低频信号在膏盐覆盖区成像中的应用研究

针对复杂膏盐区深层成像困难的实际问题，首先分析了膏盐层的地质、地球物理特征，说明了原位地层条件下处于蠕动状态非均匀分布的膏盐层对地震波场的强烈吸收和散射作用是造成其下伏地层成像困难的主要原因。其次设计了一个简单的膏盐层模型，采用波动方程粘弹介质波场数值模拟技术，分析了单道记录中以膏盐层为界的浅层和深层地震反射信号振幅谱的频率差异，证明了介质对波场的散射和吸收作用是与地震信号的频率密切相关的，低频信号具有较强的抗散射和抗吸收能力，更易于穿透非均匀膏盐层。实际资料的处理结果证明了利用低频信号可以提高膏盐覆盖区深层成像质量。

Use of low-frequency signals to improve imaging quality under gypsum

Research on the characteristics of geologic and geophysical properties of gypsum stratum shows the effect of absorption and scattering of in situ gypsum stratum on seismic wavefield is the main factors that impede the imaging of strata under gypsum.We analyzed the difference between frequencies of shallow and deep seismic reflections on amplitude spectrum from wave equation numerical simulation on a 2 D visco elastic model.It reveals the absorption and scattering of medium to waves are related to the frequency of seismic signals and low frequency signals are superior in resisting absorption and scattering.Real data results also confirm that low frequency signals can be used to boost the quality of imaging under the gypsum.