bluuebunny/crossref_metadata_2025 huggingface dataset:
Dendritic cells and immunosuppression after organ transplantation1
Authors: Daniel Volker
Published: September 2008

Dendritic cells (DC) start out on every immune reaction. They can initiate or suppress an immune response against antigen. Their diagnostic and therapeutic utilization is a research topic in transplantation medicine. One goal of studies in transplantation-immunology is the identification of transplanted patients, whose immunosuppressive treatment can be reduced or potentially discontinued without an impairment of graft function. The induction of tolerogenic DCs and their immunological monitoring in the patient blood would be an option for the realization of this goal. In experiments with cell cultures and animals, DCs were identified as target cells of immunosuppressive drugs. Clinical studies with transplant recipients showed alterations of DC subpopulations in the patient blood depending on the immunosuppressive drugs and their dosage. Up to now, no DC sub-population could be identified in the blood of transplant recipients that would allow prospectively a discontinuation of the immunosuppressive protocol. Further studies in vitro and in vivo are necessary to define the DC subsets that are relevant for the induction and maintenance of transplant tolerance.
Marriage as Prostitution in Berg's Lulu
Authors: dos Santos Silvio José
Published: September 2008

Writing to Schoenberg on August 7, 1930, Berg explained the differences between the libretto for his new opera and the original plays by Frank Wedekind, and in particular the return of Lulu's “victims” (her husbands) as her clients in the final scene of the opera. While Berg sought to create a large-scale symmetry with this return, he also posited a link between marriage and prostitution that did not exist in Wedekind's texts. Significantly, Berg was not alone in equating these two institutions; numerous Victorian writers had already made arguments in this regard. In fin-de-siècle Vienna this issue was widely debated and reflected some prevailing views of female sexuality, including those expressed in the influential works of Otto Weininger and Karl Kraus. Indeed, as is well documented, Berg was keenly engaged in these issues.

The association of marriage with prostitution was a crucial element in Berg's conception of the opera. Evidence found in the autograph manuscripts and the finished work confirms that Berg represented these institutions as essentially the same at several levels of the work. This is revealed in his musical portrayal of Lulu, the Prince, the Man servant, and the Marquis, as well as in such musical choices as his borrowing of Wagner's wedding march from Lohengrin and his use of Wedekind's Konfession, a song about prostitution. Indeed, the representation of the two institutions is directly linked to the opera's musical language, particularly the transition from tonal to twelve-tone structures in the final act. Most importantly, this representation reflects Berg's construction of identities for the main characters in the opera and, by extension, the sociocultural issues portrayed in this seminal work.
Part-Time Training in Pediatric Residency Programs: Principles and Practices
Authors: Gordon Mary Beth , McGuinness Gail A. , Stanton Bonita F. , Brooks Susan , Chiang Vincent W. , Vinci Robert , Sectish Theodore C.
Published: September 2008

Despite growing interest in part-time work, few pediatricians are pursuing part-time residency training. There is currently little guidance for programs or residents who wish to design an alternative path through residency. In this article we review the need for part-time residencies and address obstacles to be overcome in their initiation. Strategies are offered for residents and program directors planning part-time training pathways, with recommendations for implementation amid a changing environment for graduate medical education. The needs of trainees, residency programs, hospitals, and credentialing organizations are considered.
Acidentes com corpo estranho em menores de 15 anos: análise epidemiológica dos atendimentos em pronto-socorro, internações e óbitos
Authors: Martins Christine Baccarat de Godoy , Andrade Selma Maffei de
Published: September 2008

Analisou-se os acidentes com corpo estranho entre menores de 15 anos, residentes em Londrina, Paraná, Brasil, atendidos em serviços de emergência/internação ou que morreram por estas causas, em 2001. Os dados foram obtidos nos hospitais gerais e no Núcleo de Informação em Mortalidade do município. Foram estudadas 434 crianças vítimas de acidentes com corpo estranho, revelando uma taxa de internação de 3,7% e uma taxa de óbito de 0,7%. Houve predomínio do sexo masculino (53,7%) e o maior coeficiente foi na faixa etária de 1 a 3 anos (7,2 por mil crianças). A penetração de corpo estranho em orifício natural (olho, fossas nasais e conduto auditivo) representou 94%, a inalação/ingestão de alimentos ocorreu em 2,8%, a inalação/ingestão de objetos em 2,5% e a inalação de conteúdo gástrico em 0,7% dos casos, sendo responsável por todos os óbitos. A presente investigação pode contribuir no sentido de permitir aos planejadores analisar tendências, priorizar ações que contemplem a prevenção e atenção às vítimas desses eventos e desenvolver estratégias para a reestruturação dos serviços a fim de tornar mais eficiente o gerenciamento dos recursos.
Hábitos de higiene bucal e utilização de serviços odontológicos em escolares de uma cidade da Região Sul do Brasil
Authors: Freddo Silvia Letícia , Aerts Denise Rangel Ganzo de Castro , Abegg Claídes , Davoglio Rosane , Vieira Patrícia Conzatti , Monteiro Lisiane
Published: September 2008

