bluuebunny/crossref_metadata_2025 huggingface dataset:
Contribution to the discussions on the origin of the cerrado biome: Brazilian savanna
Authors: Pinheiro MHO. , Monteiro R.
Published: March 2010

Theories that attempt to explain the origin of the cerrado biome are mostly based on the isolated action of three major factors: climate, fire and soil. Another factor that has been mentioned is that of human interference. We hypothesise that the evolutionary origin of this biome resulted from the complex interaction of climate, fire and soil, with climate being the triggering agent of this assumed interaction. Fire, as well as acid and dystrophic soils, would be factors involved in the selection of savanna species throughout climatic events, during the Tertiary and the Quaternary, e.g. Pliocene and Pleistocene. The genesis of the physiognomies that would give rise to cerrado sensu lato, rather than forest formations, could have occurred due to the strong pressure exerted by the reduction in water availability, and the selection of the species adapted to the new conditions imposed by the environment. The characteristics of cerrado sensu lato soil, originated from edaphic impoverishment caused by lixiviation and successive past fires, would remain, even after hydric availability increased following the Pleistocene glaciations.
Climate and host plant characteristics effects on lepidopteran caterpillar abundance on Miconia ferruginata DC. and Miconia pohliana Cogn (Melastomataceae)
Authors: Scherrer S. , Diniz IR. , Morais HC.
Published: March 2010

Folivore cerrado caterpillars are found on their host species in low frequencies, which vary between plants and throughout the year. We analysed the effects of climatic variation and of the characteristics of two host species (Miconia, Melastomataceae) on caterpillar abundance. The work was carried out in a cerrado sensu stricto area in Brasília, Federal District, Brazil, from May 1998 to September 1999. One hundred plants of each species were inspected monthly. All caterpillars found were collected and raised in the laboratory with Miconia leaves as food sources. Climatic data for the study area and plant characteristics such as local density, spatial distribution, foliar phenology, leaf pilosity and nutritional content were used to test the effects on caterpillar abundance. Less than 10% of the plants had larvae. Caterpillars were more frequent and abundant in M. pohliana, which was also present at higher densities than M. ferruginata. Low caterpillar frequency in host plants and an abundance peak during the dry season are consistent patterns for different cerrado Lepidoptera larvae. This abundance peak, however, is not coincident with higher leaf production in host species. We suggest that M. pohliana's higher local density and better leaf digestibility can account for the higher abundance of caterpillars in this species.
Hermaphroditism among dioecious Tagelus plebeius (Lightfoot, 1786) (Mollusca, Psammobiidae) and Iphigenia brasiliana (Lamarck, 1818) (Mollusca, Donacidae) on the Cachoeira River Estuary, Ilhéus, Bahia, Brazil
Authors: Ceuta LO. , Boehs G. , Santos JJB.
Published: March 2010

The samples of Tagelus plebeius and Iphigenia brasiliana were manually collected on the Cachoeira River estuary region (Ilhéus, BA, Brazil) between August 2005 and August 2006, with a periodicity of 15 days, with 20 animals collected/sampled, performing 500 samples from each species. The animals were measured, eviscerated and kept in solution of Davidson and after 24-30 hours, they were transferred to ethanol 70%. The material was processed for routine histology, with paraffin embedding, obtaining 7 μm thick slices, stained with Harris hematoxilin and Eosin (HE). By light microscopy analysis, 2 cases of hermaphroditism (0.4%) in T. plebeius samples and one case (0.2%) in I. brasiliana were registered with predominance of female over male follicles.
Natural occurrence of the Fusarium solani on Tityus stigmurus (Thorell, 1876) (Scorpiones: Buthidae)
Authors: Santana-Neto PL. , Albuquerque CMR. , Silva APP. , Svedese VM. , Lima EALA.
Published: March 2010

Members of the Fusarium solani species complex are agents of human mycoses, also affecting plants and other animals. Nevertheless, this fungus has not been reported on scorpions. Ten specimens of Tityus stigmurus collected in the field and showing their surface covered by white mycelia were used to assess fungus presence in the animal after its death. Identification of the fungi was based upon the cultural and morphological characteristics. The fungus was isolated from chelicerae and intersegmental regions. Infected individuals had their behaviour modified by reducing feeding and locomotion. None of the infected individuals survived. It is likely that this fungus may have a role in the regulation of field scorpion populations.
Diet of the freshwater stingray Potamotrygon motoro (Chondrichthyes: Potamotrygonidae) on Marajó Island (Pará, Brazil)
Authors: Almeida MP. , Lins PMO. , Charvet-Almeida P. , Barthem RB.
Published: March 2010

The stomach contents of 137 examples of Potamotrygon motoro caught in 3 locations (Muaná, Afuá and Lake Arari) on Marajó Island were analysed. The values of the Index of Relative Importance (IRI) and its respective percentage (%IRI) were calculated. The level of repletion 1 (¼ full) was the most representative for both sexes, as well as for immature and mature specimens. Most of the food items found were well-digested. The food items identification indicated the presence of 15 orders, including insects, mollusks, crustaceans, annelids and fish. Differences in diet were observed among the locations studied when comparing %IRI, crustaceans being the most preferred in Afuá, fish in Lake Arari and mollusks in Muaná.
Mitochondria in the midgut epithelial cells of sugarcane borer parasitized by Cotesia flavipes (Cameron, 1891)
Authors: Pinheiro DO. , Silva MD. , Gregório EA.
Published: March 2010

