【摘要】 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。更多还原

【Abstract】 The challenges for the complex geological structure imaging are the great changes in vertical and horizontal velocity in the complexity of surface and subsurface geological conditions.Pre-stack depth migration makes the fine imaging in the complex geological structures.By comparison with effect of pre-stack depth migration between Kirchhoff integration and wave equation,we propose data preparing,time-domain model,velocity-depth model,and chosen method of pre-stack depth migration during pre-stack depth migration realization.We use the Kirchhoff integration to get a fine velocity-depth model,which executes the several iterations and optimize velocity to target lines.We also use two methods to test the migration in the research area.The example results show that both two methods have ability to image accurately in the complex geological structure,but are different in signal to noise ratio.The wave equation is chosen in the high signal to noise ratio area,whereas the Kirchhoff integration does in the low one.The different migration methods need velocity-depth models.The effect of imaging is different in areas with signal to noise ratios.更多还原