Estudo transversal investigando associação entre hábitos de higiene bucal e utilização dos serviços odontológicos, fatores sócio-demográficos e relacionados ao estilo de vida em amostra representativa de 1.170 escolares de 7ª série do ensino municipal de Gravataí, Rio Grande do Sul, Brasil. A associação entre os desfechos e sexo; cor da pele; inserção sócio-econômica; estilo de vida sedentário; uso de álcool e tabaco; e consumo de balas, refrigerantes e chocolates foi investigada com regressão de Cox univariada. Entre os jovens estudados, 77,8% escovavam os dentes > 3 vezes/dia, 31,9% utilizavam fio dental, 68,9% visitavam o dentista anualmente e 50% consultaram por motivo curativo. As meninas apresentaram maior freqüência de escovação do que os meninos. Os jovens com baixa inserção sócio-econômica, os com estilo de vida sedentário e os que experimentaram tabaco apresentaram menor uso diário de fio dental e consultas odontológicas anuais, e mais consultas curativas. O consumo de balas associou-se à menor utilização de serviços odontológicos e o de refrigerantes à maior freqüência de consultas curativas. O estilo de vida saudável associou-se com melhores hábitos de higiene bucal e utilização de serviços odontológicos.
Mercúrio total em músculo de cação Prionace glauca (Linnaeus, 1758) e de espadarte Xiphias gladius Linnaeus, 1758, na costa sul-sudeste do Brasil e suas implicações para a saúde pública
Authors: Dias Adriana C. L. , Guimarães Jean R. D. , Malm Olaf , Costa Paulo A. S.
Published: September 2008

Foram analisadas as concentrações de mercúrio total (THg) em tecido muscular do tubarão azul Prionace glauca e do teleósteo Xiphias gladius, vulgarmente conhecido como espadarte, provenientes das regiões sul e sudeste da costa brasileira, para verificar se estas se encontram dentro dos padrões legais para consumo humano. As amostras foram obtidas utilizando-se o programa REVIZEE, de agosto a setembro de 2001, e por intermédio de uma empresa de pesca em Itajaí, Santa Catarina. Foi analisado um total de 95 espécimes, testando-se as correlações entre THg, comprimento (cm) e peso (kg). As concentrações de mercúrio total em todas as amostras variaram de 0,13 a 2,26µgg-1 (peso úmido). A média de mercúrio total em P. glauca foi de 0,76 ± 0,48µgg-1 (p.u.), e em X. gladius foi de 0,62 ± 0,31µgg-1 (p.u.) com diferença não significativa (teste Mann-Whitney, p < 0,05). Em cerca de 16% das amostras, o THg excedeu o limite de 1µgg-1 (Agência Nacional de Vigilância Sanitária) e em 62% excedeu o limite de 0,5µgg-1 (Organização Mundial da Saúde - OMS). O consumo regular (100 g.dia-1) de P. glauca e de X. gladius resultaria em uma ingestão diária de THg que excederia em mais de duas vezes o limite diário de ingestão recomendado pela OMS.
Dor lombar em usuários de um plano de saúde: prevalência e fatores associados
Authors: Matos Mauro Gomes , Hennington Élida Azevedo , Hoefel Ana Lúcia , Dias-da-Costa Juvenal Soares
Published: September 2008

Com o objetivo de determinar a prevalência de dor lombar nos últimos três meses e fatores associados foi realizado um estudo transversal, com indivíduos de ambos os sexos, de 20 a 59 anos titulares do plano de saúde da COOPERSINOS da Universidade do Vale do Rio dos Sinos. Foram utilizados questionários auto-aplicados incluindo questões demográficas, sócio-econômicas, ocupacionais e hábitos de vida. Entre os 775 indivíduos a prevalência de dor lombar no último ano foi de 52,8% (IC95%: 49,3-56,3) e nos últimos três meses foi de 46% (IC95%: 42,5-49,5). Através de regressão de Poisson foram encontradas associações para dor lombar nos últimos três meses nos indivíduos de 40 a 49 anos, naqueles que consideravam seu trabalho penoso e nos fumantes. Apesar da elevada prevalência de dor lombar na população estudada e de ter provocado dificuldades no desempenho das atividades laborais, a condição não foi incapacitante. Mesmo que 29,9% dos trabalhadores tenham referido dificuldades para realizar suas atividades de vida diária ou no trabalho por dor lombar, detectou-se absenteísmo muito baixo.
A implicação de trabalhadores de ambulatórios municipais, em Uberaba, Minas Gerais, Brasil, na reorganização de serviços preconizada pelo Sistema Único de Saúde
Authors: Goulart Bethania Ferreira , Freitas Maria Imaculada de Fátima
Published: September 2008