The sugarcane borer Diatraea saccharalis (Lepidoptera: Crambidae) has been controlled by Cotesia flavipes (Hymenoptera: Braconidae); however, very little is known about the effect of the parasitism in the host organs, including the midgut. This work aims to verify mitochondrial alteration in the different midgut epithelial cells of D. saccharalis parasitized by C. flavipes. Midgut fragments (anterior and posterior region) of both non-parasitized and parasitized larvae were processed for transmission electron microscopy. The mitochondria of midgut epithelial cell in the parasitized larvae exhibit morphological alteration, represented by matrix rarefaction and vacuolisation. These mitochondrial alterations are more pronounced in the anterior midgut region during the parasitism process, mainly in the columnar cell.
Reproduction of the fish community of Passa Cinco Stream, Corumbataí River sub-basin, São Paulo State, Southeastern Brazil
Authors: Rondineli GR. , Braga FMS.
Published: March 2010

The aim of this work was to evaluate the reproduction (verifying if there was reproductive activity and, if so, with what intensity) of the most abundant species of the fish community in Passa Cinco stream, in relation to the dry and wet season periods and to the longitudinal gradient, through the application of the reproductive intensity index (RII). The sample collection was carried out during one year with six samplings (May, July, September and November 2005, and January and March 2006) in five different points of Passa Cinco stream, contemplating sites of orders two to six. The following fishery equipment was used: a sieve, electric fishery equipment, gill nets and fish-traps. The values of the reproductive intensity index for the dry period were 2.86 and for the wet season 3.17, which indicates the wet season (November to March) as the period when most of the species reproduced. The values of the index for collection point were: 0.78 for site 1, 3.56 for site 2 and 2.89 for site 3. Site 2, which presented the highest value, was the main reproduction place for most of the species. The adults' prevalence in the analysed species suggests, in an isolated way, that those species use the system as a reproduction area. However, when that information was crossed with the values of RII, when intermediate values were considered, it is possible to state that the system is used by the species as much as a reproduction area as a feeding area.
Acoustic communication and vocalization microhabitat in Ameerega braccata (Steindachner, 1864) (Anura, Dendrobatidae) from Midwestern Brazil
Authors: Forti LR. , Strüssmann C. , Mott T.
Published: March 2010

Ameerega braccata is an aposematic, small dendrobatid anuran known from its type-locality, Chapada dos Guimarães, in the State of Mato Grosso, and from a few additional localities in Mato Grosso do Sul and Goiás States, Brazil. The advertisement call of A. braccata is composed of a single unpulsed note, with a frequency range from 3.5 to 4.2 KHz (N = 110), and average duration of 65.8 ms (N = 110, SD = 11.6). The territorial call is composed of five or six repeated notes, structurally similar to advertisement call notes. The courtship call is emitted in close-range interactions between male-female during the courtship event and may reach frequencies of 2.2 to 5.3 KHz (N = 10), with shorter notes (average duration 43 ms; N = 10; SD = 4.9). Call duration, note duration and call rate of the advertisement call showed high variation (>15% of coefficient of variation), and dominant frequency showed low variation (<4%). The properties with higher variation possibly respond to climatic features and male social position. When producing advertisement calls, males were usually found at an average height of 31.4 cm (N = 19, SD = 12.2 cm), mainly on leaves of shrubs and herbaceous plants (59%). Individuals of A. braccata were found in open physiognomies in the Cerrado ("campo sujo" and "cerrado stricto sensu"), as opposed to that found by previous researchers, who reported an association of the species with gallery forests in the Cerrado.
Histological study of the dynamics in epidermis regeneration of the carp tail fin (Cyprinus carpio, Linnaeus, 1758)
Authors: Böckelmann PK. , Ochandio BS. , Bechara IJ.
Published: March 2010

Teleostean fins when partially amputated suffer a regenerative process called epimorphic regeneration, characterized by the following stages: healing, based on the formation of a multistratified epidermal layer, the formation of a mass of pluripotent cells known as blastema, the differentiation of these cells, the synthesis and disposition of the extracellular matrix, morphological growth and restoration. The epidermis has a fundamental role in the regenerative process of fish fins, as the healing time of this structure leads it to a faster regenerative process and it also works as a defense against the external environment. In this sense, due to the fast regeneration shown by the epidermis, the aim of this paper is to study the histology of the regenerative dynamics of the carp fin tail (Cyprinus carpio), under the light and transmission electron microscope. Epidermic regeneration begins right in the first hours after the fin amputation and it continues throughout the regenerative process. After 24 hours, an apical epidermal cap is established. Cytoplasmatic prolongations and intercellular junctions are observed and the cells of the basal layer of the epidermis change from the cubic form to the cylindrical, due to the development of the cytoplasmatic organelles responsible for the synthesis of the basal membrane, lost after amputation. These results show the importance of histological studies in regenerative processes. We believe that the association of molecular biology with histological studies can throw further light onto these regenerative dynamics.
Correção da cifose de Scheuermann: estudo comparativo da fixação híbrida com ganchos e parafusos versus fixação apenas com parafusos
Authors: Garcia Enguer Beraldo , Souza Sebastião Vasconcelos de , Gonçalves Roberto Garcia , Silveira Ramon Teodoro , Garcia Eduardo Beraldo , Garcia Liliane Faria , Garcia Juliana Faria
Published: March 2010

