bluuebunny/crossref_metadata_2025 huggingface dataset:
Técnicas exploratórias para localizar potenciais usuários de transporte público urbano
Authors: Alves Víctor Frazão Barreto , Silva Antônio Nélson Rodrigues da , van der Waerden Peter
Published: October 2014

O objetivo deste estudo é identificar e encontrar potenciais usuários de transporte público através do emprego de mapas construídos em um sistema de informações geográficas. O método considera a divisão do município estudado em zonas, em função do código postal. Estas zonas são caracterizadas pelos atributos socioeconômicos da população e do sistema de transporte. Diante da hipótese de melhoria na qualidade do transporte público, dois segmentos de usuários de automóvel foram considerados: usuários que trocariam para ônibus e usuários que continuariam preferindo o carro. Duas técnicas (Modelo Logit e Redes Neurais Artificiais) foram utilizadas com o intuito de reproduzir esse comportamento de escolha dos usuários. Assim, é possível caracterizar espacialmente o impacto de alterações no sistema de transportes ou no perfil da população sobre o potencial de utilização do transporte público. Um cenário de aumento na densidade populacional permitiu identificar, por exemplo, regiões da cidade de São Carlos com potenciais usuários.
El mercado de transporte aéreo: lecciones de política de una revisión de la literatura
Authors: Agostini Claudio A.
Published: October 2014

En la industria de transporte aéreo en Chile, existe hoy libre ingreso a los mercados, libertad de precios y una mínima intervención del estado. Sin embargo, la evolución de la industria ha generado discusión y preocupación pública en los últimos años respecto a qué tan competitivo es el mercado de transporte doméstico de pasajeros, especialmente en rutas donde opera sólo una aerolínea. Algunas de las preocupaciones y discusiones de política pública similares a las que existen hoy en Chile, han sido el foco de la literatura económica en el tema desde la regulación de los mercados aéreos a fines de los 70 y se han acentuado últimamente con las distintas fusiones y alianzas entre aerolíneas. El gran avance que ha habido, tanto teórico como empírico, ha permitido entender las características específicas de esta industria y los determinantes del grado de competencia en los mercados, por lo que una revisión de la literatura permite obtener lineamientos relevantes para Chile con el objeto de orientar el análisis y discusión de políticas públicas. El objetivo de este trabajo entonces, es hacer una revisión de la literatura económica que de luces respecto a los elementos críticos que uno debería considerar para evaluar el grado de competencia de la industria y los potenciales riesgos anticompetitivos existentes. Dichos elementos permiten orientar la investigación futura respecto a los efectos de la actual política aerocomercial chilena en el grado de competencia en el mercado doméstico y evaluar la implementación de políticas públicas que permitan hacer más competitivo el mercado.
Um modelo integrado de simulação-otimização para a avaliação de um novo negócio de aeronaves de propriedade compartilhada
Authors: Lopes Juliana da Serra Costa , Cunha Claudio Barbieri da
Published: October 2014

Este artigo descreve um modelo integrado de simulação-otimização para auxiliar na avaliação de uma nova operação de jatos de propriedade compartilhada, que surge na fase de planejamento de um novo negócio, quando é necessário avaliar localizações alternativas para as bases onde ficam os jatos (quantas e onde), assim como estimar a mínima frota requerida e a quantidade de viagens vazias (“deadhead”) que não geram receita. O problema de determinação da frota ótima e alocação das aeronaves aos voos é modelado como um problema de fluxo em rede espaço-tempo de mínimo custo, com base em demandas diárias de vôos geradas a partir de simulação de Monte Carlo. O modelo foi implementado em ambiente de planilha Excel com automatização de todos dos procedimentos de simulação e de montagem e resolução do modelo de otimização, de tal modo que os dados possam ser alimentados, atualizados e modificados, e os modelos processados por qualquer pessoa sem conhecimento ou domínio de pesquisa operacional.
Liberalização econômica e universalização do acesso no transporte aéreo: é possível conciliar livre mercado com metas sociais e ainda evitar gargalos de infraestrutura
Authors: Zimmermann Nara , Oliveira Alessandro V. M.
Published: October 2014

A liberalização econômica do transporte aéreo brasileiro trouxe visíveis benefícios ao setor, com preços mais baixos e maior popularização. Houve, entretanto, mais concentração da operação em grandes aeroportos e perda de cobertura regional. O presente trabalho tem por objetivo analisar a evolução do número de aeroportos servidos pelo transporte aéreo regular brasileiro, bem como os índices de concentração de operações e a cobertura ao longo do território nacional. Serão abordados aspectos contidos no processo de desregulação econômica que o mercado aéreo brasileiro sofreu nos anos 1990 e início dos anos 2000, fazendo com que o transporte aéreo nacional passasse a ser mais competitivo e eficiente, mas também com operação mais concentrada geograficamente. Estes fatores acarretaram benefícios e malefícios aos passageiros: por um lado, preços mais baixos, alta indução do tráfego aéreo e maior acessibilidade de novos segmentos de consumidores; por outro, crescimento acelerado pressionado das infraestruturas aeroportuária e do espaço aéreo - com decorrentes gargalos geradores de congestionamentos e atrasos - e piora na cobertura geográfica. Este estudo desenvolveu um modelo econométrico que possibilitou análise de potenciais variáveis explicativas da cobertura do transporte aéreo, bem como sua influência e impacto no número de aeroportos servidos.
Eficiência portuária: análise das principais metodologias para o caso dos portos brasileiros
Authors: Falcão Viviane Adriano , Correia Anderson R.
Published: October 2014

