bluuebunny/crossref_metadata_2025 huggingface dataset:
Linkage Map ofLissotritonNewts Provides Insight into the Genetic Basis of Reproductive Isolation
Authors: Niedzicka Marta , Dudek Katarzyna , Fijarczyk Anna , Zieliński Piotr , Babik Wiesław
Published: May 2017

Linkage maps are widely used to investigate structure, function, and evolution of genomes. In speciation research, maps facilitate the study of the genetic architecture of reproductive isolation by allowing identification of genomic regions underlying reduced fitness of hybrids. Here we present a linkage map for European newts of the Lissotriton vulgaris species complex, constructed using two families of F2 L. montandoni × L. vulgaris hybrids. The map consists of 1146 protein-coding genes on 12 linkage groups, equal to the haploid chromosome number, with a total length of 1484 cM (1.29 cM per marker). It is notably shorter than two other maps available for salamanders, but the differences in map length are consistent with cytogenetic estimates of the number of chiasmata per chromosomal arm. Thus, large salamander genomes do not necessarily translate into long linkage maps, as previously suggested. Consequently, salamanders are an excellent model to study evolutionary consequences of recombination rate variation in taxa with large genomes and a similar number of chromosomes. A complex pattern of transmission ratio distortion (TRD) was detected: TRD occurred mostly in one family, in one breeding season, and was clustered in two genomic segments. This is consistent with environment-dependent mortality of individuals carrying L. montandoni alleles in these two segments and suggests a role of TRD blocks in reproductive isolation. The reported linkage map will empower studies on the genomic architecture of divergence and interactions between the genomes of hybridizing newts.
A Systemic Analysis of Transcriptomic and Epigenomic Data To Reveal Regulation Patterns for Complex Disease
Authors: Xu Chao , Zhang Ji-Gang , Lin Dongdong , Zhang Lan , Shen Hui , Deng Hong-Wen
Published: May 2017

Integrating diverse genomics data can provide a global view of the complex biological processes related to the human complex diseases. Although substantial efforts have been made to integrate different omics data, there are at least three challenges for multi-omics integration methods: (i) How to simultaneously consider the effects of various genomic factors, since these factors jointly influence the phenotypes; (ii) How to effectively incorporate the information from publicly accessible databases and omics datasets to fully capture the interactions among (epi)genomic factors from diverse omics data; and (iii) Until present, the combination of more than two omics datasets has been poorly explored. Current integration approaches are not sufficient to address all of these challenges together. We proposed a novel integrative analysis framework by incorporating sparse model, multivariate analysis, Gaussian graphical model, and network analysis to address these three challenges simultaneously. Based on this strategy, we performed a systemic analysis for glioblastoma multiforme (GBM) integrating genome-wide gene expression, DNA methylation, and miRNA expression data. We identified three regulatory modules of genomic factors associated with GBM survival time and revealed a global regulatory pattern for GBM by combining the three modules, with respect to the common regulatory factors. Our method can not only identify disease-associated dysregulated genomic factors from different omics, but more importantly, it can incorporate the information from publicly accessible databases and omics datasets to infer a comprehensive interaction map of all these dysregulated genomic factors. Our work represents an innovative approach to enhance our understanding of molecular genomic mechanisms underlying human complex diseases.
A Pathway-Centered Analysis of Pig Domestication and Breeding in Eurasia
Authors: Leno-Colorado Jordi , Hudson Nick J , Reverter Antonio , Pérez-Enciso Miguel
Published: May 2017

Ascertaining the molecular and physiological basis of domestication and breeding is an active area of research. Due to the current wide distribution of its wild ancestor, the wild boar, the pig (Sus scrofa) is an excellent model to study these processes, which occurred independently in East Asia and Europe ca. 9000 yr ago. Analyzing genome variability patterns in terms of metabolic pathways is attractive since it considers the impact of interrelated functions of genes, in contrast to genome-wide scans that treat genes or genome windows in isolation. To that end, we studied 40 wild boars and 123 domestic pig genomes from Asia and Europe when metabolic pathway was the unit of analysis. We computed statistical significance for differentiation (Fst) and linkage disequilibrium (nSL) statistics at the pathway level. In terms of Fst, we found 21 and 12 pathways significantly differentiated at a q-value < 0.05 in Asia and Europe, respectively; five were shared across continents. In Asia, we found six significant pathways related to behavior, which involved essential neurotransmitters like dopamine and serotonin. Several significant pathways were interrelated and shared a variable percentage of genes. There were 12 genes present in >10 significant pathways (in terms of Fst), comprising genes involved in the transduction of a large number of signals, like phospholipase PCLB1, which is expressed in the brain, or ITPR3, which has an important role in taste transduction. In terms of nSL, significant pathways were mainly related to reproductive performance (ovarian steroidogenesis), a similarly important target trait during domestication and modern animal breeding. Different levels of recombination cannot explain these results, since we found no correlation between Fst and recombination rate. However, we did find an increased ratio of deleterious mutations in domestic vs. wild populations, suggesting a relaxed functional constraint associated with the domestication and breeding processes. Purifying selection was, nevertheless, stronger in significantly differentiated pathways than in random pathways, mainly in Europe. We conclude that pathway analysis facilitates the biological interpretation of genome-wide studies. Notably, in the case of pig, behavior played an important role, among other physiological and developmental processes.
Propuesta de zonificación ambiental del corredor biológico interurbano río María Aguilar, Costa Rica
Authors: Solano-Monge Fabián
Published: May 2017