OBJETIVOS: avaliar o grau de correção da cifose de Scheuermann, em 6 pacientes que se submeteram à instrumentação híbrida composta por ganchos e parafusos (H) e 17 fixados apenas com parafusos (P). MÉTODOS: 23 pacientes, com cifose de Scheuermann, submetidos a tratamento cirúrgico por dupla via com início pela via anterior, seguido pela via posterior. Do conjunto de pacientes, 6 foram operados com fixação híbrida e 17 com uso exclusivo de parafusos pediculares. O tratamento cirúrgico foi indicado para cifose rígida, variando de 60º e 105º e portadores do sinal de Risser acima de 4. RESULTADOS: observou-se, no Grupo H, cifose pré-operatória média de 84,17º e no pós-operatório de 47,5º. No Grupo P, a média de cifose no pré-operatório era de 80,35º e, no pós-operatório, de 33,53º. CONCLUSÃO: concluiu-se que os dois tipos de fixação apresentaram resultados muito satisfatórios, contudo, sendo ainda superior quando fixados só com parafusos.
Resultados imediatos da correção cirúrgica de escoliose idiopática do adolescente por via posterior com instrumentação após liberação anterior por videotoracoscopia
Authors: Puertas Eduardo Barros , Curto David Del , Ueta Renato Hiroshi Salvioni , Martins Filho Délio Eulálio , Wajchenberg Marcelo
Published: March 2010

OBJETIVO: descrever os resultados imediatos da aplicação da liberação anterior por videotoracoscopia, seguida de instrumentação por via posterior para correção cirúrgica da escoliose idiopática do adolescente. MÉTODOS: foram selecionados 20 pacientes, no período de agosto de 1989 a maio de 2001, com escoliose idiopática do adolescente, padrão de curva torácica direita rígida, King III. Inicialmente realizou-se a abordagem pela via anterior com liberação por videotoracoscopia e depois a via posterior para correção e fixação com instrumental de Hartshill, em um mesmo tempo cirúrgico. RESULTADOS: todos os procedimentos foram completados com sucesso com videotoracoscopia, sem necessidade de conversão para toracotomia. A média de idade dos pacientes foi de 15,7 anos (12 a 21 anos). Em relação aos dias de internação, obteve-se um tempo médio de permanência de 9,45 dias (5 a 26 dias). A média entre os valores angulares foi, no pré-operatório, de 66,25º Cobb (48º a 92º Cobb), e no pós-operatório, de 31,2º Cobb (15º a 45º Cobb). Como complicações, quatro pacientes tiveram nevralgia intercostal (20%) e um caso de atelectasia (5%). CONCLUSÕES: a discectomia por videotoracoscopia é um método efetivo e seguro para tornar flexíveis as curvas escolióticas rígidas. No entanto, trata-se de um procedimento tecnicamente difícil, que requer treinamento árduo e prolongado, com curva de aprendizado extensa.
Uso de morfina intratecal en artrodesis lumbar
Authors: Ibaceta Ronald Schulz , Cornejo Nicolás Macchiavello , Ramirez Sergio , Escobar Jaime , Villagrán Marcos Ganga , Schulz Hermann
Published: March 2010

OBJETIVO: determinar la eficacia y la seguridad del uso de morfina intratecal, en bajas dosis, en pacientes sometidos a cirugía de instrumentación y artrodesis lumbar. MÉTODOS: estudio prospectivo, randomizado, ciego y controlado. Fueron utilizados dos grupos de pacientes: Grupo Estudio, que recibió morfina intratecal al final de su cirugía, y Grupo Control que sólo recibió el protocolo de analgesia estándar. RESULTADOS: se encontraron diferencias significativas en la escala visual análoga (EVA) entre los dos grupos a las 12 horas postoperatorias. La EVA en reposo promedio del Grupo Estudio fue de 2,15 cm y el del Grupo Control, 5 cm (p=0,013). En actividad, el Grupo Estudio presentó una EVA promedio de 4,36 cm, y el Grupo Control 6,9 cm (p=0,029). No se encontraron diferencias en relación a las complicaciones entre los dos grupos. CONCLUSIÓN: el uso de morfina intratecal, en bajas dosis, es seguro y efectivo en el control del dolor en las primeras 12 horas postoperatorias en cirugía de artrodesis lumbar.
Avaliação epidemiológica das fraturas da coluna torácica e lombar dos pacientes atendidos no Serviço de Ortopedia e Traumatologia do Hospital Getúlio Vargas em Recife/PE
Authors: Pereira André Flávio Freire , Portela Luiz Eduardo Duque , Lima Guilherme Didier de Andrade , Carneiro Wagner Cabral Gomes , Ferreira Marcus André Costa , Rangel Túlio Albuquerque de Moura , Santos Ricardo Barreto Monteiro dos
Published: March 2010

