Abstract：The object of cross-hole seismic exploration is to obtain the underground seismic data having both higher frequency and high resolution.But recent cross-hole seismic exploration has fallen a pitfall,that is,most of the rays in cross-hole seismic exploration is in the region beyond critical angle.Through some cases analysis,the paper determined whether the incident angle of ray in cross-hole seismic exploration being less than critical angle or larger than critical angle is the mark of success or failure.Adopting forward modeling of elastic wave-equation in the paper,when beds are horizontal and shooting is in the borehole,the seismic wavefield quickly surpasses the critical angle on both left and right sides,formed very complex wavefield confusion zone(the authors call it as "the tip of a horn").The ray theory is no longer available in this zone.The first break cannot be correctly acquired,resulted in very difficult of cross-hole imaging.Therefore,the paper clearly pointed out that the way out for the next developing cross-hole seismic exploration lies in controlling the incident angle of ray within critical angle and ensuring the source to have sufficient energy.
李庆忠, 王建花. 井间地震勘探的误区及出路[J]. 石油地球物理勘探, 2004, 39(1): 1-11.
Li Qingzhong, Wang Jianhua. Pitfall of cross-hole seismic exploration and way out. OGP, 2004, 39(1): 1-11.
