The Prediction Of Shear Wave Velocity And AVO Forward Modeling

Shear wave velocity is a parameter that geophysicists always want to obtain and is essential in AVO forward modeling. But at present there is no effective method to calculate shear wave velocity.For this,Through studying the theories of seismic rock physics modeling, the paper summarizes the methods of the seismic rock physics modeling, and establishes the process of base on modeling rock matrix, rock frame, fluid saturated rock and pore fluid basing on the Gassmann equation. By forward modeling, velocity prediction and Biot coefficient calculation the paper finds the problems in the process of rock physics modeling, especially in the modeling of rock frame, and points out that the Krief model and the critical porosity model does not apply to low-pressure or low-porosity rock. So in this paper we use the consolidation parameter of the Pride model to predict the shear wave velocity.Based on the calculated shear velocity, exact reflection coefficients are calculated and AVO forward modeling is carried out by using intergrated Zoeppritz' equations. And the effects of various on AVO are analyzed through some typical models, especially the rockphysics parameters, such as porosity, shale friction and water saturation. Above achievements offer some basic data to predict the properties of rock and fluid, which can efficiently reduce the uncertainty and ambiguity of seismic interpretation. In addition, the effects of anisotropy is discussed using simplified anisotropic refection coefficient equations. In this paper, Two typical models are employed to show that the algorithm is correct and feasible.Practical application in certain areas shows that S-wave velocity estimation based on rockphysics improves the accuracy of AVO forward modelling, and the analysis of rockphysics parameters effect on AVO can reduce the uncertainty of fluid prediction. The approved conclusion is valuable.