Análise microfaciológica e qualitativa dos folhelhos do Membro Jaguariaíva, Formação Ponta Grossa, Bacia do Paraná

Abstract

The researches made in Paraná Basin looking for the gas potential generator of low Devonian rock formations match with a new study boundaries. The investigation for a successful exploration of shale plays needs of the knowledge about gas amount available to be extracted and its associated cost. However, the TOC content, the description of petrographic fabric and clay minerals should be considered in order to connect the sealant, generator and reservoir quality of the microclastic rock. The studies were carried out in two wells located on Apucarana subbasin (PALEOSUL 03-JA-PR) and the Alto Garças subbasin. Five microfacies were recognized based on mineralogy, grain size and fossiliferous contents. Microstructures were analyzed to define the characteristics of generators rocks of the possible Ponta Grossa-Ponta Grossa petroleum system. These microstructures occur preferably on the well PALEOSUL 03-JA-PR and are represented by erosive features related to trative flow, reflecting the alternation of decantation and trative process. The smallest numbers of microstructures on well PALEOSUL 02-RV-MS are associated with biogenic activity. The mineralogical composition of shales analyzed by X-Ray diffractometry shows illite and kaolinite in all samples while interlayered of illite-smectite and chlorite-smectite were indentified just on Apucarana subbasin. The vermiculite is common in shale of Alto Garças subbasin. Quartz, muscovite, feldspars and siderite are present on samples of two subbasins and point to a proximal continental source. Scanning electron microscope (SEM) analyses confirm the petrographic and X-Ray diffractometry results. The data of the wells studied in this thesis indicate contrasting diagenetic parameters and thermal history for the two subbasins and a consequent influence on sedimentation conditions. The samples are classified as argillites, clay siltstones and sandy siltstones with poor perspectives to work like a sealant rock. On the other hand, there is a possibility of these shales behave as a non-conventional reservoirs.