INTRODUÇÃO: as fraturas da coluna torácica e lombar estão se tornando mais frequentes, devido ao aumento dos acidentes de alta energia. Elas apresentam um elevado índice de morbidade e mortalidade, acarretando grandes prejuízos socioeconômicos. OBJETIVO: analisar a epidemiologia das fraturas torácicas e lombares de pacientes atendidas no Serviço de Ortopedia e Traumatologia do Hospital Getúlio Vargas em Recife (PE). MÉTODOS: este estudo é uma análise epidemiológica dos pacientes com fraturas da coluna torácica e lombar, admitidos na emergência do Hospital Getúlio Vargas no período de 1º de novembro de 2007 a 30 de abril de 2008. Foram admitidos 42 pacientes com fraturas da coluna torácica e lombar, perfazendo um total de 54 vértebras fraturadas. RESULTADOS: observou-se que as fraturas da coluna torácica e lombar foram mais frequentes no gênero masculino, com uma média de idade de 39 anos. As quedas de altura foram responsáveis por 61,9% dos casos, seguida dos acidentes com motos (19,05%). Lesões neurológicas estiveram presentes em 14,28% dos casos e o tratamento cirúrgico foi realizado em 50% deles. CONCLUSÃO: as fraturas da coluna torácica e lombar, no presente estudo, foram frequentes nos adultos jovens, do gênero masculino, trabalhadores e causadas por queda de altura.
Uso da câmara de ar em cirurgia ortopédica: aplicações, vantagens e desvantagens
Authors: Goncalves Jose Carlos Barbl , Fernandes Yvens Barbosa , Silva Rafael Barreto , Cipoli Fernando
Published: March 2010

OBJETIVO: o trabalho visou à difundir o uso da câmara de ar, de forma sistemática, em cirurgias ortopédicas, como suporte e protetor das saliências ósseas, em especial nas cirurgias de longa duração. MÉTODOS: trata-se de um estudo prospectivo não randomizado, realizado entre 2002 e 2007, totalizando de 264 procedimentos ortopédicos. RESULTADOS: verificou-se que, independente do tempo de cirurgia, não houve áreas de pressão nas proeminências ósseas ou lesões de nervos periféricos no pós-operatório. CONCLUSÃO: os resultados do presente estudo permitiram recomendar a câmara de ar como uma excelente opção de suporte em cirurgias ortopédicas, pois se trata de um dispositivo de baixo custo, fácil obtenção e alta reprodutibilidade.
O trauma raquimedular
Authors: Del Bel Elaine A , Silva Célia A da , Mladinic Miranda
Published: March 2010

A medula espinhal dos mamíferos adultos não permite a regeneração de axônios. Por razões ainda desconhecidas, as fibras neurais falham em cruzar o sítio da lesão, como se não houvesse crescimento, desde a primeira tentativa. Quais mecanismos poderiam explicar a perda da capacidade de regeneração? As cicatrizes formadas pelas células da glia seriam uma consequência da falha na regeneração ou a causa? Diversas linhas de evidência sugerem que a regeneração da medula espinhal seria impedida no sistema nervoso central pela ação de fatores locais no sítio da lesão, e que o sistema nervoso central não-lesado é um meio permissivo para o crescimento axonal, na direção de alvos específicos. Uma vez que os axônios são induzidos adequadamente a cruzar a lesão com o auxílio de implantes, fármacos ou células indiferenciadas, as fibras em regeneração podem encontrar a via específica e estabelecer conexões corretas. O que ainda não se sabe é que combinação de moléculas induz/inibe o potencial de regeneração do tecido e que mecanismos permitem aos neurônios formarem conexões específicas com os alvos com os quais são programados a fazer.
Acute food deprivation reduces expression of diazepam-binding inhibitor, the precursor of the anorexigenic octadecaneuropeptide ODN, in mouse glial cells
Authors: Compère V , Lanfray D , Castel H , Morin F , Leprince J , Dureuil B , Vaudry H , Pelletier G , Tonon M C
Published: March 2010

In the central nervous system of mammals, the gene encoding diazepam-binding inhibitor (DBI) is exclusively expressed in glial cells. Previous studies have shown that central administration of a DBI processing product, the octadecaneuropeptide ODN, causes a marked inhibition of food consumption in rodents. Paradoxically, however, the effect of food restriction on DBI gene expression has never been investigated. Here, we show that in mice, acute fasting dramatically reduces DBI mRNA levels in the hypothalamus and the ependyma bordering the third and lateral ventricles. I.p. injection of insulin, but not of leptin, selectively stimulated DBI expression in the lateral ventricle area. These data support the notion that glial cells, through the production of endozepines, may relay peripheral signals to neurons involved in the central regulation of energy homeostasis.
Solution-Gas Drive in Heavy Oil: Field Prediction and Sensitivity Studies Using Low Gas Relative Permeability
Authors: Kumar R. , Pooladi-Darvish M.
Published: March 2010

The favourable behaviour of heavy oil reservoirs under solution- gas drive has intrigued the oil industry for a long time. Many mechanistic models have been proposed to explain this behaviour. This paper investigates one of the theories that attributes the low producing GOR and high recovery of heavy oil to low gas mobility.

A simulation study was carried out on a commercial black oil simulator to match the "typical" production data of heavy oil fields in Lindbergh and Frog Lake. Sensitivity studies were carried out to investigate the effect of gas relative permeability on oil recovery. The effect of sand production, which is an integral part of heavy oil production in Western Canada, was also investigated. A parameter was used in the simulator to account for the increased permeability due to sand production.

