富有机质岩石横波速度预测方法

Aiming at the disadvantage that the influence of kerogen distribution and pore structure on velocity is not taken into account in the rock physics model of organic-rich rock, we present a method for S-wave velocity prediction of organic-rich rock by integrating the rock physics model(Kuster-Toksöz) with a nonlinear global optimization algorithm. In this method, the organic-rich rock is equivalent to a mixture of minerals, kerogen particles and fluid-containing pores, in which kerogen particles and pores are both equivalent to ellipsoid-shaped inclusions. The effect of kerogen distribution and pore shape on S-wave velocity is described according to the change of the aspect ratio of ellipsoids. The error between the predicted and mea-sured P-wave velocities is applied to establish the inverse objective function. Then calculate two parameters, the equivalent kerogen particles and the equivalent pore aspect ratios, by the optimization algorithm. The S-wave velocity is predicted based on the inverted parameters. Compared with three single-adaptive parameter methods commonly used in the industry, the new method of S-wave velocity prediction based on kerogen and pore aspect ratios simultaneously inverted from P-wave velocity (or P-and S-wave velocities) is more effective.