背斜顶部凸界面反射特征分析

Analysis of reflection characters for convex interface of anticlinal apex

四川石油管理局成都计算中心,成都 610212

Chengdu Congdu Computer, Center, Sichuan Petroleum Administration, Chengdu 610212

通常背斜顶部凸界面可用半径为R的一段圆弧来模拟, R的变化反映了凸界面的曲率大小, 即凸界面的宽窄程度, 而平界面只是凸界面的一种特例, 由此推导出凸界面的菲涅尔带表达式。在相同条件下, 凸界面的菲涅尔带小于平界面的菲涅尔带, 故凸界面具有发散能量的作用。R的变化对菲涅尔带面积有较大的影响, 从而引起反射能量有较大变化。应用模型正反演技术并结合实例分析发现, 凸界面反射波的动力学特征同平界面的比较具有它的特殊性, 而高陡背斜的叠加剖面与偏移剖面的反射特征也存在较大差异。因此, 不能单纯地用平界面的条件下得出的结论和观点来处理、解释背斜顶部的地震资料, 这一点在高陡背斜的地震勘探中显得十分重要。

The convex interface of anticlinal apex can be simulated with an arc. The radius of the arcR shows the curvture of the convex interface, while the flat interface is a special case of convex interface. From this, the expression of Fresnel zone of convx interface is derived. Under the same condition, the Fresnel zone of convex interface is smaller than that of flat interface. Therefore the convex interface has a function of scattering energy. The variation of R has a larg influence on the Fresel zoneand therebby results in the change of reflected energy.From the inversion and example analysis, it can be found that the dynamic characteristic of convexinterface renected wave is specific in comparison with that of flat interface reflected wave, and that thestack section of high dipping anticline is differant from the migration section in reflection characters.Hence, those conlusions derived under flat interface condition can not simply used for the processing andinterpetation of sesmic data from anticlina apex. This viewpoint is very important in seismic prospecting of high dipping anticline.