Abstract

Glacial deposits have recently been attracting the attention of petroleum geologists. Oman has about 3.5 billion bbl of oil in place in Carboniferous Gondwanan glacial sandstones; Bolivia produces about 10 MMbbl (oil and gas) annually, approximately 70% comes from Carboniferous glacial deposits: Australia has 22 gas fields in glacial Early Permian reservoirs.

The Paraná Basin in Brazil has the largest Gondwanan Carboniferous-Permian deposits, covering more than 700000 km2. To date the Itararé Group has had several gas finds and some subcommercial gas production. Currently, Petrobrás, the Brazilian oil company, is putting a great deal of effort, mostly seismic surveys and some drilling, in an attempt to find commercial hydrocarbons in the Paraná Basin. Being an important target in this exploratory process the Itararé Group deserves detailed study aiming at sand body geometry (reservoir-rocks), diamictite distribution (seal-rocks) and their trapping mechanisms. The main purpose of this paper is to present an overview of the stratigraphy and hydrocarbon potential of the Itararé Group based upon well logs, core description, and outcrop information.

The Itararé Group is subdivided into three main formations: Lagoa Azul, Campo Mourāo, and Taciba. A red bed unit, called the Aquidauana Formation, predominates in the northern realm of the Paraná Basin.

Introduction

The Paraná Basin is located in southern Brazil with extensions into Argentina, Paraguay, and Uruguay. In Brazil alone it covers an area of approximately 1000000 km2 (Fig. 5.1).

The Itararé Group is probably the most continuous and thickest temperate glacial-marine sequence in South American Gondwana. It covers an area larger than 700000 km2 and it is thicker than 1300 m in the central part of the Paraná Basin (Fig. 5.2).