含随机正交裂缝层状岩石的地震波频散和衰减  

Seismic dispersion and attenuation in layered rocks with random orthogonal fractures

作　　者：孙浩[1] 韩同城 符力耘 SUN Hao;HAN TongCheng;FU LiYun(National Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao 266580,China;Laboratory for Marine Mineral Resources,Qingdao Marine Science and Technology Center,Qingdao 266071,China)

机构地区：[1]深层油气全国重点实验室(中国石油大学(华东)),青岛266580 [2]青岛海洋科技中心海洋矿产资源评价与探测技术功能实验室,青岛266071

出　　处：《地球物理学报》2024年第9期3527-3543,共17页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42174136,41821002);山东省杰出青年科学基金(ZR2021JQ14);中央高校基本科研业务费(22CX07004A)资助。

摘　　要：作为流体流动的通道,广泛分布于地层中的裂缝决定着地层渗流能力的大小,因此裂缝的探测对油气勘探与开发具有重要意义.地震勘探是探测裂缝的常用手段,当地震波在饱和含相交裂缝层状岩石中传播时,可引发层间流、裂缝-背景波致流(FB-WIFF)和裂缝-裂缝波致流(FF-WIFF),岩石内部的流体流动使得岩石弹性参数随频率变化并伴随能量损耗,进而导致地震波发生频散和衰减.本文建立了层间流、FB-WIFF和FF-WIFF共同影响下含随机正交裂缝层状岩石弹性参数频散和衰减的计算公式并分析了含随机正交裂缝层状岩石弹性参数C_(33)频散和衰减的影响因素及规律.结果表明:层间流阶段C_(33)的频散和衰减与相邻两层之间弹性模量的差异直接相关,当两层之间弹性模量无差异时,C_(33)不发生频散和衰减,C_(33)的频散和衰减随着两层之间弹性模量差异的增大、两层之间层厚差异的减小而增强;FB-WIFF和FF-WFF阶段C_(33)的频散和衰减主要受到各层背景孔隙纵横比、背景孔隙度、裂缝纵横比、裂缝密度的影响,其中,FB-WIFF阶段C_(33)的频散和衰减分别随着背景孔隙纵横比、背景孔隙度、裂缝密度的增大和裂缝纵横比的减小而增强;FF-WIFF阶段C_(33)的频散和衰减分别随着背景孔隙度、裂缝密度的增大和背景孔隙纵横比、裂缝纵横比的减小而增强.研究结果提高了对含随机正交裂缝层状岩石中地震波频散和衰减的认识并为利用地震勘探资料定量评价裂缝提供了理论支持.As a channel for fluid flow,fractures that are widely distributed in the formation determine the effective permeability of the formation.As a result,the detection of the fractures has a significant impact on the exploration and development of oil and gas.Seismic survey is a common means of detecting the fractures.When seismic waves propagate in the saturated layered porous rocks with intersecting fractures,wave-induced fluid flow can occur between the adjacent layers(interlayer flow),between the fractures and the background pores(FB-WIFF),and within the intersecting fractures(FF-WIFF).Fluid flow inside the rocks makes the elastic parameters of the rocks vary with frequency that accompanies the energy loss,leading to the dispersion and attenuation of seismic waves.This paper develops theoretical models for the dispersion and attenuation of the elastic parameters of layered porous rocks with random orthogonal fractures under the joint influence of interlayer flow,FB-WIFF and FF-WIFF,and analyses the influencing factors and rules of the dispersion and attenuation of the elastic parameter C_(33).The results show that the dispersion and attenuation of C_(33)in the interlayer flow stage are directly related to the difference in the elastic moduli between the two adjacent layers.When there is no difference in the elastic moduli between the two adjacent layers,C_(33)does not disperse and attenuate,and the dispersion and attenuation of C_(33)are enhanced with the increase of the difference in the elastic moduli between the two adjacent layers and with the decrease of the difference in the layer thickness between the two adjacent layers.The dispersion and attenuation of C_(33)in the FB-WIFF and FF-WIFF stages are mainly affected by the background pore aspect ratio,background porosity,fracture aspect ratio and fracture density of each layer,in which the dispersion and attenuation of C_(33)in the FB-WIFF stage are enhanced with the increase of the background pore aspect ratio,the background porosity,the fracture density,and

关 键 词：正交裂缝 层状岩石 频散 衰减 

分 类 号：P631[天文地球—地质矿产勘探]