Los corredores biológicos son reconocidos por su importancia como conectores de elementos y funciones ecológicas. Aquellos posicionados en ambientes urbanos son cruciales para el funcionamiento tanto ambiental como social y económico en su zona de influencia. Sin embargo, estos últimos poseen importantes desafíos en su consolidación y manejo, al estar con frecuencia expuestos a condiciones de estrés y disturbio humano. En este artículo se mezcla el análisis geográfico desde perspectivas de ordenamiento territorial, urbano, biogeográfico e hídrico para realizar una propuesta de zonificación ambiental aplicada al corredor biológico interurbano río María Aguilar, Costa Rica. Se utilizó una metodología de análisis mixto que considera, además de la búsqueda de bases de datos, registros y fuentes secundarias, la aplicación del método estadístico de jerarquías analíticas propuesto por Thomas Saaty. Después de realizar el procedimiento de pares ordenados de forma satisfactoria, el área pudo ser dividida en niveles de intervención desde muy alta hasta muy baja, lo que permitirá gestionar, de manera más efectiva, la zona de influencia. Se realizan una serie de recomendaciones enmarcadas dentro del Plan Nacional de Desarrollo 2015-2018 y la Política Nacional de Ordenamiento Territorial.
The Black Church: A Tree with Many Branches
Authors: Jabir Johari
Published: May 2017

“The Black Church” is a popular phrase, often uttered with little consideration of the historical dissonances that make up Black Christianity. Despite the ways Black Christianity has shared in the common aim of dignity, humanity, and freedom asserted throughout the broader history of Black religion, there has never been one monolithic Black Church. However, when viewed as a “tree with many branches,” to borrow Christopher Small’s terminology for describing the tradition of Black music making, the Black Church represents a tradition with multiple performance practices and politics that have changed throughout history. Today, many young Black activists have turned to the Black church for political support only to find most clergy unwilling to make the kind of bold gestures of resistance seen in the Civil Rights era of the 1960s. Also, younger Black activists have found the current church particularly hostile toward queer identities. The church they face, however, is not the sum total of the Black Church as a tradition. This essay is a mediation in and meditation on the Black Church’s interaction with contemporary Black activism and the tradition of Black working-class church activism as a “usable past,” a spiritual resource for the current crossroads in Black citizenship. I speak of Black working-class churches as a descriptive frame rather than in the exclusively demographic sense. Black working-class communities brought Black labor activism into churches, but further investigation is needed to adequately describe the membership of congregations discussed here. As an alternative to traditional Black Church historiography, viewing some of the connections among class, culture, and queerness can reveal how Black spirituality thrives beyond the view of the church from the top down, but it also demonstrates how and why this version of the Black church had to be sacrificed in the onslaught of neoliberalism.
“A Relatively New Discovery in the Modern West”: #BlackLivesMatter and the Evolution of Black Humanism
Authors: Floyd-Thomas Juan
Published: May 2017

Prompted by the current debate and cognitive dissonance surrounding the #BlackLivesMatter protest campaign’s desired goals of securing freedom, justice, equality, and human dignity for people of African descent in the United States, this article addresses this social movement as an extension of Black humanism. This claim is a direct result of the #BlackLivesMatter movement’s sui generis origin and evolution beyond any identifiable Black religious institution. Robin D. G. Kelley reminds us that “insisting that we are human and productive members of [American] society has been a first principle of Black abolitionist politics since at least the eighteenth century.” Thus it is important to recognize the contemporary significance of #BlackLivesMatter by placing it within a broader historical context that resonates with many tenets of the traditional Black freedom struggle yet also charts future directions, including nontheistic thought and praxis such as atheism, agnosticism, humanism, and other expressions of unbelief as part of the broader African American experience. In 2009, Pew Research Center data on religious pluralism in the United States revealed that more than 12 percent of African Americans nationwide readily self-identified as being unaffiliated with any particular religion. This group of Black nonbelievers constitutes the third largest cohort within African American religious life—a major development in the history of African American faith and culture that ought to be more fully explored and explained. Scholars have discussed the origins and varied nature of Black humanism at considerable length; this article builds upon that existing research by examining the origins and nature of Black humanism within the history of the Black freedom struggle.
Safiya Bukhari on Leading by Example
Authors: Bukhari Safiya
Published: May 2017

