正交各向异性介质中的剪张源震源机制与矩张量特征  

Focal mechanisms and moment tensor in orthorhombic anisotropic media

作　　者：唐杰[1] 温雷 王浩[1] 张文征 Tang Jie;Wen Lei;Wang Hao;Zhang Wenzheng(School of Geosciences,China University of Petroleum (East China),Qingdao,Shandong 266580,China)

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266580

出　　处：《石油地球物理勘探》2018年第6期1247-1255,I0006,共10页Oil Geophysical Prospecting

基　　金：国家自然科学基金项目(41504097,41874153)资助.

摘　　要：水力压裂区在整体上呈现各向异性特征,深入研究和分析水力压裂区的各向异性参数对震源机制和矩张量的影响成为必要。本文研究了干燥和完全饱水垂直正交裂缝介质的地震波响应特性,通过各向异性介质参数和源张量获得各向异性介质中的微地震矩张量,分析了震源区各向异性对双力偶分量(DC)、补偿线性偶极子分量(CLVD)和各向同性分量(ISO)的影响,并对比了裂缝及其所含流体的特征参数对地震波响应特性的影响效果。研究结果表明:各向异性介质中由于剪张破裂产生的非DC分量依赖于破裂方式、各向异性介质的类型、裂缝参数及断面方向等,干燥裂纹介质中的ISO分量较高,水饱和裂纹介质中产生较高的CLVD分量、而ISO较小;各向同性与各向异性介质中剪张源的远场P波辐射花样存在差异,震源特征和介质各向异性会对地震波走时、极性和振幅产生明显影响。探究水力压裂区各向异性参数对震源机制的影响效果对微地震震源描述具有重要意义。Hydraulic fracturing zones have anisotropic characteristics on the whole.It is necessary to analyze the influence of anisotropic parameters on the focal mechanism and the moment tensor.This paper studies shear-tensile focal mechanism and seismic moment tensor when the source is located in anisotropic media,analyzes the influence of the focal anisotropy on double couple (DC)components, compensated linear vector dipole (CLVD)components,and isotropic (ISO)component.The seismic response characteristics of dry and saturated orthorhombic anisotropy media is also analyzed.Effects of crack parameters and fluid parameters on seismic response are discussed.The following understandings are obtained based on our research:A. The moment tensor in the anisotropic media can be obtained by anisotropic parameters and source quantity;B.The non-DC components caused by shear rupture in anisotropic media depend on the type and intensity of the anisotropy and the direction of the fault plane.High ISO components appear in dry crack media and high CLVD components in water saturation media;C.The far field P wave radiation patterns are different between isotropic and anisotropic media,source characteristics and media anisotropy have significant effects on seismic wave traveltime,amplitude,and polarity.

关 键 词：正交各向异性 微地震 震源机制 地震矩张量 剪张源 

分 类 号：P631[天文地球—地质矿产勘探]