Desenvolvimento de sistemas de pastas leves para aplicação em cimentação de poços petrolíferos com baixo gradiente de fratura

All around the world, naturally occurring hydrocarbon deposits, consisting of oil and gas contained within rocks called reservoir rocks , generally sandstone or carbonate exists. These deposits are in varying conditions of pressure and depth from a few hundred to several thousand meters. In general, shallow reservoirs have greater tendency to fracture, since they have low fracture gradient, ie fractures are formed even with relatively low hydrostatic columns of fluid. These low fracture gradient areas are particularly common in onshore areas, like the Rio Grande do Norte basin. During a well drilling, one of the most favorable phases for the occurrence of fractures is during cementing, since the cement slurry used can have greater densities than the maximum allowed by the rock structure. Furthermore, in areas which are already naturally fractured, the use of regular cement slurries causes fluid loss into the formation, which may give rise to failures cementations and formation damages. Commercially, there are alternatives to the development of lightweight cement slurries, but these fail either because of their enormous cost, or because the cement properties were not good enough for most general applications, being restricted to each transaction for which the cement paste was made, or both reasons. In this work a statistical design was made to determine the influence of three variables, defined as the calcium chloride concentration, vermiculite concentration and nanosilica concentration in the various properties of the cement. The use of vermiculite, a low density ore present in large amounts in northeastern Brazil, as extensor for cementing slurries, enabled the production of stable cements, with high water/cement ratio, excellent rheological properties and low densities, which were set at 12.5 lb / gal, despite the fact that lower densities could be achieved. It is also seen that the calcium chloride is very useful as gelling and thickening agent, and their use in combination with nanosilica has a great effect on gel strength of the cement. Hydrothermal Stability studies showed that the pastes were stable in these conditions, and mechanical resistance tests showed values of the order of up to 10 MPa

Motivações para adoção: uma perspectiva da Psicologia Evolucionista

Parental investment increases the offspring s survival, though it decreases the opportunities for the parents to invest in a future progeny. In a broad sense, this investment is directed to one s own descendant, but in some cases, such as in adoption, resources are directed to non-relatives even in the absence of fitness benefits. Once there are many factors involved in adoption, this study investigated adopters candidates, aiming to analyze aspects considered by them for adopting, based on the Evolutionary Psychology s perspective. We analyzed the judicial proceedings´ files people who had been inlisted for adoption at the 2ª Childhood and Adolescence Law Court, Natal-RN. The adopter s motivations were classified into biological or social reasons. A relationship between adopters´ age and kind of motivation was found: requirements of young people were related to biological reasons while requirements of the old ones were related to social reasons. Fertility, mainly female requirer´s fertility, underlie this relationship, considering that women fertility is strongly influenced by age. The reasons to adopt were also related to the age of the desired child, once that people who wanted children older than 25 months alleged social reasons while those that wanted younger babies alleged biological reasons. There are lots of motives to adopt a child, but the phenomenon of adoption is broadly acknowledged by society as an act of love and the adoptive parents are often regarded as kind and generous people. It was observed, instead, that the reasons to adopt comes from the adopters themselves, related to the fulfillment of personal needs, such as increasing the family, carrying out mother/father role or having a company or someone to care form them in elderly age

Participação social e designação de espécie-bandeira: ações complementares à conservação de um parque estadual em área urbana

Facing environmental problems the planet appears several alternative preventive and control on behalf of the equation between development and environmental protection. One of the alternatives implemented in Brazil to conservation of biodiversity was the creation of protected natural areas regulated by the National System of Conservation Units (SNUC). This is an integrated study of the Comunication / Environmental Conservation, which prioritizes social participation as a complementary in the conservation process, the particular case of the Dunas do Natal State Park, the first conservation area in Rio Grande do Norte, for full protection. It takes into account the roles environmental, scientific and Park, which harbors a unique biodiversity, including endemic species and the fact being located in an urban area. It proposes the use of two complementary instruments, such as strategies for conservation. Considering the various individual experiences, it was analyzed the perception that the community is directly related to the Park. From this promoted the democratization of information about the park, its biodiversity and conservation. As another conservation tool, it was suggested the use of a flagship species for the park, or a body chosen symbol for environmental or social reasons, in order to protect and conserve certain natural environments, from the understanding and co -community participation. In this case, as proposed flag Coleodactylus natalensis species, the lizard-the-litter, to be endemic remnants of Atlantic Forest Park as having the type locality, be one of the smallest species of the world, South America's lowest-dependent shadow of the forest, sensitive to human action and therefore very vulnerable. This suggestion finds support in the degree of public acceptance that interacts directly with the Park, as a result of the evaluation of their perceptions. It was further observed in this study that this symbology to be used in order to promote the democratization of the Park and its biodiversity has an identification result, curiosity and probable involvement of the population with the issues of the Park