Arquitectura. Ritos y ritmos

Este libro está dedicado a cuantos aún creen en el beneficio de la Arquitectura que a todos y a todas y en todas partes, salvo cuando ocasionalmente navegamos, nos sustenta y envuelve. No es, ni de lejos, un recetario. Es más bien un cuestionario que invita a pensar. Convencido de que la Arquitectura no se enseña, sino más bien ella nos enseña a vivir, el autor ha puesto por escrito aquellos interrogantes que, a lo largo de cuatro décadas, él mismo formuló de palabra, invitando a sus estudiantes y estudiosos a aprender de ella, interrogándola. Hablamos, pues, de Arquitectura. Hace dos tercios de siglo, Bruno Zevi, arquitecto e historiador vinculado al llamado Movimiento Moderno, publicó un libro titulado Saber ver la arquitectura. En su época fue un best-seller. Este libro apunta a algo diferente. Pues no trata de saber ver, sino de saber habitar la arquitectura. Lo que podría haber sido su título, porque éste es su propósito: y el que traza su itinerario. Un itinerario que va del lugar que habitamos en el planeta (la tierra) a la luz que nos remite al sistema (el cosmos) al que pertenecemos. El trayecto del libro contempla, a lo largo de sus 28 capítulos, otras tantas estaciones, o cuestiones, en las que el lector puede a su antojo subirse al tren o apearse de su discurso. Bien entendido que la fe en el poder de la Arquitectura no se discute: se da por supuesta. Ella está presente en cada uno de nuestros pasos sobre la tierra, alimenta el fuego de nuestros hogares, vehicula y canaliza el agua que sacia nuestra sed y ventila el aire que respiramos. En ella se dan cita, pues, los cuatro elementos de la sabiduría clásica del mundo. El libro agrupa las dichas 28 cuestiones en cuatro paquetes de siete, dos y dos. Los dos primeros atienden a los ritos, o protocolos, en los que se ejercita la voluntad de habitación. Los cuales, a su vez, suponen una toma de posesión con respecto al territorio, su geografía y su historia, su topografía y su paisaje, sus asentamientos y sus mitos. Y los dos siguientes refieren sus ritmos, materiales y formales, a través de los cuales la arquitectura se confabula con la vida y redunda en ella. Por medio del ritmo la arquitectura escenifica el rito de la habitación.

A low cost system for the prediagnosis of the human tremor

Human tremor can be defined as a somewhat rhythmic and quick movement of one or more body parts. In some people, it is a symptom of a neurological disorder. From the mathematical point of view, human tremor can be defined as a weighted contribution of different sinusoidal signals which causes oscillations of some parts of the body. This sinusoidal is repeated over time, but its amplitude and frequency change slowly. This is why amplitude and frequency are considered important factors in the tremor characterization, and thus for its diagnosis. In this paper, a tool for the prediagnosis of the human tremor is presented. This tool uses a low cost device (<$40) and allows to compute the main factors of the human tremor accurately. Real cases have been tested using the algorithms developed in this investigation. The patients suffered from different tremor severities, and the components of amplitude and frequency were computed using a series of tests. These additional measures will help the experts to make better diagnoses allowing them to focus on specific stages of the test or get an overview of these tests. From the experimental, we stated that not all tests are valid for every patient to give a diagnosis. Guided by years of experience, the expert will decide which test or set of tests are the most appropriate for a patient.