Esta pesquisa foi desenvolvida em dois ambulatórios municipais de especialidades na cidade de Uberaba, Minas Gerais, Brasil. Busca compreender a implicação dos trabalhadores de saúde no seu trabalho e nas propostas de reorganização de serviços de saúde, sob a ótica deles e considerando a gestão participativa preconizada pelo Sistema Único de Saúde (SUS). A pesquisa foi realizada com nove trabalhadores que apresentam ou não formação específica em saúde, mas estão envolvidos com atividades no setor. Os participantes foram sorteados por categoria profissional ou função (grupos: odontológico, infra-estrutura, médico, serviço social, psicologia, coordenação, enfermagem e farmacêutico e bioquímico), considerando-se um participante por "categoria" de cada serviço. O conteúdo foi analisado fundamentando-se nos procedimentos da análise estrutural de narração. Foram identificadas três categorias: a gerência, implicação no trabalho e implicação nas propostas do SUS. Ressalta-se que este estudo não pretende universalizar resultados sobre a implicação dos trabalhadores em saúde, no geral, mas aponta para a importância de se compreender a interação entre o modelo gerencial e a reorganização de serviços preconizada pelo SUS.
Utilização de medicamentos por aposentados brasileiros: 2 - Taxa de resposta e preenchimento de questionário postal em Belo Horizonte, Minas Gerais, Brasil
Authors: Ribeiro Andréia Queiroz , Acurcio Francisco de Assis , César Cibele Comini , Rozenfeld Suely , Klein Carlos Henrique
Published: September 2008

São descritos a taxa de resposta e o preenchimento de questionários auto-administrados num inquérito postal sobre o perfil de utilização de medicamentos por aposentados e pensionistas do INSS, de 60 anos ou mais de idade no Município de Belo Horizonte, Minas Gerais, Brasil, em 2003. Os questionários foram enviados duas vezes para os endereços de 800 indivíduos sorteados por amostragem aleatória simples, com base no banco de dados do INSS. A taxa de resposta ao inquérito postal foi de 47,8% e não houve diferença significativa tanto entre participantes e não participantes quanto entre respondentes iniciais e tardios em relação às características selecionadas. Para a maioria das variáveis sócio-demográficas e de saúde, os percentuais de omissão de respostas não ultrapassaram 5%, tanto no total da amostra, quanto em cada um dos subgrupos de respondentes. As informações mais omitidas ocorreram para as variáveis relativas ao uso de medicamentos, com destaque para a não-utilização de medicamentos que deveriam ser usados, a dose e laboratório fabricante do medicamento. Nossos resultados indicam que o detalhamento de aspectos relacionados ao uso de medicamentos deve ser reconsiderado em questionários de autopreenchimento.
Mulheres idosas enfrentando a institucionalização
Authors: Pavan Fábio José , Meneghel Stela Nazareth , Junges José Roque
Published: September 2008

O tema desta pesquisa é a institucionalização de idosos sob a perspectiva dos estudos de gênero. O objetivo é entender os efeitos do processo de institucionalização na vida de idosas e estratégias para enfrentar esta situação. A metodologia é qualitativa e a pesquisa foi realizada em uma instituição de longa permanência para idosos, que atende 110 pessoas procedentes da região do Alto Uruguai, Rio Grande do Sul, Brasil. Para a coleta dos dados foram organizados grupos de discussão com a participação de dez idosas. Utilizou-se a análise de conteúdo e foram identificadas três categorias principais: o asilo como instituição total, gênero, e estratégias de enfrentamento à institucionalização. Metade das mulheres escolheu viver no asilo, enquanto que outras denunciaram a situação de internação e consideram o asilo "um depósito de velhos". A categoria gênero atravessa o fazer das mulheres que realizam atividades domésticas no "lar", para ajudar a passar o tempo. As estratégias para enfrentar o asilamento compreendem os rituais religiosos, as atividades artesanais e passeios.
The Denial of Emergency Protection: Factors Associated With Court Decision Making
Authors: Jordan Carol E. , Pritchard Adam J. , Wilcox Pamela , Duckett-Pritchard Danielle
Published: September 2008

Despite the importance of civil orders of protection as a legal resource for victims of intimate partner violence, research is limited in this area, and most studies focus on the process following a court’s initial issuance of an emergency order. The purpose of this study is to address a major gap in the literature by examining cases where victims of intimate partner violence are denied access to temporary orders of protection. The study sample included a review of 2,205 petitions that had been denied by a Kentucky court during the 2003 fiscal year. The study offers important insights into the characteristics of petitioners and respondents to denied orders and outlines individual, contextual, structural, qualitative/perceptual, and procedural factors associated with the denial of temporary or emergency protective orders. Recommendations for statutory changes, judicial education, and future research to remedy barriers to protection are offered.
Caring and Compassion When Working With Offenders of Crime and Violence
Authors: Stefanakis Harry
Published: September 2008