Sabendo que mais de 80% do comércio internacional brasileiro é realizado via marítima, o setor portuário assume uma importância indiscutível no processo de crescimento econômico nacional, inclusive como um fator de desenvolvimento sócio econômico no seu entorno. Dentro desse contexto, a necessidade de avaliar o desempenho portuário se torna essencial para assegurar a competitividade dos produtos nacionais em mercados externos. Neste artigo, são abordadas as duas principais metodologias de avaliação de eficiência portuária, em especial a Fronteira Estocástica e a Análise Envoltória de Dados. Serão levantadas evidências do desempenho das técnicas existentes e quais se adequam melhor para o caso da avaliação da eficiência portuária. A fronteira estocástica apresentou como principal vantagem o fato de comparar os resultados dos portos analisados com parâmetros técnicos ou normalizados, porém, só consegue analisar um produto por vez. A análise envoltória de dados, por sua vez, tem como vantagem a possibilidade de analisar múltiplos produtos, porém, com um número reduzido de dados amostrais.
Capacidade do lado aéreo dos aeroportos brasileiros
Authors: Alves Cláudio Jorge Pinto , Fraga Rafael
Published: October 2014

O crescimento da demanda pelo transporte aéreo tem exigido ações para adequação da capacidade instalada nos aeroportos. Normalmente tais obras requerem vultosos recursos e trazem preocupações socioambientais. Uma ampliação em qualquer setor do aeroporto necessita uma visão sistêmica para garantir que a obra vai efetivamente propiciar ganhos ao aeroporto como um todo e não simplesmente se transferir o gargalo dentro do sistema. Neste artigo são mostrados os resultados dos cálculos das capacidades de dois subsistemas do lado aéreo dos vinte principais aeroportos brasileiros. Apenas em quatro aeroportos se mostra a ocorrência de um balanceamento entre as suas capacidades. Nos demais, um ou outro subsistema se caracteriza como limitante. Para esses casos, a ampliação da capacidade do aeroporto somente se viabiliza se as ações se voltarem para o subsistema limitado.
Fusões no transporte aéreo: estudos e tendências
Authors: Ueda Thiago Vinicius Alves
Published: October 2014

O presente artigo apresenta recentes estudos da literatura acerca dos efeitos das fusões para o bem-estar social dos usuários do transporte aéreo, mais especificamente, como o processo impacta no preço das passagens e nas frequências de voos. Os resultados sugerem que fusões entre companhias aéreas "legacy" nos EUA tem causado significante aumento nos preços das passagens e redução nas frequências de voo. Além disso, fusões parecem resultar em redução de preços quando companhias low-cost estão envolvidas, salvo bilhetes adquiridos com poucos dias de antecedência. Por fim, fusões entre companhias network e low-cost mostram-se prejudiciais para os consumidores, mas a magnitude do impacto varia de acordo com a competição entre as companhias anteriormente em rotas específicas.
A Phase I/II Study of XELIRI Plus Bevacizumab as Second-Line Chemotherapy for Japanese Patients With Metastatic Colorectal Cancer (BIX Study)
Authors: Hamamoto Yasuo , Yamaguchi Tatsuro , Nishina Tomohiro , Yamazaki Kentaro , Ura Takashi , Nakajima Takako , Goto Ayumu , Shimada Ken , Nakayama Norisuke , Sakamoto Junichi , Morita Satoshi , Yamada Yasuhide
Published: October 2014

Background.

Capecitabine is used mainly with oxaliplatin to treat metastatic colorectal cancer (mCRC). Results from capecitabine plus irinotecan (XELIRI) with or without bevacizumab (BV) have been reported in Europe but not in Japan. Consequently, the safety and efficacy of XELIRI plus BV in Japanese patients with mCRC were assessed in a single-arm phase II study.

Methods.

Eligible patients had had prior chemotherapy containing BV for mCRC and wild-type or heterozygous UGT1A1. Therapy in each 21-day treatment cycle consisted of capecitabine (800 mg/m2 twice daily on days 1–15), irinotecan (200 mg/m2 on day 1), and BV (7.5 mg/kg on day 1). The primary endpoint was dose-limiting toxicity in phase I and progression-free survival (PFS) in phase II.

Results.