NONE
Multi-criteria selection of building materials
Authors: Maskell Daniel , Thomson Andrew , Walker Pete
Published: May 2017

Rational selection of building materials for their optimal performance and minimal environmental impact is complex, as materials are multi-functional. Beyond the primary function for which a material or product has been identified, such as insulation, the contribution to additional aspects of building performance may be conservatively overlooked. For example, important properties, such as latent and hygrothermal performance, are rarely considered when selecting insulation materials. Consequently, if materials are to be used optimally, there is a need for reliable and robust ranking methods based on a multi-criteria analysis. This will help to facilitate the most optimal selection of materials for building performance, environmental impact and occupant well-being. This paper describes four statistical methods of comparing and ranking different building materials. A critical appraisal of these methods is presented following implementation with a reference material data set. Finally, recommendations for future development and adoption of material selection tools are outlined.
Book review
Authors: Mair Robert
Published: May 2017

It's Warmer Down Below: The Autobiography of Sir Harold Harding, 1900–1986
Predicting tunnelling-induced ground movements and interpreting field measurements using numerical analysis: Crossrail case study at Hyde Park
Authors: Avgerinos V. , Potts D. M. , Standing J. R. , Wan M. S. P.
Published: May 2017

Ground response to the construction of the Crossrail tunnels in London Clay beneath Hyde Park has been modelled numerically using advanced finite-element analyses. The soil model used for modelling the London Clay was a kinematic hardening soil model (named M2-SKH). This model, when used for the St James's Park greenfield site, provided excellent predictions of tunnelling-induced ground movements. Comparison of the results from the analysis of the Hyde Park greenfield site with associated field monitoring data also suggests excellent predictions, even though in this case the tunnels were: of larger diameter; deeper in the London Clay; and constructed with earth-pressure-balance machines. The influence of lining permeability was found to influence significantly short- and longer-term predictions. Interpretation of the predicted surface and subsurface vertical and horizontal displacements due to the construction of the Crossrail tunnels exemplifies how numerical analysis can assist in explaining and identifying potential ambiguities in field measurements.
Numerical modelling of headed bar joints subjected to tension
Authors: Vella Jean Paul , Vollum Robert L. , Jackson Andrew
Published: May 2017

The paper addresses the analysis and design of narrow cast in situ joints between precast concrete elements, in which continuity of reinforcement is achieved through overlapping headed bars. Using headed bars minimises the lap length required within the cast in situ joint region. The paper describes a non-linear finite-element model (NLFEM), which was used to simulate a series of tension splice tests carried out by the authors to simulate the tensile zone of a joint loaded in pure flexure. The tests studied the influences of concrete strength, transverse reinforcement, confining shear studs, headed bar spacing and lap length on joint strength. Results show that the NLFEM captures the behaviour of the joint well. Parametric studies are carried out with the validated numerical model to investigate the effects of variables not considered in the tests, such as shear stud size, cover and out-of-plane offset of the headed bars. The NLFEM provides otherwise unavailable insights into joint behaviour and is considered suitable for the design of standard joint configurations. Additionally, it can assist the development of design-oriented analysis methods.
Correlation of rearfoot angle to Q-angle in patellofemoral pain syndrome: a prospective study
Authors: Dileep K.S. , Harish Krishna , Mohammed Rameez P.
Published: May 2017

Background: Objective of the study was to evaluate the correlation between rearfoot posture to Q-angle in patients with patellofemoral pain syndrome.

Methods: This is a two-year prospective observational study in which all patients with patellofemoral pain syndrome in the age group of 20-30 years were included in the study. The static Q-angle and the rearfoot angles of these subjects were measured and analyzed statistically for their correlation.

Results: There were sixty patients who fulfilled the inclusion criteria of the study. Pearson product moment correlation showed 27% subjects having rearfoot valgus and 73% having rearfoot varus angle. T test showed statistically significant Q-angle for rearfoot varus compared to rearfoot valgus.

Conclusions: Rearfoot varus is more commonly associated with patellofemoral pain syndrome. The Q-angle increases in both rearfoot varus and valgus but is significantly more in patients with rearfoot varus. 
A CONFIGURAÇÃO DO GÊNERO CÔMICO
Authors: Carli Elisana De
Published: May 2017

A CONFIGURAÇÃO DO GÊNERO CÔMICO
A EXPERIENCIA DA CONSTRUÇÃO COLETIVA DE UM CURSO TÉCNICO VOLTADO AOS POVOS INDÍGENAS DO SUDESTE PARAEN
Authors: Santana Tatiana De Oliveira , Paim Elison Antonio
Published: May 2017

A EXPERIENCIA DA CONSTRUÇÃO COLETIVA DE UM CURSO TÉCNICO VOLTADO AOS POVOS INDÍGENAS DO SUDESTE PARAEN
Currículo e globalização: perspectivas e articulações nas relações de poder e de campo científico
Authors: Junior Arlindo Soares Albergaria , Rufino Islanne Ariel Marinho , Silva Luiz Flávio da , Mata Magali Amorim , Dias Marluce Gavião Sacramento , Pedretti Roseli Garcia
Published: May 2017

