叠前地震反演精度影响因素

Study of influential factors on pre-stack seismic inversion accuracy

叠前地震反演能够提供更加丰富的地球物理信息,但影响其反演精度的因素较多。设计了包含不同速度特征的地质模型,再对基于地质模型提取的地震模型数据体进行反演,将反演结果与理论值进行误差对比,分析了初始约束模型、信噪比、反演子波选取、反射系数计算公式选择对叠前地震反演精度的影响。结果显示,精度高的初始约束模型反演结果好于精度低的初始约束模型;信噪比大的地震数据体的反演结果优于信噪比小的地震数据体;选取的反演子波与地震数据主频的匹配程度越近似,反演精度越高;可以选取适用条件相对较合理的Zeoppritz方程作为反射系数计算公式。地质模型数据与实际资料反演结果对比表明,构建与实际地质模型弹性属性接近的反演初始参数模型,对采集数据进行滤波去噪和修饰处理提高地震资料信噪比,通过测井和地震资料提取主频与地震数据相匹配的反演子波以及反射系数计算公式等参数的合理选择有利于提高叠前地震反演精度。

Pre-stack seismic inversion can offer more geophysical information, but its accuracy can be affected by variable factors. For this reason, firstly, geological models of various velocity characteristics are designed, then, the pre-stack inversion is carried out for the seismic data extracted based on the geological model, and then, based on comparison of the inversion error to the theoretical model, influential factors of pre-stack seismic inversion such as initial constrained model, signal-noise ratio, inversion wavelet and reflectivity computational formula are analyzed. The study indicates that: the more accurate the initial constrained model, the better the inversion results; the higher the signal-noise ratio of the seismic data, the better the inversion results; the closer the wavelet matching with the seismic dominant frequency, the more accurate the inversion results; and Zeoppritz equation can be used as reflectivity computational formula because of its relatively reasonable applicability. The geological model and actual data inversion shows that inversion accuracy can be increased by establishing initial inversion model with elastic properties close to those of the actual model, boosting signal-noise ratio through filtering and modifying seismic data, extracting wavelet matching with the seismic dominant frequency from well logging and seismic data, and using applicable reflectivity computational formula.