A total of 34 patients (6 in phase I, 28 in phase II) were enrolled from May 2010 to June 2011. Baseline characteristics included a median age of 60 years (range: 22–74 years) for 24 men and 10 women. No dose-limiting toxicities appeared in phase I. Median PFS was 240 days (95% confidence interval: 179–311 days). Overall response rate was 18.1%, and the disease-control rate was 90.9%. The incidence of adverse events frequently associated with irinotecan and capecitabine were neutropenia (any grade, 55.9%; grade 3 or 4, 11.8%), diarrhea (any grade, 50%; grade 3 or 4, 5.9%), and hand-foot syndrome (any grade, 61.8%; grade 3 or 4, 5.9%).

Conclusion.

Our results suggest that XELIRI plus BV is well tolerated and effective as a second-line treatment for mCRC in Japanese patients. This regimen could be especially appropriate for patients resistant to oxaliplatin-based regimens.
Managing the wildlife tourism commons
Authors: Pirotta Enrico , Lusseau David
Published: October 2014

The nonlethal effects of wildlife tourism can threaten the conservation status of targeted animal populations. In turn, such resource depletion can compromise the economic viability of the industry. Therefore, wildlife tourism exploits resources that can become common pool and that should be managed accordingly. We used a simulation approach to test whether different management regimes (tax, tax and subsidy, cap, cap and trade) could provide socioecologically sustainable solutions. Such schemes are sensitive to errors in estimated management targets. We determined the sensitivity of each scenario to various realistic uncertainties in management implementation and in our knowledge of the population. Scenarios where time quotas were enforced using a tax and subsidy approach, or they were traded between operators were more likely to be sustainable. Importantly, sustainability could be achieved even when operators were assumed to make simple rational economic decisions. We suggest that a combination of the two regimes might offer a robust solution, especially on a small spatial scale and under the control of a self‐organized, operator‐level institution. Our simulation platform could be parameterized to mimic local conditions and provide a test bed for experimenting different governance solutions in specific case studies.
Spatial heterogeneity increases diversity and stability in grassland bird communities
Authors: Hovick Torre J. , Elmore R. Dwayne , Fuhlendorf Samuel D. , Engle David M. , Hamilton Robert G.
Published: October 2014

Grasslands are inherently dynamic in space and time, evolving with frequent disturbance from fire and herbivores. As a consequence of human actions, many remaining grasslands have become homogenous, which has led to reduced ecosystem function, biodiversity loss, and decreased ecological services. Previous research has shown that restoring inherent heterogeneity to grasslands can increase avian diversity, but the amount of heterogeneity (i.e., number of patches or fire return interval) and the impact on avian community stability have yet to be investigated. We used a unique landscape‐level design to examine avian response to interacting fire and grazing across multiple experimental landscapes that represented a gradient of fire‐ and grazing‐dependent heterogeneity. We used seven landscapes (430–980 ha;x¯= 627 ha) with varying levels of patchiness ranging from annually burned (one single patch) with spring‐only fires to a four‐year fire return interval with spring and summer fires (eight patches). This design created a range of heterogeneity as a result of pyric herbivory, an ecological process in which fire and grazing are allowed to interact in space and time. We found that greater heterogeneity across experimental landscapes resulted in increased avian diversity and stability over time. An index of bird community change, quantified as the sum of the range of detrended correspondence analysis axis site scores, was nearly four times greater in the most homogenous experimental landscape when compared to the most heterogeneous experimental landscape. Species responses were consistently positively associated with increased heterogeneity at the landscape scale, and within‐experimental‐landscape responses were most often related to litter cover, litter accumulation, and vegetation height. We conclude that increased fire‐ and grazing‐dependent heterogeneity can result in high variability in the bird community at finer, transect scales, but increased diversity and stability at broad landscape scales. We recommend that future management efforts in rangelands focus on restored disturbance processes to increase heterogeneity and improve grassland bird conservation.
To predict the niche, model colonization and extinction
Authors: Yackulic Charles B. , Nichols James D. , Reid Janice , Der Ricky
Published: October 2014

Ecologists frequently try to predict the future geographic distributions of species. Most studies assume that the current distribution of a species reflects its environmental requirements (i.e., the species' niche). However, the current distributions of many species are unlikely to be at equilibrium with the current distribution of environmental conditions, both because of ongoing invasions and because the distribution of suitable environmental conditions is always changing. This mismatch between the equilibrium assumptions inherent in many analyses and the disequilibrium conditions in the real world leads to inaccurate predictions of species' geographic distributions and suggests the need for theory and analytical tools that avoid equilibrium assumptions. Here, we develop a general theory of environmental associations during periods of transient dynamics. We show that time‐invariant relationships between environmental conditions and rates of local colonization and extinction can produce substantial temporal variation in occupancy–environment relationships. We then estimate occupancy–environment relationships during three avian invasions. Changes in occupancy–environment relationships over time differ among species but are predicted by dynamic occupancy models. Since estimates of the occupancy–environment relationships themselves are frequently poor predictors of future occupancy patterns, research should increasingly focus on characterizing how rates of local colonization and extinction vary with environmental conditions.
Factors Influencing Adoption of and Adherence to Indoor Smoking Bans Among Health Disparity Communities
Authors: Rees Vaughan W. , Keske Robyn R. , Blaine Kevin , Aronstein David , Gandelman Ediss , Lora Vilma , Savage Clara , Geller Alan C.
Published: October 2014

Objectives. We assessed current home smoking behaviors and secondhand smoke (SHS) levels among parents of children in low-income, racial/ethnic minority communities in Massachusetts.

