川西丰谷地区三维AVO油气检测技术应用研究

利用川西丰谷三维宽方位地震资料，采用基于Fred.J.Hillterman简化方程的AVO技术，进行了三维AVO反演，得到垂向入射反射系数（NI）和泊松反射系数（PR）两个主要AVO属性体。通过测井数据岩石物理特征分析、已知井的AVO模型正演、流体替换和交绘图分析，可以实现从测井岩石物理属性到地震AVO属性的定量标定，进而对三维AVO属性剖面进行解释。在川西丰谷三维地震资料偏移距范围内，含气砂岩与含水砂岩的测井岩石物理特征存在明显的差异，储层砂体中气、水流体的变化可以导致不同的AVO异常。从交绘属性体中提取的须四段储层AVO属性异常分布表明，无论AVO属性剖面或属性平面展布均与实际钻井结果吻合，证实AVO反演属性对储层中含流体性质具有更直接、更准确的区分能力，在丰谷地区须家河组储层含气性检测中具有良好的应用实效。

APPLICATION STUDY OF 3D HYDROCARBON DETECTION TECHNOLOGY IN FENGGU AREA IN WESTERN SICHUAN BASIN

AVO technology based on Fred. J. Hillterman reduced equation is used to perform 3D AVO inversion of the 3D seismic data with wide azimuth of Fenggu area in western Sichuan basin to obtain two AVO attribute volumes, i.e. vertical incidence reflection coefficient (NI) and Poisson reflection coefficient (PR). Seismic AVO attributes can be quantitatively calibrated with logging petrophysical attributes by petrophysical characteristic analysis of logging data, AVO forward modeling of the known wells, fluid displacement and cross plot analysis, and then 3D AVO attribute profile can be interpreted. Within the offset distance of the seismic data in the study area, logging petrophysical characteristics of gas sand are quite different with water sand, and changes of gas and water in sandbodies can cause different AVO anomalies. Distribution of AVO attribute anomaly of the 4~ th member of Xujiahe Formation extracted from the cross-plotted attribute volumes shows that both the profile and plane map of AVO attribute coincide with the real drilling results, verifying that property of fluid in reservoir can be more directly and accurately recognized through AVO attribute inversion. This technology has been successfully applied to gas potential detection of the reservoirs in Xujiahe Formation in Fenggu area.