Simulation of Reflection and Scattering Waves in Acoustic Logging While Drilling

摘要

To extract the reflection signals from the logging while drilling (LWD) data for the goal of geo-steering, it was significant to investigate the propagation of those arrivals separately. Yet the reflection responses which are produced by the medium discontinuity at the drill bit and the bottom of borehole, could cover the signals we need. In this work, we investigated the wave fields generated by the scattering effects, which confirmed that the collar and the Stoneley waves produced a strong reflections of the Stoneley and the collar waves at the bottom of the well, respectively, through the finite difference modeling. In the LWD model of the heterogeneous formation in front of the drill bit with infinite borehole, the reflect collar waves were received, revealing that the energy of the collar wave could propagate along the well. According to the simulation results, we suggested one install the receivers below the transmitter, which was better for separation of the direct waves and reflect waves by the f-k filtering.