Methods. We used a cross-sectional design to assess home smoking rules, smoking status, cigarettes smoked in the home, and barriers and benefits to attaining a smoke-free home among 138 caregivers (mean age = 30.0 years; 92% women) of children aged 0 to 6 years, between April 2010 and September 2012. Indoor SHS was assessed using a nicotine dosimeter.

Results. Households with no ban reported a higher weekly mean number of cigarettes smoked in the home (114 cigarettes/week) than homes with partial (71 cigarettes/week) or complete (30 cigarettes/week) bans (P < .01). Smoking occurred outside more than inside homes with partial or complete bans. Air nicotine levels were positively associated with no household smoking ban, current smoking by the caregiver, and smoking indoors.

Conclusions. Strategies to reduce home SHS should focus on a “complete” home smoking ban and smoking cessation. SHS mitigation strategies such as smoking outside were associated with lower SHS among participants unable to maintain a complete ban, and might enhance the likelihood of longer term success while immediately reducing home SHS.
The Convention on the Rights of Persons With Disabilities: A Foundation for Ethical Disability and Health Research in Developing Countries
Authors: Durham Jo , Brolan Claire E. , Mukandi Bryan
Published: October 2014

The United Nations Convention on the Rights of Persons with Disabilities (CRPD) has foregrounded disability as a human rights and equity issue, elevating it to a priority global research area.

Academics from Western universities are likely to play an increasing role in disability health research in developing countries. In such contexts, there is a need to bridge the gap between procedural ethics and the realities of disability research in cross-cultural contexts.

We provide guidance on engaging in ethical disability health research that intersects with and upholds the CRPD. We highlight challenges and tensions in doing so, underscoring the need to be sensitive to the sociocultural and political context of disability that determines how ethical research should proceed. We conclude with 5 recommendations.
Illness Absences Among Beryllium Sensitized Workers
Authors: Watkins Janice P. , Ellis Elizabeth D. , Girardi David J. , Cragle Donna L. , Richter Bonnie S.
Published: October 2014

Objectives. This study examined absence rates among US Department of Energy workers who had beryllium sensitization (BeS) or were diagnosed with chronic beryllium disease (CBD) compared with those of other workers.

Methods. We used the lymphocyte proliferation test to determine beryllium sensitivity. In addition, we applied multivariable logistic regression to compare absences from 2002 to 2011 between workers with BeS or CBD to those without, and survival analysis to compare time to first absence by beryllium sensitization status. Finally, we examined beryllium status by occupational group.

Results. Fewer than 3% of the 19 305 workers were BeS, and workers with BeS or CBD had more total absences (odds ratio [OR] = 1.31; 95% confidence interval [CI] = 1.18, 1.46) and respiratory absences (OR = 1.51; 95% CI = 1.24, 1.84) than did other workers. Time to first absence for all causes and for respiratory conditions occurred earlier for workers with BeS or CBD than for other workers. Line operators and crafts personnel were at increased risk for BeS or CBD.

Conclusions. Although not considered “diseased,” workers with BeS have higher absenteeism compared with nonsensitized workers.
A Public Health Response to Data Interoperability to Prevent Child Maltreatment
Authors: Nguyen Loc H.
Published: October 2014

The sharing of data, particularly health data, has been an important tool for the public health community, especially in terms of data sharing across systems (i.e., interoperability). Child maltreatment is a serious public health issue that could be better mitigated if there were interoperability.

There are challenges to addressing child maltreatment interoperability that include the current lack of data sharing among systems, the lack of laws that promote interoperability to address child maltreatment, and the lack of data sharing at the individual level. There are waivers in federal law that allow for interoperability to prevent communicable diseases at the individual level.

Child maltreatment has a greater long-term impact than a number of communicable diseases combined, and interoperability should be leveraged to maximize public health strategies to prevent child maltreatment.
Local Medicaid Home- and Community-Based Services Spending and Nursing Home Admissions of Younger Adults
Authors: Thomas Kali S. , Keohane Laura , Mor Vincent
Published: October 2014

We used fixed-effect models to examine the relationship between local spending on home- and community-based services (HCBSs) for cash-assisted Medicaid-only disabled (CAMOD) adults and younger adult admissions to nursing homes in the United States during 2001 through 2008, with control for facility and market characteristics and secular trends. We found that increased CAMOD Medicaid HCBS spending at the local level is associated with decreased admissions of younger adults to nursing homes. Our findings suggest that states’ efforts to expand HCBS for this population should continue.
Workplace Wellness Programs: How Regulatory Flexibility Might Undermine Success
Authors: Pomeranz Jennifer L.
Published: October 2014

The Patient Protection and Affordable Care Act revised the law related to workplace wellness programs, which have become part of the nation’s broader health strategy. Health-contingent programs are required to be reasonably designed. However, the regulatory requirements are lax and might undermine program efficacy in terms of both health gains and financial return. I propose a method for the government to support a best-practices approach by considering an accreditation or certification process. Additionally I discuss the need for program evaluation and the potential for employers to be subject to litigation if programs are not carefully implemented.
Legal Mechanisms Supporting Accountable Care Principles
Authors: Ramanathan Tara
Published: October 2014

Public health and private providers and facilities may shape the future of the US health system by engaging in new ways to deliver care to patients.

