bluuebunny/crossref_metadata_2025 huggingface dataset:
¿La crisis de la biodiversidad es la crisis de la taxonomía?
Authors: Villaseñor José Luis
Published: February 2015

El compromiso de integrar una lista florística que plasme el conocimiento de la diversidad vegetal a corto plazo, solamente será alcanzado con un cuerpo sólido de taxónomos especialistas, el cual, en lugar de fortalecerse, más bien parece estar en decaimiento. Los objetivos de este trabajo son discutir el papel que han jugado los taxónomos mexicanos en el conocimiento de la flora de México y cuál es el capital humano con que se cuenta en la actualidad, así como analizar el conocimiento que se tiene actualmente sobre la flora de México y su relevancia en las estrategias de conservación de la biodiversidad. Se proponen además, estudios novedosos que podrían complementar el conocimiento taxonómico para lograr definir las zonas más importantes de riqueza y endemicidad ( hotspots ) que complementen o actualicen nuestro Sistema Nacional de Áreas Naturales Protegidas. Los principales resultados señalan que la tasa de descripción de especies nuevas todavía muestra un sesgo importante en el número total de especies en la flora mexicana, ya que cada año se adiciona un número importante, ya sea como especies o como registros nuevos. Gran parte del descubrimiento de la diversidad faltante es obtenido con la revisión especializada del estudio de las colecciones científicas, aunque el número de taxónomos especialistas ha sufrido una disminución considerable. Se discuten algunas líneas emergentes de estudio que han ayudado a definir mejores estrategias de búsqueda y análisis de la biodiversidad, que seguramente facilitarán el trabajo de exploración e investigación de este componente desconocido de la diversidad vegetal del país. Se propone que, evitando la crisis que enfrenta actualmente la taxonomía, se minimizará de manera importante la crisis de la biodiversidad y de otras áreas de investigación afines. Desafortunadamente, el problema de la desaparición de los taxónomos en el mundo (y México no es la excepción), se debe en gran parte a los mecanismos de evaluación de la producción académica, a los ingresos obtenidos mediante recursos extraordinarios (subsidios a proyectos), y al factor de impacto de las revistas donde se publican los resultados. Se debe resolver esto para evitar considerarlos una especie en extinción.
Algunas reflexiones en torno al trabajo florístico en México
Authors: Rzedowski Jerzy
Published: February 2015

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Are conservation organizations configured for effective adaptation to global change?
Authors: Armsworth Paul R , Larson Eric R , Jackson Stephen T , Sax Dov F , Simonin Paul , Blossey Bernd , Green Nancy , Klein Mary L , Lester Liza , Ricketts Taylor H , Runge Michael C , Shaw M Rebecca
Published: February 2015

Conservation organizations must adapt to respond to the ecological impacts of global change. Numerous changes to conservation actions (eg facilitated ecological transitions, managed relocations, or increased corridor development) have been recommended, but some institutional restructuring within organizations may also be needed. Here we discuss the capacity of conservation organizations to adapt to changing environmental conditions, focusing primarily on public agencies and nonprofits active in land protection and management in the US. After first reviewing how these organizations anticipate and detect impacts affecting target species and ecosystems, we then discuss whether they are sufficiently flexible to prepare and respond by reallocating funding, staff, or other resources. We raise new hypotheses about how the configuration of different organizations enables them to protect particular conservation targets and manage for particular biophysical changes that require coordinated management actions over different spatial and temporal scales. Finally, we provide a discussion resource to help conservation organizations assess their capacity to adapt.
Likelihood analysis of spatial capture‐recapture models for stratified or class structured populations
Authors: Royle J. Andrew , Sutherland Chris , Fuller Angela K. , Sun Catherine C.
Published: February 2015

We develop a likelihood analysis framework for fitting spatial capture‐recapture (SCR) models to data collected on class structured or stratified populations. Our interest is motivated by the necessity of accommodating the problem of missing observations of individual class membership. This is particularly problematic in SCR data arising from DNA analysis of scat, hair or other material, which frequently yields individual identity but fails to identify the sex. Moreover, this can represent a large fraction of the data and, given the typically small sample sizes of many capture‐recapture studies based on DNA information, utilization of the data with missing sex information is necessary. We develop the class structured likelihood for the case of missing covariate values, and then we address the scaling of the likelihood so that models with and without class structured parameters can be formally compared regardless of missing values. We apply our class structured model to black bear data collected in New York in which sex could be determined for only 62 of 169 uniquely identified individuals. The models containing sex‐specificity of both the intercept of the SCR encounter probability model and the distance coefficient, and including a behavioral response are strongly favored by log‐likelihood. Estimated population sex ratio is strongly influenced by sex structure in model parameters illustrating the importance of rigorous modeling of sex differences in capture‐recapture models.
The magnitude and spatial patterns of historical and future hydrologic change in California's watersheds
Authors: Thorne James H. , Boynton R. M. , Flint Lorraine E. , Flint Alan L.
Published: February 2015