Getting tougher on men who use violence is a rallying cry for people on both sides of the political spectrum. This article challenges the notion that a punitive framework increases safety and promotes nonviolence. The dominant worldview in today’s culture and science is based on a fragmentary perspective that reinforces disconnections that facilitate rather than prevent further violence and abuse. In contrast, the nonfragmentary perspective is also scientifically valid but has very different implications for how we treat each other. This nonfragmentary perspective makes visible compassionate responses to violence that can be more effective in ending abuse and building peace in our lives and relationships. Research to support this conclusion is provided.
Concentrated sodium chloride brine solutions as an additional treatment for preventing the introduction of nonindigenous species in the ballast tanks of ships declaring no ballast on board
Authors: Santagata Scott , Bacela Karolina , Reid David F. , Mclean Kevin A. , Cohen Jill S. , Cordell Jeffery R. , Brown Christopher W. , Johengen Thomas H. , Ruiz Gregory M.
Published: September 2008

Currently, seawater flushing is the only management strategy for reducing the number of viable organisms in residual sediments and water of ballast tanks of vessels declaring no ballast on board (NOBOB) that traffic ports of the eastern United States. Previously, we identified several species of freshwater and brackish-water peracarid crustaceans able to survive the osmotic shock that occurs during open-ocean ballast water exchange and, potentially, to disperse over long distances via ballasted ships and NOBOB vessels. We tested the efficacy of concentrated sodium chloride brine solutions as an additional treatment for eradicating the halotolerant taxa often present in the ballast tanks of NOBOB ships. The lowest brine treatments (30 ppt for 1 h) caused 100% mortality in several species of cladocerans and copepods collected from oligohaline habitats. Several brackish-water peracarid crustaceans, however, including some that can survive in freshwater as well, required higher brine concentrations and longer exposure durations (45–60 ppt for 3–24 h). The most resilient animals were widely introduced peracarid crustaceans that generally prefer mesohaline habitats but do not tolerate freshwater (required brine treatments of 60–110 ppt for 3–24 h). Brine treatments (30 ppt) also required less time to cause 100% mortality for eight taxa compared with treatments using 34 ppt seawater. Based on these experiments and published data, we present treatment strategies for the ballast tank biota often associated with NOBOB vessels entering the Great Lakes region. We estimate the lethal dosage of brine for 95% of the species in our experiments to be 110 ppt (95% confidence interval, 85–192 ppt) when the exposure time is 1 h and 60 ppt (95% confidence interval, 48–98 ppt) when the exposure duration is 6 h or longer.
Instruments of Support at Emergency Response Planning in Urban Environment Situated at the Peripheral Area Around Industrial Facilities
Authors: Sandres G. C. , Silva C. , Chaves L.
Published: September 2008

Emergency Response Planning for major accidents – toxic gas leaks, fires and explosions – is a powerful tool for the chemical industry today, mainly at large-scale facilities such as oil refineries. This topic has been discussed intensively since a series of major accidents occurred at several places around the world. Organizations, industries and society have been paying close attention to this issue in order to implement the correct actions for dealing with this type of problem. In Brazil, oil refineries are often located in densely populated areas whose residents are vulnerable to major accidents, particularly because of the high-risk industrial activities conducted at these facilities.

The preparation of specific Emergency Response Plans for areas surrounding industrial complexes involves fast response systems, with the use of appropriate tools – such as Geographic Information Systems (GIS) and Risk Analyses – supporting decisions that must be taken in critical situations. Consequently, regional mapping that encompasses sets of elements constituting urban environments is very important within the External Emergency Response Planning context. Additionally, modeling critical accident scenarios that affect not only assets, but also employees and neighboring communities, portrays the actual extent of the area affected by the accidents under analysis.

By deploying the GIS as tool and modeling critical accident scenarios, georeferenced data can be generated, stored and handled, in addition to presenting the potential of spatial integrated analyses. The inclusion of geoprocessing technology, which is a vital tool for this type of planning, streamlines the integration of these data with quantitative risk analyses, constituting a powerful instrument that examines the composition of critical accident scenarios and their consequences in urban areas and outlying areas around industrial complexes. The integration of these tools is essential as a decision support system for Emergency Response Planning.

The use of support tools for dealing with emergency situations is a crucial step for dealing with major industrial accidents. The integrated use of these tools, specially the GIS and Risk Analyses, offers a fresh view of this issue and the science, making approaches to this type of problem more representative. Above all, it examines and quantifies analyses of urban environments around outlying industrial areas, fostering the development of integrated actions that help mitigate widespread impacts caused by industrial activities.
Gas Shut-off Treatment in Oil Carbonate Reservoirs in Saudi Arabia
Authors: Al-Dhafeeri A. M. , Nasr-El-Din H. A. , Al-Mubarak H. K. , Al-Ghamdi J.
Published: September 2008

Gas coning or channeling is a serious problem in many oil fields. It can reduce oil production significantly. Therefore, it is important to minimize excessive gas production. Production at high gas/oil ratio is a problem, which occurs because of the high gas mobility in the formation. Gels and foams have often been used to reduce gas movement into the wellbore of oil wells.

Oil production from an oil producer in a carbonate reservoir declined due to excessive gas production. A detailed diagnostic work was conducted to determine the source and entry of gases into this well. In addition, several gelling systems were examined in the laboratory as a means for gas shut-off in this well.

