Key points are not available for this paper at this time.
Abstract We use the low-frequency reflected Stoneley-wave mode to locate permeable fractures intersecting a borehole and to estimate their effective apertures. Assuming a model in which the average aperture of the fracture is roughly constant, theoretical work relates the magnitude of the Stoneley-wave reflectivity to an effective fracture width. We treat both the case of a horizontal fracture and the case of a fracture crossing the borehole at an angle.Laboratory experiments verify the analytic solution for the case of a horizontal fracture. Full-waveform array sonic data were also acquired in a wellbore with a long recording time (25.5 ms) in order to capture the late Stoneley-wave arrivals. The data processing involves computation of the Stoneley-wave reflectivity response using the measured direct and reflected Stoneley-wave arrivals. A least-squares fit to the arrival time of the reflected-wave arrivals is used to estimate the locations of permeable fractures, and the effective width of the fractures is estimated by comparing the computed Stoneley-wave reflectivity to the theoretical response from a parallel-plate model. Test-well results are consistent with a borehole televiewer analysis.
Hornby et al. (Sun,) studied this question.