The results indicate that the field performance can be matched by using low gas mobility and incorporating improved permeability due to sand production. Neither of them alone was sufficient for matching the field performance. The use of a low gas mobility was successful to explain high pressure-gradients in the field, by acting as a pressure maintenance mechanism, and leading to a high recovery under solution-gas drive.

Intruduction

PanCanadian has been one of the major operators in the Lindbergh and Frog Lake heavy oil fields of northeast Alberta(1). The production in these fields is from the Upper Mannville group. The producing formations contain oil of 12 – 14 ° API with in situ viscosities of 3,000 – 10,000 cp. The fields have shown recovery much in excess of what can be predicted by applying conventional flow equations. Many heavy oil wells under primary production have produced about 15% of the original oil in place (OOIP) in 10 years(1). The primary oil production in these fields is accompanied by sand production and is called "Cold Production." A typical well in the Lindbergh and Frog Lake fields under depletion has produced an average of 9,200 m3 of oil and about 230 m3 of sand in 1,000 days(1).

Several tests have been carried out to determine the mechanism responsible for the favourable behaviour of these reservoirs. Metwally and Solanki(1) presented a simulation model to match the field production behaviour. The authors postulated that reservoir porosity and permeability are increased due to sand production. Additionally, the authors showed that a pressure support mechanism needs to be incorporated to match recovery data; an external aquifer was therefore incorporated into the model.

Similar to Metwally and Solanki(1), we use a commercial simulator to match the production data. We show that the use of low values for gas relative permeability results in pressure maintenance and substantial oil production. Accounting for the low gas mobility along with the improved permeability resulted in a match of the field data. Sensitivity studies are reported, which show that both the effects of low gas mobility and improved permeability are required for a match.
Phase Equilibria Relevant to Acid Gas Injection, Part 1-Non-Aqueous Phase Behaviour
Authors: Carroll J.J.
Published: March 2010

The design of an acid gas injection scheme requires a significant amount of information regarding phase equilibria. The purpose of this paper is to review the literature for the available experimental data, and survey methods for calculations of the non-aqueous equilibria. This study will be limited to the following components: hydrogen sulfide, carbon dioxide, methane, ethane, propane, and, to some extent, water.

It is demonstrated that the widely available Peng-Robinson equation of state is adequate for predicting the non-aqueous phase equilibria in these mixtures. However, the design engineer should be cognizant of the capabilities of the model selected to perform the calculations. If uncertain, it is wise to verify the software package, and more importantly the chosen model, by comparing it with experimental data. Available data are compiled as a part of this paper.

ACID GAS INJECTION

Acid gas injection has become the environmentally friendly way to deal with the unwanted by-product of the sweetening of natural gas. In the future it may become a means of dealing with carbon dioxide from other sources as well.

In a basic acid gas injection scheme, the acid gas off the amine regenerator tower is compressed and transported via pipeline to an injection well. From there, it is injected into a suitable formation for disposal. The formation is selected based on geological criteria such as the size of the disposal reservoir, and the containment of the injected acid gas. In an acid gas injection scheme, pressures can range from near atmospheric up to 30 MPa or more; the upper limit is dictated by the selected reservoir. The temperature can range from about 30 °C up to as much as 200 °C; again the upper limit is being the reservoir conditions.

The design of the injection scheme requires a thorough knowledge of the phase equilibria encountered in wet acid gas mixtures. This paper reviews the experimental investigations into the relevant systems. This study is limited to the following components: hydrogen sulfide, carbon dioxide, methane, ethane, propane, and water. Even so, an interesting variety of phase equilibria will be presented. The design engineer is advised to be aware of all of the various phenomena encountered in mixtures of these components, as they will have a significant effect on the design.

Experimental Investigations

In this section, experimental investigations important to acid gas injection will be reviewed. Typically, in acid gas injection schemes, we are not concerned with hydrocarbons heavier than propane. So, for this study, only equilibrium between the acid gas components and methane, ethane, and propane will be considered.

Hydrogen Sulfide +Carbon Dioxide

The most important non-aqueous system involved in acid gas injection is the binary mixture hydrogen sulfide +carbon dioxide, since acid gas is composed almost exclusively of these components.

Two early studies of the phase equilibrium in the system hydrogen sulfide +carbon dioxide were Bierlein and Kay(1) and Sobocinski and Kurata(2).
Rules of Thumb in Well Testing: What Works and Doesn't Work-and Why
Authors: Brown L.P. , Hawkes R.V.
Published: March 2010

Rules of thumb appear in every profession. They are developed when practitioners observe a repeated cause and effect relationship. This paper presents some rules of thumb used by practitioners in well testing, examines their validity and limits, and in some cases, develops their theoretical basis. The paper is presented as a forum for discussion among well testing practitioners.

Introduction

Rules of thumb evolve in every civilization and culture as humans experience and observe cause and effect relationships. Rules that don't work are discarded; rules that do work become part of the culture, tradition, practice, or science.

Rules may be very general (i.e., Well groomed people are more pleasant than poorly groomed people) or quite specific (i.e., Sands in this area with less than 5% porosity are not productive). Rules, as illustrated in the above examples, can also lull us into false security or even devastating error.