The results of several logs identified two zones for gas production. The first zone 6,000-6,500 ft is responsible for 80% of the gases produced from well A. Another zone, 7,200 – 7,400 ft is responsible for the remaining gases. Several chemical means were evaluated for total shut-off of these two zones. These systems were compatible with formation brines. The gelation time can be controlled by varying the cross-linker concentration, or by injecting a preflush to cool down the formation. A surfactant system with a source of calcium was evaluated to be used for gas shutoff purpose. This system produced a precipitate that can be removed by toluene and other hydrocarbons.
Field Case Histories Demonstrating the Critical Roles Played by Multiphase Flow Models in Appropriate Production Log Interpretation
Authors: Ouyang Liang-Biao , Suthichoti Polpipat
Published: September 2008

Production logging (PLT) has been routinely practiced in oil and gas industry to estimate oil, water, and/or gas production profile, determine fluid entry or exit location and amount along perforation interval(s), and detect major oil/gas/water producing layers. Through successful PLT surveys and appropriate interpretation, we may also identify thief zones and high perm channels, locate injected fluid breakthrough, monitor fluid front movements, detect crossflow and fluid migration, assist in reservoir simulation studies, etc.

After a PLT is run, subsequent workover is routinely performed aiming at reducing water production while maintain or even increase oil and/or gas production from the well. Unfortunately, mixing results have been obtained through workover operations designed based on PLT, due to poor logging procedure, unreasonable PL tool selection, poorly executed surveys, inappropriate interpretation, etc.

With the existence of two or three phase flow in a well, the interpretation of production logs becomes critical for achieving successful assessment of major oil, water and gas entries and thus a successful workover operation. Under most circumstances, an appropriate interpretation of production logs relies heavily on the selection of a reasonable multiphase flow model to correctly capture complex multiphase flow features in the wellbore.

In this paper, major flow characteristics of multiphase flow in a wellbore will first be described. Different correlations and mechanistic models to describe multiphase fluid flow will then be introduced; the pros and cons of correlation/model will be highlighted. Impacts of multiphase flow models on interpretation results of production logs will be investigated.

Several field case histories will be discussed in detail to illustrate the critical roles played by multiphase flow models in production log interpretation. For each field case history, the background information of well production, reservoir sands, production logging survey and interpretation, workover efforts and results, and so on, will be included. PLT interpretation based on selected multiphase flow models will be shown and compared with workover results.
Analysis of Reservoir Performance of the Messoyakha Gas Hydrate Reservoir
Authors: Grover Tarun , Moridis George J. , Holditch Stephen A.
Published: September 2008

The Messoyakha Gas Field is located in Siberian permafrost. The field has been described as a free gas zone, overlaid by hydrate layer and underlain by an aquifer of unknown strength. The field was put on production in 1970 and has produced intermittently since then. Some characteristic observations were increase in average reservoir pressure during shut-in, perforation blocking due hydrate formation and no change in gas-water contact. It is believed the increase in reservoir pressure was caused by the hydrate layer dissociation, rather than aquifer influx. The objective of this study is to use numerical model to analyze the observed production data from the Messoyakha field. In this study, a range of single-well 2D cross-sectional models representative of Messoyakha have been developed using Tough + Hydrate reservoir simulator. The simulation results were analyzed and compared with various field observations. Further, we have done a parametric study of reservoir properties of hydrate capped gas reservoir. We have used Tough + Hydrate to simulate the observed gas production and reservoir pressure data at Messoyakha. We simulated various scenarios that help to explain the field behavior. We have evaluated the effect of various reservoir parameters on gas recovery from hydrates. Our work should be beneficial to others who are investigating how to produce gas from hydrate capped gas reservoir.We were able to generate results that are very similar to the reported flow rates and pressure behavior in Messoyakha Field. The value of absolute permeability in the hydrate layer and the lower free gas layer substantially affects the continued dissociation of hydrates during shut-down. We also modeled the formation of secondary hydrates near the wellbore that can cause the reduced gas flow rates. The important parameters affecting the gas production are the formation permeability in the gas layer, the effective gas vertical permeability in hydrate layer, the location of perforations, and gas hydrate saturation. We have described various scenarios which are beneficial as well as detrimental in producing gas from hydrate capped gas reservoirs. We have also listed various parameters that should be carefully measured for accurate modeling work.
Well-Included Flowbased Grid Generation for Heterogeneous Reservoirs
Authors: Gherabati S. A. , Dabir B. , Hesami A.
Published: September 2008

Fine grid geocellular reservoir characterizations often include detailed description of geological and geometric complexity. Since this volume of details can not be handled by commercial reservoir simulators, some degree of coarsening is necessary. The fundamental agenda in coarse grid generation includes development of finer grids in regions with higher flow. Available methods in literature suffer from draw back of inability to consider both the well and geological features which mostly affect the flow response. This study introduces a new method of grid coarsening (flow based) procedure. The procedure encompasses tracing streamline from boundary to the well, monitoring velocity trend along streamline to identify high flow region and selection of appropriate points on streamlines as grid nodes. Differentiating the analytical equation of the streamline path results in developing velocity vectors and adding them up will yield a new term called cumulative velocity. Using this term, the grid points are easily identified which after implementation of Delaunay triangulation and Laplacian smoothing algorithms the main CVFE (Control Volume Finite Element) grid is produced. In addition, a robust up-scaling technique was used to calculate the tensor of permeability.

