AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Stratigraphic Architecture, Distribution, and Quality of Pre-salt Lacustrine Source Rocks of the Greater Campos Basin, Offshore Brazil
(1) E&P Technology, Hess Corporation, Houston, TX.
(2) Production, Hess Corporation, Houston, TX.
(3) Exploration, Hess Corporation, Houston, TX.
A regional sequence stratigraphic framework has been developed using well log data to define the stratigraphic architecture and distribution of pre-salt lacustrine source rocks in the Greater Campos basin, offshore Brazil. This framework is used as a context for characterizing the organic richness, thickness, and ultimate expellable potential of the lacustrine source rocks. The basis for the stratigraphic framework is the identification and correlation of four major unconformities that partition the pre-salt section into Upper Sag (Alagoas), Transitional/Lower Sag (Jiquia), and Synrift (Buracica/Aratu) successions. Within these successions, multiple sequences are recognized and source rocks are associated with the maximum flooding surface (mfs) intervals of the individual sequences.
The lacustrine source rocks have been characterized using geochemical analyses (TOC and Rock-Eval), well-log based DLogR analysis, and core/cuttings descriptions. These data indicate the presence of source rocks of variable organic richness and thickness in all the successions. The best development of thick, rich, source rocks is associated with the mfs intervals of the Jiquia sequences. Sequences within the Alagoas and Buracica/Aratu successions contain the least development of source rock intervals. The lateral distribution of all the source rocks is complicated by stratal discontinuities such as onlap and truncation.
In this study, the sequence stratigraphic and geochemical characterization of source rocks derived from pre-salt wells in the Campos basin is subsequently applied to the Santos basin. This integrated approach forms the basis for regional basin modeling efforts to understand the volumetric contributions of lacustrine source rocks to the recent giant pre-salt discoveries of offshore Brazil.