盆山结合部近地表速度结构与静校正方法研究——以西南天山与塔里木盆地结合部为例

盆山结合部位近地表结构复杂,地震资料信噪比低,静校正问题突出。以横穿西南天山与塔里木盆地的某二维地震测线为例,通过分析盆地、盆山结合部和山区的典型单炮记录,确定了一套基于浮动基准面的层析静校正流程——对起伏地表的高程进行平滑,将其作为浮动基准面;在该基准面上应用初至波层析反演方法计算炮、检点静校正量,并应用于数据体上;之后对该数据体进行速度分析和动校正等常规处理,再应用高程法计算浮动基准面到最终基准面的炮、检点静校正量。实际应用效果表明,该方法能较好地解决盆山结合部资料中的中、长波长静校正问题,地震剖面的成像质量得到了明显提高。

Near-surface velocity structure and static correction of basin-mountain junction zone:case study on the junction belt of western part of South Tianshan and Tarim Basin

In basin-mountain junction zone,near-surface structure is complex,S/N of seismic data is low and statics problem is serious.Taking a 2-D seismic line crossing western part of South Tianshan and Tarim basin as an example,by analyzing the typical single shot record from basin,mountain-basin junction belt and mountain,a series of tomography statics workflow based on floating datum was identified.Firstly,the elevation of rugged surface is smoothed and taken as floating datum.Then,on this floating datum,first break tomography inversion method is applied to calculate statics of shot points and receiving points,the calculated results are used on data set.Finally,conventional processing including velocity analysis and normal moveout is carried out on data volume,and elevation method is used to calculate the statics of shot points and receiving points between floating datum and terminal datum.Actual application results show that the method can effectively solve the middle-wavelength and long-wavelength statics problem of the seismic data from basin-mountain belt,meanwhile,the seismic imaging quality has been obviously improved.