Abstract Borehole images obtained with the Formation MicrScanner Tool (FMS) have added a new dimension to reservoir description and characterization. As confidence in fracture detection and analysis grows in the petroleum industry, more emphasis is been placed on the modeling of fracture distribution within the reservoir. The FMS logs that have been run in several wells in the Maracaibo Basin (Tretiary and Cretaceous Formations) have been used with cores, open hole logs and conventional dipmeter in an integrated approach to reservoir description. To assist in the interpretation and quantification of fractures, especialized image analysis have been developed. Borehole imagery records fracture orientation and allows natural or induced fractures to be distinguished. Quantitative analysis of fracture revealed with the FMS images has been greatly advenced with the development of the FRACVIEW software. During FRACVIEW analysis, different kinds of fractures are grouped into statistical or geological sets using the Image Examiner Workstation (FLIP) according to fracture density, lenght, width and porosity. Such information is proving to be a valuable guide to the positioning, testing and completion of new wells.