多方位拖缆地震数据融合处理在惠州凹陷的应用

Application of fusion processing of multi-azimuth towing cable seismic data in Huizhou sag

目前惠州凹陷已实现全三维覆盖,但常规三维地震的常规拖缆采集方位角窄、获得的地下反射波场信息不完整,难以实现对复杂断裂及潜山构造的有效照明。而宽方位地震对陡倾角成像及复杂构造成像相比常规拖缆采集有明显改善,但施工难度较大、采集成本也十分的高昂。为此,进行了基于多次采集的多方位拖缆地震数据开展融合处理试验。结果表明:①基于单方位差异化宽频保幅处理、保持方位优势的一致性处理、方位各向异性网格层析速度建模和真方位PSDM融合处理,较好地解决了采集方位变化带来的速度各向异性问题,实现了对不同方位地震数据的有效融合;②不同方位融合处理后的地震成果资料断面成像清晰,古近系至基底成像品质明显改善、中深层地震反射波组特征清晰,频率信息丰富。结论认为:将现有的不同方位采集的拖缆地震数据进行匹配融合处理,有效增加了采集照明度,改善了地震成像效果,提高了地震资料信噪比,是一种有效且低成本的勘探方式。

To date,Huizhou sag has been fully covered by 3D seismic survey.However,it is difficult to realize effective illumina-tion for the complex faults and buried-hill structures by conventional 3D seismic acquisition with conventional towing cable,since it features narrow azimuth and obtains incomplete information of underground reflection wave field.In contrast,wide azimuth seismic survey has better performance in imaging of steep dip angle and complex structure,but it is hard to be operated with high cost of ac-quisition.In this study,a fusion processing experiment was made based on multi-azimuth towing cable seismic data collected by mul-tiple acquisitions.The results indicate that(1)the combination of single-azimuth differential broad-frequency and amplitude-retention processing,azimuth-dominated consistency processing,grid tomographic velocity modeling of azimuthal anistropy,and true-azimuth prestack depth migration(PSDM)processing effectively solves the problem of velocity anisotropy caused by the change in seismic ac-quisition azimuth,so that seismic data of different azimuths can be fused effectively;and(2)by the fusion processing,the clear profile imaging from seismic data,the improved imaging quality of Paleogene to basement,clear features of medium-deep seismic reflection wave groups,and rich frequency information are obtained.It is concluded that the fusion processing of multi-azimuth towing cable seismic data can effectively improve the acquisition illumination,seismic imaging quality and signal to noise ratio of seismic data.It is an effective and low-cost exploration technique.