Flux-continuous finite volume scheme was used to solve the associated flow equation in the coarse block. The generated grid pattern is finer in high flow regions and can successfully adapt itself based on type of geological features presented.

Pressure was the main criteria for comparison the results of this study with those of Cartesian coarse grid. The results indicated that the response of the model with coarse grids (flow based) is more consistent with a fine model. The major advantage of the introduced method is its capability in handling the geological features within the grid. It is worthy to mention that the positioning of the well and adjustment of the required refinements around it are done automatically.
A Correlation of the Interfacial Tension between Supercritical Phase CO2 and Equilibrium Brines as a Function of Salinity, Temperature and Pressure
Authors: Bennion D. Brant , Bachu Stefan
Published: September 2008

The modeling of CO2 sequestration in saline aquifers is becoming increasingly important as this method emerges as the prime technology available for the disposal of large volumes of anthropogenically-generated CO2, thus reducing atmospheric CO2 emissions. The interfacial tension between the saline brine in the aquifer and the injected CO2 phase has a strong effect on the capillary pressure and relative permeability characteristics of the CO2-brine displacement, and proper understanding of the IFT level is necessary for accurate modeling and evaluation of such a process. This paper provides a summary of 168 brine-CO2 interfacial tension measurements conducted using a drop pendant interfacial tension apparatus at temperatures ranging from 41 to 125 °C, pressures from 2,000 to 27,000 kPag and salinities from 0 ppm (distilled water) to over 334,000 ppm. The dataset was regressed to develop an empirical correlation to predict the brine-CO2 IFT over the range of conditions evaluated in this work. The correlation, including temperature, pressure and salinity dependence, fits the measured data with an overall regression coefficient in excess of 0.94. In addition, a very strong relationship was found between computed gas-water ratio (dissolved CO2) and interfacial tension. An additional correlation was developed to model this effect, also with a high regression coefficient of 0.92. Since the gas-water ratio is a much easier parameter to measure than IFT, this provides a rapid and inexpensive method to estimate in-situ IFT from available or CO2 solubility data.
Determining Environmental Tradeoffs Associated with Low Impact Drilling Systems
Authors: Haut Richard C. , Burnett David , Rogers John , Williams Tom
Published: September 2008

An environmental scorecard is being developed to determine the tradeoffs associated with implementing low impact drilling technology in environmentally sensitive areas. The scorecard will assess drilling operations and technologies with respect to air, site, water and biodiversity issues. Low environmental impact operations will reduce the environmental footprint of operations by the adoption of new methods to use in (1) getting materials to and from the rig site (site access), (2) reducing the rig site area, (3) using alternative drilling rig power management systems, and (4) adopting waste management at the rig site.

The scorecard enables a dialog to be established and maintained among all interested, concerned and affected stakeholders. In this manner, the oil and gas industry has a new way of seeing itself within the larger network.

The scorecard presented in the paper provides the means to demonstrate the connectivity between energy production and the affected ecosystem.

The Houston Advanced Research Center (HARC) and Texas A&M University have been leading an industry consortium effort to investigate the development of low impact drilling systems.

The work originated in 2005 and funding was obtained by the U.S. Department of Energy for 2006 through 2008.

The goal of the low impact drilling systems project is to reduce the environmental impact of rig operations through integration of low-impact site access and site operations. The paper will discuss the scorecard that is being developed. The scorecard methodology presents an ecological understanding of the tradeoffs associated with producing energy. The EFD scorecard will be developed in detail for a coastal margin ecosystem and the methodology will be documented to enable the scorecard to be replicated at other ecosystems wherever reservoirs are produced. This scorecard methodology is being developed through a series of workshops being held with ecologists, botanists, wildlife management experts and others in addition to oil and gas industry experts.
Modeling of Drilling Fluid Losses in Naturally Fractured Formations
Authors: Majidi R. , Miska S. Z. , Yu M. , Thompson L. G. , Zhang J.
Published: September 2008

Significant mud losses often occur while drilling in fractured formations. Severe problems arise when drilling fluids invade high permeability conductive fractures that the well path intercepts. The industry has recently started to monitor mud loses in order to identify the fractures and characterize them. Methodologies are available to characterize the geometry and conductivity of the fractures by quantitative analysis of field measurements. These methodologies are mainly based on mathematical models that describe the physical phenomenon and the mechanism under which the flow within the fractures takes place. Once the models are provided one can look for causes of the problem and methods to minimize it.

This paper presents a new model for mud loss of non-Newtonian drilling fluids into naturally fractured formations. Flow of Yield-Power-Law (Herschel-Bulkley) fluids has been coupled with Newtonian reservoir fluid in a single fracture. The governing equations are derived based on principles of conservation of mass and linear momentum for drilling fluid and pressure diffusion for reservoir fluid. Results are obtained based on semi-numerical solutions and plotted in terms of mud loss volumes versus time. The results demonstrate how rheology of the drilling fluid and formation fluid properties can influence mud losses. The relative contributions of both drilling and reservoir fluids is determined and compared.

