VSP资料在储层预测中的应用

VSP data application in reservoir prediction

砂、泥岩地层中储层因含气往往导致纵波速度降低,从而与围岩速度重叠或接近,此时应用常规声阻抗反演方法难以识别储层。测井资料分析发现泊松比能较好地分辨储层和围岩,因此提取并综合利用泊松比参数是识别储层的一个有效方法。本文提出利用零井源距VSP资料拾取的高精度初至获得精细的纵、横波速度,通过转换得到泊松比参数,同时基于非零井源距VSP纵、横波剖面进行纵、横波联合反演,得到纵、横波阻抗和泊松比剖面,通过对泊松比剖面分析可识别有效储层。应用该方法在SLG气田进行储层预测,结果与实钻情况吻合,取得了良好效果。

When gas reservoirs are in sandstone and shale,it is very difficult to distinguish them from surrounding rocks using conventional acoustic impedance inversion methods because reservoir P-wave velocity decreases.But based on logging data analysis,the Poisson's ratio of reservoirs is diffe-rent from that of surrounding rocks.So Poisson's ratio is the key parameter to identify this kind of reservoirs.This paper presents a method which uses the high accuracy of zero-offset VSP data to obtain accurate P-wave and S-wave velocities,and then the Poisson's ratio curve at well site.At the same time,we can get P-wave and S-wave sections from offset VSP data,which can be translated to AI,EI and Poisson's ratio sections by joint P-wave and S-wave inversion.The prediction is made on Poisson's ratio sections.Prediction results obtained by this method in SLG gasfield match very well with drilling.