Print this pageRift Heat Flow Evolution of the Santos Basin
Hydrocarbon maturation expressed in terms of vitrinite reflectance, Tmax and biomarkers are not consistently correlated to each other, therefore they indicate different maximum palaeo-temperature of the reservoirs and depth to the source rocks. Very often, the estimated thermal results, calibrated with borehole temperature and vitrinite reflectance data, display broad uncertainties that indicate either a high or low average paleo heat flow regimes. This apparent contradiction has been difficult to explain in terms of heat flow history. High gravity anomalies interpreted as part of an aborted sea-floor spreading center could explain such discrepancies in the Santos Basin. Such interpretation is consistent with observed geophysical patterns but thermal anomalies do not seem that high.
A basin wide evaluation was carried in the Santos Basin, Brazil, using 2-D seismic data, geochemical and well data to investigate the basement geometry, tectonic subsidence patterns, stretching factors maps and the correspondent heat flow anomalies. The approach to estimate heat flow and tectonic subsidence histories takes into account mass balance of the lithosphere, isostatic corrections and account for the restored salt thickness in time. In order to calibrate the simulation results, several wells covering a wide range of depth and area of the basin were selected from the BrazilGeodata bank. Measured values of vitrinite reflectance, BHT temperature data, Tmax and oil geochemistry were used to check those parameters estimated by the simulator.
The thermal effects might result multiple hydrocarbon generation/migration pulses that might have significant exploration implications. The rift architecture and its associated heat flow evolution are pertinent to predict hydrocarbon quality, reservoir temperature and cementation throughout the sub-salt sequences, especially in the ultradeep water giant hydrocarbon province of the greater Campos/Santos basin.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil