Estratigrafia mecânica aplicada às rochas carbonáticas da Formação Irati (Permiano) na região do alto estrutural de Pitanga - SP, Bacia do Paraná

• Autor(a) principal: Cerri, Rodrigo Irineu [UNESP]
• Data de Publicação: 2015
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/143992; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2016-08-18/000868791.pdf
• topic: Geologia estratigráfica; Hidrocarbonetos; Rochas carbonaticas; Paraná, Bacia

This work present data on the distribution of fractures in rocks from the Assitência Member (Irati Formation). The study was carried out in quarries near Rio Claro, Saltinho and Ipeúna. The Assistência member is characterised be the occurrence of a 2 - 3 meters thick layer of dolomitic carbonate at the base, overlaid by a sequence of alternating layers (15-30 cm) of black shale and carbonate. The aim is to characterise the distribution and formation of fractures, taking into account relationship between fracture development and the relative proportion of incompetent (shale) to competent (carbonate) strata within the vertical section. Results show that only major fractures extrapolate the mechanical boundaries presented by shale layers. Mechanical units have a significant influence on the vertical fracture terminations and the overriding control on fracture height is the presence of the laterally continuous shales. In two of the studied areas (quarries near Rio Claro and Saltinho), about 80% of the fracture heights terminate at the mechanical boundaries. In these areas, fractures that extrapolate the mechanical boundaries have NW-SE direction, the same orientation of importante faulting systems that occur in the area (Passa Cinco - Cabeças and Ipeúna - Piracicaba falting systems). Interestingly, most of these fracture planes are impregnated with oil. On exception is the the fracturing pattern observed in a quarry near Ipeúna, where all fratures terminate at the first mechanical boundary above the mais carbonate layer (30-40 cm thick shale). But, remarkably, some fractures with NE-SW direction that occur within the main carbonate layer are filled with a significant amount of high density oil. Furthermore, breccias occur along these structures and oil is present within the clasts. It is worth mentioning that NE-SW faults are described for this area. This is an interesting field analogue of a fractured carbonate reservoir...