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逆时偏移理论基于全波动方程,是目前最精确的偏移技术之一,比克希霍夫积分偏移更适于复杂构造成像。HSX地区地表起伏较大,地下构造复杂,实现逆时偏移应用,首先必须解决速度建模的问题,通过构建特征层位的方法,将具有相同或相近波场特性的地层划分成组,通过特征层位约束可以大大提高层析反演的效率,有效改善了速度建模的精度。逆时偏移基于双程波动方程进行波场逆时外推,必然会产生低频噪音。拉普拉斯算子滤波技术有效压制了噪音,保持了剖面的特征。实际资料应用表明,逆时偏移对断层接触关系和大角度断裂系统的复杂构造成像效果要优于克希霍夫积分偏移。
The inverse time migration theory is based on the full wave equation and is one of the most accurate migration techniques so far. Compared with Kirchhoff integral migration, it is more suitable for complex structure imaging. In the HSX area, the ground surface has a large fluctuation and the underground structure is complex. To realize the application of reverse time migration, the speed modeling problem must be solved first. By constructing the feature horizon, the strata with the same or similar wave field characteristics are divided into groups, The characteristic horizon constraint can greatly improve the efficiency of tomographic inversion and effectively improve the accuracy of velocity modeling. Inverse time migration based on the two-way wave equation of the wavefield anti-time extrapolation, will inevitably produce low-frequency noise. Laplacian filter technology effectively suppress the noise, maintaining the profile features. The application of actual data shows that the imaging effect of inverse time migration on fault contact relationship and complex structure of large angle fracture system is better than Kirchhoff integral migration.