Evaluación del temblor humano a través de dispositivos de bajo coste

El temblor humano puede definirse como un movimiento rápido y, en cierta manera, rítmico de una o más partes del cuerpo. En algunas personas, este movimiento puede ser un síntoma de alguna alteración a nivel neurológico. Desde el punto de vista matemático, el temblor humano puede ser definido como una suma ponderada de diferentes señales sinusoidales que causan oscilaciones de algunas partes del cuerpo. Esta sinusoide se repite en el tiempo pero su amplitud y frecuencia cambian lentamente. Por esta razón, la amplitud y la frecuencia son consideradas factores importantes en la clasificación del temblor y por tanto útiles en su diagnóstico. En este artículo, se presenta una herramienta de ayuda al diagnóstico del temblor humano. Esta herramienta usa un dispositivo hardware de bajo coste (<$40) y permite calcular las principales componentes de esta sinusoide asociada al temblor de una manera precisa. Como casos de estudio se presentan su aplicación a dos casos reales para probar la bondad de los algoritmos desarrollados. Los casos muestran pacientes que sufrían temblores con distinta severidad y que han realizado una serie de tests con el dispositivo para que el sistema calculara las principales componentes del temblor. Estas medidas aportadas por el sistema ayudarían en un futuro a los expertos a tomar decisiones más precisas permitiéndoles centrarse en determinadas fases del test o la realización de tests más específicos para evaluar mejor las características propias del temblor del paciente. De la experimentación realizada podemos afirmar que no todos los tests son válidos para el diagnóstico para todos los pacientes. Será finalmente la experiencia del profesional el que decidirá finalmente qué test o conjunto de tests son los más apropiados para cada paciente.

Transferencia y Difusión de tecnologías para el cultivo de especies aromáticas y medicinales a pequeños productores de la provincia de Córdoba

En la Facultad de Ciencias Agropecuarias de la UNC se llevan adelante, desde el año 1996, proyectos de domesticación y mejoramiento de especies aromáticas y medicinales, con el fin de capacitar y apoyar técnicamente a recolectores y pequeños productores. Los productos derivados del cultivo de especies aromáticas y medicinales presentan un mercado creciente con demanda a nivel tanto nacional como internacional, lo cual lleva a una explotación en aumento de las especies aromáticas y medicinales nativas. Dentro de la problemática en que se engloban las especies aromáticas y medicinales, dado su uso tradicionalmente irracional y no sustentable, es de fundamental importancia difundir su cultivo con ejemplos concretos. Difundiendo de este modo paquetes tecnológicos generados en la Universidad a manos de productores que dispongan de requerimientos básicos (en cuanto a infraestructura y disponibilidad o apertura a estos nuevos cultivos). De esta manera se puede demostrar a la comunidad la factibilidad de generar emprendimientos productivos y sustentables con estas especies como alternativa de cultivo para pequeños productores fundamentalmente hortícolas. La idea del proyecto surge en base a la necesidad, de pequeños productores fundamentalmente hortícolas de la Provincia de Córdoba, de apoderarse de conocimientos hasta ahora desconocidos en cuanto al cultivo de plantas aromáticas y medicinales, que puedan contribuir al fortalecimiento de sus economías, y a un desarrollo social y económico sostenible. La importancia del proyecto radica en la posibilidad de capacitar a pequeños productores e implementar tecnologías aplicadas al cultivo de plantas aromáticas y medicinales, junto a la implementación de las buenas prácticas agrícolas (BPA) en dichos emprendimientos, tomando la información de las experiencias productivas como fuente de nuevo conocimiento. Es necesario destacar el interés por parte de los destinatarios en desarrollar sus propias iniciativas de emprendimientos productivos, que surgieron del contacto con el grupo de trabajo. El acercamiento de la universidad a esta comunidad resultó de disparador de nuevas iniciativas al sentirse apoyados y contenidos para abordar nuevos cultivos con especies desconocidas para ellos. La metodología utilizada pretende pasar de una extensión intensiva en recetas a una intensiva en conocimientos, siendo los técnicos y profesionales participantes, claramente un nexo entre la investigación y el productor, pero promulgando la acción participativa de este, manteniendo una relación estrecha con los destinatarios, donde intervenir en el sistema sea esencialmente formar parte del mismo, y cooperar para que exista aprendizaje recíproco y ambos se apoderen de los conocimientos generados. El proyecto plantea la realización de una etapa en la unidad académica (FCA - UNC), en la cual se dispone de las instalaciones y todas las herramientas necesarias para llevar a cabo jornadas-taller para la producción de estas especies que luego servirán para la implantación de parcelas intensivas demostrativas en el predio perteneciente a los productores participantes. Los productores aportarán herramientas de trabajo necesarias, terreno para el cultivo e infraestructura para camas de siembra y/o invernaderos. Se llevarán a cabo talleres de capacitación, entrevistas, encuestas, debates, tutorías y asesoramientos para asegurar una verdadera transferencia, capacitación y apropiación de los contenidos y tecnologías que se pretenden diseminar. El impacto esperado pretende difundir y transferir paquetes tecnológicos para el cultivo de especies aromáticas y medicinales en los productores hortícolas, remarcando la importancia del recurso natural, y la necesidad de preservación debido a la creciente degradación de algunas de ellas, como por ejemplo la peperina. Logrando de este modo acompañar a futuro, la formulación o implementación de emprendimientos productivos a largo plazo en los productores interesados.

