bluuebunny/crossref_metadata_2025 huggingface dataset:
Produção de progesterona in vitro pelas células do corpo lúteo bovino ao longo da gestação
Authors: La Paz Mariana N. , Fonseca Vanessa U. , Campos Danila B. , Artoni Laura P. , Sousa Liza M. M. C. , Papa Paula C.
Published: December 2007

O presente trabalho foi desenvolvido para testar a hipótese de que células luteínicas bovinas em cultivo, provenientes dos três terços de gestação, comportam-se da mesma maneira que células in vivo em relação à produção de P4. Foram coletadas amostras de corpos lúteos (CL) de 90 (n=3), 150 (n=3) e 210 (n=3) dias de gestação obtidos em abatedouro. Sob condições assépticas, as células foram mecanicamente dispersas e cultivadas em placas de 96 poços. Após 24 horas de cultivo foram feitas a lavagem dos poços e a adição do precursor pregnenolona. Os tratamentos foram realizados em octuplicata para cada tempo de tratamento (24, 48 e 96 horas) com três repetições de cada período gestacional. As amostras de meio de cultura e as células foram coletadas 24, 48 e 96 horas após adição do precursor e acondicionadas em freezer a -20ºC até o processamento. A progesterona foi dosada através de radioimunoensaio e o conteúdo protéico pelo método de Lowry. Os resultados foram analisados estatisticamente e considerados diferentes quando p<0.05. Foi observada maior produção de P4 aos 90 dias de gestação (35,277±0,075), posterior decréscimo aos 150 dias (28,820±0,231) e novo aumento aos 210 dias (32,777±0,099). A produção de P4 em células cultivadas por 24 horas foi maior (p<0,05) em células oriundas do grupo de 90 dias (2,912±0,047) quando comparado a 150 (2,669±0,137) e 210 dias (2,741±0,088). As 48 e 96 horas de cultivo, células luteínicas bovinas de 90 dias produziram mais P4 que células de 210 dias (2,934±0,029 e 2,976±0,121 respectivamente x 2,760±0,059 e 2,695±0,149, respectivamente; p<0,05), que por sua vez produziram mais do que células de 150 dias (2,334±0,084 para 48 horas e 2,205±0,136 para 96 horas). Aos 150 dias de gestação a produção de progesterona apresentou diminuição gradativa ao longo das 96 horas de cultivo. Essas diferenças podem ser explicadas pela expressão gênica diferencial de enzimas ou também de fatores presentes na cascata esteroidogênica de acordo com a idade gestacional. Este modelo de cultura celular luteínica poderá ser utilizado em estudos funcionais uma vez que o padrão de secreção de P4 mimetizou o que ocorre in vivo.
Avaliação imunoistoquímica da proteína ciclooxigenase-2 nas neoplasias colorretais e sua relação com fatores patológicos prognósticos
Authors: Brambilla E , Moreira Luis Fernando , Serafini Eduardo Pretto
Published: December 2007

OBJETIVOS: Avaliar a prevalência da proteína ciclooxigenase-2 (COX-2) nas neoplasias colorretais e sua relação com os parâmetros patológicos prognósticos para o câncer colorretal. MÉTODO: 65 lesões neoplásicas colorretais foram avaliadas através de imunoistoquímica para a presença de COX-2, também foram analisados fatores patológicos prognósticos e estadiamento das lesões. RESULTADOS: A COX-2 expressou-se positivamente em 27% dos adenomas tubulares, 40% dos adenomas vilosos e 70% nos carcinomas. Diferença estatisticamente significante foi obtida na expressão da COX-2 entre adenomas e carcinomas, porém não houve significância nas demais variáveis estudadas. CONCLUSÃO: A expressão da COX-2 parece variar progressivamente com a progressão da lesão neoplásica, mas não influencia os parâmetros patológicos de mau prognóstico.
Valor do gradiente de pressão retal e anal na evacuação em megacólon adquirido
Authors: Fang Chia Bin , Klug Wilmar Artur , Aguida Helly Angela Caram , Ortiz Jorge Alberto , Capelhuchnik Peretz
Published: December 2007

O megacólon resulta de lesão extensa dos plexos mioentéricos, a qual se traduz por incoordenação motora do cólon com inércia funcional e acalasia do esfíncter anal. Disso resulta duplo distúrbio, em que à dificuldade motora agrega-se o obstáculo para evacuar. Para que haja eliminação fecal é necessário que a pressão retal ultrapasse a anal, havendo um gradiente reto-anal. O objetivo do trabalho foi avaliar este gradiente em 29 pacientes portadores de megacólon, em que as pressões retais e anais foram medidas ao evacuar, comparadas com pessoas normais. Os resultados mostraram que havia pressão retal em centímetros de água aumentada em homens (72,2 ± 29,1) e mulheres (64,5 ± 20,1), superando as respectivas pressões anais de evacuação (66,4 ± 23,2 e 62,1 ± 28,7). As pressões de evacuação, por sua vez, eram muito maiores que as do grupo controle. Isto permitiu concluir haver uma reação adaptativa com maior esforço muscular para evacuar, a fim de superar o obstáculo da acalasia.
Exame histopatológico em espécimes de doença hemorroidária operada: revisão de 2.134 casos
Authors: Cruz Geraldo Magela Gomes da , Santana Jorge Luiz , Santana Sandra Kely Alves de Almeida , Constantino José Roberto Monteiro , Chamone Bruno Cunha , Ferreira Renata Magali Ribeiro Silluzio , Neves Peterson Martins , Faria Marina Neves Zerbini de
Published: December 2007

