Print this page3D Petroleum System Modeling in Deepwater Santos Area; Main Results and Considerations
This study comprises of 3D Petroleum System Modeling of the deep water portion of the Santos Basin, encompassing the blocks BM-S-8, BM-S-9, BM-S-10 and BM-S-11 Cluster Blocks. It encompasses the most important recent worldwide discoveries including the giant fields of Tupi and Iara and the successfully tested prospects of Bem-te-Vi, Guará, Carioca and Parati. The uncertainty related with the cumulated volumes in this area is mainly associated with reservoir quality and distribution. The announced volumes until now comprise the largest accumulations of Tupi and Iara, although modeling results shows few small to medium size accumulations, some of them may be not economics due the depth and oil prices. A consistent modeling workflow was carried out encompassing 3D seismic interpretation and depth conversion, detailed facies model, salt restoration and uncertainty analysis. Results indicates that three main recognized source rocks are at least within oil windows in whole area and some deep parts are inside of gas generation window and are already about of 70 % transformed. Pressure conditions at the model can be considered essentially hydrostatic at present. Predicted reservoir temperatures are about 70° C in Tupi high area (at 5030 m). These relative low temperatures are due the cooling effect caused by high salt heat transfer through time. The main expulsion peak occurs from 118 Ma to 98 Ma due to the strong basin deepening just after salt deposition (113 to 112.8 Ma), additional expulsion peaks were recognized from 85 to 65 Ma. The top of Alagoas Sag sequence comprising the microbial carbonates and laminites was considered the best reservoir in the model and it was able to keep about 66 Bbbl OIP. Modeling results showed a high relationship between expelled versus cumulated volumes demonstrating high petroleum system efficiency (about 20%). It’s due the effectiveness of generation and migration process (highs generated mass, relatively short distance migration and presence of structural highs performing concentration) in addition with unusual seal capacity promoted by salt. Multi compositional analysis of predicted accumulations shows a mixing between oils originated by three source rock levels with estimated API degrees varying from 33° to 30°, although the contributions from Alagoas source rocks are less expressive than lower levels. Mass balance analysis based on stochastic uncertainties modeling point to an active and overcharged petroleum system.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil