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本文用地震地层学的方法,对盐城凹陷地震剖面作了初步的分析.根据地震反射波的终止特征,将盐城凹陷新生界划分成11个地震亚层序,并根据各亚层序的区域意义,分别归属于3个层序或2个超层序。在地震层序划分的基础上,作者利用地震反射结构、振幅、连续性和层速度特征,着重对B_3和B_6亚层序进行了地震相分析。结合本区现有的钻井地质资料,进行综合转相工作,恢复了渐新统的沉积相和沉积环境,指出油气聚集的有利部位。文章认为:渐新世早期,盐城凹陷是向心充填式断陷湖泊沉积。多源水流自北向南,自西向东汇聚于南部深湖区。凹陷南陡北缓,从南向北呈湖泊——扇三角洲——三角洲平原相的沉积特征。南部陡坡带发育有洪积——冲积沉积。渐新世后期,向心式断陷盆地转为超越式以河流相沉积为主的沉积盆地。来自北、东北、西三个方向的水流,在凹陷中部汇聚后,沿盐城大断裂前缘向东流去。作者指出:小型的扇三角洲是B_8亚层序沉积类型油气勘探的最有利部位。主河流砂相沉积,结合构造的有利部位是B_6亚层序构造——沉积复合次生油气勘探的有利部位。
In this paper, the seismic stratigraphy method is used to analyze the seismic profile of Yancheng Sag.According to the termination features of the seismic reflection wave, the Cenozoic strata of Yancheng Sag are divided into 11 seismic sub-sequences, and according to the regional significance of each sub-sequence , Belong to three or two super-sequence respectively. Based on the sequence of seismic sequences, the authors make an analysis of the seismic facies by using the characteristics of seismic reflection structure, amplitude, continuity and velocity of layer. Combined with the existing drilling geological data in this area, a comprehensive phase inversion work was carried out to restore the sedimentary facies and depositional environment of the Oligocene, pointing out the favorable sites for hydrocarbon accumulation. The article argues that, during the Oligocene, the Yancheng sag was a centripetal-faulted lacustrine sedimentation. Multi-source water from north to south, from west to east converge in the southern deep lake. The depression is steeply north-easterly and sedimentary features of lacustrine-fan delta-delta plain facies from south to north. The southern steep slope developed alluvial-alluvial deposits. In the late Oligocene, the Cenozoic faulted basin turned into a sedimentary basin dominated by fluvial facies. The water flows from the north, northeast and west directions converge in the middle of the depression and flow eastwards along the front of Yancheng Great Fault. The authors point out that small fan delta is the most favorable site for hydrocarbon exploration in B_8 sub-sequence sedimentary types. Sedimentary facies deposition of the main river and favorable sites of the combined structure are favorable sites for B 6 sub-sequence structural-sedimentary composite petroleum exploration.