Mejoramiento de insecticidas de banda verde por incorporación en ciclodextrinas, co-cristales y niosomas

La aplicación de agroquímicos para proteger granos y vegetales es una parte importante de los procedimientos corrientes en el manejo integrado de plagas ya que 20- 40% de la producción mundial potencial se pierde cada año por plagas, malezas y enfermedades. La necesidad de modificar la naturaleza química de los pesticidas para hacerlos más amigables con el ambiente llevó al desarrollo de un gran número de pesticidas clasificados como de banda verde, menos tóxicos, menos contaminantes y más selectivos que los tradicionales. Entre ellos se incluyen los insecticidas reguladores de crecimiento (IGR) seleccionados para este proyecto. Sin embargo, como compuestos orgánicos, tienen baja solubilidad acuosa lo que usualmente requiere de la formulación para su uso agrícola con otros vehículos como aceites o solventes que son contaminantes. Las regulaciones internacionales son cada vez mas estrictas en cuanto al uso de pesticidas por lo que es muy importante el desarrollo de tecnologías apropiadas para la utilización de compuestos de banda verde en los cultivos de la región. Nuestra propuesta se enfoca en generar formas alternativas (‘paquetes moleculares’ multi-componentes) de estos IGR que tengan mayor solubilidad acuosa que los compuestos no tratados, posibilitando su formulación en medio acuoso ambientalmente amigable. Las rutas elegidas comprenden la inclusión de los IGR dentro de sistemas nanoestructurados como la cavidad de ciclodextrinas (CDs), su incorporación en co-cristales y el encapsulado en niosomas. Las CDs son moléculas cíclicas biodegradables y no-tóxicas, formadas por unidades de glucosa. Los niosomas son vesículas microscópicas con un corazón acuoso encerrado por una membrana de surfactantes no iónicos que forman estructuras bicapa cerradas. Los co-cristales resultan de la interacción entre un compuesto y un co-formador con una estructura complementaria con el primero que permite la formación de enlaces puente H entre ambos. Los tres procesos involucran interacciones ‘suaves’ entre el IGR y la otra especie, dejando intacta la integridad biológica del insecticida. Se espera así obtener una diversidad de sistemas para diferentes opciones de formulación. Se eligieron IGR derivados de benzoilfenilurea (BPU), dibenzoilhidracinas (DBH) e isopreno, clasificados como clase U (unlikely to present acute hazard in normal use) por la OMS que tienen relativamente baja toxicidad para humanos y otros mamíferos, alta selectividad para insectos y muy poca solubilidad acuosa. Luego del aislamiento de las nuevas construcciones moleculares, se establecerán los efectos sobre las propiedades fisicoquímicas de los IGR. Se efectuarán estudios en estado sólido y en solución. Los complejos sólidos en CDs preparados por distintos métodos se examinarán por FTIR y RMN en estado sólido, microscopía FTIR, difracción de Rayos X de polvo y monocristales, TGA, DSC y microscopía ‘hot stage’. Por RMN, dicroísmo circular inducido y titulación calorimétrica isotérmica se estudiarán aspectos termodinámicos y estructurales de la inclusión en solución. El efecto sobre la solubilidad y estabilidad química de los IGR se investigará midiendo, respectivamente, las velocidades de disolución de los complejos y las velocidades de degradación de los IGR en presencia y ausencia de CDs. Para la obtención de co-cristales se usarán moléculas co-formadoras ‘GRAS’ (generally regarded as safe) elegidas en base a la complementariedad de sus grupos funcionales capaces de formar enlaces de H con los de los IGR. Las medidas de los puntos de fusión y velocidad de disolución son parámetros importantes para determinar su eventual utilidad. Los niosomas se prepararán en presencia de los IGR por distintas técnicas usando los surfactantes no iónicos y no tóxicos Tween 20 y 80, Span 20 y 80 y Brij-35. Se analizarán el tamaño y morfología de los agregados por microscopía de transmisión electrónica y se determinará la estabilidad en el tiempo de los niosomas por UV-vis.