Currículo e globalização: perspectivas e articulações nas relações de poder e de campo científico
A Propriedade Intelectual e a Vacina contra a Peste da Manqueira
Authors: Chamas Claudia Inês
Published: May 2017

Fundadas nos modelos de reputação e mérito, através da quantidade e qualidade das publicações, as universidades e instituições de pesquisa contemporâneas aperfeiçoaram estratégias para divulgar aos seus pares e à sociedade, o mais rapidamente possível, suas realizações. Como afirmou Jean-Baptiste de Lamarck:1 “It is not enough to discover and prove a useful truth previously unknown (...) it is necessary also to be able to propagate it and get it recognised.” A codificação (formalização) dos conhecimentos e a sua divulgação são elementos centrais na cultura acadêmica. A publicação científica constitui forma complementar ao trabalho laboratorial, criando público, disseminando informação nova, ordenando autoridade, dando crédito e estabelecendo precedências. Seja para cientistas da indústria ou do meio universitário, o reconhecimento da prioridade é alicerce fundamental do sistema de recompensas. Porém, é importante ressaltar que outras recompensas podem ser obtidas por meio de outros caminhos.
The application of high-resolution atmospheric modelling to weather and climate variability in vineyard regions
Authors: Sturman Andrew , Zawar-Reza Peyman , Soltanzadeh Iman , Katurji Marwan , Bonnardot Valérie , Parker Amber Kaye , Trought Michael C. T. , Quénol Hervé , Le Roux Renan , Gendig Eila , Schulmann Tobias
Published: May 2017

Grapevines are highly sensitive to environmental conditions, with variability in weather and climate (particularly temperature) having a significant influence on wine quality, quantity and style. Improved knowledge of spatial and temporal variations in climate and their impact on grapevine response allows better decision-making to help maintain a sustainable wine industry in the context of medium to long term climate change. This paper describes recent research into the application of mesoscale weather and climate models that aims to improve our understanding of climate variability at high spatial (1 km and less) and temporal (hourly) resolution within vineyard regions of varying terrain complexity. The Weather Research and Forecasting (WRF) model has been used to simulate the weather and climate in the complex terrain of the Marlborough region of New Zealand. The performance of the WRF model in reproducing the temperature variability across vineyard regions is assessed through comparison with automatic weather stations. Coupling the atmospheric model with bioclimatic indices and phenological models (e.g. Huglin, cool nights, Grapevine Flowering Véraison model) also provides useful insights into grapevine response to spatial variability of climate during the growing season, as well as assessment of spatial variability in the optimal climate conditions for specific grape varieties.
How to adapt winemaking practices to modified grape composition under climate change conditions
Authors: Dequin Sylvie , Escudier Jean-Louis , Bely Marina , Noble Jessica , Albertin Warren , Masneuf-Pomarède Isabelle , Marullo Philippe , Salmon Jean-Michel , Sablayrolles Jean Marie
Published: May 2017

Aim: In the context of climate change, adaptation of enological practices and implementation of novel techniques are major challenges for winemakers. The potential interventions are linked in particular with the alcohol content and the global acidity of wine. Here, we review current microbiological and technological strategies to overcome such issues.

Methods and results: Reducing ethanol concentration poses a number of technical and scientific challenges, in particular looking for specific yeast strains with lower alcohol yield. Several non-genetically modified organism (GMO) strains – S. cerevisiae or interspecific hybrids of the Saccharomyces genus – have yet been developed using different strategies, and some of them allow decreasing the final ethanol concentration by up to 1%. Several membrane-based technologies have also been developed not only to reduce the ethanol content of wines but also to increase the acidity and more generally to control the wine pH. New strategies are also proposed to improve the control of winemaking, especially the management of alcoholic fermentation of sugar-rich musts and the control of oxidation during the process.

Conclusion: Reducing ethanol of wines  and increasing their acidity are good examples of novel techniques  of interest in the context of climate change. Other strategies are still under study to adapt winemaking practices to changes in grape composition.

