应用叠前纵横波联合反演技术预测气水界面

Prediction of Gas-water Interface by Joint Inversion of Pre-stack P and S wave

川东北地区飞仙关组鲕滩气藏大多属于岩性一构造复合圈闭所控制的边水气藏，在单个气藏圈闭内具有统一的气水界面。通过建立地质模型和地球物理模型，从分析储层及流体测井响应特征入手，在物理模型上应用叠前纵横波联合反演技术预测气水界面取得了较理想的效果，而且在实际地震数据上得到了验证。研究结果表明：川东北鲕滩储层具备地震气水预测工作的基础条件，泊松比可以较好地避免岩性因素的影响，用于直接找气，它可以排除水层、非储层及一些低孔储层，适用于区分低电阻率及高阻水层。对于主要受构造控制的边水气藏．只要有一口井的横波资料．采用叠前纵横波联合反演技术进行气水预测．就能大致探明气水界面。

Most of oolitic gas reservoirs of Feixianguan Formation, northeastern Sichuan Basin, are edge-water gas reservoirs controlled by lithologic-structural combination trap. Within a single trap, there exists a uniform gas-water interface. In this study, based on the establishment of geological and geophysical models, analysis on the log-response characteristics of reservoir and fluid, the gas-water interface has been predicted satisfactorily by applying joint inversion of prestaek P- and S-wave to physical model. Furthermore, the result has been verified by the actual seismic data. It shows that： （1） oolitic reservoir in northeastern Sichuan Basin has basic conditions of seismic prediction for gas and water;, （2） Poisson＇s ratio can avoid the effect of lithologic factors and may be used to detect gas directly. Based on Poisson＇s ratio, water zone, non-reservoir and some low-porosity reservoirs may be removed. It is applicable to distinguish low resistivity zone and high resistance water zone. For edge-water gas reservoir mainly controlled by structure, if S-wave data of one well is available, the gas-water interface can be predicted by the joint inversion.