Em 34.000 pacientes coloproctológicos atendidos em 38 anos, foi feito o diagnóstico de DH como doença principal em 9.289 pacientes (27,3%), dos quais 2.417 (26,0%) foram submetidos à hemorroidectomia, tendo sido feito exame histopatológico em peças cirúrgicas de 2.134 pacientes (88,3%). O objetivo deste trabalho é analisar os resultados dos exames histopatológicos dos 2.134 espécimes examinados e confronta-los com a literatura correlata. O EHP corroborou 100% dos diagnósticos de DH nos 2.134 espécimes examinados. O exame proctológico constatou doenças anais concomitantes (DAC) à DH em 1.122 pacientes dos 9.289 pacientes portadores de DH (12,1%); dos 2.417 pacientes operados de DH, a cirurgia foi em conjunto com as DAC em 729 pacientes (30,2%); e o EHP confirmou as DAC em 530 dos 729 espécimes examinados (72,8%). Os diagnósticos de DAC operadas que atingiram os mais elevados índices de confirmação pelo EHP foram: 100,0% dos 89 casos de fístula anal, 100,0% dos 22 casos de condilomas anais acuminados, 79,0% (211) dos 267 casos de hipertrofia de papilas anais, 68,5% (217) dos 317 casos de fissura anal e 66,7% (2 casos) dos 3 casos de tumor anal. O EHP detectou, nos 2.134 espécimes, 37 casos de outras doenças não diagnosticadas antes da cirurgia (1,7%), que foram, por ordem de freqüência: esquistossomose (18 casos), amebíase (5 casos), doença de Crohn anal (4 casos), melanoma anal (2 casos), CCE (2 casos), doença de Bowen (2 casos), tuberculose anal (2 casos), câncer cloacogênico (1 caso) e linfoma (1 caso). Os autores concluem que é extremamente importante a realização do EHP em todos os espécimes cirúrgicos de hemorroidectomia, tanto para corroborar o diagnóstico de DH, quanto para corroborar diagnósticos pré-operatórios de doenças anais concomitantes à DH, e mesmo doenças anais concomitantes não detectáveis pelo exame proctológico.
Polipose múltipla familiar: análise de 44 casos tratados no Hospital das Clínicas da FMRP-USP
Authors: Silva Andreza Regina de B. M. da , Parra Rogério Serafim , Rolo Jaicer Gonçalves , Bueno Filho Roberto , Féres Omar , Rocha José Joaquim Ribeiro da
Published: December 2007

Os autores apresentam análise retrospectiva de 44 pacientes com Polipose Múltipla Familiar tratados no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto,Universidade de São Paulo, entre janeiro de 1991 a julho de 2005. Foram estudados aspectos epidemiológicos (idade, sexo), genéticos, principais sintomas, antecedentes pessoais e aspectos envolvendo tratamento cirúrgico e complicações pós-operatórias, comparando os achados com os da literatura correlata. Dos pacientes, 31 são do sexo masculino e 13 do feminino com idade média de 32 anos (14 - 60 anos). Os sintomas prevalentes foram: sangramento intestinal (62,5 %), alteração do hábito intestinal (60%), e com menor freqüência dor abdominal (45 %) e emagrecimento (30%). Relataram casos de polipose familiar 67,5% dos pacientes e 62,5% referiram parentes com antecedente de neoplasias (intestinal e extra-intestinal). Cerca de 32,5% dos pacientes já apresentavam neoplasia de cólon na época do diagnóstico da polipose,com idade média de 39 anos. O tratamento cirúrgico foi realizado em 95,4% dos pacientes: 35,7% foram submetidos à proctocolectomia total(9 casos com bolsa ileal em J e 6 casos com ileostomia definitiva) e 59,2% a colectomia total com ileorretoanastomose. Atualmente 57% dos pacientes avaliados ainda estão em seguimento com reavaliações periódicas, 7% faleceram e 27% abandonaram o tratamento.
Cisto dermóide simulando neoplasia retro-retal
Authors: Carvalho Erlon de Ávila , Pontinha Tatiane de Fátima Baco Saraiva , Oliveira Jackeline Ribeiro , Braga Eustáquio de Carvalho , Baldim José Ademar
Published: December 2007

Cisto dermóide é uma formação tumoral constituída por um enclausuramento epidérmico contendo folículos pilosos, glândulas sebáceas e localizadas geralmente no pescoço.
A system to evaluate the performance of hydraulic nozzles used in stored grain preotection trials
Authors: Vásquez-Castro Javier A. , Baptista Gilberto C. de , Gadanha Jr. Casimiro D. , Trevizan Luiz R.P.
Published: December 2007

We developed a system to evaluate the performance of hydraulic nozzles used in stored corn and wheat grain protection experiments. An insecticidal mix was used as test fluid to determine the transversal volumetric distribution and droplets spectrum of a model TJ-60 8002EVS hydraulic nozzle. A mobile application system was built to apply a rate equivalent to 5 L t-1 and obtain theoretical concentrations of 10 and 0.5 mg kg-1 of fenitrothion and esfenvalerate, respectively. The corn and wheat grains were spread out as a fine layer. Three glass slides (0.1 × 0.05 m) were placed on the top surface of the grains to ensure that the intended application rate was achieved. After treatment, the deposits on both matrices were analyzed by gas chromatography. The fenitrothion deposit was higher than esfenvalerate, and the deposit on wheat was higher than on corn grains (P < 0.05). The deposits on the glass slides reached values of 100 and 93% of the intended theoretical fenitrothion and esfenvalerate concentrations, respectively. Deposits on the grains were lower than on the glass slides, with values of 64 and 52% of the intended theoretical fenitrothion and esfenvalerate concentrations, respectively. The results obtained demonstrate a high effectiveness of the method for evaluation of the performance of hydraulic nozzles when an insecticidal mix is used as test fluid. The factors that influenced insecticide deposition on glass slides and on grains are discussed in the present work.
Meyer and schilz function to estimate common bean seed water content evaluated by radiofrequency
Authors: Berbert Pedro Amorim , Molina Marília Berbert , Viana Alexandre Pio , Carlesso Vinícius de Oliveira , Oliveira Marcia Terezinha Ramos de
Published: December 2007