“Accountable care” contracts allow private health care and public health providers and facilities to collaboratively serve defined populations. Accountable care frameworks emphasize health care quality and cost savings, among other goals.

In this article, I explore the legal context for accountable care, including the mechanisms by which providers, facilities, and public health coordinate activities, avoid inefficiencies, and improve health outcomes. I highlight ongoing evaluations of the impact of accountable care on public health outcomes.
Sexually Transmitted Infections Among Incarcerated Women: Findings From a Decade of Screening in a Los Angeles County Jail, 2002–2012
Authors: Javanbakht Marjan , Boudov Melina , Anderson Laura J. , Malek Mark , Smith Lisa V. , Chien Michael , Guerry Sarah
Published: October 2014

Objectives. We describe and report findings from a screening program to identify sexually transmitted infections (STIs) and HIV among female inmates in Los Angeles County Jail.

Methods. Chlamydia and gonorrhea screening was offered to entering female inmates. Women were eligible if they were (1) aged 30 years or younger, or (2) pregnant or possibly pregnant, or (3) booked on prostitution or sex-related charges. Voluntary syphilis and HIV testing was offered to all women between 2006 and 2009. This analysis reports on data collected from 2002 through 2012.

Results. A total of 76 207 women participated in the program. Chlamydia prevalence was 11.4% and gonorrhea was 3.1%. Early syphilis was identified in 1.4% (141 of 9733) and the overall prevalence of HIV was 1.1% (83 of 7448). Treatment levels for early syphilis and HIV were high (99% and 100%, respectively), but only 56% of chlamydia and 58% of gonorrhea cases were treated.

Conclusions. Screening incarcerated women in Los Angeles County revealed a high prevalence of STIs and HIV. These inmates represent a unique opportunity for the identification of STIs and HIV, although strategies to improve chlamydia and gonorrhea treatment rates are needed.
Impact of the Transparent Reporting of Evaluations With Nonrandomized Designs Reporting Guideline: Ten Years On
Authors: Fuller Thomas , Peters Jaime , Pearson Mark , Anderson Rob
Published: October 2014

Objectives. We assessed how the Transparent Reporting of Evaluations with Nonrandomized Designs (TREND) reporting guideline was used by authors and journal editors in journals’ instructions to authors. We also evaluated its impact on reporting completeness and study quality.

Methods. We extracted data from publications that cited TREND on how TREND was used in those reports; we also extracted information on journals’ instructions to authors. We then undertook a case–control study of relevant publications to evaluate the impact of using TREND.

Results. Between 2004 and 2013, TREND was cited 412 times, but it was only evidently applied to study reports 47 times. TREND was specifically mentioned 14 times in the sample of 61 instructions to authors. Some evidence suggested that use of TREND was associated with more comprehensive reporting and higher study quality ratings.

Conclusions. TREND appeared to be underutilized by authors and journal editors despite its potential application and benefits. We found evidence that suggested that using TREND could contribute to more transparent and complete study reports. Even when authors reported using TREND, reporting completeness was still suboptimal.
Improving Global Access to New Vaccines: Intellectual Property, Technology Transfer, and Regulatory Pathways
Authors: Crager Sara Eve
Published: October 2014

The 2012 World Health Assembly Global Vaccine Action Plan called for global access to new vaccines within 5 years of licensure. Current approaches have proven insufficient to achieve sustainable vaccine pricing within such a timeline. Paralleling the successful strategy of generic competition to bring down drug prices, a clear consensus is emerging that market entry of multiple suppliers is a critical factor in expeditiously bringing down prices of new vaccines. In this context, key target objectives for improving access to new vaccines include overcoming intellectual property obstacles, streamlining regulatory pathways for biosimilar vaccines, and reducing market entry timelines for developing-country vaccine manufacturers by transfer of technology and know-how. I propose an intellectual property, technology, and know-how bank as a new approach to facilitate widespread access to new vaccines in low- and middle-income countries by efficient transfer of patented vaccine technologies to multiple developing-country vaccine manufacturers.
Integrating Unconventional Resource Opportunities into an Exploration and Production Portfolio
Authors: Chorn Larry , Dusterhoft Ron
Published: October 2014

Basin-centered and tight oil source rock reservoirs are abundant across the world, but their potential and contribution have only been recognized and considered for exploitation within the last 15 years. Fundamental differences exist between conventional and unconventional resources (UR) lifecycles; these differences require conceptual changes by management and strategic planners in energy companies.

