Acoustic wave field in fluid-filled borehole surrounded by TI formations produced by a phased arc array source

We study acoustic wave field in a fluid-filled borehole associated with a TI formation produced by a phased arc array source, and analyze the sensitivity of this source to azimuthal anisotropy of formation shear waves in order to develop a new anisotropy evaluation method. Results show that this source is able to generate acoustic field of multi-azimuthal order, and the primary acoustic modes are the monopole modes and dipole modes. In HTI formations, the waves excited by sources with different radiation azimuths propagate with different velocities. The azimuthal sensitivity of phased arc array to formation shear anisotropy is mainly contributed by flexural modes produced by this source. Compared to a traditional cross-dipole source, the phased arc array transmitter can be used to evaluate formation heterogeneity and increase the measurement number around the borehole decreasing uncertainty of inverted results. Additionally, this source has the function of multipole sources. Therefore, it is possible to obtain the most reliable anisotropy measurements by using optimized phased control strategy with this source.