Sing-well shear-wave reflection survey using a dipole acoustic source has recently emerged as an effective application technology to image geological structures away from borehole. The reflected wavefield is strongly influenced by the radiation characteristic of the borehole acoustic source. Besides radiating energy into the formation, the source excites a flexural wave propagating along borehole, greatly reducing the efficiency of the borehole radiator. Using the concept of acoustic energy flow density, we develop a method to evaluate the radiation property and efficiency of a dipole source by comparing the energy flow of radiated waves away from borehole to that of the flexural wave along borehole. Using this method, we study the frequency variation characteristics of the energy flow and radiation efficiency for a dipole source in a fluid-filled borehole. Our analysis results show that the radiation efficiency of SH-wave is much greater than these of P-and SV-wave. The radiation efficiency of dipole source is frequency dependent and is most prominent in the frequency range around 4 kHz. The theoretical results of our work provide a useful reference for the design and development of a dipole imaging tool.
Presentation Date: Thursday, October 20, 2016
Start Time: 9:45:00 AM
Location: 168
Presentation Type: ORAL