Rules, whether general or specific, are empirical and may be based on sound, if not well understood, physical, economic, social, or other principles. They allow us to shortcut some thinking processes and, in doing so, can cause us to make costly mistakes. As we grow more and more experienced, we personally develop and adopt new rules of thumb. It is important that we periodically, or at least initially, examine those rules to make sure that they are appropriate for each new situation.

In well testing, we use and misuse various rules of thumb. In this discussion, we investigate some of the more common and even private rules to discover their theoretical justifications and the limits of their applicability. Contributors to this paper were invited to submit their favorite rules and to present the physical justification for their existence.

A Rule of Thumb Gone Bad

In reviewing rules of thumb, we will examine one from the world of medicine to avoid bringing discredit on the practice of petroleum engineering. This rule was applied with sometimes disastrous results.

The practice of "bleeding" to cure various ailments was widespread prior to the 20th century. Bleeding involves draining not insignificant quantities of blood from a sick patient. Today, we laugh at the thought that physicians routinely used bleeding on patients and are glad that the practice has been discontinued. How did the practice come about and why was it popular?

Contemporary experiments on laboratory animals show that bleeding reduces fever in sick animals. We can speculate that someone, at some time in the past, observed this effect and applied it successfully to reduce fever in humans. Having success, he "published" his results, probably by word of mouth, and others tried it. The practice got out of control when practitioners applied it outside of the narrow window of symptoms which it effectively addressed.

Today, we don't bleed people, even to reduce fever. We have developed modern pharmaceutical methods for fever control. Perhaps these too will someday be regarded as misapplications.
On Lateral and Helical Buckling of a Rod in a Tubing
Authors: Lukasiewicz S.A. , Knight C.
Published: March 2010

The paper analyzes lateral and helical buckling of a rod sub-merged in fluid in tubing. The purpose of the paper is to revisit the controversy regarding the formula for the helical buckling load that still exists in the literature. The relation between the critical helical buckling force and the helix-pitch has been reexamined. Our analytical calculations and experimental tests confirm the results obtained by Cheatham and P.D. Pattillo(1). The effect of the pressure acting on the rod was included in the analysis to explain the so-called "fictitious forces" introduced by Lubinski(2).

Introduction

In the oil and gas industry, Lubinski's equation(2) for the critical buckling load for a rod in a tube has been given high credibility. However, this equation causes some controversy [see Equation (15) of the present paper]. Lubinski's equation is often used to evaluate the stability of tubes. It is also important in the analysis of the stability of sucker rods. The oil pressure and the forces resulting from pump action cause the compressive force acting on the rod at the bottom of the well. Often this compressive force causes the rod to buckle; specifically, to buckle in a helical form. The rod first buckles laterally. However, with the increase of the compressive force, the helical buckling occurs. The rod coils around the inside of the tube and the axial stiffness of the rod is reduced significantly. The buckling of the rod can produce large negative effects on the work of the pump. The helically-buckled sucker rod has muchlower axial stiffness and reduces the stroke of the plunger. The buckling-related lateral deformations cause much greater wearing of the rod, the tubing, and the pump. It is therefore important to determine the correct value of the critical buckling force.

There are different opinions about Lubinski's equation. For example, J.B. Cheatham and P.D. Pattillo(1), solving the problem by means of virtual work principle, found that the critical helical buckling force is two times smaller than the force predicted by Lubinski. They are of the opinion that there are two critical force relations corresponding to loading and unloading and that the value of the real critical buckling force lies between these two forces. Y.W. Kwon(3), solving the problem using the beam-column equation, obtained a result identical to Lubinski's formula.

In this paper, the lateral and helical buckling of a rod submerged in a fluid in a tube has been reexamined. Using virtual works and modifications that allow for the elimination of some approximations used in Cheatham and Pattillo's(1) work, an equation for the critical helical buckling force has been developed. This equation sets the buckling force two times lower than Lubinski's equation. The formula for the critical helical buckling load for the rod or tube submerged in a liquid has been derived for a case of constant compressive force and side surface pressure. It has been assumed that the weight of the rod is negligible as compared to other forces.
Evaluation of the Bottom Water Reservoir VAPEX Process
Authors: Frauenfeld T. , Jossy C. , Rispler K.
Published: March 2010

In 1998, Butler and Mokrys proposed a "Closed-Loop Extraction Method for the Recovery of Heavy Oils and Bitumens Underlain by Aquifers." The process has potential application to many Alberta and Saskatchewan heavy oil reservoirs. The objective of our work was to produce an experimental evaluation of solvent-assisted process options for bottom water reservoirs. The current work is entirely experimental, and provides data that may be used to back up a numerical simulation effort.

The experimental series modelled a bottom water process in order to determine its feasibility for a field-scale oil recovery scheme. A series of five experiments were run in an acrylic visual model. Pujol and Boberg's scaling criteria(1) were used to produce a lab model scaling a field process by a geometric ratio of 100:1, and compressing field time by a ratio of 10,000:1. The model simulated a slice of a 30 m thick reservoir with a 10 m thick bottom water zone, containing a pair of horizontal wells at the oil-water interface, offset by 25 m. For field prediction, experimental results were scaled up to represent a 30 m thick reservoir (20 m thick oil zone) with 500 m horizontal wells.