Unconventional resources lack a traditional exploration phase because the presence of shales and tight formations are widely known as a result of exploration activities for conventional resources. In addition, the variability of geologic properties in UR accumulations forces operators into a time-consuming appraisal phase to determine best practices for the particular character of the UR under study. After a development program has been sanctioned by management, the organization assumes a multi-decade program of drilling and stimulation, gathering system extension over a large area, and surface facility flexibility. Therefore, unconventional resources have been described as ‘statistical plays.’ This is true unless and until the operator has achieved static and dynamic models of the asset and is no longer hostage to local mean values and, more importantly, large standard deviations.

Consequently, UR capital commitments differ from those of conventional opportunities. URs have much longer economic lives and require nearly continuous capital investment. URs provide management with the opportunity to begin a development program, and then suspend and resume it in the future because each investment in a UR can be considered to be a unique portfolio entity. This paper addresses the strategic planning issues associated with capital commitments, resource and reserve recognition, and production forecasting in each stage in the lifecycle of a UR opportunity. The paper uses a basic, probabilistic planning model to evaluate the various approaches. The intent is to understand how UR opportunities can be blended into a portfolio containing conventional portfolio entities.
An Experimental Study of the Swelling Properties of Unconventional Shale Oil Rock Samples Using both Water-Based and Oil-Based Muds
Authors: Emadi H. , Soliman M. Y. , Samuel R. , Heinze L. R. , Moghaddam R. B. , Hutchison S.
Published: October 2014

Although many shale oil wells have been drilled in recent years, the industry as a whole is still at the beginning of the learning curve with respect to shale oil drilling operations. Drilling through shale oil formations can be problematic and impose significant costs to operators attributed to wellbore stability problems. These problems include but are not limited to tight holes, stuck pipe, fishing, sidetracking, and well abandonment. Therefore, to more efficiently and effectively drill through such formations, operators should better understand their properties.

So far, few experiments have been conducted on shale oil rock samples to better understand their properties while drilling using oil-based mud (OBM). Most experiments have been performed on common shale core samples, which are significantly different from oil shale samples in terms of mineralogy, cation exchange capacity (CEC), pore fluid, and swelling properties.

This study investigates the swelling properties and CEC of shale oil core samples from the Eagle Ford field in the laboratory. Specifically, scientists submerged samples in 7% potassium-chloride (KCl) brine and OBM and then used strain gauges and the V-Shay data acquisition system to record both lateral and axial swellings for submerged and non-submerged areas. They then compared the effects of drilling fluid on the swelling properties of the rock samples and, consequently, on borehole stability during drilling operations.

All of the experiments were performed in an environmental chamber, which allowed maintaining a constant temperature. The samples were taken from the vertical, horizontal, and diagonal (45°) directions relative to the layering to help determine the optimum well path that would encounter the least possible wellbore stability problems associated with swelling during drilling operations. The results demonstrate that the swelling properties and CEC of the shale oil core samples are different from the common shale core samples. The study quantified the shale/fluid properties, interactions, and effects of the different fluids on rock properties in unconventional reserves. The results of the study can help drilling engineers more precisely understand unconventional shale oil rock properties. The results of the study should also help design a more effective drilling fluid for field applications, as well as more accurately predict the mechanism of formation failure.
Case Study: Completion Design Optimization for Barnett Oil Producing Area
Authors: Holderby Eric , Dahl Jeff , Spaid John , Dusterhoft Ron , Adams Ian
Published: October 2014

Throughout the past several years, economic and technological advancements in the North American shale market with respect to drilling and hydraulic fracturing operations have helped create a "typical" operating scheme for producing from the multiple shale formation reservoirs currently being exploited. This typical scheme focuses on operational efficiency and cost reduction to drive profitability in these markets. While operational efficiency and effective cost control have led to more profitable operations in these shale reservoirs, the unknowns regarding the subsurface of these highly complex formations can often create situations of operating without sufficient information to optimally design drilling and completions strategies to produce larger volumes of hydrocarbon from the reservoir.

Opposed to conventional operations, the amount of basin and asset knowledge being collected and developed in most of these shale plays is much lower, and thus can result in poor development decisions, leading to less than optimum economic performance. Focus on subsurface knowledge as well as collaboration between the various aspects of developing an asset is essential to helping discover and produce more oil and gas from these complex reservoir systems.

This paper examines a case study of three wells in Wise County, Texas, in the Barnett shale, where a collaborative subsurface insight investigation and drilling and completions optimization process were used to illustrate the production benefit achieved through improved reservoir understanding. Within this process, an asset earth model was created using the collected information from wireline logging, logging while drilling (LWD), core testing, mechanical rock and fluid properties, formation mineralogy, and wellbore image logging. Additionally, for the completions design strategy, microseismic measurement and image log fracture matching and complex fracture modeling software tools were used to define and model the growth of the stimulated fracture network during hydraulic fracturing completions.