Derivation of density-independent dielectric functions for moisture determination in grains is important for the implementation of on-line sensors in automated driers. The object of this study was to investigate the Meyer and Schilz function [(epsilon'1)/epsilon"] for indirect and non-destructive water content measurement of seeds of common bean by radiofrequency, where epsilon' and epsilon" are the relative permittivity and the dielectric loss factor, respectively. Samples consisted of common bean seeds variety Campeão-3 at moisture contents ranging from 11.5 to 20.6% w.b., and bulk densities from 756 to 854 kg m-3, performing dielectric measurements in a room at 20 ± 1ºC and 66 ± 2% relative humidity. The model could estimate common bean seed moisture content with a standard error of the estimate, and maximum error of 0.5 and 1.0 percentage point in moisture, w.b., respectively.
Reuse of sand, crushed sugarcane and peanut hull-based substrates for cherry tomato cultivation
Authors: Fernandes Carolina , Corá José Eduardo , Braz Leila Trevizan
Published: December 2007

The reuse of substrates for more than one growing season is an alternative to reduce production costs. The objective of this work was to evaluate the yield and quality fruits of the cherry tomato (Lycopersicon esculentum) grown in reused substrates. The experimental design was a complete randomized block, with a factorial array of 7 × 2 (seven substrates and two growth periods), with four replications. The seven substrates consisted of different combinations of sand (S), crushed sugarcane (CS) and peanut hull (PH). The substrates used were: S1 = S; S2 = [(2/3 S) + (1/3 CS)]; S3 = [(2/3 S) + (1/3 PH)]; S4 = [(2/3 S) + (1/6 CS) + (1/6 PH)]; S5 = [(1/2 S) + (1/2 CS)]; S6 = [(1/2 S) + (1/2 PH)] and S7 = [(1/3 S) + (1/3 CS) + (1/3 PH)]. These substrates were tested as new (one growth season), and reused (two sequentially growth seasons). The cherry tomato average yield was 9.07 kg m-2 when growth on the new substrates, and 8.44 kg m-2 when growth on the reused ones. The fruit quality was not affected by the reutilization of the substrates. The average values were 6.5 ºBrix for total soluble solids; 0.6 g for citric acid per 100 g for total titratable acidity and 4.2 for pH. A substrate consisting of equal parts of the three components can be recommended as a good growth medium for cherry tomato. All the substrates tested can be efficiently reused, at least once.
Anemia e ferropenia em gestantes: dissensos de resultados de um estudo transversal
Authors: Bresani Cristiane Campello , Souza Bresani Ariani Impieri de , Batista Filho Malaquias , Figueiroa José Natal
Published: December 2007

OBJETIVOS: descrever as freqüências de anemia e ferropenia em gestantes de baixo risco, de acordo com a ferritina sérica e diferentes pontos de corte da concentração de hemoglobina (Hb). MÉTODOS: estudo transversal, utilizando-se banco de dados com 318 gestantes atendidas no período de maio de 2000 a junho de 2001, no Instituto Materno Infantil Prof. Fernando Figueira-IMIP, em Recife, Pernambuco. Determinou-se a freqüência de anemia e/ou ferropenia em função da ferritina e dois diferentes pontos de corte da Hb (11,0 e 10,5g/dL). Os dados foram analisados nos programas Epi-Info 6.04b e Minitab v.14.2. O projeto foi aprovado pelo Comitê de Ética em Pesquisa do IMIP. RESULTADOS: as freqüências de anemia (Hb<11,0g/dL) e anemia ferropriva (Hb<11,0g/dL; ferritina<12ng/mL) foram 56,6% e 10,7%, respectivamente. Mudando o ponto de corte da Hb (<10,5g/dL), a freqüência de anemia foi reduzida para 37,4% e de anemia ferropriva para 7,9%. Os valores de ferritina sérica foram maiores nas anêmicas do que nas não anêmicas, independente do ponto de corte de Hb considerado na definição da anemia. CONCLUSÕES: a freqüência de anemia na amostra foi compatível com o esperado, porém, a proporção de anemia ferropriva foi muito aquém. Os valores de ferritina se comportaram de maneira inversa ao que teoricamente, era esperado.
Anos potenciais de vida perdidos por mulheres em idade fértil na cidade do Recife, Pernambuco, vítimas de morte por homicídio nos anos de 2001 e 2002
Authors: Arnold Marianne Weber , Silva Maria Arleide , Falbo Neto Gilliatt Hanois , Haimenis Rossana Paula
Published: December 2007