Significance and impact of the study: [Membrane-based technologies can be used to reduce the ethanol content of wines or to increase the acidity.  Microbiological strategies will also be soon available for winemakers.
Issues to be considered for strategic adaptation to climate evolution – is atmospheric evaporative demand changing?
Authors: Schultz Hans Reiner
Published: May 2017

The predicted developments in climate are region-specific and adaptation can only be successful considering the regional characteristics with its diverse technical, environmental, economic and social implications. Beyond some obvious adaptation strategies in response to emerging environmental constraints for example there are many more “basic” challenges below “the surface”. One of the key concerns for many regions is the availability of water and how increasing temperature will drive the evaporative demand of the atmosphere. For this, individual regions need to be analysed to quantify possible associated risks. This paper will address differences in regional water relations of grape growing areas in different parts of the world as a basis to address the points listed above.
Grapevine phenology in France: from past observations to future evolutions in the context of climate change
Authors: García de Cortázar-Atauri Iñaki , Duchêne Eric , Destrac-Irvine Agnes , Barbeau Gérard , De Rességuier Laure , Lacombe Thierry , Parker Amber Kaye , Saurin Nicolas , Van Leeuwen Cornelis
Published: May 2017

Aim: Phenology is a key factor in explaining the distribution and diversity of current vineyards in France. This work has the objective to summarize the different studies developed in France to analyze grapevine phenology.

Methods and results: Several topics are presented: a general description of all historical databases and observatory networks developed in France during the last 70 years; an overview of the different models developed to calculate the main phenological stages; an analysis of the main results obtained using these models in the context of studies of climate change impacts on viticulture in France; and finally a general discussion about the main strategies to adapt the phenological cycle to future climate conditions.

Conclusion: This review emphasizes that even if phenology is not the only trait to be considered for adapting grapevine to climate change, it plays a major role in the distribution of the current variety x vineyard associations.

Significance and impact of the study: It is therefore critical to continue to study phenology in order to better understand its physiological and genetic basis and to define the best strategies to adapt to future climatic conditions.
What is the expected impact of climate change on wine aroma compounds and their precursors in grape?
Authors: Pons Alexandre , Allamy Lucile , Schüttler Armin , Rauhut Doris , Thibon Cécile , Darriet Philippe
Published: May 2017

The intrinsic quality of a wine is strongly linked with its volatile compound composition involved in the complexity of wine’s subtle flavor nuances. Those reminiscent of green pepper, herbaceous, blackcurrant, blackberry, figs or prunes are strongly linked with the maturity of the grapes. Nowadays it is well accepted that macroscopic effects of climate change modify the environmental conditions of grape growing at local scale in all the vineyards across the world. The expected effects on grape and wine production can be positive when they increase the maturity of the grapes, but when the conditions are too warm and too dry they induce opposite effects producing grapes and wines with a lower intrinsic quality. These effects were perceived in young wines but also in older wines kept several years in bottle.

In this article, we provide some examples of effects of climate change and growing conditions on grapevine and wine quality expressed as flavors and antioxidant composition. We also report some results associated with the incidence of grape growing conditions on white and red wine aging potential and on the composition of old wines.

Finally, we discuss the opportunities for vine growers and winemakers to manage the quality of their grapes and wines in this climate change context.
Long-Lived Epidermal Cancer-Initiating Cells
Authors: Youssef Marina , Cuddihy Andrew , Darido Charbel
Published: May 2017

Non-melanomatous skin cancers (NMSCs), which include basal and squamous cell carcinoma (BCC and SCC respectively), represent a significant burden on the population as well as an economic load to the health care system, yet treatments of these preventable cancers remain ineffective. Although primary prevention is possible through minimising sunlight exposure, the World Health Organisation estimates that between 2 and 3 million new cases of NMSCs are diagnosed each year, accounting for 1 in 3 of all newly diagnosed cancers. Furthermore, studies have estimated there has been a 2-fold increase in the incidence of NMSCs between 1960s and 1980s. The increase in cases of NMSCs as well as the lack of effective treatments makes the need for novel therapeutic approaches all the more necessary. To rationally develop more targeted treatments for NMSCs, a better understanding of the cell of origin, in addition to the underlying pathophysiological mechanisms that govern the development of these cancers, is urgent. NMSCs are generally thought to arise from specific types of stem cells that become the source of clonal expansion of tumourigenic cells. Previous research on SCC has alluded to these stem cells being localised in the basal compartment of the skin, which ordinarily houses the progenitor cells that contribute towards wound healing and normal cell turnover of overlying epidermal skin layers. More recent research has suggested that commitment to differentiation, which requires exiting the basal, progenitor-cell compartment, is a reversible mechanism. Genetic modifications engage differentiated cells into dedifferentiation, converting them into cancer-initiating cells (CICs) and thereby promoting a tumourigenic environment. Here we explore the most recent developments in the understanding of skin SCC cell of origin, and discuss a case study illustrating the loss of the Grainy-head like 3 (GRHL3) transcription factor in suprabasal layers, which confers a tendency towards tumour development and thereby challenging the “stem cell” theory of tumourigenesis.
Trends in Vaca Muerta Horizontal Wells Stimulation
Authors: Johanis P. E. , Triffiletti G. E.
Published: May 2017

Until the recent crude and gas price decrease in late 2015, development in the Vaca Muerta shale experienced profitable production through improved methods, efficiency, and economics control.