This model allows for predicting fluid losses for a given drilling fluid, formation fluid and operational conditions. Conversely, one can evaluate hydraulic aperture of the fractures by continuously monitoring mud losses and finding the best fit of field measurements of mud loss to the model. Field data are used to demonstrate the practical application of the proposed technique.

The proposed model is valuable for drilling operations because it can help in minimizing the loss of expensive drilling fluids through optimization of drilling fluid rheological properties and selecting appropriate lost circulation materials. The model also benefits production operations by minimizing formation damage. In addition, well completion schemes can be optimized based on the improved knowledge of the near-wellbore fracture characteristics.
Discussion on Formation Fluid Density Measurements and Their Applications
Authors: Godefroy Sophie , Zuo Julian , Fujisawa Go , O'Keefe Michael , Ardila Mario , Cañas Jesus , de Santo Ilaria , Cig Koksal
Published: September 2008

Knowledge of formation fluid density is necessary for a variety of applications. It provides information on pressure gradient, zonal compartmentalization, transition zone characterization, thin beds analysis, and other reservoir qualities. It also contributes to estimates of the commercial value of the produced fluid and is a critical parameter used in modeling of the reservoir fluids through the equation of state (EOS) to obtain a better representation of fluid Pressure/Volume/Temperature (PVT) properties. Various techniques exist today for the measurement of formation fluid density. These measurements can be taken either at surface on captured fluid samples or downhole in real time using formation tester tools. The different techniques include laboratory PVT analysis of a fluid sample brought to surface, pressure gradients, downhole optical spectroscopy, and, recently developed, density measurements with the in-situ densimeter, which determines density by measuring the resonance characteristics of a vibrating object immersed in the fluid.

Although PVT analyses have excellent accuracy, downhole measurements have an advantage over surface measurements as they provide in-situ measurements under reservoir conditions without depending on the quality of the fluid from the sample bottle and sample transfer. They also allow better reservoir characterization without the need for an extensive sampling program. Pressure gradient surveys have been successfully used for decades to provide density measurements of the formation fluids. Although the measurement depends on the accuracy of both pressure measurement and depth, it provides density unaffected by flowline condition of formation testers and mud filtrate contamination. Downhole flowline sensors, such as spectroscopic sensors and vibrating rods, have the advantage of providing density measurements of the fluid itself rather than relying on other parameters such as depth, but they are sensitive to flowline conditions. Whereas the estimation of density from the spectroscopic method relies on an empirical model that cannot be used in every condition, the vibrating rod in-situ density sensor gives a direct physical measurement and is thus the preferred method of measurement whenever available.
A New Multi Laterolog Tool with Adaptive Borehole Correction
Authors: Zhou Z. , Corley B. , Khokhar R. , Maurer H. , Rabinovich M.
Published: September 2008

The Dual Laterolog (DLL) is one of the most commonly used resistivity logging devices in environments with highly conductive (salt-saturated) drilling mud and high formation resistivity. However, this device produces only two apparent resistivity logs with different radial depths of investigation, and it has a relatively low vertical resolution. Several array laterologs have been developed during the 1990s to improve both the vertical and radial resolution of measured formation resistivity. Each of these devices provides several depths-of-investigation measurements. However, most of these measurements, especially the shallow ones, are subject to borehole and eccentricity effects in very conductive muds and large boreholes. These effects can be severe. Therefore, conventional borehole corrections based only on borehole size, mud conductivity, and a fixed value of tool eccentricity (typically used for DLL measurements) become ineffective.

A newly developed array laterolog device, Multi Laterolog, is based on the Dual Laterolog principle but with four independent focused measurements. This device is effectively shorter in total length than the traditional DLL and provides higher vertical resolution. Four measurements with different depths of investigation yield a detailed radial resistivity profile. A hardware-based feedback loop is employed to ensure the required focusing.

To overcome the problems of the borehole and eccentricity effects on shallow measurements, we have developed a model-based adaptive borehole correction (ABC) technique. It is based on a radial 1-D inversion approach that properly corrects laterolog measurements for the borehole effect including determining and accounting for the unknown tool eccentricity. At every logging depth, we determine four earth-model parameters: tool eccentricity (Ecc), formation resistivity (Rt), invasion zone resistivity (Rxo), and invasion length (Lxo). After that, we apply the model-based correction by modifying the tool response in a borehole with mud resistivity Rm to a response in a borehole with virtual mud resistivity equal to Rxo (or to Rt if the formation is not invaded). This approach guarantees that in uninvaded intervals all four laterolog curves are properly "stacked", while in invaded intervals they show a reliable and consistent resistivity profile. The forward modeling used in inversion is based on the five-dimensional interpolation of pre-calculated look-up tables of various eccentered tool responses. Therefore, the inversion is very fast and the new borehole correction algorithm can be applied in real time. As a by-product, we output the length and resistivity of the invaded zone in invaded intervals. Thus, this correction scheme can provide Rt, Rxo and Lxo for thick beds together with borehole- and eccentricity-corrected curves at the wellsite. We illustrate the advantages of the Multi Laterolog and the model-based adaptive borehole corrections on synthetic data and on field data examples.
Nonisothermal and Productivity Behavior of High Pressure Reservoirs
Authors: App J. F.
Published: September 2008