OBJETIVOS: determinar a freqüência dos óbitos de mulheres em idade fértil segundo os quatro principais grupos de causas básicas de óbito, calcular os Anos Potenciais de Vida Perdidos (APVP) para homicídio, comparando-o com as outras causas de morte mais freqüentes e os coeficientes de APVP destas quatro causas de óbito. MÉTODOS: estudo descritivo, tipo corte transversal, incluindo as declarações de óbito de mulheres com idade entre 10 e 49 anos, na cidade de Recife, Pernambuco, nos anos de 2001 a 2002. A causa básica de óbito foi classificada de acordo com a CID-10, os APVP foram analisados segundo critérios do Ministério da Saúde e de Romeder e McWhinnie, utilizando-se o Epi-Info 2000. RESULTADOS: o grupo das neoplasias foi a causa de óbito mais freqüente (25,7%), seguida das doenças do aparelho circulatório (21,2%), causas externas (17,6) e doença infecciosa e parasitária (9,6%). Os homicídios foram responsáveis por 49% (4380) do total de anos potenciais de vida perdidos, com um coeficiente de APVP de 8,82. O coeficiente de APVP para câncer de mama correspondeu a 4,14 e 3,77 para o infarto agudo do miocárdio. CONCLUSÕES: o risco das mulheres perderem anos potenciais de vida por homicídio foi 2,1 vezes maior do que por câncer de mama e 2,3 do que por infarto agudo do miocárdio.
Developing the evidence base for waste and resources policy
Authors: Blakey N. C. , Wilson D. C. , Smith N. A.
Published: December 2007

The purpose of this paper is to provide a progress report on the UK Department for Environment, Food and Rural Affairs' (Defra) planned approach to waste and resources research after the first three years of implementation. Defra set up its waste and resources research programme (WRRP) in 2004 to deliver a sound evidence base for better-informed policy development and implementation for sustainable waste and resources management. The first step was to take a ten-year forward look at policy and evidence needs, and from that to prepare a three-year research and development strategy. The strategy was implemented by way of annual action plans and calls for tender: more than 80 research projects have been delivered or are currently active. The WRRP has acted to some extent as a ‘pilot’ for the development of Defra's wider approach to evidence and innovation. As the programme prepares its new strategy up to 2011, the authors offer a number of conclusions which may be of value to others who are considering the development of an evidence base to support policy, and make a number of recommendations specific to the future of their own programme. Key success factors include close, joint working between the evidence and policy teams and close coordination between the many providers of research outputs in the waste and resources field.
Eliminating Human Error During Coiled Tubing Operations
Authors: Burgos Rex , Allcorn Marc , Mallalieu Robin , Vicens Jorge
Published: December 2007

In the last decade, several successful initiatives have been introduced to mitigate the risk of coiled tubing pipe failure while performing interventions in oil and gas wells. Through the use of reasonably accurate computer modeling, the industry has seen a marked reduction in the number of pipe failures associated with material fatigue caused by the constant plastic deformation occur-ing during pipe-tripping operations. Similarly, the judicious practice of employing off-line pipe-quality inspection tools, as well as the availability of real-time monitoring of pipe geometry through a variety of devices has contributed to a more predictable and more favorable pipe performance.

A study of root causes for coiled tubing (CT) pipe failures during a 5-year period indicates that a substantial percentage of incidents were attributed to human error. This type of incident involves the application of excessive overpull, resulting in pipe necking or complete parting of the pipe because of tensile failure. Similarly, too much snubbing force will cause pipe buckling and compressive failure. Both have the undesirable result of a damaged CT string (at best) or a compromised well control security (at worst). Using a properly trained and fully competent crew can minimize such events. However, the arduous and stress-filled nature of live-well CT operations will limit the elimination of this human element.

This paper presents an effective means for eliminating the possibility of human error becoming a factor in conditions that could result in a pipe failure during normal CT operations. Through the incorporation of a specialized system in the coiled tubing unit controls, a safety device is put in place to provide a shutdown feature when specific job-designed setpoints are exceeded.

This paper provides a discussion of the features and capabilities of such a system. It cites details of recent experiences demonstrating the benefits with use of the device in actual CT interventions.
The Kinetics of Sulphate Deposition in Seeded and Unseeded Tests
Authors: Boak L. S. , Sorbie K. S.
Published: December 2007

In a previous paper (Boak et al. 2005), we addressed the issue: What level of sulphate reduction is required to eliminate the need for scale inhibitor squeezing? In this earlier work, we developed the idea of a simple kinetic scheme for sulphate deposition on the basis of a "safe envelope" concept within which the system could operate. Central to the safe envelope approach is the choice of rate constant for barite deposition and this can be estimated experimentally under various conditions appropriate to the specific field application. Experimental results on kinetic barite deposition in low sulphate brine mixtures were presented previously (Boak et al. 2005). However, these previous results were carried out for unseeded solutions (i.e., no solid barite or sand particles were added to the scaling solutions). The following questions were raised

If barite particles were present, would this mean that the solution supersaturation (Sp) would reduce to 1 very rapidly thus over-ruling any kinetic deposition effects? Does the presence of sand particles have the same effect as barite particles? In the case of both barite or sand particles does the size of the particles (i.e. the surface area per unit mass) have any effect on the barite deposition rate?

In addition, a very simple kinetic model for bulk deposition of barite was used for which the long time behavior was that barite is deposited until the limiting ion was totally consumed. However, it is known that barite has some solubility at higher levels of sodium chloride and the kinetic model should limit to this value. This may be an important consideration especially in lower sulphate (or lower barium) brines.

