Robert E Fryklund1, William G Dickson2, Mark E Odegard3
(1) Phillips Petroleum Do Brasil, Ltda, Rio de Janeiro, Brazil
(2) DIGs, Stafford, TX
(3) GETECH Inc, Stafford, TX
ABSTRACT: Lagoa Feia of Brasil's Campos Basin: Observations on Source Potential and Quality
Oils discovered in Brasil's super-giant Campos Basin have been generated from one source interval, the Upper Barremian to Lower Neocomian Lagoa Feia Formation. Three key elements of the Lagoa Feia Petroleum System (LFPS) are: distribution of source pods or depositional areas; source rock maturity; and hydrocarbon migration history. The distribution of Lagoa Feia source pods was published by Dias, 1988 and Mello, 1994, based largely on well penetrations. Using gravity, magnetics, new depth-to-basement maps and 2D seismic, we have taken strides towards a better understanding of these elements.
Initially, we extensively revised the source pod mapping for the Greater Campos Basin. The main source basin is about 1300 km long by 150 - 340 km wide, containing eight sub-basins with the inferred thickest and richest accumulations including pods in deepwater Campos and two large areas in southern Santos.
Maturity mapping of the pods requires getting a good handle on heat flow including the definition of crustal type. A heat flow map has been constucted for the Greater Campos Basin and several anomalies are illustrated.
Migration history is equally important for the LFPS. Quick-look analyses from cross-plots of depth below mudline vs API gravity suggest rules to help assess the risk of encountering low vs high mobility oil. Oils in Oligo-miocene reservoirs with above 1200 m of overburden should have gravities at or above 20 API; as should oils in Eocene reservoirs exceeding 1800 m of overburden and Upper Cretaceous reservoirs with 2600 m.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado