裂缝型碳酸盐岩储层方位各向异性弹性阻抗反演  

Azimuth anisotropic elastic impedance inversion in fractured layered carbonate rock reservoir

作　　者：陈怀震 印兴耀[1] 杜炳毅 张广智[1] 

机构地区：[1]中国石油大学(华东)地球科学与技术学院

出　　处：《地球物理学进展》2013年第6期3073-3079,共7页Progress in Geophysics

基　　金：国家重点基础研究发展计划"973"项目(2013CB228604);国家油气重大专项(2011ZX05014-001-010HZ);中国石化地球物理重点研究室基金;中央高校基本科研业务费专项资金(14cx06015A)联合资助

摘　　要：弹性阻抗是声阻抗的延伸和扩展,研究裂缝型碳酸盐岩储层的弹性阻抗特征能够更好地识别裂缝储层位置,为裂缝储层油气勘探提供有效的地球物理依据.本文从各向异性介质理论出发,将含垂直裂缝的碳酸盐岩储层等效为具有水平对称轴的横向各向同性介质,并推导了方位各向异性弹性阻抗计算公式,分析了方位各向异性弹性阻抗随入射角和方位角变化的特征.同时提出了方位各向异性弹性阻抗的最小二乘反演:首先从方位各向异性弹性阻抗公式出发,求取裂缝型碳酸盐岩储层的反射系数;其次利用褶积模型合成方位地震道集,并对其添加不同信噪比的随机噪声;最终利用最小二乘算法估测方位各向异性弹性阻抗.选取实际工区测井数据和二维复杂裂缝模型对方位各向异性弹性阻抗反演方法进行试算,研究发现,当信噪比为2时,方位各向异性弹性阻抗的反演值与真实值之间吻合较好,满足反演要求.Elastic impedance is extension of acoustic impedance, this paper aims to put forward azimuth anisotropic elastic impedance inversion method to help effectively predict fracture reservoir. Based on anisotropic media theory, fractured carbonate reservoir can be equivalent to transverse isotropic media with horizontal axis of symmetry. And it derives the formula used to calculate azimuth anisotropic impedance, and studies the characteristic of elastic impedance varied with incidence angle and azimuth angle. At the same time, it studies azimuth anisotropic elastic impedance least square inverse method. First, starting from the anisotropic elastic impedance formula, it calculates the reflection coefficient of the fractured carbonate reservoir; secondly, it chooses convolution model to generate azimuth synthetic seismic gathers, and joints different S/N random noise to the gathers; at last, it estimates anisotropic elastic impedance using least square inverse method. Well log data and 2D complex fracture model are chose to prove the azimuth anisotropic elastic impedance inversion method. It got a conclusion that anisotropic elastic impedance inverse result can match the real value reasonably until the S/N ratio is 2：1.

关 键 词：弹性阻抗 裂缝 各向异性 方位角 反演 

分 类 号：P631[天文地球—地质矿产勘探]