浅水三角洲砂体分散体系控制因素研究——以渤海海域石臼坨凸起明化镇组下段为例

Study on Control Factors of Dispersion System in Shallow-water Delta Sand Body——A case study of Lower Minghuazhan Formation in Shijiutuo Uplift of Bohai Sea Area

基于钻井、测井、地震及古生物资料,对渤海海域石臼坨凸起明化镇组浅水三角洲砂体分散体系的控制因素进行研究。结果表明,浅水三角洲沉积体系内砂体的展布受层序结构、微古地貌和基准面旋回的共同控制。层序结构控制了砂体垂向上的非均一性,低位体系域砂体最富集、其次为晚期高位体系域,早期高位体系域和湖侵体系域砂体不发育。微古地貌控制了砂体横向非均一性,次级洼地区更利于分流河道与河口坝沉积,砂体相对富集。基准面旋回控制了砂体叠置样式,基准面的升降决定了砂体的展布规模和垂向的连通性。

Based on the drilling,logging,seismic and paleontological data,the control factors of sand dispersion system in the shallow-water delta sedimentary system were studied in Lower Minghuazhan Formation of Shijiutuo Uplift in Bohai Sea Area.The results indicated that the sandbody distribution in the shallow-water delta dispersion system was controlled by sequence structure,micro geomorphology and base-level cycle.the non-uniformity of sandbody was vertically controlled by the sequence structure,sandbody in the Lowstand systems tract was the richest,followed by the late highstand systems tract,and the sandbody in early highstand system tract and transgressive system tract were undeveloped.its horizontal non-uniformity was controlled by micro geomorphology,the secondary depression area was more beneficial for the deposition of distributary channel and mouth bar,where the sandbody was relatively enriched.The base-level cycle controls the sandbody superimposition style.The base-level rise and fall determine the distribution scale and vertical connectivity of the sandbody.