A numerical investigation of the acoustic mode waves in a deviated borehole penetrating a transversely isotropic formation

Abstract

A 2.5-dimensional method in frequency wave-number domain is developed to investigate the mode waves in a deviated borehole penetrating a transversely isotropic formation. The phase velocity dispersion characteristics of the fast and slow flexural mode waves excited by a dipole source are computed accurately at various deviation angles for both hard and soft formations. The sensitivities of the flexural mode waves to all elastic constants in a transversely isotropic formation are calculated. Numerical results show that, for a soft formation, the fast flexural mode wave is dominated by c 66 at high deviation angles and low frequencies, while the slow flexural mode wave is dominated by c 44 at the same conditions. Waveforms in time domain are also presented to support the conclusions. deviated borehole, transverse isotropy, acoustic mode waves, dispersion curve, sensitivity analysis PACS number(s): 43.2.Mv, 43.20.Jr, 91.60.Lj Citation: Liu L, Lin W J, Zhang H L, et al. A numerical investigation of the acoustic mode waves in a deviated borehole penetrating a transversely isotropic formation.

On Transient Response of Piezoelectric Transducers

“…For example, Ricker first used Ricker wavelet to describe acoustic source in seismic exploration [24], while Tsang and Radar used Tsang wavelet to describe that in acoustic-logging [25]. Following them, almost researchers used the mathematical expressions of these two wavelets or a variety of somewhat over simplified acoustic-source functions (such as Green's function, truncated Gaussian pulse and so on) in the forward model-research of acoustic-measurement or in inversion analysis/processing of measured acoustic signal [26][27][28][29][30][31][32][33][34][35][36][37][38][39]. These wavelets are only some assumed mathematical expressions and did not give the real relationship between driving-voltage signal and radiated acoustic signal-wavelet.…”