TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractFor the first time, in Venezuela, a detailed, complete study of naturally fractured reservoirs using the recent technological advances was performed. Since the first drilled well within the very tight (5 mD) cretaceous sandstone (San Juan Formation) diagenetically highly cemented by quartz overgrowth, the existence of natural fractures was suspected due to high production rates (3000 bopd) after hydraulic fracturing an interest in fractures characterization became important for the field. Furthermore, these assumptions were growing with the analysis of pressure transient tests of several DST and Buildup surveys, which have shown double-porosity behaviour. During the drilling it was frequently observed strong lost of circulation at several depths within the San Juan Formation.Orocual Field, within El Furrial Trend, located in North Monagas area, East of Venezuela, is structurally a Fold Propagation Fault resulting in anticlines associated with thrust faults. San Juan Formation, a complex barrier island deposits, bearing condensated fluids (41° API) is the most important reservoir within Orocual Field. Cores and Well Logs provided the basis to strongly confirm the presence of a fracture network within the reservoir. With the use of recent technological advances (core scanning and imaging, side-by-side display) which permits a detailed corelog calibration and integration, a NNW-SSE orientation of the fractures observed and measured in the cores was possible, the findings are consistent with the regional tectonical stress. Integrated analysis with breakouts borehole image processing, 3D seismic structural interpretation, in-situ stress measurements and second derivatives maps yield us to establish the first maps of fractures orientation and density. Parameters such as aperture, spacing, density, length and angles have been measured to define patterns and tendencies that it will feed the simulated dynamic fractures model. A better understanding of the historical production behaviour has been reached and a simulated, geostatistical fractures modelling is under development to establish correlative trends matching between production and fractures network orientation, density and dynamical properties of the fractured system.

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