This paper presents an overview of "typical" previous completions and subsurface information collected before implementation of the new process in comparison to changes made to the drilling and completions designs used on three wells, as well as an overview of the types of information collected to supply the earth model. Examples of the fracture matching and complex fracture modeling for the wells helps illustrate the design and optimization of hydraulic fracturing treatments in a complex shale reservoir. Finally, a production results comparison is presented to illustrate a significant increase to production of hydrocarbon through better reservoir understanding and drilling and completion designs.
Production Enhancement In Arctic Environment: The Multilateral Experience For Viscous Oil
Authors: Raniolo S. , Mancini S. , Brega F. , Rovellini M. E. , Gentil P. , Malpeli M.
Published: October 2014

The paper presents the experience of a multilateral well campaign for a viscous oil field and its benefits in terms of production.

The field is located in the North Slope of Alaska. The production start up was in January 2011. The main hydrocarbon reservoir is a Cretaceous sedimentary series developed in a sand lobe environment within the Schrader Bluff formation. The structure is a monocline gently dipping to NE with a gross thickness of about 30–35 ft. The oil presents different characteristics due to the instauration of a biodegradation process. Oil densities vary between 16°-19° API with associated viscosities in the range of 50–200 cP at reservoir conditions.

The crude quality and drill pad constraints (one offshore, one onshore) drove the development concept which consisted of a waterflood linedrive with horizontal producers and water injector wells located side by side. The lateral sections are 6,000′–10,000′ long through the reservoir with undulating counter-phase trajectories across the two main sand bodies. A challenging horizontal reach/depth step-out ratio around 6.5 has been achieved. The completion string was equipped to provide the capability of integrating a complex reservoir monitoring plan including distribute temperature surveys, inflow control devices and polymer tracers. The choice came out from the need of minimizing the cost and mitigating risk with the highest respect for the environment and the local communities.

With the goal of increasing reservoir contact, the multilateral concept consisting of undulating counter-phase dual-laterals was tested in August 2013. This initial test was followed by a limited campaign. As a result, well production doubled with respect to the average before the intervention. Similar productivity improvements were also observed in the new producers. At the time production was sustained by 20 producers and 15 injectors. Since then, eight additional laterals were added to existing producers and three new development wells were drilled and completed. The fieldwide step-change was evident with an overall production enhancement around plus 82% in May 2014.

After the first encouraging results, the multilateral campaign has been extended to all the producers and is now standard practice for the remaining development wells in this field.
Flushing Away the Profit: the Potential Misapplication of Unconventional Fracturing Technology on a Global Scale
Authors: Rylance M. , Martin A. N.
Published: October 2014

It would have been difficult, if not impossible, to have been working in the oil and gas industry in recent years, without having heard of hydraulic fracturing and the revolution that has taken place using this technique when combined with horizontal wells, in unconventional resources across North America. In addition, you could be forgiven for believing that the hydraulic fracturing technique is a relatively new and recent approach, rather than the very well established science and engineering discipline that it is. Even within the industry, both operators and service providers, there appears to be a variable level of understanding and familiarity with applicability of unconventional technology. Such variation is in danger of overlooking the extensive breadth of knowledge that the industry has built up over more than 60 years of fracturing in the conventional reservoir environment.

The demarcation between conventional and unconventional formations is not a very clear one and in addition to the various definitions themselves, such nomenclature is often misapplied by the industry from one location to another. What can probably be agreed upon are the end-points that apply, namely that conventional formations are driven by well understood Darcy flow regime behaviour and drainage, whereas unconventional formations require to be somehow actuated, enabled and/or stimulated in order to provide an environment whereby a sustained flow rate can be experienced. As part of the drive to expand the application of unconventional technology across a global stage, it appears that such differentiation is at times, not fully respected or appreciated.

Globally, there is anecdotal evidence that some operators and service providers are attempting to transfer unconventional technology, without an associated detailed understanding of the nature of the formation planned to be stimulated. This often results in both operational issues and poor well productivity, neither of which are ever well publicised. However, the fact is that with increasing frequency, completion approaches that are perfectly valid for the unconventional environment, are being applied to conventional regimes for which they are not suited.

This paper will attempt to distinguish between the appropriate completions technologies for both unconventional and conventional formations and will indicate the potential pitfalls that await those who do not give appropriate consideration to such fundamental differences. Whilst the globalisation of such technology is of course to be encouraged, any misapplication will only result in disappointment and cause delays to any such global development.
Improved Assessment of Pore-Size Distribution and Pore Connectivity in Multiple-Porosity Systems using Superparamagnetic Iron Oxide Nanoparticles and NMR Measurements
Authors: Cheng Kai , Chi Lu , Heidari Zoya
Published: October 2014

Nuclear magnetic resonance (NMR) measurements are considered among the most reliable methods to evaluate porosity and pore-size distribution in fluid-bearing rocks. However, in reservoirs with complex pore geometry, there is still a challenge to accurately interpret NMR data to evaluate petrophysical properties of these reservoirs. In this paper, we propose to inject superparamagnetic iron oxide nanoparticles (SPION) into rock samples with multiple-porosity system (including natural fractures) and then quantify their impact on NMR measurements. The comparison of NMR data before and after nanoparticle injection improves characterization of pore-size distribution and pore connectivity.