Process‐based models that link climate and hydrology permit improved assessments of climate change impacts among watersheds. We used the Basin Characterization Model (BCM), a regional water balance model to (1) ask what is the magnitude of historical and projected future change in the hydrology of California's watersheds; (2) test the spatial congruence of watersheds with the most historical and future hydrologic change; and (3) identify watersheds with high levels of hydrologic change under drier and wetter future climates. We assessed change for 5135 watersheds over a 60‐year historical period and compared it to 90‐year future projections. Watershed change was analyzed for climatic water deficit, April 1st snowpack, recharge, and runoff. Watersheds were ranked by change for the historical and two future scenarios. We developed a normalized index of hydrologic change that combined the four variables, and identified which watersheds show the most spatial congruence of large historical change and continued change under the two futures. Of the top 20% of all watersheds (1028), 591 in the Sierra Nevada Mountains and Northwestern ecoregions have high spatial congruence across all time periods. Among watersheds where change accelerates in the future, but not historically, a majority are congruent between both climate models, predominantly in the Sierra Nevada, Cascade Ranges and the Northwestern ecoregions. This congruence of impacts in watersheds under drier or wetter scenarios is driven by snowpack, but in areas with low snowpack, hydrologic change varied spatially depending on projected precipitation and temperature, with 151 watersheds in Northwestern California showing high levels of drying under the drier scenario, while 103 watersheds in Central western and Southwestern California show increasing hydrologic activity under the wetter scenario. In some regions, the loss of snowpack allows the cycle of runoff and recharge to function without delay represented by springtime snow melt, causing these watersheds to become more immediately hydrologically responsive to changing climate. The study also found watersheds with low rainfall that have already passed through their highest response to changing climate, and show less future change. The methods used here can also be used to identify watersheds resilient to changing climate.
Closer to the rear edge: ecology and genetic diversity down the core‐edge gradient of a marine macroalga
Authors: Zardi G. I. , Nicastro K. R. , Serrão E. A. , Jacinto R. , Monteiro C. A. , Pearson G. A.
Published: February 2015

A fundamental goal in ecology is to understand distribution and abundance of species. Peripheral populations inhabiting the trailing‐edge of a species' distribution may carry considerable ecological and evolutionary value yet being most threatened under predicted climate change scenarios. However, the nature of species distributional limits and the ecological and genetic implications of living at low latitude rear edges remain unclear. The assumption that population abundance declines towards range edges, where environmental selective pressure increases, is the basis of a wide range of ecological and evolutionary predictions. Empirical data have provided contrasting evidence about the consequences of living at low latitude distributional limits, raising concerns regarding their generality and highlighting the need for combined multidisciplinary tests. Here, we provide a long‐term, comprehensive evaluation of latitudinal patterns in genetic diversity, demographic, morphological and life history traits in the marine macroalga Fucus guiryi.

The center to edge transition was mirrored by increasing water and air temperature gradients, with sea surface temperature of coldest months being the most relevant influence on F. guiryi traits. Overall, we identified a strong correlation between ecological data, collected over one year at bimonthly intervals, and distance to the range center. We found decreasing population and individual size towards distributional margins. Similarly, reproductive capacity, threshold size for reproduction, density of reproductive population and recruitment rates showed a core to edge reduction. Temporal variability of individual reproductive effort and recruitment rates did not conform to the general pattern. In contrast, population genetic data did not show a core‐edge gradient, as gene diversity and allelic richness were not significantly lower at edge populations, contradicting predictions of higher drift and bottlenecks for smaller edge populations.

The contrasting support provided by genetic and ecological data highlights the need to combine multiple and cross‐disciplinary evidence for a comprehensive understanding of ecological and evolutionary mechanisms linked to species ranges.
Association Between Periodontal Disease and Overweight and Obesity: A Systematic Review
Authors: Keller Amélie , Rohde Jeanett F. , Raymond Kyle , Heitmann Berit L.
Published: February 2015

Background: Periodontitis and obesity are among the most common chronic disorders affecting the world's populations, and recent reviews suggest a potential link between overweight/obesity and periodontitis. However, because of the scarcity of prospective evidence, previous reviews were primarily based on cross‐sectional studies, with only a few longitudinal or intervention studies included. This study's objective is to examine the time‐dependent association between obesity and periodontitis and how weight changes may affect the development of periodontitis in the general population. Therefore, longitudinal and experimental studies that assessed the association among overweight, obesity, weight gain, waist circumference, and periodontitis are reviewed.

Methods: Intervention and longitudinal studies with overweight or obesity as exposure and periodontitis as outcome were searched through the platforms PubMed/Medline and Web of Knowledge.