High pressure, low permeability reservoirs have been encountered in various parts of the world within the past few years. Commercial development of these reservoirs may require high drawdowns, possibly in excess of 6,000 psi. The impacts of drawdown in this range are: 1) increases in near wellbore temperatures due to Joule-Thomson expansion of the reservoir fluids and, 2) significant reductions in oil viscosity. The effects of large drawdown are evaluated with a transient, single-phase thermal simulator in which the oil viscosity is modeled as both temperature and pressure dependent and Joule-Thomson expansion of the reservoir fluids is considered. Results indicate near wellbore temperature increases of 4 to 24°F for drawdowns between 2,000 to 10,000 psia due to Joule-Thomson expansion of the reservoir oil and connate water. Furthermore, if oil viscosity is not modeled as pressure dependent productivity indices will be under predicted and analysis of well tests will result in estimated skin values lower than actual. Temperature profiles within the formation are presented for a range of rates and drawdowns. Additionally, a comparison of maximum wellbore temperatures and profiles between transient, steady state and macroscopic energy models is presented. Technical rationale is also presented to explain the transient heating or cooling phenomena which occur immediately after a rate change. Synthetic well tests are generated to illustrate the impact of high drawdown on well test interpretation. These tests show a region of improved mobility in the near wellbore region due to the reduction in the oil viscosity.
Paraffin Deposition During the Flow of Water-in-Oil and Oil-in-Water Dispersions in Pipes
Authors: Bruno Antonio , Sarica Cem , Chen Hong , Volk Michael
Published: September 2008

Two different crude oils with significantly different physical properties, South Pelto Crude Oil and Garden Banks Condensate, were studied extensively in the small-scale flow loop of Tulsa University Paraffin Deposition Projects. A total of eight oil-water deposition tests, two single-phase deposition tests, and two inversion point tests were successfully conducted. Four different water cuts were selected for each fluid.

The deposit thickness showed a decreasing trend with increasing water cuts for both the South Pelto oil and Garden Banks condensate tests. In contrast to South Pelto's water continuous results, which showed no deposit, a Garden Banks condensate test with 85% water cut did generate a very thin and hard deposit film. This result indicates that there has to be a different deposition mechanism than the ones based on conventional diffusion theory. A reduction in Reynolds number caused by the increased apparent viscosity of the mixture also resulted in a lower paraffin content of the deposits. The volume fraction of water in the deposit is lower than the initial water cut of the mixture for both fluids. Garden Banks showed less water fraction in the deposit compared to South Pelto.

Couto's (2004) preliminary oil-water paraffin deposition model was validated against experimental data. Several modifications are proposed to account for water concentration in the deposit and changes in the diffusion coefficient for water dominated flows. Model predictions agree fairly well with experimental data acquired in this and previous studies.
Shale Volumes Have Large Uncertainties in the Lower Tertiary Deepwater
Authors: Wiltgen N.
Published: September 2008

Exploration in the Gulf of Mexico has progressively moved farther and farther offshore. Initially oil companies concentrated on the shelf and then moved into the deep water and the Miocene trend. With the acquisition and processing of data farther offshore, attention has switched to a new trend in the Lower Tertiary.

This is an emerging play in the deepwater Gulf of Mexico, to date there have been 12 announced discoveries out of 19 wells drilled. Geoscientists expect to see well developed stacked turbidites that define basin floor fans. This trend data is only for Alaminos Canyon, Keathley Canyon and Walker Ridge.

Shale is a mud rock that can have an extremely variable assortment of minerals, and is usually a nonreservoir rock. This kind of sedimentary rock contains a significant volume of clay minerals has many types of clay minerals with widely varying different compositions and log responses. So estimations of shale/clay volume carry large uncertainties. For our purposes we will assume the minerals in the shale are the clay minerals, plus the same minerals that are in the adjacent "sand" seen by the ECS mineral model.

With help from the integration of spectroscopy and triple-combo logs, the important variable the apparent grain density, can be calculated as a function of the 4 measured elements Si, Ca, Fe and S. This method becomes even more certain when the method is calibrated to a core data base to correlate the weight fractions of elements. We will convert bulk density, and with grain density from SI, FE, CA and S to porosity. Mr. Herron's paper SPE 77631 gives the formulas for this methodology for four types of combinations of non-arkose, sub-arkose and arkose.

The advantages and shortcomings of this method will be discussed and how they involve the spectrometer measurements with the element-mineral relationships. It is extremely important to have core with porosity, grain density, water saturation and permeability. But the key information from the core is quantitative XRD to truly have confidence in the significance of this method.