地震资料空间分辨率计算及理论分析

Calculation and theoretical analysis of the spatial resolution of seismic data

分辨率的概念从时间域扩展到空间域,产生了横向分辨率、水平分辨率、纵向(垂向)分辨率、法向分辨率、方向空间分辨率等多个概念。从叠前偏移的成像椭圆出发,利用几何方法推导了均匀介质假设条件下共炮检距道集中分辨率的精确表达式,理清了各分辨率概念的内在联系。进一步通过理论计算讨论了横向分辨率随炮检距、观测点位置及深度的变化特点,对比分析了3种横向分辨率计算式的差异性。研究结果表明,前人近似横向分辨率计算公式容易高估地震资料的实际分辨能力。对于确定的炮检距和观测点位置,横向分辨率随观测点埋深呈非线性变化。当埋深约为0.7倍炮检距时,通常可获得最大横向分辨率。

The concept of resolution extends from the time domain to the spatial domain,generates multiple concepts including lateral resolution,horizontal resolution,vertical resolution,normal resolution,directional spatial resolution and so on.By studying the imaging ellipse of prestack migration,the accurate expression of resolution on the common offset vector gather in the homogeneous medium were deduced by geometric method,which clarify the intrinsic relationships between the above mentioned concepts.We further discussed the variation features of lateral resolution along with offset,observation position and depth through theoretical calculation.And then,we analyzed and compared the differences between the three lateral resolution expressions.The research result shows that the previous approximate formula of lateral resolution will overestimate the actual resolution of seismic data easily.For a fixed offset and observation position,the lateral resolution changes nonlinearly with the buried depth of observation points.When the buried depth is about 0.7times of the offset,we can obtain the maximum lateral resolution.