Fractured Reservoir Characterization Using Borehole Eletrical Images And Dipole Sonic Data:A Bolivian Case

Major gas trends have developed in South Bolivian reservoirs. The reservoir rocks are often very hard<br>formations, extremely fractured, and with virtually no primary porosity. Through the use of wellbore imaging and<br>other logging techniques, stress-induced compressive failure and tensile failure of the wellbore wall can be<br>detected, and shear failure (i.e., slip along preexisting shear faults) can be identified.<br>We present a combined technique that exploit wellbore electrical image and dipole sonic data which enable a<br>complete fracture characterization. In the absence of core data, FMS* Formation MicroScanner, FMI** Fullbore<br>Formation MicroImager and DSI* Dipole Sonic Imager wireline logs provided valuable geologic information.<br>The high-resolution geologic interpretations of the FMS and FMI data were able to routinely identify fractures in<br>the wireline resistivity images. Image features are oriented in space, and quantitatively characterized, with their<br>density, aperture and porosity estimated.