地震勘探中的三维随机介质模拟及其特点分析

Simulations and characteristics analysis of 3-D random medium in seismic prospecting

常规的均匀层状介质理论已经不适用于高分辨率地震勘探,需要进一步发展随机介质理论,为研究复杂非均匀介质中的地震波场理论奠定基础。本文首先利用三维Von Karman型自相关函数模拟三维随机介质并给出了详细的建模流程,通过引入三维锥形函数,来压制建模时离散计算产生的误差,提高了模型的可信度。然后详细讨论了自相关长度、谱指数、标准差对建立的三维随机介质模型的影响。最后分析了模型内的速度变化和概率分布情况。模拟结果表明利用三维Von Karman型自相关函数可以更灵活地模拟三维随机介质。

The conventional layered medium seismic wave field theory has been unable to fit the highresolution seismic exploration, we need further develop random medium theory in order to lay the foundation for the study of complex seismic wave-field theory in heterogeneous medium. This paper firstly gives the detailed process of 3-D Von Karman type autocorrelation function to simulate 3-D random medium and introduces 3-D cone-shape function to surpress discrete calculation errors of modeling and improve the credibility of the model, and then discusses the impact of autocorrelation length, spectral exponent and standard deviation on 3-D random medium. Finally, we analyze the velocity change and the probability distribution of model. The results show the method of that simulating 3-D random medium with Von Karman autocorrelation function is more flexible.