Recôncavo Basin: current status

Abstract

Convering an area of over 10 000 km², the Recôncavo Basin is composed of a NE-SW-trending half graben, whose sedimentary dips SE. The genesis of this rift is related to the NW-SE-trending extensional stress field which acted in Gondwana during the Mesozoic. Basin sedimentation can be sub-divided into two major sequences: pre-rift and rift. The former constitutes a record of subaerial sedimentation that was progressively drowned and that culminated in lacustrine sedimentation (the Aliança, Sergi, and Itaparica fms. and the Tauá Member of the Candeias Formation). Initiating with deposits of interbedded shales and limestones (Candeias Formation) associated with turbidite deposits, the rift sequence later evolved lo deltaic sedimentation (Ilhas Group), ending with fluvial sedimentation (São Sebastião Formation). Hydrocarbon accumulations are distributed along the entire sedimentary column, in fifteen producing plays. Proved volume for the basin stands ai 680 million m³ of oil and 30 billion m³ of non-associated gas. In spite of the advanced stage of exploration of the Recôncavo Basin, some areas have not yet been sufficiently prospected. Present efforts are aimed ai improving seismic quality and ai locating subtle mixed, and stratigraphic traps over a large part of the basin.