Experimental results are presented in this paper which both address and answer the above questions, and extend the analysis with an improved kinetic model for barite deposition. Even in the presence of seed materials (barite and sand of various surface areas), clear rate effects can be observed and rate constants can be derived. As expected, barite seed material of higher surface area induces faster depletion of the scaling ions to a supersaturation ratio of 1 than barite of lower surface area. However, allowing for the effect of surface area, the barite seed material shows a clearly enhanced potential to induce scale formation than the sand. In addition, the safe envelope model is extended by considering a more accurate analytical kinetic model which limits correctly to the equilibrium solubility of barite at long times.
Alkaline Flood Prediction Studies, Ranger VII Pilot, Wilmington Field, California
Authors: Mayer E. H. , Breit V. S.
Published: December 2007

This paper discusses the design of a simulator to model alkaline displacement mechanisms, along with the current understanding of in-situ caustic consumption. Assimilation of laboratory coreflood and rock consumption data, and their use in one- and two-dimensional (1D and 2D) limited-area simulations and in threedimensional (3D) model of the entire pilot project are given.

This paper also reports simulation studies of alkaline flood behavior in a small 2D area of a field for various concentrations, slug sizes, long-term consumption functions, and two relative-permeability adjustment mechanisms. The scale-up of 2D simulation results and their use in a 271-acre [1096.7-ha], seven-layered, 3D model of the pilot are also discussed and 3D simulator results are compared with initial field alkaline flood performance.

Finally, recommended additional applications of the simulator methods developed in this pilot and in other alkaline floods are discussed.
The Effect of Stress-Dependent Permeability on Gas Production and Well Testing
Authors: Ostensen R. W.
Published: December 2007

The effect of stress-dependent permeability on gas production and well testing in tight gas sands was studied by use of a modified pseudopressure that included stress dependence. This work assumes that information on cores is applicable to reservoir behavior. Because microcracks are the primary path for flow through tight-gas-sand cores, average stress-dependent permeabilities were found as an average over all crack orientations in a nonuniform stress field, with a horizontal stress only 0.6 times the vertical one. Initial in-situ permeabilities are found to be two to five times the values obtained from uniformly restressed cores. Stress dependence decreases initial gas production by at most 30%, with the loss increasing with reservoir depletion. Buildup tests yield reliable results for the properties at average reservoir pressure. Drawdown tests are more sensitive to stress effects and are much less reliable.
Stress Gradient Affects the Height of Vertical Hydraulic Fractures
Authors: Thiercelin M. J. , Lemanczyk Z. R.
Published: December 2007

Fracture height is a critical input variable in current hydraulic-fracturing-treatment design. This paper presents the results of a laboratory study regarding the effect of the in-situ horizontal stress gradient acting as a potential barrier in limiting the height of a hydraulically created vertical fracture. The experiments consisted of creating fractures in cylindrical samples of polymethylmethacrylate (PMMA) and measuring the ensuing heights. The stress gradient was induced by preventing any radial displacement at the sample ends while simultaneously applying an axial load. A two-dimensional (2D) analysis was used to predict the extent of crack development as a function of fluid pressure in the fracture. The experimental results confirm that high stress gradients can act as barriers in containing fracture height. Our experimental approach permits quantitative results to be obtained that are in good agreement with those predicted from the calculations.
Cyclic Steaming of Tar Sands Through Hydraulically Induced Fractures
Authors: Dietrich J. K.
Published: December 2007

Fracture dimensions and process mechanisms that resulted from cyclic steam stimulation above fracturing pressure in German and Canadian tar sands are analyzed with numerical modeling. Horizontal fracture radii of 100 ft [30.5 m] and vertical fracture half-lengths of 250 ft [76.2 m] with fracture surface areas of 30,000 to 70,000 sq ft [2787 to 6503 m2] are sufficient to reproduce steam injectivity into reservoirs containing highly viscous oil and negligible amounts of movable water saturation. Mechanisms that are important during fluid loading and unloading of induced fractures include thermal expansion of tar oil, countercurrent imbibition of water and oil caused by capillary pressure effects, and fracture compressibility.
A New Approximate Analytic Solution for Finite-Conductivity Vertical Fractures
Authors: Lee Sheng-Tai , Brockenbrough John R.
Published: December 2007

A new analytic solution, based on an approximate trilinear flow model, is developed to study the transient behavior of a well intercepted by a finite-conductivity vertical fracture. The solution accounts for the effects of skin, wellbore storage, and fracture storage. Both constant-pressure and constant-rate cases are considered. The solution is simple and reliable for short-time analysis. Combining this solution with a semilog asymptotic solution provides a reliable tool for analysis and formation evaluation of fractured wells. We also demonstrate that the optimization technique is a convenient means of formation parameter estimation. A set of early-time asymptotic solutions is also presented. These solutions provide qualitative and quantitative relations of the simultaneous influences of wellbore storage, fracture storage, and skin damage on early-time wellbore pressure behavior.
Rheological Study of Foam Fracturing Fluids Using Nitrogen and Carbon Dioxide
Authors: Reidenbach V. G. , Harris P. C. , Lee Y. N. , Lord D. L.
Published: December 2007

A practical mathematical model based on experimental data is presented for calculation of rheological properties of N2 and CO2 foam stimulation fluids. The laminar flow model is a yield pseudoplastic type, with viscosity dependent on foam quality, yield point, base liquid consistency index (K′), and flow behavior index (n′). Turbulent foam flow data were analyzed with API RP39 procedures but were modified to include variable density effects of foam fluids.

