Fractures in carbonates exist at all scales, creating complex flow networks in the reservoir. As a consequence, the movement of hydrocarbons and other fluids is often not as expected or predicted. Understanding these flow networks is fundamental to achieving better prediction, production performance, and ultimate recovery.
The detection of fractures in the reservoir involves the use of a range of downhole measurements with which fractures intersecting boreholes can be measured and characterized. The FMI fullbore formation microimager provides a borehole image based on a large number of microresistivity measurements. Such measurements provide detailed information such as orientation, depth, and aperture of the fractures. In non-conductive mud systems an image of the fractures can be obtained using the OBMI oil-base microimager, or the UBI ultrasonic borehole imager. Stoneley wave measurements, from the Sonic Scanner acoustic scanning platform, help to differentiate between open natural fractures and drilling induced ones.
Downhole logging-while-drilling (LWD) imaging services, such as the geoVISION imaging-while-drilling service, enable images to be transmitted in real time while drilling; aiding fracture evaluation while drilling and providing information which can impact completions planning. Early measurements provided by LWD can also be used to fine-tune any additional near wellbore petrophysical characterization program. It is also important to accurately understand formation geomechanics in order to successfully complete a well. The Sonic Scanner technology measures the formation axially, azimuthally, and radially to deliver a 3D acoustic characterization that is needed to evaluate both intrinsic and stress-induced anisotropy.