--> New Pre-Salt Exploration Opportunities in the Deepwater of the Campos Basin, Brazil

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New Pre-Salt Exploration Opportunities in the Deepwater of the Campos Basin, Brazil

Abstract

This work considers the hydrocarbon exploration potential of the pre-salt in outboard central-south Campos Basin, immediately to the east of major producing fields and discoveries. The opportunities have resulted from a preliminary seismic interpretation of the informally named BC-200 merged-survey composed of reprocessed 3D non-proprietary PreSDM seismic surveys. Most of the area is open acreage, in deep to ultra-deepwaters (>2000 meters) and could be offered in future pre-salt bid-rounds by ANP, the Brazilian E&P Regulatory Agency. Several wells, targeting post-salt reservoirs, were drilled in the area without any commercial gas or oil discoveries being made. Recently, following notable pre-salt discoveries in the Santos and Campos basins, exploration efforts have been successfully shifted to the rift/sag sequences beneath the salt, often below existing producing fields as well as in new exploration areas (e.g. BMC-33 block). Detailed investigation and mapping of the pre-salt in the BC-200 allowed the delineation of several pre-salt plays: i) Structural Play in coquinas (Late Rift to Sag); ii) Stratigraphic/Combination Play in coquinas (Late Rift to Sag); iii) Microbial Build-up Play on rift shoulders (Sag microbialites) and; iv) Microbial Build-up Play on volcanic complexes (potentially large limestone units beneath the salt nucleated on top of large volcanic complexes in distal settings). The hydrocarbons for these opportunities are considered to have been from the same source-rock interval (the lacustrine Lagoa Feia Formation) that has sourced most of the oil and gas of the discovered fields in the Campos Basin. Coquinas are the reservoir targets to the west while potential limestone microbial build-up's, similar to the ones in the Santos Basin, could constitute impressive targets in the east and northeast of the survey area as indicated by the seismic facies and observed geometries. A thick evaporitic succession provides the main sealing unit for the potential accumulations. The Coquinas Structural Play offers low exploration risk scenarios, while potential build-up's over the tops of volcanic complexes have high risk due to reservoir presence/quality and migration. However, this last play could provide the largest exploration rewards as some of these positive features that lie just beneath the salt have hundreds of square kilometers of closure, offering potential for multi-billion barrels of hydrocarbon discoveries.