To combine public domain hydrocarbon production datasets with detailed proprietary drilling information, operators and service companies can use completion, logging, and well stimulation data. These data enable analysis of trends and improvements that occur during drilling, fracturing, and production of horizontal wells targeting both shale oil and gas in the Vaca Muerta and help provide economic, efficiency, and productivity improvements.

In recent years, more than 500 wells have been drilled in the Neuquén basin in the Vaca Muerta, the majority of which are located in the Loma Campana field. Other areas under development include El Orejano, La Amarga Chica, Aguada Pichana, Sierras Blancas, Cruz de Lorena, Bandurria, Aguada Federal, La Invernada, Bajo del Choique, and Puesto Silva Oeste. As of January 2016, Vaca Muerta monthly production of oil and gas was 6.7 million bbl and 13 million barrels of oil equivalent (BOE), respectively, representing 12 and 5% of total Neuquén basin production.

A database was created including 47 records of horizontal stimulated wells that target the Vaca Muerta. Each register includes information related to location [well name, latitude, longitude, ground level, total depth (TD)]; production (operator, first oil date, effective time on, monthly oil, gas and water production); drilling (casing, liner, shoes, cementing); completion (directional survey, stages, clusters, perforations, plugs); fracturing [pump time, pressure, instantaneous shut-in pressure (ISIP), fracture gradient, horsepower, fluid type, injection rate, fluid volume, proppant type, proppant mesh, proppant mass, injection rate]; and production (cumulatives, rates, decline rate, recovery estimates, flow regime).

Several correlations and crossplots between variables were developed and analyzed to identify trends and establish normal and anomalous behavior. The validity of using early production to estimate longer periods was confirmed, enabling creation of a complementary series of production data with modeled forecasts and estimated ultimate recoveries.

Production data were then standardized by stages, horizontal length, proppant sacks (100 lbm) pumped, and fluids injected; after this, the records were sorted by productivity to determine average standardized production and typical completion and stimulation.

Observing these values over time highlights trends toward longer wells with more stages and smaller sized proppant. Simultaneously, a recent shift to shale gas objectives located slightly basinward is indicated by deeper wells, where less fluid and more horsepower were used during stimulation.
Field Treatment of an Injector Well in a Sandstone Formation Using a Low Corrosive Environmentally Friendly Fluid that Does Not Require Flow-Back
Authors: Nuñez W. , Bautista O. , Cepeda F. A. , Kleber M. A. , Dos Santos A. A. , Oliveira E. , Rodriguez O.
Published: May 2017

Throughout a waterflood project, injector wells can experience scale build up mostly related to formation-water incompatibilities; as a consequence, injectivity index (II) decreases and vertical conformance can suffer leading to poor sweep efficiency. Stimulation treatments are required to reestablish well injectivity; usually Hydrochloric acid and Regular Mud Acid are used in sandstone reservoirs. Such treatments involve a number of difficulties such as handling highly corrosive fluids, risk of clay instability, secondary reactions and time-consuming flowback of spent treatment in low pressure reservoirs.

Recently, a novel chemical was identified to effectively dissolve scale obstructions in injector wells while avoiding the operational constrains found in traditional acidizing jobs, including the need of flowback. Fluids containing the environmentally friendly chelating agent Glutamic acid N, N diacetic acid (GLDA), were tested in the laboratory under downhole conditions to evaluate the dissolution of a scale sample from the field composed by Fe2O3 and CaSO4. Additionally, core-flood, compatibility and corrosion tests were carried out to evaluate the interaction with clays, formation and well's metallurgy. Results showed effective dissolution of the scale sample, while being fully compatible with formation clays and fluids which indicated that the treatment could be left downhole and pushed into the formation without causing further formation damage. Furthermore, corrosion tests showed no need of corrosion inhibitor for a low carbon tubular under tested conditions.

Field implementation took place in an on-shore injector well completed selectively with injection valves between packers. A two stage treatment was designed; the target of the first phase was cleaning out the injection valve itself and the tubing-casing annular space of this interval, and the second stage aimed the dissolution of scale located in the perforations and deeper into the formation. Step rate tests were performed before and after the treatment to evaluate well injectivity. Low injection treatment rates and soaking allowed enough time for the GLDA to effectively dissolve the scale obstruction along the treated interval; spent treatment was pushed further into formation once regular water injection was reestablished with a 51% increase in its injectivity index. The use of GLDA in the field was considered cost-effective due to the lack of additives, no need for of N2 to kick-off flow-back, nor flow-back fluids neutralization and disposal.
Drilling Optimization of Argentina Horizontal Tight Sand Wells
Authors: Torres-Cabrera N. , Pozo M. , Finessi A. A.
Published: May 2017

Argentina tight sand wells present a hostile drilling environment with hard, abrasive, and interbedded lithology. Consequently, bottomhole assembly (BHA) behavior is difficult to predict; tools and drilling performance are often affected, leading to poor rates of penetration (ROP), unplanned trips to surface, and even lost-in-hole (LIH) scenarios. The root causes of problems during this project in the Mulichinco formation were determined to be hole cleaning, weight transfer, and vibration; this paper describes the evolution of drilling improvements based on real-time and post-well analyses.

