反射波波形反演技术及其陆地资料应用

Reflection waveform inversion and its application to onshore seismic data

目前随着油气勘探的不断发展,深部油气藏受到广泛关注,高精度深层速度建模与成像是一个亟待解决的难题.全波形反演充分利用叠前地震数据的运动学和动力学信息,具有揭示复杂地质背景下构造细节的能力,是目前建模精度最高的方法之一.然而,波形反演本身是一个高度的非线性问题,反演易陷入局部极值不能收敛.在实际应用时,常规全波形反演受限于炮检距以及地震数据的有效频带范围,因而对深层的反演结果并不准确.与常规全波形反演相比,反射波波形反演利用反射波信息代替回折波信息,是提高深层反演质量的有效途径.为此,利用地下介质的构造信息,通过结构张量滤波算法对梯度进行预处理,保证反演方向正确以及反演过程稳定.陆地资料应用结果表明:本文方法能够反演出更加符合地下地质规律的高分辨率速度模型,有利于深部目的层成像与目标评价.

At present,with the fast development of oil-gas exploration,deep reservoir has been widely concerned.The high precision velocity modeling and imaging in deep reservoir is an urgent problem to be solved.Full Waveform Inversion(FWI)can make full use of kinematic and dynamic information in prestack seismic data,and has the ability to reveal structural details under complex geological background.It is one of the methods with the highest modeling accuracy.However,the inversion itself is highly nonlinear,and the iterative process is easy to fall into local extremum and can not converge.The conventional FWI is limited by the offset and effective frequency band of seismic data,the inversion result of deep layer is not accurate.Compared with the conventional FWI,RFWI makes use of the reflection wave instead of diving wave,which is an effective way to improve the inversion quality of deep structures.Therefore,the structure information of underground media is used to preprocess the gradient through the structure-tensor filtering algorithm,which makes the inversion process correct and stable.The inversion results of onshore seismic data show that the method of this paper can get the high-resolution velocity model conformed to the underground geological law,and is conducive to deep target imaging and evaluation.