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复杂地质构造成像面临的主要难题是地表及地下地质条件复杂,速度纵横向变化剧烈。叠前深度偏移能够使复杂构造准确成像,通过对比Kirchhoff积分法和波动方程法叠前深度偏移优缺点,给出叠前深度偏移实现过程中的数据准备、时间域模型建立、速度模型建立及叠前深度偏移方法选择。利用Kirchoff积分法能够对目标线进行多次迭代优化速度的优势,获得准确的速度—深度模型,用2种偏移方法对研究区的不同资料进行偏移。应用实例表明,2种方法对复杂构造都能够准确成像,但对信噪比的依赖程度不同,在信噪比相对较高的区域波动方程具有明显的优势,而在信噪比极低的区域,Kirchoff积分法更具有优势。经分析得出不同偏移方法对采用速度模型的精度要求不同,在具有不同信噪比的地区得到的成像结果表现为不同的效果。
Complicated geological structure of the main challenges facing the imaging surface and underground geological conditions are complex, the vertical and horizontal changes in speed violent. By comparing the advantages and disadvantages of Kirchhoff integral method and wave equation prestack depth migration, prestack depth migration is able to accurately image complex structures. Data preparation, time domain model establishment, velocity model Establishment and prestack depth migration method selection. The Kirchoff integral method can be used to optimize the speed of the target line by multiple iterations. The accurate velocity-depth model can be obtained. Two kinds of migration methods are used to offset the different data in the study area. The application examples show that the two methods are capable of accurately imaging complex structures, but have different dependence on signal-to-noise ratio, and have obvious advantages in the region of relatively high signal-to-noise ratio. However, in regions with very low signal-to-noise ratio , Kirchoff integral method has more advantages. The analysis shows that the different migration methods have different requirements on the accuracy of the velocity model. The imaging results obtained in different SNR regions show different effects.