The experimental rates were negatively impacted by continuous low permeability layers and by oil with an initial gas content. The lower effective diffusion rates required that the surface area exposed to solvents be increased in order to achieve commercial oil recovery rates. The Bottom Water Process described in this report offers the opportunity to do just that, as the large surface area of the oil water interface between the wells will provide contact for solvent by injecting gas at the interface. Given an appropriate well spacing, high production rates should be possible.

Introduction

The Alberta Research Council (ARC) has done several years of investigative work into solvent-assisted heavy oil recovery processes(2, 3). The present report describes a particular contribution to solvent-assisted oil recovery technology; a comparative scaled physical model study of bottom water process options. The results of this work showed scaled field rates of 25.3 m3/d and a live oil scaled rate of 16.5 m3/d, both at 25 m offset well spacing.

Mechanisms of the Bottom Water VAPEX Process

The Bottom Water VAPEX Process, illustrated in Figure 1, is a recovery process depending on the interplay of several mechanisms for its success. The solubility of the gas in the oil is controlled by the k-values of the oil/solvent system. Diffusion, hydrodynamic dispersion, and swelling also play a role in the movement of gas into the reservoir oil.

The oil flow is enabled by viscosity reduction due to the dissolution of solvent in the oil. Oil-solvent contact is further augmented by capillary pressure moving some oil into the vapour chamber zone, as was observed in Experiment #2. Heterogeneity of the reservoir sand further increased the surface produced by capillary action, but excessive layering can hinder the movement of oil, as was shown by Experiment #3.
Laboratory Model Flow Tests
Authors: Maguss H. , Flock D.L.
Published: March 2010

The problem of utilization of core laboratory model flow tests for thepurposes of field evaluations has been studied by an investigation of scaledlaboratory model experiments. Results have indicated that under a wide range ofconditions where stabilization has not been attained the recovery obtained bywater frontal displacement in model flow tests is rate sensitive. The problemhas been approached by considering the unsteady state equations describinglinear flow through a porous medium which are not subject to formal solution.Variables and parameters have been grouped to form "scaling coefficients" forcorrelation purposes. Results obtained and explanations of the observedphenomena are presented and discussed.

Introduction

There is ample evidence in the literature as to the effect of waterinjection rates on oil recovery both in water wet and oil wet systems. Variousinvestigations have shown that with increased water injection rates, the oilrecovery would be increased, decreased, or rate independent. Although thesestudies have clarified certain aspects of linear waterflooding behavior, therestill exists some contradictory or misunderstood concepts which affect theapplicability of laboratory model flow tests for field performanceprediction.

On the basis of developed theory it is realized that flooding behavior isdependent upon the length of the system, the rate of injection, core propertiesand the fluid viscosities. Moreover, this theory suggests that linearwaterfloods, if carefully conducted, should exhibit scaling and stabilizationproperties. An experimental investigation verifying these properties in anoil-wet system was performed by Rapoport and Leas. However, in water-wetsystems, experimental results appear inconsistent. This may be attributed tothe fact that the scaling and stabilization properties have not beensatisfactorily attained in many cases.

The tests reported in this paper were conducted on what was believed to bewater-set systems using water as the displacing fluid and low viscosity oils asthe displaced fluid. The results of waterflood tests performed on anunconsolidated sand pack, an alundum core, and a limestone core are presented.The application of such data for reservoir prediction is discussed.
Made in Canada - One Manufacturer's Approach
Authors: Jones C.R.
Published: March 2010

Due to the pressure exerted on foreign industry to build their products inCanada, extensive studies were conducted by Cooper-Bessemer of Canada over aseven year period. Their approach to the normal necessary large capitalexpenditure for a low unit volume, cyclic heavy equipment market, along withpictures of components produced, purchased or imported is presented. By leasinga plant in a surplus labour area and installing only general purpose machinetools that can be kept busy, overhead and direct labour costs can becontrolled. Components in various stages of manufacture are purchased fromforty to fifty Canadian suppliers. A formula applied to U.S. costs comparedwith Canadian costs dictates whether a component is made, purchased orimported. Canadian suppliers have done an outstanding job of producing pistons, cylinders, heads, flywheels, crossheads, nuts, bolts and so forth for the largeslow speed engines and compressors they are building. "Canadian content" isoften discussed in terms of man-hours, material, dollars or percentages. Due tothe differences in accounting policies of various companies, the results areoften misleading. A realistic and simplified interpretation that makescomparisons meaningful is gaining general acceptance. It is suggested that"Canadian content" should be interpreted as the difference between the sellingprice and the value of the goods and services imported. Customs set standardvaluations so comparisons are fair and easy to audit. Any money that does notleave the country adds to the gross national product, be it expenditure, profitor taxes.