The objectives of this paper are (a) to improve assessment of pore-size distribution and pore connectivity in the heterogeneous multiple-porosity system containing natural fractures, and (b) to enhance the reliability of reservoir characterization in challenging reservoirs such as complex carbonates and organic-shale formations. We conducted coreflood experiments to inject SPION in rock samples from sandstone, carbonate, and organic-shale formations, and obtained NMR T2 distribution before and after SPION injection. We also numerically simulated the NMR responses in different rock samples using a random walk algorithm. The comparison of simulated NMR T2 distribution before and after nanoparticle injection confirmed the experimental results well.

The results of laboratory experiments show non-uniform distribution of SPION in the porous media. We observed that the long-relaxation-time peaks in NMR T2 distribution significantly shifts to short-relaxation-time in the presence of nanoparticles, indicating that inter-connected large pores/fractures are most easily pervaded by SPION. However, the original short-relaxation-time peaks remained at the same positions with almost the same amplitudes and shapes after SPION injection, indicating that small pores are not pervaded by SPION. The same accumulative volume of water in the rock before and after SPION injection indicates that SPION pervasion in the rock only results in the shift of T2 relaxation time, but does not affect estimates of total porosity. We conclude from the experiments and numerical simulations that natural fractures, interconnected and isolated large pores, and small intra-granular pores can be accurately differentiated in NMR T2 distribution with the aid of SPION.
Borehole Casing Sources for Electromagnetic Imaging of Deep Formations
Authors: Marsala A. F , Hibbs A. D. , Morrison H. F.
Published: October 2014

The borehole to surface electromagnetic (BSEM) and crosswell electromagnetic (EM) methods have been shown to produce adequate subsurface electric current to image fluid distribution at reservoir depth. These methods have been proven to be an efficient way to transmit EM signals deep into the reservoir, but their field deployment is potentially expensive and logistically challenging. This is because several days of logging conveyance inside a borehole is required to implement them.

The ability to efficiently transmit EM signals inside the reservoir without a wellbore intervention has a tremendous potential impact in terms of cost reduction and deployment opportunity for reservoir fluid mapping and monitoring, thanks to EM technologies in the field. In BSEM a current electrode is placed inside the wellbore at reservoir depth and a counter electrode is located adjacent to the wellhead at the surface. The reservoir fluids are then imaged through measurements of several hundred EM receivers deployed at the surface. An innovative approach illustrated in this work is using a borehole casing to provide a way to introduce an electric current into the earth at considerable depth.

A new way to increase the current flowing in the subsurface at large offsets from the well is to combine a casing with one or more remote surface electrodes, located at a radial distance of approximately the casing depth. Contrary to common expectations, a conducting casing is actually an advantage when used in conjunction with an electric source.

Further, we analyze the performance of two specific variants of a casing with remote electrodes, showing the capability to detect small electrical features at a depth of 2 km out to greater than 2 km from the well. One of these source configurations has the considerable advantage that it does not require any well intervention for downhole operation. The model projections are compared to pilot surveys conducted in Saudi Arabia and at two sites in the USA with well depths of up to 2,100 m. Finally, we project the capability to detect small volumes of bypassed oil and establish the location of the oil-water boundary at significant depth and offset from a vertical well.
Wellbore Trajectory Control Using Minimum Well Profile Energy Criterion for Drilling Automation
Authors: Liu Zhengchun , Samuel Robello
Published: October 2014

When deviated from the planned wellbore path, it is imperative for a system to take correction actions. A new trajectory control model is developed based on minimum well profile energy criterion to achieve smooth well paths. In this model, the returning path from a deviated position (Xn-2, Yn-2, Zn-2, αn-2, φn-2) to the planned trajectory position (Xn, Yn, Zn, αn, φn is divided into two sections, each of which has its own length ΔD1, inclination change rate καi, and azimuth change rate κφi, i=n, n-1. The incremental well profile energy of the correction path can be computed as a function of section lengths, curvatures, and torsions. From the constant section build/drop rate settings and geometric relationships, five equations can be established corresponding to the changes of three-dimensional (3D) space coordinates and orientation angles (ΔX, ΔY, ΔZ, Δα, and Δϕ). By applying minimum well profile energy criterion, a unique solution set of deviation correction parameters (ΔDi, καi, and κϕi, i=n, n-1) can be obtained.

Different trajectory calculation algorithms are employed to solve the aforementioned deviation correction parameters. The results are consistent from the simple balanced tangential method, the industry standard minimum curvature method, and the more accurate natural curve method. The model is tested using wellbore trajectory simulations of different two-dimensional (2D) and 3D well paths. The simulation results show that the new trajectory control model, in comparison with proportional- integral-derivative (PID) control and fuzzy control methods, yields much smoother wellbore trajectories. Consequently, the new model is promising to reduce torque, drag, and friction of the drilling string.

Unlike PID and fuzzy control methods, which usually require subjective inputs of several controller parameters, the new trajectory control model offers deterministic solutions based on objective minimum-energy criterion. This is a significant advantage for the limited computation power of downhole tools. In addition, the settings of constant inclination/azimuth change rate in each correction section also provide benefits such as less frequent steering required; hence, less electric power consumption and less abrasion failure of downhole tools.