火成岩区地震波传播规律研究

Study of seismic wave propagation regularity in igneous rock area

（石油大学CNPC物探重点实验室，北京 100083）

(University of Petroleum, Key Lab of Geophysical Exploration, CNPC, Beijing, China, 100083)

高速层屏蔽是地震勘探中的一个难题。采用Zoeppritz方程，研究了火成岩高速层界面上地震波的反射与透射特性，采用一阶应力速度弹性波方程交错网格高阶有限差分法模拟、射线追踪法和有效反射系数法相结合的方式，研究了火成岩高速层中弹性波传播规律，发现火成岩层对地震波具有能量屏蔽和路径屏蔽2种屏蔽作用。提出了采用P波广角反射和P波高速层内局部转换广角反射波消除火成岩高速层对地震波的屏蔽作用。模型试验结果表明，该方法可以减弱高速层的屏蔽作用，提高深层目标层的反射波能量。

The shielding effect of high velocity layer (HVL) is a tough problem in seismic exploration The characteristics of reflection and transmission of seismic waves on the interface between high velocity layer igneous rock and low velocity layer were studied using Zoeppritz equation The propagation regularity of elastic waves in HVL was analyzed by staggered-grid finite difference method of one order stress-velocity elastic wave equation, ray tracing, and effective reflection coefficient It was found that there are two shielding effects, energy shielding and path shielding, when seismic waves travel in igneous rocks This paper proposed to overcome the shielding effects by using wide-angle P-wave reflections and localized converted waves (PSPPSP) The effectiveness of the method was tested on modeling data