宽/窄方位角勘探实例分析与评价(二)

Analysis and appreciation of wide/narrow azimuth exploration cases(II).

前人的研究表明,现有的各向同性和各向异性偏移成像理论,均难以有效地消除各向异性断裂带的影响,如在叠前深度偏移处理中经常会遇到断裂带成像模糊(阴影带)问题。为此本文针对在中国西部吐鲁番盆地山前断裂带采集的全方位角三维地震勘探数据,以断裂带及其相关的裂缝性储层为勘探目标开展了宽/窄方位角观测效果评价研究。研究中对数据采用相对保持振幅的常规时间域处理。通过分析不同方位角观测的叠加剖面、相同CDP分析点道集、相干数据体等地震属性信息之间的差异后认为:在地层相对比较平坦、速度场相对简单和具有一定信噪比的条件下,对于断裂较为发育的地区而言,采用宽方位角(纵横比大于0.5)勘探比窄方位角可获得更好的多方向小断层的成像效果,同时可以获得较清晰的断裂带及其储层的空间范围。

The studies of the predecessors showed that current isotropic and anisotropic migrated imaging theories are difficult in effectively eliminate the in- fluence of anisotropie faulted belts, for example, the issue of smeared imaging for faulted zone (shadow area) can he often met in prestaek depth migration processing. For that reason, the paper carried out appreciated study of effects of wide/ narrow azimuth survey by using 3-D full-azimuth seismic data acquired on piedmont fracture belts of Tulufan Basin in the west of China and taking fracture belts and its relevant fractured reservoir as exploration targets. The data processing in the study was ordinary processing in time domain with relative amplitude reservation. It is considered through analyzing the differences between seismic at tributes information such as stack sections with different azimuth angles, gathers with same CDP analyzed points and coherent data volume in different azimuths that in a condition of comparatively plain strata ,relative simple velocity fields and hav ing certain signal to-noise ratio, using wide azimuth (aspect is greater than 0. 5) survey can obtain better imaging results of multi oriental minor faults than by narrow azimuth survey in developed fracture belts and can also obtain more distinct faulted zone and spatial scope of reservoir at the same time.