. In addition to being more potent inhibitors and more safe to handle, nanosilicas offer the possibility of lower environmental cost. High concentrations of potassium chloride are not necessarily required when nanosilicas are included in a mud design for shale inhibition.
A New Subsea Large Load Deployment System
Authors: Krasin T. , Lee B. , Newlin P. , Brennan K. , Nicoll R. , Wilson C. , Noseworthy N. , Chitwood J. , Schroeder A. , Gay T. , Cercone D. , Pappas J. M.
Published: April 2016

This study is part of a public-private partnership / industry sponsored project developing a detailed design of a qualified subsea 3,000+ barrel chemical storage and injection system, that requires maturing an innovative subsea facilities deployment and recovery technique for large and heavy loads. This paper describes the innovative Anchor Handling Tug Supply (AHTS) based method that was developed to provide this installation capability which is readily adaptable for accurate, safe, and cost effective subsea placement of a wide range of subsea systems and components.

Design and simulation studies, supplemented with an industry Subject Matter Expert (SME) populated Qualitative Risk Assessment (QRA), have validated the features and functional performance for installing and recovering the chemical and injection facilities, which have a projected mass of around 1,000mT. The initial application is to install the 3,000 useable barrel chemical storage and injection system, after which with minor engineering and procedure updates, will be suitable for the cost effective installation and recovery of other large and heavy subsea facilities.

The business driver to mature this technology is the operational cost savings that is achieved by using two anchor handling vessels of opportunity for operational support. In addition, the same installation spread is capable of recovering the installed facilities should facility repair, maintenance, or refurbishment be required. The recovery procedure is essentially the reverse of the installation operations.

Thus the potential exists for this deployment technology to create an environment for game changing conditions impacting the architecture, installation, and maintenance of major subsea installations as the technology is matured and field utilized. This significant developmental project is being monitored and advised by industry representatives through the active representation of operators, service companies, and OEMs participating in the project's technical advisory committee and through the significant contribution of data and expertise.
Hull, Mooring and Riser Concept Selection for Deepwater Field Development in Offshore Northwest Australia
Authors: Wu Yongyan , Lu Roger , Wang Tao , Vijayaraghavan Vishnu , Eide Rolf
Published: April 2016

Several recent large natural gas discoveries in offshore northwest Australia make the area one of the hottest regions for offshore energy activities. Selection of a field development option in early phase will significantly affect overall project economics, schedule and risk, and is complicated by uncertainties in metocean, topsides, subsea layout, and flow assurance. This paper presents a rational screening process for deepwater gas field development in offshore Northwest Australia.

The screening starts with a fair number of potential alternatives using Field Options Generator. Invalid or obviously inferior combinations were eliminated and this yields a "longlist". The next step of screening involves a method called Analytic Hierarchy Process (AHP) to rigorously filter the longlist options. Based on pairwise comparisons, AHP is a multi-criteria decision-making methodology which improves the qualitative and quantitative aspects of the decision-making process. The results are "shortlisted" options. Finally, an Even Swaps Analysis (ESA), which focuses on improving alternatives instead of eliminating, is applied to reach final concept selection for the definition phase.

The field is located in deep water offshore Australia. The region is known for long-period Southern Ocean swells, strong trade winds, monsoonal flow interactions, and high plasticity calcareous soil. The "Field Options Generator" generates thousands of concepts. All concepts are grouped into "families" based on "Substructure" building blocks: Deep Draft Semi, Conventional Draft Semi, TLP, Spar, Round-Shaped FPU, and Ship-Shaped FPU. Removing the obviously invalid combinations gives a reasonable number of "Long List" options. The AHP method is thereafter applied to give weights of eight criteria, which yields a short-list of five concepts including Semi and Spar-based solutions. As both hull concepts have advantages and disadvantages, instead of passively viewing alternatives as monolithic ideas, Even Swaps Analysis provides an opportunity to focus on how to improve the alternatives in terms of criteria for a rational trade-off, and finally the concept of Semi with lazy wave riser is recommended.

As offshore industry moving toward deep-water with more technical / financial risks and uncertainties involved, rigorous field option selection is necessary. This paper uses a novel process combing AHP with ESA which decreases subjectivity and increases rationality during an early phase concept selection. The paper is of particular interest as a reference for selecting field development options suitable for the offshore northwest Australia area and other challenging locations.