Water-based foam apparent viscosities compare closely to Mitchell's Bingham plastic model at high shear rates. The yield pseudoplastic model also includes viscous effects of gelling agents and measurement at much lower shear rates. Comparison of predicted pipe friction was made to actual field wellhead pressures with good agreement.
Using the Hollow-Core Test To Determine Acid Reaction Rates
Authors: Gdanski R. D. , Norman L. R.
Published: December 2007

Effects of chemical additives on acid reaction rates may be determined by observation of acid reaction in hollow limestone cores. Reactivities of acids containing (1) surfactant gelling agents, (2) polymeric gelling agents, (3) crosslinked polymeric gelling agents, and (4) fluid loss additives were measured. Effects of chemical and filter cake retardation were assessed, and experiments were conducted with and without fluid leakoff at temperatures of 150 to 300°F [65 to 150°C].
A Numerical Technique for Tracking Sharp Fronts in Studies of Tertiary Oil-Recovery Pilots
Authors: Jensen O. K. , Finlayson B. A.
Published: December 2007

A numerical front-tracking technique, based on a transformation of the governing equations into a moving coordinate system (MCS), is applied to a finite-element reservoir simulator. The method is especially suited for studies of tertiary oil-recovery pilots with chemical flooding and other miscible displacement processes. The new front-tracking technique is compared to conventional finite-element formulations with a uniform grid over the entire domain. Comparisons with other methods show that computer time can be greatly reduced with the same accuracy.
Through-Casing Reservoir Evaluation
Authors: Cannon Darrel E. , LaVigne Jack A.
Published: December 2007

Evaluation of complex carbonates and formations with unknown formation water salinities is difficult though now possible. Processing of both elastic and inelastic spectra of pulsed-neutron gamma-ray spectrometry tools (GST's™) can provide lithologic information comparable to core and openhole logs and water saturation values in formations of unknown water salinity. Quick looks can be obtained from basic measurements, but quantitative values require processing. Saturation information improves as porosity increases.
Low-pH Methanol: An Alternative for Stimulation in Water-Sensitive, Tight, Dirty Sandstones
Authors: Ortiz J. , McLane J. E.
Published: December 2007

Heavily clay-laden, low-permeability sandstones have always presented difficulties in stimulation. The most common treatment for such formations has been a crosslinked 40/60-lbm hydroxypropyl guar (HPG) in KCl water, but the results have not always reached expectations.

This paper characterizes one of these formations by scanning-electron-microscope/energy-dispersive-spectrometer (SEM/EDS) evaluation of mineralogy and lithology. The core samples were subjected to conventional and experimental treatment fluids by a nitrogen gas reference core-flow apparatus to find the optimum stimulation treatment.
Mechanical Degradation of Polyacrylamide Solutions in Core Plugs From Several Carbonate Reservoirs
Authors: Martin F. D.
Published: December 2007

This paper presents results of laboratory studies on mechanical degradation of partially hydrolyzed polyacrylamide (HPAM) solutions in core samples from several different carbonate reservoirs. Studies in carbonates are of particular importance because several of the larger polymer projects are in carbonate reservoirs and because data on carbonate rocks have not previously been available. Many of the data in the literature were obtained with solutions of polymer-in-brine. Because HPAM polymers are generally more efficient in fresh waters, lower-salinity waters were used for the bulk of the present study. Investigated variables included polymer molecular weight, polymer concentration, and salinity of the aqueous solvent. HPAM samples used were commercial products of various molecular weights. Results were compared with correlations previously developed for sandstone core plugs and unconsolidated sands. The extent of induced degradation was monitored by comparison of viscosities and screen factors before and after flow through the core plugs at various flow rates.

During injection of low-salinity polymer solutions through low-permeability carbonate core plugs, the extent of induced mechanical degradation was higher than values estimated with existing correlations obtained with higher-permeability porous media. Severe nonuniformities in the low-permeability carbonate core caused difficulties in our attempts to relate the degradation of existing correlations. Thin sections of the core materials were very helpful in the qualitative understanding of the differences in injectivity and mechanical degradation for cores from the various reservoirs. Cores with relatively uniform porosity performed differently from those that were very nonuniform, even though the permeabilities were similar.

The induced mechanical degradation of the polymer reduced the viscoelastic and pseudoplastic nature of the HPAM solutions. As expected, the extent of mechanical degradation increased as the polymer molecular weight increased. Residual viscosities and screen factors of the sheared solutions, however, were often greater for the higher-molecular-weight HPAM polymers. Higher salinities or calcium concentrations of the solvent resulted in increased degradation. Thus, use of low-salinity water or softened fresh water can reduce the level of irreversible shear degradation.
Factors Affecting Perforating Charge Performance and Relationship to Port Plug Condition
Authors: King G. E. , Bingham M. D. , Kidder R. W.
Published: December 2007

A series of perforating tests was run in surface targets to determine whether the conditions of the port plug from a perforating gun could be used as a relative indication of entrance hole shape and perforation penetration. Tests that used centralized and decentralized guns in large cement targets showed that a strong correlation exists between casing-entrance hole shape and the shape of the hole in the port plug of the gun. Also, if the charge was misaligned or double-jetted, resulting in cutting of the side of the port plug or the gun, target penetration was sharply reduced. Data were also collected on such influences as gun clearance, charge weight and liner type, multiple casing strings, defective charges, and age of charges.
Cleaning and Testing of Used Submersible Pumps To Reduce Lifting Costs
Authors: Divine D. L.
Published: December 2007

A technique has been developed to clean used submersible pumps chemically without the expense of tearing down the pump and rebuilding it. After the cleaning process, the pump is tested arid its performance is plotted against the manufacturer's catalog curve. More than 70% of the pumps put through this process have been rerun without being rebuilt, with substantial savings to the operator.

