Novo método para estimativa do gradiente de fratura para poços de petróleo

The development of oil wells drilling requires additional cares mainly if the drilling is in offshore ultra deep water with low overburden pressure gradients which cause low fracture gradients and, consequently, difficult the well drilling by the reduction of the operational window. To minimize, in the well planning phases, the difficulties faced by the drilling in those sceneries, indirect models are used to estimate fracture gradient that foresees approximate values for leakoff tests. These models generate curves of geopressures that allow detailed analysis of the pressure behavior for the whole well. Most of these models are based on the Terzaghi equation, just differentiating in the determination of the values of rock tension coefficient. This work proposes an alternative method for prediction of fracture pressure gradient based on a geometric correlation that relates the pressure gradients proportionally for a given depth and extrapolates it for the whole well depth, meaning that theses parameters vary in a fixed proportion. The model is based on the application of analytical proportion segments corresponding to the differential pressure related to the rock tension. The study shows that the proposed analytical proportion segments reaches values of fracture gradient with good agreement with those available for leakoff tests in the field area. The obtained results were compared with twelve different indirect models for fracture pressure gradient prediction based on the compacting effect. For this, a software was developed using Matlab language. The comparison was also made varying the water depth from zero (onshore wellbores) to 1500 meters. The leakoff tests are also used to compare the different methods including the one proposed in this work. The presented work gives good results for error analysis compared to other methods and, due to its simplicity, justify its possible application

Um Estudo de Politicas e Práticas do uso do GNV no transporte público urbano do Brasil

The use of Natural Gas Vehicle has had a fast increase lately. However, in order to have a continuous success this Program needs to develop converting devices of Otto-cycle engines, gasoline or alcohol, to the use of NGV (Natural Gas Vehicle) that presents low cost, maintaining the same original development of the vehicle and low level of emissions, considering the PROCONVE rules. Due to the need to diversify the matrix in order to avoid energetic dependence and due to strict pollution control, it has increased in the Brazilian market the number of vehicles converted to the use of NGV. The recent regulation of the PROCONVE, determining that the converted engines with kits should be submitted to emission testing, comes to reinforce the necessity of the proposed development. Therefore, if we can obtain kits with the characteristics already described, we can reach a major trust in the market and obtain an increase acceptance of the vehicle conversion for NGV. The use of natural gas as vehicle fuel presents several advantages in relation to liquid fuels. It is a vehicle fuel with fewer indexes of emissions when compared to diesel; their combustion gases are less harmful, with a major level of safety than liquid fuels and the market price is quite competitive. The preoccupation that emerges, and the motivation of this project, is to know which are the main justifications for such technology, well accepted in other countries, with a low index or emission, with a high level of safety, where its maintenance becomes low, reminding that for this it is necessary that this technology has to be used properly, and once available in the market will not motivate interest in the urban transportation companies in Brazil, in research centers in general. Therefore this project exists to show the society in a general way the current vision of the main governmental factors, of the national research centers and of the private companies concerning the use of natural gas vehicles in urban transport vehicles, in order to give a major reliability to the population as well as to motivate national market competitiveness with a low cost and reliable product and to enrich the national technology

Desempenho de um veículo flex em bancada dinamométrica de chassi

Flex-fuel vehicles are equipped with Otto Cycle internal combustion engines and have the capability of functioning with more than one type of fuel, mixed at the same tank and burned in the combustion chamber simultaneously. This sort of motorization is a world pattern due to the scarcity of petroleum, the trade of several types of fuels, technology advances and the restriction imposed to gas emissions to the atmosphere. In Brazil, the Flexfuel vehicles are a reality, specially the ones using fuel with 20 to 25% anhydrous alcohol mixed with gasoline and those that use natural gas or original liquid fuel (gasoline or hydrated ethanol). The Brazilian model Fiat Siena, the object of this present scientific investigation, is equipped with a unique electronic central capable of managing the liquid or gaseous fuels. The purpose of this research was to perform a comparative analysis in terms of performance (in terms of both potency and consumption) of a tetra-fuel vehicle - using a chassis dynamometer, operating with different fuels: common gasoline, premium gasoline, Podium gasoline, ethanol or natural gas. It became necessary to develop a bench of tests and trials procedures, as well as to know the functioning of the electronic management of the vehicle under analysis. The experiments were performed at the automotive laboratory in CTGAS-ER (Center of Gas Technologies and Renewable energies) at the light of Brazilian standard ABNT, NBR 7024: Light on-road vehicles - measurement of fuel consumption. The essay results on specific fuel consumption using common gasoline, premium gasoline and Podium gasoline have shown similar results, both for urban and road driving cycles

Fresamento com ar quente: uma proposta para minimizar a formação de trincas térmicas em ferramentas de metal duro

