渤海湾盆地黄骅坳陷缓坡带新近系河流相层序发育特征及沉积充填演化

渤海湾盆地黄骅坳陷缓坡带新近系是以陆相河流沉积为主的地层,从层序地层学的角度寻找该类沉积中特征的岩性—地层油气藏是当前关注的焦点。以黄骅坳陷新近系明化镇组、馆陶组为研究对象,充分利用已有的岩心、钻井和地震资料,在层序界面识别基础上,建立了研究区高分辨率层序地层格架,划分出1个超长期旋回层序、7个长期旋回层序和若干中短期基准面旋回层序。馆陶组发育多断缓坡型层序地层模式,层序结构为仅保留基准面上升半旋回的非对称型,沉积充填以切割叠置的辫状河砂体为主;明化镇组发育稳定缓坡型层序地层模式,层序结构为上升半旋回大于下降半旋回的不完全对称型,沉积充填为泥包砂的曲流河沉积。层序发育早期的多断坡折带内侧辫状河复合砂体是研究区新近系最有利的储集砂体。

Sequence stratigraphy and sedimentary filling evolution of fluvial facies of the Neogene of gentle slope belt in Huanghua Depression,Bohai Bay Basin

The Neogene of gentle slope belt in Huanghua Depression of Bohai Bay Basin is mainly composed of continental fluvial sediments. To explore the lithologic-stratigraphic reservoirs by using the theories of sequence stratigraphy is the current focus. The Minghuazhen Formation and Guantao Formation of Neogene in Huanghua Depression are the research objects. Based on the existing core, drilling and seismic data, together with the sequence interface recognition, the high-resolution sequence stratigraphic framework in the study area was established, including one super long-term cycle sequence, seven long-term cycle sequence and a number of middle-term and short-term cycle sequence. Filled by superposed sand bodies of braided river, the sequence stratigraphic model of multi-fault gentle slope with the structure of unsymmetric type, which only retained the rising stage of base level cycles, was developed in the Guantao Formation. The sequence stratigraphic model of stable slope with the sequence structure of uncompletely symmetrical type, which was mainly composed of rising stage of base level cycles, was developed in the Minghuazhen Formation. The composite sand bodies of braided river on the inside of multi-fault slope break in the early stage of sequence development is the most favorable reservoir sand body in the study area.