斜井VSP高斯射线束正演方法

A method of Gaussian beam forward modeling in deviated-well VSP

高斯射线束正演方法是一种将波动方程和射线理论相结合的方法,适用于复杂地质构造,与常规射线正演模拟方法相比,高斯射线束正演结果不仅包含了运动学变化信息,并且具有较合理的动力学变化特征,不存在盲区问题。文中针对理论和实际正、逆断层模型,开展了斜井VSP观测方式下的P波波场正演模拟,探讨了采用斜井VSP高斯射线束正演方法模拟波场的断层异常特征及其识别问题,结果表明该方法可有效解决因盲区造成的运动学信息不完整及波场振幅保真问题,其运算速度相比波动方程有限差分法提高了100倍以上。

Gaussian beam forward modeling is a method to combine the wave equation with the ray theory,and suitable for complex geological structures.In contrast to the conventional ray forward modeling,Gaussian beam forward modeling will obtain the results that contain both information of kinematic changes and more reasonable characteristics of dynamic changes and have no blind-area problem.For the theoretical and actual models of normal and reverse faults,a forward modeling in P wave field was conducted in deviated well VSP,and the abnormal characteristics of faults and their identification in Gaussian beam forward modeling were discussed.The results have indicated that this method ma effectively solve the problems such as incompleteness of kinematic information due to blind areas and amplitude fidelity in wave field,and that its computation speed increased by over 100 times of that of finite difference forward mod eling with wave equation.