Cistatina C : um marcador de função renal promissor em doentes com lúpus eritematoso sistémico?

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Uso de água produzida na formulação de fluidos de perfuração

Drilling fluids have fundamental importance in the petroleum activities, since they are responsible for remove the cuttings, maintain pressure and well stability, preventing collapse and inflow of fluid into the rock formation and maintain lubrication and cooling the drill. There are basically three types of drilling fluids: water-based, non-aqueous and aerated based. The water-based drilling fluid is widely used because it is less aggressive to the environment and provide excellent stability and inhibition (when the water based drilling fluid is a inhibition fluid), among other qualities. Produced water is generated simultaneously with oil during production and has high concentrations of metals and contaminants, so it’s necessary to treat for disposal this water. The produced water from the fields of Urucu-AM and Riacho da forquilha-RN have high concentrations of contaminants, metals and salts such as calcium and magnesium, complicating their treatment and disposal. Thus, the objective was to analyze the use of synthetic produced water with similar characteristics of produced water from Urucu-AM and Riacho da Forquilha-RN for formulate a water-based drilling mud, noting the influence of varying the concentration of calcium and magnesium into filtered and rheology tests. We conducted a simple 32 factorial experimental design for statistical modeling of data. The results showed that the varying concentrations of calcium and magnesium did not influence the rheology of the fluid, where in the plastic viscosity, apparent viscosity and the initial and final gels does not varied significantly. For the filtrate tests, calcium concentration in a linear fashion influenced chloride concentration, where when we have a higher concentration of calcium we have a higher the concentration of chloride in the filtrate. For the Urucu’s produced water based fluids, volume of filtrate was observed that the calcium concentration influences quadratically, this means that high calcium concentrations interfere with the power of the inhibitors used in the formulation of the filtered fluid. For Riacho’s produced water based fluid, Calcium’s influences is linear for volume of filtrate. The magnesium concentration was significant only for chloride concentration in a quadratic way just for Urucu’s produced water based fluids. The mud with maximum concentration of magnesium (9,411g/L), but minimal concentration of calcium (0,733g/L) showed good results. Therefore, a maximum water produced by magnesium concentration of 9,411g/L and the maximum calcium concentration of 0,733g/L can be used for formulating water-based drilling fluids, providing appropriate properties for this kind of fluid.

Tensoativo derivado do ácido cítrico: síntese e aplicação em fluidos de perfuração de emulsão inversa

This work describes the synthesis and study of the application of a new surfactant (Triester Lipophilic – TEL) obtained by citric acid with octanol. It is reaction was followed by thin layer chromatography (TLC) and after purification the product was characterized by proton and 13 – carbon nuclear magnetic resonance spectroscopy ( H and 13C NMR), thermogravimetric analysis (TGA) and surface tension analysis of oil-in-water emulsions. The TEL performance as surfactant in ester, n-paraffin and biodiesel based drilling fluids on the 70/30 and 60/40 water- oil rations (WOR) was evaluated by comparative tests of two commercial products used in the fields. These drilling fluids were aged in roller oven at 200 0 F during 16 h. The rheological and electric stability measurements were carried out at 135 ºF, the phase separation was evaluated after seven days at rest and the filtrate volume of drilling fluids was determined at high temperature and high pressure. The rheological behavior of the drilling fluids was evaluated by the flow curves. The results showed that the drilling fluids studied here presented Binghamian behavior as well as the used in the oil fields. The laboratory tests showed that the TEL reduced the filtrate volume and promoted the enhance of the thermal and mechanical stabilities.