This paper discusses the process used in cleaning and inspection. The test bench will be described, along with the metering accuracy and calibration techniques. Use of the actual pump curve for improving production will be covered, along with statistical data on more than 1,200 new and used pumps.
Penetration-Rate Performance of Roller-Cone Bits
Authors: Warren T. M.
Published: December 2007

The rate of penetration (ROP) obtained with a roller-cone bit is limited by either the cuttings-generation or cuttings-removal process. An ROP model that includes the effect of both the initial chip formation and cuttings-removal processes is presented. Laboratory observations show that the reduction in ROP at high borehole pressure is the result of both local cratering effects and global cleaning effects.
Experimental Studies of Oil Withdrawal From Salt Cavities by Freshwater Injection
Authors: Reda Daniel C. , Russo Anthony J.
Published: December 2007

The U.S. Strategic Petroleum Reserve (SPR) program coordinates storage of crude oil in underground salt caverns. Oil removed from these caverns by the injection of water into a brine volume located beneath the oil will be recovered through a production pipe near the top of the cavern. The critical question concerning this procedure was whether the crude oil would protect the salt walls from dissolution on exposure to unsaturated brine following oil/brine interface passage.

Oil/brine/salt interactions were investigated experimentally. Cylindrical cavities were created by hollowing out salt cores from one end, leaving the circular wall and bottom as an integral piece. In four experiments, a salt cavity was placed vertically in a pressure vessel and was filled with crude oil overlying a saturated-brine "pocket." The vessel was sealed and pressurized to actual SPR-cavern pressure. Fresh water was injected down a tube into the brine pocket, displacing the oil upward for recovery through a production tube. A traversable gamma-beam densitometer positioned above the initial saturated-brine/oil interface defined the presence or absence of salt dissolution (cavity shape change) during the transient oil-withdrawal process. Such measurements showed salt-wall recession immediately following interface passage in all tests; i.e., crude-oil adherence and/or penetration at the salt wall failed to protect the salt from dissolution when exposed to unsaturated brine. Measured post-test cavity shapes corroborated the transient results. Both transient and steady-state measurements were in good agreement with numerical predictions generated by sansmic (Sandia Solution-Mining Code) once "no oil-layer protection" was assumed.
Strength Development of 2CaO/SiO2-Silica Cement Under High-Temperature and High-Pressure Conditions
Authors: Sasaki S. , Kobayashi W. , Okabayashi S.
Published: December 2007

To cement deep oil wells and high-temperature geothermal wells, special cements with superior cementing properties, hardening characteristics, and durability under high-temperature and high-pressure conditions are required. Therefore, we have been accumulating technical data on a special cement consisting of 2CaO/SiO2 and silica.

In this paper, strength development at 290 to 842°F [143 to 450°C] was investigated for the mixtures of three 2CaO/SiO2 modifications (γ, β, and α′) and quartz. Various analyses were carried out on hardened specimens, and the mechanism of hydrothermal reaction for these mixtures is discussed.

Within the limits of this experiment, we conclude that the strength of 2CaO/SiO2-quartz mixtures depends on 2CaO/SiO2 modifications, curing temperature, and curing time, but the influences of curing pressure and increasing rate of temperature are relatively minor. Moreover, we assume that the difference of reaction rate of 2CaO/SiO2 and quartz, the type of hydration products, and the producing conditions will result in the difference of strength, depending on 2CaO/SiO2 modification.
Vinyl Sulfonate Copolymers for High-Temperature Filtration Control of Water-Based Muds
Authors: Perricone A. C. , Enright D. P. , Lucas J. M.
Published: December 2007

This paper describes the properties of two synthetic high-molecular-weight vinyl sulfonate copolymers and their use in water-based muds for controlling high-temperature filtration properties. Vinyl sulfonate copolymers are more effective at high temperatures because they are not depolymerized by the hydrolytic and oxidative environments of the drilling mud, as are derivatives of polysaccharides, and they do not form insoluble salts in the presence of electrolytes.

Laboratory tests show that these copolymers are effective filtration-control agents for water-based muds over a wide range of electrolyte concentrations and that they remain effective after aging at 350°F [177°C]. The effectiveness of these copolymers has been demonstrated in field tests.
Permeability Reduction of Unconsolidated Media Caused by Stress-Induced Silica Dissolution
Authors: Udell K. S. , Lofy J. D.
Published: December 2007

Permeability measurements were made on glass beads and Ottawa sand under uniform confining stress conditions. Extreme permeability reduction (95%) of the glass beads was observed at temperatures exceeding 150°C [302°F] and a confining pressure of 13.8 MPa [2,000 psi] with distilled water as the flowing fluid. Permeability reduction (40%) in the Ottawa sand was also observed at high temperature and confining pressure. Effluent analysis revealed high concentrations of silica. Subsequent 300-hour experiments with Ottawa sand exhibited a steady decrease in permeability with time. Scanning electron microscope (SEM) photographs of postexperiment cores indicate that the permeability reduction is caused mainly by stress-induced silica dissolution at grain contacts.
Design and Construction of a Pilot Steamdrive Project in a Remote Desert Environment
Authors: Haines Michael R.
Published: December 2007

A pilot steamdrive test has begun in the Marmul oil field in south Oman. It is intended that 1,774 U.S. tons/D [1610 Mg/d] of dry saturated steam will be injected into the test area for approximately 5 years to test the steamdrive process quantitatively. The surface facilities, consisting of a water treatment plant and steam generators, have been designed for reliable operation in the hot, remote desert environment.
Development of a Subsea Wireline Winch System
Authors: Graser J. A.
Published: December 2007

This paper describes a subsea wireline winch system designed to work over subsea well completions from a dynamically positioned work vessel in North Sea conditions. The system is compared with other options, and applications for each type are suggested. Results of a land test of the prototype are described.
Experience With Permanent Bottomhole Pressure/Temperature Gauges in a North Sea Oil Field
Authors: Gallivan J. D. , Kilvington L. J. , Shere A. J.
Published: December 2007

The Beatrice oil field has been on production since 1981. Each production well is equipped with an electrical submersible pump (ESP) and a permanent bottomhole pressure/temperature gauge (PTG) that provides a continuous readout at surface. The gauge was installed primarily to monitor pump intake pressure and to avoid operation when the pressure falls below bubblepoint.

