摘要
随入射角和方位角振幅变化(AVAZ)反演是地球科学领域从叠前和方位角地震数据中估计弹性参数和各向异性参数的最广泛使用的反演方法之一,有助于预测裂缝.发育一组垂直或近垂直定向裂缝的各向同性均匀岩石储层可以等效为具有水平对称轴的横向各向同性介质(Horizontal Transversely Isotropic medium,即为HTI介质).我们的目标是开发一种适用于页岩储层裂缝预测的稳定反演方法,并充分利用页岩裂缝型储层的宽方位地震数据,提高反演稳定性.首先推导出一个HTI介质三项PP波反射系数近似表达式,该方程减少待求参数的个数,并保持足够的精度来描述HTI介质的反射特性,进而提高反演的鲁棒性.此外,开展了基于贝叶斯理论的AVAZ反演方法,提高反演的稳定性.利用柯西概率分布和高斯概率分布作为模型参数和似然函数的先验信息,提高了反演精度.通过与已有近似方程的精度分析对比,验证了基于新近似方程的反演方法的可行性.在不同噪声条件下,对所提出的反演方法进行了实际工区应用,通过实例验证了该方法在裂缝性储层反演预测中具有较高的鲁棒性和稳定性.
Amplitude Variation with Incidence and Azimuth(AVAZ)inversion is one of the most widely used inversion methods in the geosciences for estimating elastic and anisotropic parameters from pre-stack and azimuth seismic data,conducting to predict fractures.An isotropic homogeneous rock reservoir with a set of vertically or nearly vertically oriented fractures can be equivalent to a laterally isotropic medium with a horizontal axis of symmetry(Horizontal transversely isotropic medium is HTI medium).Our goal is to develop a stable inversion method suitable for fracture prediction in shale reservoirs,and to use wide-azimuth seismic data from fractured shale reservoirs to improve inversion stability.Firstly,an approximate expression of three-term PP wave reflection coefficient in HTI medium is derived,which reduces the number of parameters to be calculated and maintains sufficient accuracy to describe the reflection characteristics in HTI medium,thereby improving the robustness of the inversion.In addition,an AVAZ inversion method based on Bayesian theory was developed to improve the stability of the inversion.Using Cauchy probability distribution and Gaussian probability distribution as prior information of model parameters and likelihood function,the inversion accuracy is improved.The feasibility of the inversion method based on the new approximate equation is verified by comparing with the accuracy analysis of the existing approximate equation.Under different noise conditions,the proposed inversion method is applied in the actual work area,and it is verified by an example that the method has high robustness and stability in the inversion prediction of fractured reservoirs.
作者
陈珂磷
杨扬
井翠
衡德
樊骐铖
曾勇坚
CHEN KeLin;YANG Yang;JING Cui;HENG De;FAN QiCheng;ZENG YongJian(Sichuan Changning Natural Gas Development Limited Company,Chengdu 610000,China;China University of Petroleum(East China),Qingdao 266580,China)
出处
《地球物理学进展》
CSCD
北大核心
2022年第6期2364-2372,共9页
Progress in Geophysics
关键词
AVAZ反演
HTI介质
裂缝储层
反射系数
模型参数化
AVAZ inversion
HTI medium
Fraction reservoir
Reflection coefficient
Model parameterization