Contribuição da poliacrilamida parcialmente hidrolisada em associação com a bentonita em fluidos de perfuração aquosos

In this study, we investigated the effect of addition of partially hydrolyzed polyacrylamide (HPAM) and bentonite in the physicochemical properties of acquous drilling fluids. Two formulations were evaluated: F1 formulation, which was used as reference, containing carboxymethylcellulose (CMC), magnesium oxide (MgO), calcite (calcium carbonate - CaCO3 ), xanthan gum, sodium chloride (NaCl) and triazine (bactericidal); and F2, containig HPAM steady of CMC and bentonite in substituition of calcite. The prepared fluids were characterized by rheological properties, lubricity and fluid loss. Calcite was characterized by granulometry and thermal gravimetric analysis (TGA). The formulation F2 presented filtration control at 93◦C 34 mL while F1 had total filtration. The lubricity coefficient was 0.1623 for F2 and 0.2542 for F1, causing reduction in torque of 25% for F1 and 52 % for F2, compared to water. In the temperature of 49 ◦C and shear rate of 1022 s −1 , the apparent viscosities were 25, 5 and 48 cP for F1 and F2 formulation, respectively, showing greater thermal resistance to F2. With the confirmation of higher thermal stability of F2, factorial design was conducted in order to determine the HPAM and of bentonite concentrations that resulted in the better performance of the fluids. The statistical design response surfaces indicated the best concentrations of HPAM (4.3g/L) and bentonite (28.5 g/L) to achieve improved properties of the fluids (apparent viscosity, plastic viscosity, yield point and fluid loss) with 95% confidence, as well as the correlations between these factors (HPAM and bentonite concentrations). The thermal aging tests indicated that the formulations containing HPAM and bentonite may be used to the maximum temperature until 150 ◦C. The analyze of the filter cake formed after filtration of fluids by X-ray diffraction showed specific interactions between the bentonite and HPAM, explaining the greater thermal stability of F2 compared to the fluid F1, that supports maximum temperature of 93 ◦C.

Efeito da força iônica nas propriedades de fluidos de perfuração aquosos à base de polímeros carboxilados e sulfatados

In the well drilling operations problems caused by contamination of the drilling fluid are common. The dissolution of ions from the geological formations affects the rheological and filtration properties of the fluids. These ions shield the charges of ionic polymers, leading to its precipitation. In this work was performed a detailed study on the stability of the properties of aqueous solutions and aqueous drilling fluids in the presence of sulphated and carboxylated polymers, using carboxymethylcellulose and kappa-carrageenan as polymer compounds carboxylated and sulfated model, respectively. The effects of ionic strength of the aqueous medium containing Na+, Mg2+ and Ca2+ on rheological properties of the polymer and drilling fluids solutions were evaluated by varying the concentration of salts, pH and temperature. It was observed that the fluids with κ-carrageenan suffered less influence against the contamination by the ions at pH 9 to 10, even at higher concentrations, but higher influence on pH> 11. The fluids containing carboxymethylcellulose were more sensitive to contamination, with rapid reduction in viscosity and significant increase of the filtrate volume, while the fluid based polymer sulfated kappa-carrageenan showed evidence of interaction with cations and preserve the rheological properties and improved stability the volume of filtrate.

