摘要
本文对软地层裸眼井中由点状声源激发的弹性波传播的数值进行了研究,认为首波是以地层中纵波速度传播的无频散的几何衰减波,其传播路径可以用几何声学中的滑行波理论来解释;井内无泥浆直达波.斯通利波在v_s≤((1-p_1)/p_2v_1)^(1/2)的地层中有截止频率,且在该频率处,其相速度为地层中横波传播速度;而在v_s>((1-p_1)/p_2v_1)^(1/2)的地层中无截止频率,其最大相速度小于v_s。
Study of elastic wave propagation in soft formation is made. The elastic wave is excitedby a point sound source in an open hole. Its head wave is a kind of geometric attenuationwave with no dispersion, which is transmitted at the speed of P wave. The travel path of thehead wave can be explained with the slide wave theory of geometric sonics. There is no directmud wave in the borehole. At the cut-off frequency, the phase velocity of stonely wave is thesame as shear wave velocity in formation where v_5≤((1-p_1)/(p_2v_1))^(1/2).. But there is nocut-off frequency in the formation where v_5>((1-p_1)/(p_2v_1))^(1/2) so the maximum phase ve-locity of the stonely wave is less than v_5.
