一种新的TTI介质多参数联合层析反演方法

A new multi-parameter joint tomography inversion method for TTI medium

倾斜横向各向同性(TTI)介质具有构造复杂、速度和各向异性参数的数量级差距大、对旅行时同时产生影响等特性,因而层析反演时不稳定且存在多解性。常规的单参数顺序反演方法计算量大,存在误差累积现象,难以建立准确的速度和各向异性参数模型。在常规TTI介质层析反演的基础上,采用理论公式将数量级相差巨大的Thomsen参数转换为数量级一致的速度参数,实现了等效参数同时反演。提出了先采用稳定性较高的顺序反演获得一定精度的参数模型,再使用精度较高的同时反演进一步提高模型精度的联合反演策略。SEG标准TTI模型数据试算和实际资料处理结果表明,联合反演策略精度高、稳定性强,具有较强的有效性和实用性,适用于复杂构造地区大规模实际资料的生产应用。

Tilted Transversely Isotropic (TTI) media exhibit structural complexity,and large magnitude differences in the parameters describing anisotropy.This causes incorrect calculations of travel time and then the instability and indeterminateness of the tomographic inversion,due to which the evaluation of velocities and anisotropic parameters by conventional single-parameter sequential inversion methods becomes difficult,as such models require a large computational effort,and suffer from error accumulation.In this work,Thomsen parameters obtained by conventional tomographic inversions in TTI media,which exhibit large differences in magnitude,are converted into velocity parameters having the same order of magnitude through a theoretical formula,so as to realize a simultaneous and equivalent parameter inversion.A joint inversion strategy is then proposed,in which the highly-stable sequential inversion is performed to evaluate the model parameters.Subsequently,the simultaneous inversion is carried out to further improve the model precision.Tests on synthetic and field data demonstrated the high stability and accuracy of the simultaneous in version.Therefore,it is believed that this method has the potential for application in large-scale field data in complex structure areas.