Efeito da força iônica nas propriedades de fluidos de perfuração aquosos à base de polímeros carboxilados e sulfatados

In the well drilling operations problems caused by contamination of the drilling fluid are common. The dissolution of ions from the geological formations affects the rheological and filtration properties of the fluids. These ions shield the charges of ionic polymers, leading to its precipitation. In this work was performed a detailed study on the stability of the properties of aqueous solutions and aqueous drilling fluids in the presence of sulphated and carboxylated polymers, using carboxymethylcellulose and kappa-carrageenan as polymer compounds carboxylated and sulfated model, respectively. The effects of ionic strength of the aqueous medium containing Na+, Mg2+ and Ca2+ on rheological properties of the polymer and drilling fluids solutions were evaluated by varying the concentration of salts, pH and temperature. It was observed that the fluids with κ-carrageenan suffered less influence against the contamination by the ions at pH 9 to 10, even at higher concentrations, but higher influence on pH> 11. The fluids containing carboxymethylcellulose were more sensitive to contamination, with rapid reduction in viscosity and significant increase of the filtrate volume, while the fluid based polymer sulfated kappa-carrageenan showed evidence of interaction with cations and preserve the rheological properties and improved stability the volume of filtrate.

Influência do tempo de adição do policarboxilato em pastas de cimento Portland para cimentação de poços petrolíferos

Cement pastes used in cementing oil wells operations are prepared according to the specific characteristics of each well. The physical properties requested for each folder formulation depend on the temperature and pressure of the well to be cemented. The rheological properties of the pulp are important control parameter for efficiency in transportation and positioning the folder during the cementing operation. One of the main types of additive used for the adjustment of rheological properties of cement pastes is the dispersant additive. This work aims to study the influence of variation of the time of addition of the polycarboxylate (0, 5, 10 and 15 minutes) in cement pastes, considering the initial periods of hydration of cement particles as fundamental point for better performance dispersant additive. Pastes were prepared with a density set at 15.6 lb/gal (1.87 g/cm3) and polycarboxylate concentrations ranging from 0.01 gpc to 0.05 gpc circulation temperature (BHCT) of 51°C and static temperature (BHST) of 76 C. The pastes were characterized from a rheological measurements, volume filtered, thickening time and resistance to compression formulations. Also were carried out tests Diffraction X-ray (XRD) and Scanning Electron Microscopy (MEV). The results showed that the addition of policaboxilato after 15 minutes decreased by 70% the values of rheological parameters. According to results of DRX and MEV, the addition of dispersant after 15 minutes did not affect the chemical reactions and subsequent formation of cement hydration products. A study of the economic feasibility to realize the financial benefits of the technique, which can be seen only with the use of the technique in this work to reduce the cost of production of cement paste was carried out, can get up to $ 1015.00 for each folder 100 barrels produced with said formulations.

Influência do tempo de adição do policarboxilato em pastas de cimento Portland para cimentação de poços petrolíferos

Cement pastes used in cementing oil wells operations are prepared according to the specific characteristics of each well. The physical properties requested for each folder formulation depend on the temperature and pressure of the well to be cemented. The rheological properties of the pulp are important control parameter for efficiency in transportation and positioning the folder during the cementing operation. One of the main types of additive used for the adjustment of rheological properties of cement pastes is the dispersant additive. This work aims to study the influence of variation of the time of addition of the polycarboxylate (0, 5, 10 and 15 minutes) in cement pastes, considering the initial periods of hydration of cement particles as fundamental point for better performance dispersant additive. Pastes were prepared with a density set at 15.6 lb/gal (1.87 g/cm3) and polycarboxylate concentrations ranging from 0.01 gpc to 0.05 gpc circulation temperature (BHCT) of 51°C and static temperature (BHST) of 76 C. The pastes were characterized from a rheological measurements, volume filtered, thickening time and resistance to compression formulations. Also were carried out tests Diffraction X-ray (XRD) and Scanning Electron Microscopy (MEV). The results showed that the addition of policaboxilato after 15 minutes decreased by 70% the values of rheological parameters. According to results of DRX and MEV, the addition of dispersant after 15 minutes did not affect the chemical reactions and subsequent formation of cement hydration products. A study of the economic feasibility to realize the financial benefits of the technique, which can be seen only with the use of the technique in this work to reduce the cost of production of cement paste was carried out, can get up to $ 1015.00 for each folder 100 barrels produced with said formulations.

