Programa de Pós-Graduação em Geofísica - CPGF/IG
URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2355
O Programa de Pós-Graduação em Geofísica da UFPA (CPGF) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA). Foi o segundo no Brasil a formar recursos humanos em Geofísica em nível de pós-graduação stricto sensu. Criado em 1972, funcionou até 1992 junto com os Cursos de Pós-Graduação em Geoquímica e Geologia.
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Item Acesso aberto (Open Access) Aplicação de modelos de substituição de fluido em rochas sedimentares oriundas do nordeste brasileiro(Universidade Federal do Pará, 2015-06-06) TROVÃO, Ana Alzira Fayal; FIGUEIREDO, José Jadsom Sampaio de; http://lattes.cnpq.br/1610827269025210Carbonates reservoirs corresponds on about 50% of the hydrocarbon reservoir in the planet . This type of lithology presents different forms of heterogeneity, which are the main causes of errors in its characterization. This misunderstanding, can induces erroneous estimative elastic modules of rocks in saturated state. The main goal of this work is to perform a comparative analysis of fluid substitution models in unconventional carbonate reservoir. Specifically, fluid substitution processes analyzed in outcrops from Brazilian Northeast, under controlled laboratory conditions (temperature, pressure and degree of saturation) and under perspectives of the petrophysical and ultrasonic features by conventional theories (Gassmann, Biot) and unconventional (Brown and Korringa, Muller and Sahay). In this research, we analyzed six samples of carbonate rock and one sample of sandstone rock. The input data our analysis were: permeability, porosity, rock and grain density, elastic measures of compressional (Vp) and shear (Vs1 and Vs2) velocities. The measure of velocities was performed in cases of 100% gas (dry rock) and then replaced by water (100 % saturated by water). Our results show, that predictions performed by conventional fluid substitution models best fit in experimental measurements of sample considered homogenous. However, predictions performed by unconventional models (e. g., Muller and Sahay) shown best fit with most carbonates types, including tufa and limestanes.Item Acesso aberto (Open Access) Experimental verification of Hudson and Eshelby-Chen’s effective crack theory(Universidade Federal do Pará, 2015-12-04) HENRIQUES, Jéssica Pena; FIGUEIREDO, José Jadsom Sampaio de; http://lattes.cnpq.br/1610827269025210Physical modeling of cracked / fractured media in downscaled laboratory experiments has served as a great alternative for understanding the anisotropic media behavior. In this work, it was performed ultrasonic measurements on samples with low crack densities and different aspect ratios. The main goal was to investigate the experimental behavior of elastic parameters, such as: waves velocities and Thomsen parameters ε and 𝛾 and elastic stiffness coefficients for transverse isotropic media. Comparison of the results with the predictions made by the effective models of Hudson (1981) and Eshelby-Cheng (1993), it was also investigated in this work. Twelve samples were prepared with two types of cracks density, 5 and 8%. The cracks that have three different aspect ratios (0.133, 0.1778 and 0.2667) were formed by rubber inclusions in a homogeneous isotropic matrix resin. Moreover, an isotropic matrix sample was constructed by only epoxy resin. Among all samples, six (three for each density) have only one aspect ratio type (samples with single crack), while another six (three for each density) have three types of different aspect ratio (mixed samples). Among the predictions of the models, the Eshelby-Cheng (1993) shows a better fit in relation to the experimental results for samples with single crack (for the two densities of inclusions). However, none of the models predicts accurately with minimal tendency for the mixed samples.Item Acesso aberto (Open Access) Verificação experimental do modelo efetivo de Hudson-Crampin para meios anisotrópicos fissurados cujo o meio de fundo apresenta isotropia transversal(Universidade Federal do Pará, 2017-03-17) CHIBA, Bruce Fabini Franco; FIGUEIREDO, José Jadsom Sampaio de; http://lattes.cnpq.br/1610827269025210The physical modeling of cracked media, using scaled laboratory experiments, has been used as an alternative for understanding the effect of anisotropy on the characterization of the cracked hydrocarbon reservoir. The main objective of this work was to verify experimentally the predictions of Hudson-Crampin’s effective model to cracked media. For this purpose, ultrasonic and petrophysical measurements were performed on sixteen synthetic anisotropic samples with different crack densities distributed in four groups with distincts aspect ratios (0.08, 0.20, 0.32 and 0.52). Beside theses, one sample no cracks and weak VTI ansisotropy were used as reference sample. The cracks were simulated by void spaces in the form of discs in an matrix (made with sand and cement). Related to the estimatives of velocity performed by the theoretical models, Hudson-Crampin’s model presents a better adjustment for VP and VS propagating perpendicular to the plane of cracks for the dry and saturated conditions. These estimatives became more evident in the case where the crack density and aspect ratios are low. In addition to the velocity values, our comparison was also performed in terms of Thomsen’s parameters ε, γ and δ.