Introduction

There has been a gradual increase of pressure put on suppliers who importtheir products to manufacture in Canada for about ten years now. The approachto the problem used by Cooper-Bessemer of Canada Ltd. may be of generalinterest. It should be understood that this Company is not recommending, oreven suggesting, that what it is doing would work for others. However, in theauthor's opinion, it can be said that there is no easy way to produce heavyengines and compressors in Canada at a profit. The concept which Cooper-Bessemer of Canada is using, does allow it to get a high Canadiancontent with a relatively low capital investment.
Further Comments on Considerations in Bank Financing of Producing Oil Properties
Authors: Humphries R.G.
Published: March 2010

The budget proposals contained in the Minister of Finance budgetspeech of April 10th, 1962, will have rather significant effects on theeconomics of the oil and gas industry in Western Canada, assuming they areimplemented by the next Government after the June, 1962 election. With respectto the acquisition of producing oil properties, Resolution 8, which proposesthat the amount paid for the right, license or privilege to explore for, drillfor, or take petroleum and natural gas in Canada, are to be classed as drillingor exploration expenses for the purpose of computing deductions from income, will be most significant. The effect of this change is demonstrated byreference to the numerical examples which were part of the paper"Considerations In Bank Financing of Producing Oil Properties" presented to the13th Annual Technical Meeting of the Petroleum and Natural Gas Division of the Canadian Institute of Mining & Metallurgy.

The total acquisition cost of a producing property would be apportionedbetween tangibles, which are depreciated as formerly, and intangibles, whichwould be written off against income to the extent that it is available.

In the case of Tables I and II, where the purchaser of the working interesthas a full tax liability with no other write-offs, the net cash income to theworking interest after tax is increased by $216.8 thousand or 16.6% where theproperty is purchased by cash and 27.6% where the property is purchased by cashand loan. The increase in net cash income is equivalent to the tax which wouldbe paid on the intangible portion of the acquisition cost after depletion underthe present tax laws.

Depletion allowance will still be allowed, so that in the case of Table Ithe total of the write-off plus depletion over the life of the property will be $940.6 thousand compared with $507.2 thousand under the present tax laws. In Table II the total write-off plus depletion will be $918.6 thousand compared with $485.2 thousand at present.
The Diamond Drill in Exploration for Oil and Gas
Authors: Charlewood G.H.
Published: March 2010

Most wildcat wells are drilled with conventional oil well rigs. To reducecost of non-productive holes there is an increasing trend toward slim holes forexploration. It is suggested that a step further in this direction may be useof diamond drills.

In remote areas where cost of transportation is high; when targets, forexample pinnacle reefs, are relatively small and hard to pinpoint; whencontinuous core is an asset, the diamond drill may make economic sense. Onceproductive targets are encountered, conventional rigs become practical.

The advantages, disadvantages, limitations, and possible further adaptationof this normally "hard rock" tool in a "soft rock" environment arediscussed.

Introduction

The purpose of this presentation is to suggest avenues where the diamonddrill might be useful in exploration for oil and natural gas. The diamond drillis primarily a "hard-rock" tool and the problems of a "soft rock" environmentare different from those normally encountered by hard rock drillers.Nevertheless, under certain geological and geographical conditions the diamonddrill offers advantages which can be of economic interest to those engaged inthe search for oil and gas. This is particularly the case for stratigraphictests in remote areas.

Exploration for petroleum and natural gas and exploration for metals isconducted along the same general lines though the details vary widely. Photointerpretation, geophysics, and geological investigations indicate targetareas. Testing of these targets ultimately requires the use of drills.

Wildcat wells are drilled with essentially the same drill rigs as areproduction wells. Due to the high cost of wildcatting, considerable effort hasbeen expended to effect economies. One approach has been toward slim holedrilling. Realizing fully the limitations, it is suggested that a further stepin this direction might be through use of the diamond drill. Diamond drillshave been used successfully for stratigraphic tests in some areas and withsavings in cost of as much as 50 percent. Features of diamond drills throughwhich economies may be affected, compared to rotary rigs, include lower capitalcost, smaller crews, and lighter overall and unit weights.
Experience in Processing Core Analysis and Production Data with a Digital Computer
Authors: Smith O.J.E. , Kemp E.M.
Published: March 2010

In 1959 Imperial Oil Limited began using an IBM-705 computer for reductionof core analysis data and for calculation of capacity distributions. In thefirst study, relatively small volumes of data were processed, and manualmethods were used to correct input data and to check computer output. It wasapparent that for larger studies it would be necessary to write additionalprograms, to sort, edit, and update input data, and to summarize output.

Early in 1960 a start was made computer processing of production andinjection histories. Using experience gained in dealing with large volumes ofcore analysis information, an integrated system of programs was first developedto generate accurate master data files. Extreme care in original planning mustbe exercised to obtain an efficient operation. Evolutionary build up of a dataprocessing system is technically difficult and wasteful of both manpower andmachine time.

Introduction

Processing of core analysis and production data with a digital computerinvolves a multitude of simple calculations which would otherwise be performedusing desk machines. Computers are used to improve accuracy, and to facilitateprocessing large volumes of data.

The accuracy of computer calculations is, of course, directly dependent onthe accuracy of the input data. Once reliable input data records have beencompiled on tape, it is possible to carry out further reservoir engineeringcomputations. Master data tapes should carry sufficient information to satisfyall foreseeable future requirements.

Two fairly complex data processing systems have been developed by ImperialOil Limited to process production and core analysis data. The core analysissystem is used primarily to obtain averages of reservoir parameters and todefine stratification. The production system is used mainly to calculate dailyand cumulative production rates, and gas or water-oil ratios, for single wellsor groups of wells.