Uma nova proposta de fluidos de perfuração aquosos à base de polímeros vinílicos e bentonita para poços de alta temperatura e pressão

The advance of drilling in deeper wells has required more thermostable materials. The use of synthetic fluids, which usually have a good chemical stability, faces the environmental constraints, besides it usually generate more discharge and require a costly disposal treatment of drilled cuttings, which are often not efficient and require mechanical components that hinder the operation. The adoption of aqueous fluids generally involves the use of chrome lignosulfonate, used as dispersant, which provides stability on rheological properties and fluid loss under high temperatures and pressures (HTHP). However, due to the environmental impact associated with the use of chrome compounds, the drilling industry needs alternatives that maintain the integrity of the property and ensure success of the operation in view of the strong influence of temperature on the viscosity of aqueous fluids and polymers used in these type fluids, often polysaccharides, passives of hydrolysis and biological degradation. Therefore, vinyl polymers were selected for this study because they have predominantly carbon chain and, in particular, polyvinylpyrrolidone (PVP) for resisting higher temperatures and partially hydrolyzed polyacrylamide (PHPA) and clay by increasing the system's viscosity. Moreover, the absence of acetal bonds reduces the sensitivity to attacks by bacteria. In order to develop an aqueous drilling fluid system for HTHP applications using PVP, HPAM and clay, as main constituents, fluid formulations were prepared and determined its rheological properties using rotary viscometer of the Fann, and volume filtrate obtained by filtration HTHP following the standard API 13B-2. The new fluid system using polyvinylpyrrolidone (PVP) with high molar weight had higher viscosities, gels and yield strength, due to the effect of flocculating clay. On the other hand, the low molecular weight PVP contributed to the formation of disperse systems with lower values in the rheological properties and fluid loss. Both systems are characterized by thermal stability gain up to around 120 ° C, keeping stable rheological parameters. The results were further corroborated through linear clay swelling tests.

Uma nova proposta de fluidos de perfuração aquosos à base de polímeros vinílicos e bentonita para poços de alta temperatura e pressão

The advance of drilling in deeper wells has required more thermostable materials. The use of synthetic fluids, which usually have a good chemical stability, faces the environmental constraints, besides it usually generate more discharge and require a costly disposal treatment of drilled cuttings, which are often not efficient and require mechanical components that hinder the operation. The adoption of aqueous fluids generally involves the use of chrome lignosulfonate, used as dispersant, which provides stability on rheological properties and fluid loss under high temperatures and pressures (HTHP). However, due to the environmental impact associated with the use of chrome compounds, the drilling industry needs alternatives that maintain the integrity of the property and ensure success of the operation in view of the strong influence of temperature on the viscosity of aqueous fluids and polymers used in these type fluids, often polysaccharides, passives of hydrolysis and biological degradation. Therefore, vinyl polymers were selected for this study because they have predominantly carbon chain and, in particular, polyvinylpyrrolidone (PVP) for resisting higher temperatures and partially hydrolyzed polyacrylamide (PHPA) and clay by increasing the system's viscosity. Moreover, the absence of acetal bonds reduces the sensitivity to attacks by bacteria. In order to develop an aqueous drilling fluid system for HTHP applications using PVP, HPAM and clay, as main constituents, fluid formulations were prepared and determined its rheological properties using rotary viscometer of the Fann, and volume filtrate obtained by filtration HTHP following the standard API 13B-2. The new fluid system using polyvinylpyrrolidone (PVP) with high molar weight had higher viscosities, gels and yield strength, due to the effect of flocculating clay. On the other hand, the low molecular weight PVP contributed to the formation of disperse systems with lower values in the rheological properties and fluid loss. Both systems are characterized by thermal stability gain up to around 120 ° C, keeping stable rheological parameters. The results were further corroborated through linear clay swelling tests.