"Heavy Oil Is Where You Find It” A Brazil DW Exploration Case History

Eskil Jersing
Shell International E&P Inc., 200 N. Dairy Ashford, Houston, TX 77079

This paper will illustrate the regional context for the presence of Heavy Oil in South East Brazil and the application of corroborative prediction toolsets to increase confidence in prospect risk assessment.

The Santos, Campos and Espirito Santo basins in South East Brazil have proven to be a prolific oil province with some 24Bboe of Hydrocarbons discovered to date. Some 13.5Bbo of this figure is attributed to the Heavier Oil (Referred to as <25 API for this paper) fraction, in c.64 discoveries. This DSFR (discovered scope for recovery) resource base is predominantly located in the inboard “hinge-line” HC expulsion corridor in the North East Santos and Campos Basins.

Multiple intervals within the Aptian-Barremian (Lagoa Feia fm) lacustrine/marine rift section provide the “workhorse” source for the post-salt marine section in which the majority of accumulations are trapped. The underlying Basement structure sets up the regional migration focus into the post-salt section through Aptian “salt windows”. Within the shallower Upper Cretaceous and Tertiary part of the section, numerous Heavy oil prone combination structural-stratigraphic traps exist in multiple play segments. The giant Roncador, Marlim and Albacora fields occur in areas of thin/absent salt and large drainage/fetch areas. In the main, these fields suffer from biodegradation as a result of complex reservoir paleo-temperature histories. A narrow present day hydrocarbon expulsion “sweet-spot” corridor provides the proxy for migration fairways to these shallow reservoirs. The relationship between structural style and hydrocarbon migration influences play/lead materiality and ultimate basin scope.

Shell Brazil has used Electro-Magnetic Sea Bed Logging, Integrated Charge evaluation and DRHI (Direct Reservoir Hydrocarbon Indicators) technology driven toolsets to help reduce pre-drill prospect risk assessments. An example will be shown to this effect, which significantly helped polarize a major business decision.

AAPG Search and Discovery Article #90062©2006 AAPG Hedberg Research Conference, Veracruz, Mexico