基于近似流体替代的快速无迭代横波速度预测方法

 横波速度对于储层表征、流体识别具有重要意义。实际测井数据中横波速度信息缺乏,因而横波速度预测已成为岩石物理研究的重要内容。经验回归公式法横波速度预测都是建立在水饱和岩石的基础之上,油气饱和储层横波速度预测需要先对流体进行替代。利用无需横波速度的流体替代方法预测油气储层饱含水时的纵波速度,克服了传统流体替代方法需要横波速度的局限。再借助水饱和岩石纵波速度-横波速度回归关系式实现储层完全饱含水时的横波速度预测。进而通过密度校正,获得储层含油气时的横波速度,建立了一种快速无迭代的横波速度预测方法。将该方法成功地应用于实际测井资料的横波速度预测,预测结果表明,预测精度相对未进行流体替代的预测结果,有较大的提高,说明快速无迭代横波速度预测方法是行之有效的。

Prediction Method for Fast and Iteration-free Shear Wave Velocity Based on Approximated Fluid Substitution

The information on shear wave velocity is insufficient in realistic well logging data, even though shear wave velocity plays an important role in the reservoir characterization and fluid identification. Therefore it has become an important part of rock physics research to predict shear wave velocity (V_s). Empirical regression equations are based on water saturated rock; therefore, the fluid of hydrocarbon saturated rock must be substituted by water before shear wave velocity prediction. Using fluid substitution without shear wave velocity to predict longitudinal wave velocity (V_p) of water saturated rock, the drawback that traditional fluid substitution needs shear wave velocity for the prediction is overcome. By employing V_p-V_s regression equations of water saturated rock, reservoir shear wave velocities with water saturation are predicted. Furthermore, by using density correction, shear wave velocities of reservoir saturated by hydrocarbon are obtained, and then the method for predicting fast shear wave velocity without iteration is established and is applied to shear wave velocity prediction of realistic well logging data. The results demonstrate that prediction precision of the method proposed is obviously higher than that without fluid substitution, and fast shear wave velocity prediction method without iteration is effective.