Results: Eight longitudinal and five intervention studies were included. Two of the longitudinal studies found a direct association between degree of overweight at baseline and subsequent risk of developing periodontitis, and a further three studies found a direct association between obesity and development of periodontitis among adults. Two intervention studies on the influence of obesity on periodontal treatment effects found that the response to non‐surgical periodontal treatment was better among lean than obese patients; the remaining three studies did not report treatment differences between obese and lean participants. Among the eight longitudinal studies, one study adjusted for C‐reactive protein (CRP) and biologic markers of inflammation such as CRP, interleukin‐6, and tumor necrosis factor‐α, and inflammation markers were analyzed separately in three of the five intervention studies.

Conclusion: This systematic review suggests that overweight, obesity, weight gain, and increased waist circumference may be risk factors for development of periodontitis or worsening of periodontal measures.
Periodontal Status and Whole Salivary Cytokine Profile Among Smokers and Never‐Smokers With and Without Prediabetes
Authors: Javed Fawad , Al‐Kheraif Abdulaziz A. , Al Amri Mohammad D. , Alshehri Mohammed , Vohra Fahim , Al‐Askar Mansour , Malmstrom Hans , Romanos Georgios E.
Published: February 2015

Background: Whole salivary interleukin (IL)‐1β and IL‐6 in smokers and never‐smokers with prediabetes remains uninvestigated. The aim of this study is to assess the periodontal status and whole salivary IL‐1β and IL‐6 levels among smokers and never‐smokers with and without prediabetes (controls).

Methods: Ninety‐five males (45 with prediabetes and 50 systemically healthy controls) were included. Twenty‐seven controls and 29 patients with prediabetes were smokers. Periodontal parameters (plaque index, bleeding on probing, probing depth, clinical attachment loss, and marginal bone loss) were measured, and the number of missing teeth were recorded. Fasting blood glucose (FBG) and hemoglobin A1c (HbA1c) levels were recorded. Unstimulated whole saliva samples were collected, unstimulated whole salivary flow rate (UWSFR) was determined, and IL‐1β and IL‐6 levels were measured. P values <0.05 were considered statistically significant.

Results: FBG (P <0.05) and HbA1c (P <0.05) levels were higher among patients with prediabetes than controls. All patients with prediabetes were hyperglycemic. UWSFR was significantly higher among controls than among patients with prediabetes (P <0.05). Periodontal parameters and whole salivary IL‐1β and IL‐6 levels were comparable among smokers and never‐smokers with prediabetes. Among controls, periodontal parameters and whole salivary IL‐1β and IL‐6 levels were higher among smokers than never‐smokers (P <0.05).

Conclusions: Among controls, periodontal inflammation was worse, and whole salivary IL‐1β and IL‐6 levels are higher in smokers than never‐smokers. Among patients with prediabetes, periodontal inflammation and whole salivary IL‐1β and IL‐6 levels were comparable between smokers and never‐smokers.
The Ice and Salt Challenge: An Atypical Presentation of a Cold Injury
Authors: Vosbikian Michael M. , Ty Jennifer M.
Published: February 2015

Case:

We present a case of a healthy seventeen-year-old adolescent with a cold injury to the hands from a new phenomenon known as the “ice and salt challenge,” where adolescents hold an ice cube and salt against their skin in competition to see which participant can withstand the discomfort the longest. This competition results in a characteristic injury pattern to the hands. The patient was treated with local wound care and had no long-term deficits.

Conclusion:

It is important for orthopaedic surgeons to be aware of the ice and salt challenge because they may be the first health-care providers to witness its effects. A high index of suspicion is critical in order to properly diagnose, treat, and counsel these patients against risk-taking behaviors.
Complete Wear-Through of a Polyethylene Liner and Metal-Backed Acetabular Cup Resulting in a Unique Form of Catastrophic Total Hip Arthroplasty Failure
Authors: Knudsen Michael L. , Coobs Benjamin R. , Kyle Richard F.
Published: February 2015

Case:

We describe a case of total hip arthroplasty failure where a cobalt-chrome femoral head completely wore through the polyethylene liner and the titanium acetabular cup. The patient subsequently underwent revision total hip arthroplasty with acetabular revision and femoral head exchange.

Conclusion:

This case illustrates the natural history of catastrophic failure in a metal-on-polyethylene total hip arthroplasty design. If recognized earlier, this patient may have been a candidate for isolated liner and head exchange. Additionally, this case represents a unique complication in using mixed metals in total hip arthroplasty, where the harder cobalt-chrome femoral head wore completely through the much softer titanium component.
Subscapular Abscess in a Nine-Year-Old Female Patient
Authors: Giugale Juan M. , Bosch Patrick P. , Grudziak Jan S.
Published: February 2015

Case:

The subscapular space is a clinically concealed anatomic space where soft-tissue abscesses can form. To our knowledge, five cases of a subscapular abscess have been reported in the past thirty-four years, so there is little evidence available to guide treatment. We present a unique case of a spontaneous, subscapular abscess due to methicillin-resistant Staphylococcus aureus in a pediatric host, and we describe a surgical approach for adequate debridement.