A holistic approach was necessary to understand the evolution and interaction of each aspect of the operation, from well planning to drilling the well. All information collected and analyses performed were shared with other involved parties to continue the improvement process. The effects of various changes that were implemented were evaluated, and those that had a positive effect were replicated where possible.

During two years of tight sand well operations, the three primary problems included hole cleaning, weight transfer, and vibration. Hole cleaning was improved by closely monitoring the real-time equivalent circulating density (ECD) and torque and drag (T&D), and by adjusting the surface parameters accordingly. Comparing real-time data with the expected simulation outcomes helped to identify the optimum parameters to be used. At first, to mitigate vibration, vibration mechanisms were identified, and surface parameters were changed in an unsuccessful reduction attempt. It then became clear that the problems were associated with the BHA design, and simulations were necessary to identify the problems. Similarly, simulation results were complemented with real-time and recorded data analyses. The weight transfer problem was much more difficult to resolve. A wide variety of information was collected, including visual observation of abnormal wear in drillpipes, comparison of ROP in wells with different BHA designs, and simulations to determine the optimal positioning of the BHA and tubular components. Taking all of this information into account, adjustments were made, and weight transfer gradually improved. These combined improvements resulted in the elimination of LIH scenarios, reduction of unplanned trips caused by tool failures (primarily rotary steerable), and an average reduction of 55% of the time required to reach total depth (TD), from approximately 41.5 days to 18.5 days.

The guidelines described in this paper contribute to the technical optimization of tight sands drilling because they can be used to implement a learning curve process that is applicable for similar operations elsewhere.
Deliquification in a Mature Gas Field: Comparison of Predicted and Observed Rates after Well Workover to Install Velocity Strings
Authors: Burford J. , Falcone G.
Published: May 2017

Liquid loading is a significant issue within gas and gas condensate wells, resulting in production decline and rate instability. The Southern Gas Field serves as a case study, to investigate a field experiencing liquid loadup. The field is located in the Southern North Sea, and is being produced via natural depletion with no pressure support from the surrounding aquifer. In Yr. 9 production well A ceased to flow as a result of liquid build up, and by Yr. 11 well B also showed signs of liquid loading. The load fluid consisted of liquid condensate, and this was confirmed by wireline investigations. A decision was made by the operator to deploy two 2 3/8" velocity strings, in an attempt to extend the field lifespan, by restarting well A and returning rate stability to well B. Velocity strings are a relatively low cost deliquification method, that aim to increase the gas flow rate above the critical flow rate, enabling the well to continuously unload liquids. The design of velocity strings is crucial, as if too small a tubing is used, the velocity string can act as a choke, suffocating the well. The velocity string run in well B proved a success, however the workover in well A failed to restart the well. Batch foamer treatments were later tried in well A but proved ineffective. The effectiveness of foam to deliquifying gas wells, depends upon the composition of the load liquid, as both water and liquid hydrocarbons react differently to surfactants. Typically liquid hydrocarbons such as condensate do not foam well, and must be agitated to maintain foaming.

This study aimed to make use of Petroleum Experts Integrated Production Modelling (IPM) software to model the effect of the velocity string deployment, with regards to returning rate stability. Prosper models were created and Systems Analysis was performed and confirmed that 2 3/8" velocity strings will lift both well A and well B out of the Turner region. Prosper was also use to model the effect of using foam as an artificial lift method, with the results identifying that the water gas ratio (WGR) of the field is too low for effective deliquification using foams. A GAP model was also created for the Southern Gas Field to determine the incremental reserve gains to be had by deploying velocity strings. The simulations identified that well workovers can provide an additional 4.99 Bscf to the recoverable reserves.
Application of Transition Metal Nanoparticles in the Streams Production of Heavy Crude Oil Treatment: H2S Mitigation
Authors: Martinez S. I. , Bastidas C.
Published: May 2017

