Overview of Shale Prospects in Brazilian Onshore Basins

Pereira, Egberto¹; Bergamaschi, Sérgio; Chaves, Hernani A.; and Rodrigues, René
¹[email protected]

Brazil has been considered as one of the most important countries in terms of oil shale and shale gas resources. Most of these resources are related to Devonian, Permian, Cretaceous and Tertiary black shales. Despite having been exploratory target by nearly a century, the Brazilian Paleozoic basins remain as exploratory frontiers. On the other hand, the Cretaceous black shale sections of Parnaiacute;ba and Araripe basins and the Tertiary black shale sections of Taubaté basin was not well studied in relation to the exploratory point of view. Concerning to TOC content, the Devonian section record two intervals of interest: one comprising Late Pragian / Early Emsian and other, Late Givetian / Early Frasnian. The later one (Late Givetian / Early Frasnian) is richest in organic matter concentration. However, the conditions for oil and gas generation for these basins are closely related to the specific evolutionary model of each basin, which are very variable by region and in the time. In Permian, the high TOC content intervals are restricted to Paraná Basin, consisting in organic rich black shale (TOC > 15%). The variable burial conditions that took place in the Paleozoic basins during its evolution, including the thermal effect of igneous intrusion, suggest a large range of exploratory prospect, such as: oil shale, tar sands, tight sands and shale gas. The most promising interval of meso-cenozoic basins is the bituminous shale from Taubaté Basin, which comprise a section of about 17 meters thick. The calculated oil volume from this shale interval is about 25 million barrels per km². In this way, the main goal of the this paper is propose a high-resolution stratigraphy of some selected intervals of these sections using geochemistry and isotopic proxies to identify the most attractive interval to looking for shale oil / oil shale and shale gas.

AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013