Conclusion:

The effective treatment of a subscapular abscess depends on an accurate, rapid diagnosis and effective surgical debridement. A modified Judet approach provides adequate access to the subscapular space for debridement.
Energy 360: Listening Loudly to Our Members and Our Industry
Authors: Haldorsen Helge Hove
Published: February 2015

President's column

SPE is unique by design. It is global, it is not-for-profit, it exists for the benefit of its large and diverse membership of 143,000 and the technical content of SPE’s programs is developed by its members. Hence, SPE is an organization in which the primary beneficiaries—the workers and the customers are the same people—the members! SPE’s mission and vision (see boxes) provide us with a world of opportunity to serve our members and the exploration and production (E&P) industry as a whole. At any time, there are hundreds of new initiatives that SPE could consider in delivering an improved value proposition to our members and the E&P industry we serve.

The SPE Board of Directors, elected as global representatives of the members, allocates SPE’s resources across a portfolio of member services in alignment with SPE’s approved strategic plan and the more specific strategic objectives. The Annual Technical Conference and Exhibition (ATCE) in October 2014 in Amsterdam gave us the opportunity to hear from two important groups: senior industry executives and young professionals (YPs). We wanted to hear their ideas, desires, and concerns for improving SPE’s value proposition from their vantage point.

Initiated about 7 years ago, the Industry Advisory Council (IAC) is an international group of senior E&P executives. The IAC meets annually during ATCE. The Amsterdam venue allowed for greater participation by representatives of European companies, along with US and Middle Eastern participants.

The IAC strongly recommends that SPE continues to focus on its core mission. In doing so, SPE provides timely, objective E&P context for its members (e.g., E&P costs are too high, the industry’s competitiveness is being eroded, communities expect more of us, our field forecasts are often too optimistic, and more than 80% of project risks are nontechnical risks). The Society also provides sharing of the latest relevant technology, tools, and the best practices with members quickly to improve health, safety, security, environmental, and social responsibility (HSSE-SR) practices and the industry’s overall value creation.

The IAC also noted that if SPE continues to listen to our industry’s and our members’ needs, the Society’s sharing arenas and conferences will be preferred by the E&P industry because of its spot-on relevance. The IAC would further like to see more focus on the importance of the integration of disciplines and field development teamwork through sessions with more case study focus. I say: Let us make 2015 the year of massive cross-discipline collaboration. E&P value creation is a jigsaw puzzle with many pieces to offer. The role of the project “integrator” is to orchestrate ways of getting great pieces (ideas) from all disciplines such that we end up with the best looking field development picture we can in terms of value creation and forecasts (of schedule, cost, production, reserves, and similar) actually resembling actuals.
Technology Update: MPD Widens Offshore Drilling Capabilities
Authors: Hannegan Don
Published: February 2015

Technology Update

The second of a two-part series, this article presents an update on several managed-pressure drilling (MPD) technologies in use offshore.

Approximately one-half of all offshore conventional oil and gas resources are known or thought to be undrillable with conventional, open-to-atmosphere circulating fluids systems for safety, economic, and/or technical reasons. In deeper water, pressure on exposed formations created by a tall column of annulus returns in marine risers grossly overbalances many reservoirs, resulting in a higher proportion of undrillable prospects.

Many offshore drilling programs experience a slow rate of penetration and instances of stuck pipe, kicks, and lost circulation, which collectively account for about one-third of all the nonproductive time on drilling projects. As the elapsed time increases, so does the cost per foot drilled and the probability of other things going wrong, creating a temptation for taking short cuts to save time and money. If drilling difficulties lead to the use of excessive casing strings, the result may be reaching total depth with too small a hole for a productive well.

An inherent weakness associated with the hydraulics of conventional circulating fluids systems has become more troublesome. In the face of unexpected downhole pressure environments and wellbore instability, the only way to influence the wellbore pressure profile as drilling progresses is to change the circulating rate (mud pump speed), which influences the equivalent mud weight (EMW). The only means of applying backpressure to increase the wellbore pressure profile is to close the blowout preventer (BOP). Consequently, the primary well-control barrier is limited to the hydrostatic pressure applied to exposed formations.

The root concepts of the hydraulics of conventional drilling were founded in the Spindletop field in Beaumont, Texas, circa 1901. The “Spindletop gushers” were initially a time of celebration. However, resulting wasted resources, fires, and lawsuits prompted a need to drill into the reservoir without experiencing a blowout. The solution was to drill with weighted fluids, literally mud from a cattle pond at the time. Although drilling fluids technology has come a long way, conventional offshore drilling programs still view the hydraulics of the circulating fluids system essentially the same way— and we still commonly refer to drilling fluid as mud.
Technology Update: Directional Hybrid Drill Bit Pushes Performance Standards
Authors: Holliday Alan
Published: February 2015

Technology Update

It is inspiring to look back to 1909 when Howard Hughes Sr. and Walter Sharp introduced the roller-cone bit. The invention was the foundation for the discovery of vast amounts of oil in medium-and hard-rock formations, oil that many drillers suspected was there but was nearly impossible to reach with the bits of that day.

