| Based on systematic analysis of tectonic evolution and petroleum geology characteristics of deep water basins in the eastern part of Brazil, it is shown that these basins developed in passive continental margin mainly have gone through four evolution stages, i.e., the pre-rifting, the syn-rifting, the restricted-sea transitional and the post-rifting stages. Due to influences of regional tectonic stress fields, salt beds and volcanism, different one in the basin group plays its own basinal structures and tectonic style, and the salt beds play a pivotal role in hydrocarbon accumulation. Three sets of source rocks, three sets of reservoir and three sets of regional cap rocks develop respectively in all of marginal basins and thus three types of hydrocarbon reservoirs are comprised： (1) pre-salt rifting structural reservoirs, (2) post-salt or pre-salt carbonate reservoirs and (3) post-salt turbidite structural-stratigraphic reservoirs. On the basis of the analysis of hydrocarbon accumulation regularity and taking account of exploration practice in every basin, these deep water marginal basins can be divided into three grades of exploration potential, the good (GradeⅠ), the common (GradeⅡ) and the poor (Grade Ⅲ) one. It is suggested that the GradesⅠ andⅡ of potential areas should be prospective. |
