摘要
在纵波、SH 型横波资料处理和解释过程中,我们发现四川 HBC 地区地下介质普遍存在方向各向异性。当横波通过方向各向异性介质时,分裂成两个波:一个波的偏振方向与裂缝平行,叫快横波;另一个波的偏振方向与裂缝走向垂直,叫慢横波。采用相应的观测和处理方法,便可获得快横波和慢横波剖面。根据同一界面的快、慢横波的旅行时可以求得各向异性系数。同样,还可以利用 SH 波与转换波的速度比求取各向异性系数。各向异性系数的大小,反映了裂缝的发育程度。如果野外作了 X、Y 分量观测,室内又作了坐标旋转处理,那么,就可以进一步确定裂缝带的方向。如果未作上述工作,也可以根据构造线走向,大致确定裂缝带的发育方向。
The anisotropy of medium in HBC area in Sichuan Province was found in the pro- cessing and interpretation of P and SH wave data.Shear wave passing through anisotropic medium splits into two different waves:fast shear wave whose polarization direction is parallel to fracture trend in formations,and the slow shear wave that pola- rizes in the direction perpendicular to fracture trend.Fast and slow shear wave sections can be respectively obtained by using different layouts and data processing methods.The anisotropy coefficient can be derived from the travel times of fast and slow S-waves ar- riving at the same interface;it can also be obtained from the ratio of SH-wave velocity to converted wave velocity.Anisotropy coefficient reflects fracture density.Then the direction of fracture zone can be determined by making both X,Y-component detection in data acquisition and coordinate revolution in data processing.Without the above mea- sures taken,we can roughly determine the direction of fracture zone in the light of structure-line trend.
出处
《石油地球物理勘探》
EI
CSCD
北大核心
1992年第2期247-260,共14页
Oil Geophysical Prospecting
关键词
横波
转换波
各向异性
裂缝带
shear wave, converted wave, anisotropy, fracture zone