The in-line scavenging of hydrogen sulfide is the preferred method for minimizing the corrosion and operational risks in oil production (Rajagopal et al. 2009). On the other hand, it is known that Nanoparticles by their small size and high dispersion increase the probability of collision between molecules and minimize the diffusion problems. Additionally, oxides of iron, manganese, zinc, magnesium and copper are considered suitable sorbents for gas desulfurization at temperatures in excess of 300°C (Husein et al. 2010). The experiments were designed to apply nanoparticles for the streams treatment during enhanced heavy oil recovery (steam injection). Sorption of the H2S present in oil phases finds application for mitigating H2S forming during this process. In this study, our heavy crude oil whose viscosity is 10500 mPa.s, was obtained from a reservoir block of the Faja Petrolífera del Orinoco Hugo Chávez (FPOHC, Venezuela), with temperature about 80°C, and when the steam is injected temperature reach up to 260°C. Three types of nanoparticles were used to treat the heavy crude oil (H2S scavengers and reduce viscosity). The organic matrix was high vacuum gas oil (HVGO) which serves as the carrier of dispersed particles, to reduce both H2S production and viscosity, and the nanoparticles, based on transition metals that serve as H2S scavengers centers are, respectively, FexOy, CuxOy and NixOy. In these experiments, before reaction, the sand and the gaseous products were separated to remove any catalytic effect from the minerals and H2S present. Experiments were carried out in an autoclave reactor simulating steam injection condition (~600 psi and ~260°C). Appropriate quantities of heavy crude oil and water, and 500 ppm of dispersed nanoparticles were placed in the reactor; methane was used as reservoir gas. Results indicate the reduction of H2S production from 1500 ppm in the experiment without nanoparticles up to 100 ppm, 250 ppm and traces to FexOy, NixOy and CuxOy, respectively. Also, reductions of viscosity were obtained for all tests, from 15 to 26%.
Extra-Heavy Oil Viscosity Estimation Using PVT and Geochemical Analyses: Applications at Huyapari Field, Orinoco Heavy Oil Belt, Venezuela
Authors: Landaeta G. S. , Valencia L. E.
Published: May 2017

Huyapari is a giant field, located in the Orinoco Heavy Oil Belt of eastern Venezuela. Huyapari contains huge original oil in place (OOIP) of extra heavy crude oil (7 to 9°API) with excellent reservoir properties that enable primary production of the extra heavy crude oil by using long horizontal wells. Nevertheless, the live oil viscosity variation at reservoir conditions (1,500 to 20,000 cp) represents a production challenge in the field. This study aims to improve the fluid heterogeneity understanding in the field through the application of PVT (Pressure, Volume and Temperature) and geochemical analysis for oil viscosity estimation.

Fluid heterogeneity mapping using crude fingerprint analyses was performed to understand the variability of the oil biodegradation level across the field. PVT data provided reservoir GOR and supported the oil chemical variation. Biomarkers correlations were also evaluated to obtain a better estimation of oil viscosity, and then compared with oil viscosity measurements performed at surface and reservoir conditions.

The integration of geochemical analysis with the PVT data allowed to improve the Huyapari field correlations used for well potential estimation. A shallow reservoir of the field with few production wells and larger prospective areas was chosen to evaluate its oil viscosity variation and the methodology application. A better well placement and reservoir management strategy was established, thus demonstrating the value of this data integration.

This study demonstrates that reservoir geochemistry coupled with reservoir engineering data is a cost-effective reservoir management tool. This methodology could be useful for application in other extra-heavy oil fields where little reservoir geochemistry input has been considered in their field simulation procedures.
Are We Reasonably Certain that Reasonable Certainty Adequately Defines Uncertainty in Our Reserves Estimates?
Authors: Harrison B. , Falcone G.
Published: May 2017

Words can have many meanings, while numbers tend to have only one, so using the language of probability can better communicate the potential risks and uncertainties in developed oil and gas projects, which all employ uncertain forecasts of time, hydrocarbon price, cost, and reserves. Yet, rather than assign a probability value to the Proved or 1P deterministic estimate, SPE's Petroleum Resource Management System (PRMS) uses loosely defined expressions such as "reasonable certainty" to convey a high degree of confidence that the deterministically estimated hydrocarbon volumes will be recovered.

A literature review is conducted to highlight what biases people are prone to, and to reveal what people consider to be reasonable certainty. The study recounts the provenance of the phrase "reasonable certainty" in the oil and gas industry. Using published work on cognitive bias by acknowledged oil and gas consultants, drawing on research by Harvard University statisticians, and carrying out our own tests on industry professionals, the authors demonstrate that there are consistent, and quite different perceptions of the language of quantitative probability from those suggested in the PRMS.

Tests show repeatedly that industry professionals believe the probability value that corresponds to "reasonable certainty" is in the range 70-75%. This is far less than the implied 90% figure assigned to the probabilistic low estimate of recoverable volumes, generally taken as equivalent the 1P deterministic case. The divergence between deterministic language and associated and perceived probability is more pronounced when one considers the other reserves classes of 'Probable' and 'Possible'. Such perceptions lead to overly optimistic expectations and can result in poor investment decisions. There is a reluctance to assign probability values to deterministic reserve classes, but that should not prevent the assignment of more appropriate language within PRMS.

Project team members, experts, and stakeholders must be aware that they are all prone to cognitive bias, which when coupled with overly optimistic perceptions of uncertainty, leads to wrong decisions being made, and to projects being mismanaged.

The PRMS text could be changed to better describe the likelihood of the outcome of an event. The continued overuse of the loosely defined adjective 'reasonable' should be avoided. To convey probability greater than 90% or to describe the Low or Proved 1P case, the PRMS would better inform its users by using expressions like "very high probability", "almost certain", or "very likely".