反射地震在冀中坳陷保定凹陷精细地质结构探测中的应用

保定凹陷位于渤海湾盆地冀中坳陷西缘,其西侧以太行山山前断裂为界与太行山隆起相邻,查明凹陷内深部构造和精细地质结构,对油气勘探和深部热储调查评价有着重要的意义,同时对太行山山前断裂的发育特征的研究也有一定的帮助。反射地震勘探在深部地质结构探测中具有高精度、高分辨率的优势,因此,在保定凹陷构造单元及其外围开展了深反射地震测量,采用炸药震源激发、长排列多道接收、高覆盖次数的工作方法,获得了高品质的原始地震记录。通过静校正、叠前噪声压制、反褶积和偏移叠加等高精度成像数据处理方法技术,得到能清晰反映测区深部地质结构和构造特征的反射地震剖面。地震剖面清楚地查明了凹陷内断裂构造特征,以此划分了内部次级构造单元。根据地震剖面上识别的角度不整合面,划分了基底构造层、断陷期构造层和凹陷期构造层,并据此探讨了3个构造层的构造演化过程。

Application of the seismic reflection method in detecting the fine-scale geological structure of the Baoding sag,Jizhong depression

The Baoding sag is located on the western margin of the Jizhong depression,Bohai Bay basin.It is adjacent to the uplift of the Taihang Mountains in the west,with the piedmont fault of the Taihang Mountains as the boundary.Identifying the deep structures and fine-scale geological structure of the sag is greatly significant for the hydrocarbon exploration and the survey and evaluation of deep thermal reservoirs in the sag.Meanwhile,it also facilitates the research on the characteristics of the piedmont fault of the Taihang Mountains.Since the exploration using the seismic reflection method feature high precision and high resolution in the detection of deep geological structure,this study conducted the seismic reflection-based exploration in the tectonic units of the Baoding sag and their periphery.First,high-quality original seismic records were obtained by means of explosive source excitation,long-array multi-channel reception,and high coverage times.Then,seismic reflection sections that can clearly reflect the deep geological structure and structural characteristics of the survey area were obtained using high-precision imaging data processing techniques,such as static correction,pre-stack noise attenuation,deconvolution,and offset stack.The obtained seismic sections allowed for determining the characteristics of faults in the sag and internal secondary tectonic units.Based on the angular unconformities identified in the seismic sections,the basement structural layer and the structural layers formed during the faulting stage and the depression stage of the Baoding sag were also determined,and,accordingly,the tectonic evolutionary process of the three structural layers were discussed.