Gauge specification and installation are described. Analysis of reliability in 87 completions in 23 wells is provided. An improvement in reliability over the 3-year period (1982-84) is associated with improved isolation of the gauge signal cable.

An example of well-performance monitoring is provided for a problem well kept on production. Analysis of pressure buildups and interwell interference tests is discussed, showing how gauge data have helped refine reservoir description and guide reservoir management.
Dynamic Fluid-Loss Measurement of Oil-Mud Additives
Authors: Wyant Reece E. , Reed Ron , Sifferman Thomas R. , Wooten Susan O.
Published: December 2007

The objective of this laboratory study was to correlate the dynamic fluid loss (DFL) with the static [API high-temperature/high-pressure (HTHP)] fluid loss, the sticking coefficient, and the fluid-loss-control-agent (FLCA) concentration in oil muds. This was done as a continuing effort to use oil-mud FLCA's more efficiently in the field and to reduce pipe-sticking problems associated with deviated holes. Data were obtained with 13-lbm/gal [1558-kg/m3] inverted-emulsion muds by use of four different types of FLCA's over wide concentration ranges, but within the limits of reasonable field usage.

The DFL data (at 250°F [121 °C] and 500-psi [3447-kPa] differential pressure) were obtained with newly developed cells in which filtration occurs in an annulus around a central permeable core. An asymmetric buildup of mud solids and fluid channeling in the annulus suggest a mechanism that would greatly increase pipe-sticking tendencies in deviated wellbores.

The DFL decreased with decreasing static fluid loss. The laboratory-measured sticking coefficient, which should correlate with differential-pressure sticking in the field, was reduced as fluid loss decreased. The fluid loss generally decreased with increasing FLCA concentrations, with the major reductions occurring at concentrations of about 4 lbm/bbl [11.4 kg/m3].
Entrapment and Mobilization of Residual Oil in Bead Packs
Authors: Morrow N. R. , Chatzis I. , Taber J. J.
Published: December 2007

Phase behavior, interfacial tension (IFT), viscosity, and density data were determined for the system 2% CaCl2 brine/isopropyl alcohol (IPA)/isooctane. Liquid pairs from this system were used in a test of capillary number as a correlating function for mobilization of residual oil in geometrically similar porous media as provided by bead packs. Close correlation of results was obtained for a more than five-fold variation in permeability and a more than six-fold variation in IFT. Extensive investigation was also made of the change in trapped oil saturation given by vertical upward flooding; the ratio of gravity to capillary forces varied more than 100-fold. A correlation between trapped oil saturation and Bond number was obtained that was in good agreement with previous results obtained for gas entrapment. However, capillary numbers for entrapment of a given reduced residual oil saturation (ROS) were found to be slightly higher than those for entrapment of gas.

Relative permeabilities were independent of whether the trapped phase was oil or gas and were determined mainly by the magnitude of the trapped nonwetting-phase saturation.

Capillary numbers for mobilization of residual oil from bead packs were much higher than typical values for sandstones. For bead packs that had been consolidated by sintering, capillary numbers for prevention of entrapment increased and those for mobilization decreased. The net result was that differences in capillary numbers for mobilization and entrapment were greatly reduced and results became more akin to relationships observed for consolidated sandstones.
Inexpensive Casing-Supported Drilling Templates
Authors: Harrington J. P. , Williams L. M.
Published: December 2007

Three types of inexpensive casing-supported templates have been designed and developed for use as spacer templates for tieback operations or for simple subsea completions. Two of the template concepts have been used in three areas of the southern North Sea. The design principles and running procedures are described, and the design of ancillary equipment used in the diverless installation of these templates is also illustrated.
Drilling and Producing Operations Utilizing a Tension-Leg Platform
Authors: Irelan R. E. , Alldredge C. G. , Downie W. A.
Published: December 2007

The Hutton field, discovered in 1973, is located in U.K. Block 211/28 about 275 miles [440 km] off the Shetland Islands in 485 ft [148 m] of water. The 1979 decision to proceed with field development was significant because the structure selected would become the world's first commercial tension-leg platform (TLP). This operational review covers the predrilling and completion of the first 10 wells from a semisubmersible drilling rig, their subsequent tieback to the TLP, and the startup activity from an integrated-deck philosophy with production operations from a platform with moving trees, flexible flowlines, and production riser tensioners.
Deepwater Diverless Technology Applied to Shallow-Water Operations in Hostile Environments
Authors: Harrington J. P. , Williams L. M.
Published: December 2007

Deepwater diverless technology has been successfully applied to shallow-water drilling operations in hostile environments of the North Sea to minimize lost rig time. This technology encompasses currently available instruments and equipment, with state-of-the-art design, and operations procedures. The use of sector-scanning sonar, acoustic positioning systems, and silicon-intensified-target (SIT) low-light-level subsea TV cameras to position rigs and to install underwater templates is described. Design principles that allow the diverless installation of templates and underwater wellheads are discussed. The use of deepwater operating procedures on two shallow-water locations in the North Sea is also described. The economic advantages of using deepwater technology in these locations are illustrated.