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.

Espirito de catimbo: a moral magico-religiosa da jurema

This participative research interested in the social praxis attempts to understand the moral principles that set the magic rituals and the places of worship of three jurema centers of the potiguar region of Canguaretama. Among other inner particularly aspects of each focused catimbó-jurema center, it is being discussed the collective standards involved in the reliance and fellowship values assumed in the private magical gatherings by the juremeiras leaders and their partners, in contrast to the prestige seeking and the individualism that influence both the symbolic competitions and the witchcraft works that link these agents to the broader catimbozeiro universe of this region. Finally, the moral practices which make part of the juremeiro left-right dualism are investigated based on the understanding that the referred native pantheonic-ritual dichotomy does not necessarily express two moralities substantially adversed in terms of benefits or harms, but a series of moral actions subject to the specular logic of the tit-for tat. Thus, this research seeks to prove that this moral structure of symbolic reciprocity, as well as the witchcraft centrality in the catimbozeiro world, finds a certain causal link in a world view which guiding principle is the ontological evil of the catholic cosmology

Obtenção e caracterização de nanopartículas de argilominerais

Natural nanoclays are of great interest particularly for the production of polymer-based nanocomposites. In this work, kaolinite clays from two natural deposits in the State of the Rio Grande do Norte and Paraiba were purified with thermal treatment and chemical treatments, and characterized. Front to the gotten data, had been proposals methodologies for elimination or reduction of coarse particle texts, oxide of iron and organic substance. These methodologies had consisted of the combination of operations with thermal treatments, carried through in electric oven, and acid chemical attacks with and hydrogen peroxide. The Analyzers Thermogravimetric was used to examine the thermal stability of the nanoclays. The analysis indicated weight losses at temperatures under 110 ºC and over the temperature range of 350 to 550 ºC. Based on the thermal analysis data, the samples were submitted to a thermal treatment at 500 °C, for 8 h, to remove organic components. The X-ray diffraction patterns indicated that thermal treatment under 500 °C affect the basic structure of kaolinite. The BET surface area measurements ranged from 32 to 38 m2/g for clay samples with thermal treatment and from 36 to 53 m2/g for chemically treated samples. Thus, although the thermal treatment increased the surface area, through the removal of organic components, the effect was not significant and chemical treatment is more efficient, not affect the basic structure of kaolinite, to improve particle dispersion. SEM analysis confirms that the clay is agglomerated forming micron-size particles