The roller-cone bit changed the industry, but we may forget why its immediate predecessor, the fish-tail bit, was such a burden on drillers as they strived to probe deeper targets. Often 24 hours would not go by without a twist-off occurring, and rig hands were constantly changing bits and “fishing” parts out of the hole. For drilling anything other than loose formations near the surface, it had proved impractical.

In a century’s time, the industry has made tremendous progress. But the limitations of physics continue to challenge the dynamic performance of the bit and bottomhole assembly (BHA) in the demanding downhole environments of today’s wells.

Tools come equipped with features such as torque reducers, depth-of-cut controls, and more flexible assemblies, to mention a few. The inherent problem of controlling the reactive torque between the bit and formation, while achieving optimal performance to reduce the number of drilling days, has remained a challenge.

The introduction of the hybrid drill bit in 2011, which combined roller cones and fixed cutters, was a catalyst to revisit these basic principles and better understand the benefits and efficacy of smooth drilling. The bit excelled in controlling torque fluctuations and exceeded the durability of fixed-cutter bits and the penetration rates of roller-cone bits.

The hybrid bit soon became the standard bit for drilling in hard and interbedded formations, such as those in certain Oklahoma and Canadian plays, because it enabled drillers to reduce the number of curve runs needed. The use of the bit expanded globally, helping to improve drilling results in interbedded applications that historically have met with mixed success when medium-set roller cone or fixed-cutter bits have been used. As results continued to improve, interest in stretching the capability of the technology increased.
Can Waste Water Be Disposed of Safely?
Authors: Rao Vikram
Published: February 2015

Beyond the Headlines

Editor’s note: Professionals in the oil and gas industry often receive questions about how industry operations affect public health, the environment, and the communities in which they operate. Of particular concern today is the impact of hydraulic fracturing on the environment. In this new column, JPT is inviting energy experts to put those questions and concerns about industry operations into perspective. Additional information about the oil and gas industry, how it affects society, and how to explain industry operations and practices to the general public is available on SPE’s Energy4me website at www. energy4me.org.

 

Shale oil and gas wells use a lot of water in fracturing operations. Each well may use up to 8 million gallons, and as much as 35% of this can return as flowback water. Safe disposition of this waste water is an industry priority especially because of the widely reported past missteps in Pennsylvania. Safe disposition is completely feasible and, in fact, is being broadly practiced today.

The Nature of Flowback Water

Even if fresh water is used as the base fracturing fluid, what returns to the surface is salty. This is because the water found in association with hydrocarbons has high salinity. Shale oil and gas flowback water salinity typically range from 16,000 parts per million (ppm) to more than 300,000 in some instances. For comparison, sea water runs around 35,000 ppm. The chemicals introduced into the fracturing fluid will also be present in some proportion. These will be low in concentration because even the original fracturing fluid contains only up to about 0.5% chemicals.

Finally, one could also encounter species present in subterranean rock. These could include aromatic compounds (such as benzene) and radioactive species. Some state regulations, such as the ones pending in North Carolina, prohibit the use of aromatics in fracturing fluid so, if present, they could only have come from the subsurface. The same holds for radioactive species. In most instances, subterrestrial bacteria will also be present. All of these render the flowback water unsuited for direct discharge.

Re-use of Flowback Water

Flowback water may be reused to formulate fracturing fluid for the next operation. But since only about a third of injected water returns, additional water is needed (makeup water). In the early going, reuse was rendered costly due to the need to desalinate down to fresh water. However, more recently, all service companies have announced that they can tolerate salinities in excess of 250,000 ppm.
Low Oil Prices Make Innovation a Priority
Authors: Rassenfoss Stephen , Henni Abdelghani
Published: February 2015

Conference Review - 2014 International Petroleum Technology Conference

A sharp decline in oil prices is pushing oil and gas companies to innovate to increase efficiency and prepare to meet the world’s long-term energy needs, panelists said at the International Petroleum Technology Conference (IPTC) held in Kuala Lumpur, Malaysia, in December.

Under the theme of “Innovation and Collaboration: Keys to Affordable Energy,” the IPTC attracted an attendance record 10,318 industry professionals from 68 countries. Hosted by Malaysian state oil company Petronas and cohosted by Shell and Schlumberger, the conference featured a ministerial session, high-level plenary and panel sessions, a comprehensive multidisciplinary technical program, an exhibition, a young professionals workshop, and various educational activities.

The 3-day conference was opened by Dato’ Sri Abdul Wahid Omar, a minister in the Office of the Prime Minister of Malaysia, who delivered the keynote speech about the paradox of energy affordability. One side is positive, with more affordable prices for those buying oil and gas, thus aiding consumers and the economy. The other side is negative for oil producing countries such as Malaysia, whose collections on production represent more than half of government revenues.
The New Pathways of Multiphase Flow Modeling
Authors: Jacobs Trent
Published: February 2015

Multiphase Flow

In the realm of enabling technologies, multiphase flow modeling has proven to be one of the most important to the oil and gas industry. Without it, nearly all subsea wells would be too costly or dangerous to develop. While working to fine-tune its offshore capabilities, developers are also busy expanding the technology’s application areas to include shale field development, hydrate remediation, and heavy oil extraction.

