Shear-wave velocity is essential in various seismic exploration applications, including seismic modeling, amplitude variation with offset analysis, multicomponent seismic data interpretation and other exploration applications. This study presents a simple but effective method for S-wave velocity prediction from P-wave velocity based on granular media model. In the proposed method, the soft-sand, intermediate stiff-sand and stiff-sand models are unified with the expression of the soft-sand model with an effective coordination number. The shear modulus of dry rocks can be related to bulk modulus through the coordination number in the unified model. Elastic-wave velocities of water-saturated rocks at low frequencies can be predicted from the moduli of dry rock using Gassmann’s equation. Thus, the coordination number can be inverted from P-wave velocity of saturated rocks by combining the unified granular media model and Gassmann’s equation. Eventually, S-wave velocity of saturated rock is computed with the inverted effective coordination number. The numerical results indicate that the predicted S-wave velocities agree well with the measured velocities for the laboratory data and well logging data. The proposed method is applicable to sandstones with lithification of large ranges because the unified granular media model accounts for the media between Hashin–Shtrikman lower bound and upper bound. Moreover, the new method is quite suitable for the prediction of S-wave velocity in sandstones deposited in deep-water environment, particularly for turbidite sediment.

中文翻译：

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砂岩剪切波速度预测的一种有效方法

剪切波速度在各种地震勘探应用中至关重要，包括地震建模，带偏移量分析的振幅变化，多分量地震数据解释和其他勘探应用。这项研究提出了一种简单有效的基于粒状介质模型的P波速度预测S波速度的方法。该方法将软砂模型，中间硬砂模型和硬砂模型与具有有效协调数的软砂模型的表达式统一起来。干岩石的剪切模量可以通过统一模型中的配位数与体积模量相关。低频的水饱和岩石的弹性波速度可以使用Gassmann方程由干岩石的模量来预测。从而，结合统一的颗粒介质模型和加斯曼方程，可以从饱和岩石的纵波速度求取配位数。最终，利用反演的有效配位数计算出饱和岩石的S波速度。数值结果表明，对于实验室数据和测井数据，预测的S波速度与测得的速度非常吻合。由于统一的颗粒介质模型考虑了Hashin–Shtrikman下界和上界之间的介质，因此该方法适用于大范围石化的砂岩。而且，该新方法非常适用于深水环境下沉积的砂岩中S波速度的预测，特别是对于浊积岩沉积物。