NATURAL FRACTURE SYSTEMS: QUANTITATIVE FIELD STUDIES, PETROPHYSICAL ANALYSIS, AND APPLICATION TO RESERVOIR MODELLING J. Taal (Ph.D. student) Department of Applied Earth Sciences Section Earth Sciences Three prominent universities of Brazil collaborate in a joint research effort on mature oilfields. This research effort is funded by Petrobrás and FINEP and consists of two phases, the study of naturally fractured systems in outcrop analogs and application to assets. Delft University of Technology will participate in the first part of the research effort and is sponsored by Shell. In the arid hinterland of Bahia, a state in the northeastern part of Brazil, a site has been found that we deem excellent for the implementation of the outcrop analog study. The site is situated in the Tucano basin, an early Cretaceous, aborted rift system that is associated with the opening of the Atlantic. Here both fault related fracturing and reservoir rock properties are found that match nearby oil field characteristics. A three-dimensional fracture model will be established through the integration of analysed and interpreted geophysical, petrophysical and geological measurements. Flow simulation through the system and the modelling of the flux from matrix to fractures forms an important aspect of the work. The controlled field and well data (including tests) will be used to establish interpretation methods for fractured systems in boreholes, conceptual methods for extrapolation of fractured systems to near-well bore and reservoir scale, and evaluation of appropriate completion techniques in these systems. Furthermore the project will provide general knowledge of the geometry and petrophysics of fractured systems, their origin and fluid flow behaviour under dynamic conditions. Results in 2002 Familiarisation with the project background, a one-week field trip to determine the suitable site for the field analog study, planning of two field campaigns to be executed in 2003. Plans for 2003 Execution of two field campaigns. Interpretation of gathered outcrop analog data. Planning of a 2D seismic campaign. Planning of the drilling of two deviated wells. Planning of a 3D seismic campaign. Completed graduate courses in 2002 tg007 - Stochastic modelling and geostatistics for flow and transport in porous media.