In the 1960s, when the industry began studying how to model multiphase flow, which is the science of how liquid and gas interact inside wellbores and pipelines, little was known about the complex physics involved. Back then, an engineer’s ability to predict flow behavior was strictly limited to what could be observed at the wellhead.

Over the years, the industry invented devices that could accurately calculate flow rates, velocities, and volume fractions, along with downhole temperatures and pressures. Armed with these tools, engineers and scientists had the measurements they needed to marry computational science and fluid dynamics. More than anything else, this advancement is what has allowed offshore operators to extend their reach beyond the shallow-water fields and into those thousands of feet deep.

“What we have done is to make it possible for the industry to live with the complex multiphase flow problems that face them on a daily basis,” said James Brill, a multiphase flow expert who recently retired as a research professor of petroleum engineering at the University of Tulsa. “When the industry first moved offshore, they were afraid to go with multiphase flow pipelines because they did not know what was happening inside of them, or what kind of facilities they would have to have at the outlet end in order to handle the fluctuating rivals of gas and liquid.”

In lieu of a complete understanding of multiphase flow, Mack Shippen, a product champion for one of Schlumberger’s top multiphase modeling programs, said early offshore explorers were forced to make conservative design decisions when building a production platform.

That meant using larger than needed processing equipment and pipelines to compensate for what they did not know about the behavior of the multiphase flow. “So yes, you had a safe design but you did not have one that in today’s world would be economic,” he said, explaining that, “if it is overdesigned, then essentially money has been wasted on equipment that is more than what is necessary.” If an operator can reduce the diameter of a subsea pipeline by just 1 in. or 2 in., “the difference can be on the scale of millions of dollars in capital investment,” he said.
Drilling of Multilateral Wells in Kuwait Aided With Geochemical Analysis
Authors: Carpenter Chris
Published: February 2015

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 16617, ’Drilling of Multilateral Wells Aided With Geochemical Analysis, Kuwait,’ by Taher El Gezeery, Abdul Aziz Ismail, Khalaf Al Anezi, Monirah Al Jeaan, Jeevan Kumar Silambuchelvan, and G.S. Padhy, Kuwait Oil, and Atul Wasnik and Ahmed Al Shoeibi, Geolog International, prepared for the 2013 International Petroleum Technology Conference, Beijing, 26-28 March. The paper has not been peer reviewed.

The Burgan reservoir consists of vertically stacked channel sands along with a fault network connected to the aquifer and contains highly viscous reservoir fluid. This dramatically enhances the water mobility and results in severe premature water breakthrough, bypassing zones of oil. This paper describes the use of real-time geochemical analysis to support geosteering of a smart multilateral well located in one of the highest-potential-flow areas of Kuwait.

Introduction

The Minagish field in Kuwait was discovered in 1959 and is located in the southwestern part of the country. It contains several reservoir intervals in its stratigraphic column, varying from Early Jurassic to Late Cretaceous. The field is situated 12 km northwest of the west Umm Gudair field. The field has been penetrated by more than 180 wells, to contact not only the middle and lower Minagish reservoirs of the Lower Cretaceous but also other shallow reservoirs such as the Mishrif/ Rumaila carbonates and the Wara/Burgan sandstone. The Minagish field structure of the Wara and Burgan formations is a closed elongated asymmetrical anticline oriented in a north/south direction. The top of the Burgan structure is located at approximately 5,500-ft true vertical depth subsea.

Burgan Reservoir. This reservoir is informally divided into the upper and lower Burgan sections. Lower Burgan sands are more extensive and blocky in nature, with few variations in their properties. The lower Burgan reservoir section lies above the oil/water contact (OWC) and is of significance from a hydrocarbon-bearing perspective. Upper Burgan sands are mainly in the form of channel sands, ranging in thickness from a few feet to nearly 45 ft, and they have extensive lateral facies variation. The lower part of the Burgan has active bottomwater drive, whereas the upper part of the reservoir has an edgewater-drive system. The reservoir contains high-permeability sands on the order of a few darcies associated with active faults and has highly viscous reservoir fluid (approximately 40 cp at reservoir conditions). This heterogeneous nature of the reservoir accelerates water movement inside the reservoir and results in premature water breakthrough in the existing vertical wells and in horizontal wells, in spite of maintaining the highest standoff from the OWC.
Advanced Technologies and Solutions for Challenging Drilling Applications
Authors: Carpenter Chris
Published: February 2015

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 170566, ’Advanced Technologies and Practical Solutions for Challenging Drilling Applications,’ by M.J. Jellison, SPE, NOV Grant Prideco, and A. Chan, Workstrings International, prepared for the 2014 SPE Asia Pacific Drilling Technology Conference and Exhibition, Bangkok, Thailand, 25-27 August. The paper has not been peer reviewed.

This paper provides a review of recent technology advancements and addresses practical considerations associated with drillpipe and drillstem components for extreme drilling applications. Recent developments and enhancements in these connection designs, including new higher-strength materials, advanced thread forms, and associated improvements in torsional strength and fatigue performance, are presented. The paper discusses the engineering solutions implemented to overcome the high forces, slip-crushing concerns, and material-strength and toughness considerations for these critical applications.

Third-Generation Double-Shoulder Connection

Since the introduction of the second-generation double-shoulder connection (DSC), the industry trend has continued toward deeper and longer-reach wells, which has dictated the need for drillpipe connections with enhanced mechanical and dimensional characteristics coupled with improved makeup/ breakout speeds.

Consequently, a project was commissioned to design, analyze, laboratory test, and field trial the industry’s first third-generation DSC. A key objective of the project was to improve connection makeup/breakout speeds significantly. Mechanical and hydraulic gains were also dictated on the basis of the industry’s trend toward deeper and longer-reach wells.
Creating Value With Permanent Downhole Gauges in Tight Gas Appraisal Wells
Authors: Wilson Adam
Published: February 2015

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 164039, ’Creating Value Through Permanent Downhole Gauges in Oman Block A Tight Gas Appraisal,’ by Badar Al Busafi, SPE, Robert A. Clark Jr., SPE, and Imtiaz Adil, SPE, BP, prepared for the 2013 SPE Middle East Unconventional Gas Conference and Exhibition, Muscat, Oman, 28-30 January. The paper has not been peer reviewed.

Downhole instrumentation of the Khazzan tight gas appraisal wells provides a rare opportunity to quantify reservoir pressure and temperature dynamics. Several appraisal wells were tested initially for 3–4 weeks and subsequently shut in for approximately 1 year. The continuous downhole-gauge recordings of the resulting pressure buildups were then analyzed to quantify understanding of stimulation effectiveness, reservoir quality away from the wellbore, total producible connected gas, geomechanics, and wellbore hydraulics. This paper examines the pressure-transient analysis (PTA) of one representative well in the field.

Value of Permanent Downhole Gauges in Tight Gas

Dual permanent downhole gauges (PDHGs) were spaced approximately 100 m apart in the upper- completion design, close to the perforations, to fulfill various surveillance requirements and provide the ability to measure gradients in the wellbore in real time. The completion could be tested with PDHGs and surface gauges. A considerable effort was made to ensure that the completions could withstand multiple high-pressure fracture-stimulation jobs. This included installing polished-bore packers and special-thickness tubulars. Preplanning of fracture designs using a variety of friction factors and likely fracture gradients was performed to narrow options and design the completions. Monobore completions were planned to enable running various plugs to isolate the pay intervals as required and to ease the running of logs, tools, and coiled tubing into the wellbore. The size of the completions was optimized for fracturing, not for fluid flow.

Monitoring Hydraulic-Fracturing-Job Performance.

PDHGs have proved to be of considerable value in real-time monitoring of downhole treating pressure in stimulation jobs. For example, early detection of screenout events (before any indication of pressure problems was identified on the surface) has been demonstrated. In one case, a job was altered while pumping and proppant injection was halted before the wellbore actually screened out (Fig. 1). The surface pressure data did not reveal the pending screenout. Only a very small amount of proppant remained in the wellbore after halting pumping operations.
Tactics for Use of Diagnostic Fracture Injection Tests in Unconventional Reservoirs
Authors: Wilson Adam
Published: February 2015

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 163863, ’Diagnostic-Fracture-Injection-Testing Tactics in Unconventional Reservoirs,’ by D.D. Cramer, SPE, and D.H. Nguyen, SPE, ConocoPhillips, prepared for the 2013 SPE Hydraulic Fracturing Technology Conference, The Woodlands, Texas, USA, 4-6 February. The paper has not been peer reviewed.

To achieve optimal production from unconventional reservoirs, it is useful to determine the permeability, pore pressure, and state of stress of rock strata. An effective way to derive this information is to conduct in-situ pressure-transient tests. Because injecting fluid into or withdrawing fluid from the pore network of tight rock is difficult, diagnostic fracture injection tests (DFITs) have been used to create an analyzable pressure-decline response and to derive the minimum horizontal stress through fracture-closure identification.

Introduction

Well testing is the technique of establishing fluid flow in the reservoir by either producing from or injecting into a well and then changing or terminating the flow rate to create a transient event, usually by shutting in the well at the surface. The resulting wellbore-pressure response is then evaluated to derive reservoir properties, such as transmissibility and initial reservoir pressure.

Creating a hydraulic fracture bypasses wellbore damage and near-wellbore stress concentrations and connects the wellbore to a significant portion of the reservoir-layer thickness, enabling a representative investigation of reservoir properties.

A typical DFIT sequence is shown in Fig. 1.

