稠油油藏AVO影响因素分析

由于特殊的温压环境和形成机制，稠油油藏的密度与水非常接近，导致含稠油地层与含水地层的地震响应特征十分相似，致使应用AVO技术识别稠油的效果并不理想。为此，在稠油油藏AVO敏感因素分析的基础上，提出了一种利用AVO技术开展稠油油藏储层物性分析的新方法。首先通过基于Zoeppritz方程和Biot-Gassmann理论的岩石物理分析，以岩石弹性参数为桥梁建立反射系数与储层物性（孔隙度）、含油气性（含油饱和度）之间的关系；进而通过基于流体替换和孔隙度替换的AVO正演模拟，依次分析了含油饱和度、孔隙度对饱和稠油模型AVO特征的影响。结果表明，孔隙度是影响AVO响应特征的敏感因素，含油饱和度的影响可忽略不计。通过在锦州A油田的应用，对目的层孔隙度横向变化进行了研究，结果与钻井数据较为吻合，证实了文中方法的有效性。

AVO influence factors analysis in heavy oil saturated reservoirs

Due to a special temperature-pressure environment and forming mechanism,the heavy oil density is very close to the water density,which makes seismic response characteristics of heavy oil reservoirs very similar to that of water-bearing strata.Hence heavy oil reservoirs are very difficult to be identified with AVO.For this purpose,we propose a new petrophysical property analysis method for heavy oil reservoirs based on AVO sensitive factors.Firstly,after rock physics analysis based on Zoeppritz-equation and Biot-Gassmann theory,the relationships between reflection coefficient and petrophysical property (porosity),and reflection coefficients and oil-gas possibility (oil saturation) are established with rock elastic parameters.The influences of oil saturation and porosity on AVO characteristics of heavy oil reservoirs are then successively analyzed by the integration of fluid substitution,porosity substitution,and AVO forward modeling.Results indicate that the porosity is the major sensitive factor of AVO characteristics while the influence of oil saturation is negligible.Finally,this method is applied to the Jinzhou-A Oilfield,the lateral variation of porosity within targets is analyzed,and the result is consistent with drilling data,which confirms the effectiveness of the proposed method.