This work presents the results, analyses and conclusions about a study carried out with objective of minimizing the thermal cracks formation on cemented carbide inserts during face milling. The main focus of investigation was based on the observation that milling process is an interrupted machining process, which imposes cyclic thermal loads to the cutting tool, causing frequent stresses changes in its superficial and sub-superficial layers. These characteristics cause the formation of perpendicular cracks from cutting edge which aid the cutting tool wear, reducing its life. Several works on this subject emphasizing the thermal cyclic behavior imposed by the milling process as the main responsible for thermal cracks formation have been published. In these cases, the phenomenon appears as a consequence of the difference in temperature experienced by the cutting tool with each rotation of the cutter, usually defined as the difference between the temperatures in the cutting tool wedge at the end of the cutting and idle periods (T factor). Thus, a technique to minimize this cyclic behavior with objective of transforming the milling in an almost-continuous process in terms of temperature was proposed. In this case, a hot air stream was applied into the idle period, during the machining process. This procedure aimed to minimize the T factor. This technique was applied using three values of temperature from the hot air stream (100, 350 e 580 oC) with no cutting fluid (dry condition) and with cutting fluid mist (wet condition) using the hot air stream at 580oC. Besides, trials at room temperature were carried out. Afterwards the inserts were analyzed using a scanning electron microscope, where the quantity of thermal cracks generated in each condition, the wear and others damages was analyzed. In a general way, it was found that the heating of the idle period was positive for reducing the number of thermal cracks during face milling with cemented carbide inserts. Further, the cutting fluid mist application was effective in reducing the wear of the cutting tools.

Remoção de hidrocarbonetos do gás natural visando o ajuste do índice de metano

The use of the natural gas is growing year after year in the whole world and also in Brazil. It is verified that in the last five years the profile of natural gas consumption reached a great advance and investments had been carried through in this area. In the oil industry, the use of the natural gas for fuel in the drive of engines is usual for a long date. It is also used to put into motion equipment, or still, to generate electric power. Such engines are based on the motor cycle of combustion Otto, who requires a natural gas with well definite specification, conferring characteristic anti-detonating necessary to the equipment performance for projects based on this cycle. In this work, process routes and thermodynamic conditions had been selected and evaluated. Based on simulation assays carried out in commercial simulators the content of the methane index of the effluent gas were evaluated at various ranges of pressure, temperature, flowrate, molecular weight and chemical nature and composition of the absorbent. As final result, it was established a route based on process efficiency, optimized consumption of energy and absorbent. Thereby, it serves as base for the compact equipment conception to be used in locu into the industry for the removal of hydrocarbon from the natural gas produced

Pressupostos ontológicos para se pensar a nova tecnologia: técnica, informação e ser e tempo

La recherche presentée, realisée sur le domaine de la méthaphysique, s´agit de rassembler des pressupositions pour une fondamentation ontologique de la technologie de l´Information, basé sur la philophie de Martin Heidegger; foncièrement, sur l´analytique existentiel du Dasein dans l´ouvrage Être et Temps. À partir de la pensée sur ce qui est aujourd´hui , il s´agit d´investiguer sur quels fondaments la Nouvelle Tecnologie se fut érigée de façon a que nous sommes engajés au projet de numérisation des étants que en même temps que destine l´homme a l´oubli de l´Être, l´offre la possibilité de transformation. Le rapport entre la question de l´Être et la question de la technique est analysé comme des chemins croisés et dans ce carrefour il devient possible penser ce qui est technique, ce qui est information pour Heidegger et de quel façon les modes existentiels du Dasein sont prêtes pour caractériser l ´homme au sein de la tecnologie de l´information. Par cette appropriation, il reste penser comment c´est possible l´ouverture d´une perspective de reconduction de l´homme à la vérité de l´Être. Finalement, la structuration des fondements rends possible la réflexion discursive général: avec qui nous nous ocuppons, comme nous sommes, dans quelle direction nous nous acheminons, les thèmes générales, respectivement, des trois chapitres. Les points d´investigation du premier chapitre son: a) La caractérisation précise du Dasein, appuyé sur des considerations de Benedito Nunes, Hans-Georg Gadamer, Jacques Derrida et Rüdiger Safränski; b) Le concept de technique et son essence chez Heidegger; c) la distinction entre technique et technologie, appuyé sur le pensée de J. Ellul, Michel Séris, Otto Pöggeler, Michel Haar, Dominique Janicaud; c) Le concept de cibernetique chez Heidegger et chez Norbert Wiener; d) La caractérisation preliminaire d´information, l´analyse étimologique e philosophique, l´avis de Heidegger te les théories de Rafael Capurro; f) L´Analyse du phénomène de la numérisation des étants, des considérations de Virilio, et l´analyse d´un concept de virtuel avec Henri Bergson et Gilles Deleuze. Dans le deuxième chapitre, l´analyse des existentiels du Dasein vers le sommaire des fondements de base pour la caractérisation de la technologie de l´information comme un problème philosophique. Finalement, aprés avoir presenté les concepts introdutoires que délimitent le questionement, suivi par les indications et pressupositions ontologiques trouvés sur Être et Temps, le troisième chapitre disserte sur le péril, ce qui sauve et la sérénité, les trois mots-clés de la pensée heideggerienne sur la technique que permettent l´approche conclusif de la question