Detect fractures when drilling with oil-based mud

The use of oil-based mud to control difficult wells has been a logger's nightmare. Now, a time-lapse logging technique discriminates drilling-induced, temporary fractures from permanent ones, facilitating formation evaluation. Running a logging-while-drilling (LWD) compensated dual resistivity tool on the end of a drill-string allows real-time monitoring of resistivity curves and mechanical drilling parameters. With these data, well site personnel can evaluate pore pressures, formation strengths and real-time fracturing. Drilling efficiency can be optimized and wells can be steered to target zones. Fracture healing also can be detected using this while-drilling log data in combination with after-drilling log data. Specifically, time-lapse techniques can detect and confirm permanent fracturing that occurred while drilling.