Initially, the well is filled with water, with care taken to purge the fluid column of entrained air and gas.
Fines Migration in Fractured Wells: Integrating Modeling With Field and Laboratory Data
Authors: Carpenter Chris
Published: February 2015

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 165108, ’Fines Migration in Fractured Wells: Integrating Modeling With Field and Laboratory Data,’ by M. Marquez, W. Williams, and M. Knobles, Chevron, and P. Bedrikovetsky, SPE, and Z. You, SPE, University of Adelaide, prepared for the 2013 SPE European Formation Damage Conference and Exhibition, Noordwijk, The Netherlands, 5-7 June. The paper has not been peer reviewed.

Production and drawdown data from 10 subsea deepwater fractured wells have been modeled with an analytical model for unsteady-state flow with fines migration. The simulation results and the field data indicated a good match, within 5%. This paper describes the methodology used to integrate the modeling predictions with field and laboratory data to identify probable causes for increasing skins and declining productivity-index (PI) values.

Introduction

Fines migration is a complex phenomenon that can challenge the economic viability of a project because of well-productivity decline, lower-than- expected hydrocarbon recoveries per well, large capital expenditures to drill and complete additional wells, and high operating costs from suboptimal facility designs. Excessive fines production may also result in equipment erosion and corrosion, formation of hard-to-break emulsions, and plugging of flowlines and surface facilities, all leading to potential hazardous situations.

This paper describes a multidisciplinary approach in which fines-migration modeling has been integrated with field and laboratory data to ascertain whether fines migration may be associated with rapidly increasing skins and declining PI values observed in a subset of deepwater fractured wells. Laboratory studies exhibit fines release and migration during coreflooding and stress testing; the field well-productivity data are well-matched with the mathematical modeling.
Influence of Nitrogen Form Supply on Soil Mineral Nitrogen Dynamics, Nitrogen Uptake, and Productivity of Sugarcane
Authors: Mariano Eduardo , Leite José M. , Megda Michele X. V. , Torres‐Dorante Luis , Trivelin Paulo C. O.
Published: February 2015

Current limitations on the use of conventional N fertilizers on sugarcane (Saccharum spp.) in Brazil require the search for alternative sources with adequate N use efficiency. Field experiments were conducted in Typic Hapludox (TH) and Typic Eutrustox (TE) soils in São Paulo State, Brazil, to evaluate the dynamics of soil mineral N, N uptake, and sugarcane yield in response to N amendments including Ajifer‐8, ammonium chloride, ammonium nitrate, calcium ammonium nitrate (CAN), and urea applied on sugarcane ratoon at 100 kg N ha−1. The experiments were arranged in randomized complete block design, with four replications. The treatments were applied at 105 and 122 days after harvest of plant cane (DAH) in the TH and TE soil. Ajifer‐8 exhibited higher NH4+–N availability in the 0‐ to 20‐cm soil layer 139 DAH in the TH soil. Ammonium nitrate and CAN resulted in the highest NO3−–N values in the soil within the same period. In the TE soil, the soil mineral N content remained unaltered during all of the sampling dates. The high values of accumulated N uptake by sugarcane in both soils indicates that a good portion of the soil mineral N was take up by the plants. The Ajifer‐8 and CAN fertilizers resulted in higher sugarcane yield in both experiments, and may be used as replacement for conventional N sources. In contrast, the use of ammonium chloride resulted in low values of soil mineral N and accumulated N uptake.
Quantitative Trait Loci Mapping for Plant Height in Tobacco using Linkage and Association Mapping Methods
Authors: Cheng Lirui , Yang Aiguo , Jiang Caihong , Ren Min , Zhang Yu , Feng Quanfu , Wang Shaomei , Guan Yongsheng , Luo Chenggang
Published: February 2015

Plant height (PH) is one of the most important agronomic traits in tobacco (Nicotiana tabacum L.). To gain a better understanding of its genetic basis, the F2 and F2:3 populations derived from NC82 (P1) and Kang88 (P2) cross were developed. The 193 F2 individuals and 145 F2:3 lines were further used to identify quantitative trait loci (QTL) affecting to PH in tobacco. Two main quantitative trait loci (M‐QTL), designated qPH‐6 and qPH‐12, were mapped on genetic linkage groups 6 and 12, respectively, using linkage mapping (LM). The QTL qPH‐12 was identified as stably expressed in different tobacco generations as well as in various environments. To further verify the chromosomal interval harboring qPH‐12, a total of 96 accessions were subsequently evaluated for PH at two different sites and genotyped by 46 markers evenly distributed on chromosome 12. We found a total of four significant marker‐trait associations that were identified with three different SSR markers (P < 0.01) and could explain 11.7 to 14.8% of the phenotypic variation in PH. One marker, PT55174, showed a significant association with PH (P < 0.01) and explained 13.9 and 14.4% of the phenotypic variation at two different sites. Taken together, our results could provide a new avenue for investigating the QTL in tobacco by combining LM and association mapping (AM), and facilitating our understanding of the inheritance of PH for marker‐assisted selection (MAS) in tobacco.