渤海黄河口东洼古地貌对沉积相的控制作用

Control of paleo topography on sedimentary facies in Dongwa of Huanghekou,Bohai sea

根据最新的三维地震数据,结合钻井、岩心、壁心等资料,梳理了黄河口东洼渤南低凸起和莱北低凸起物源区沙一段沉积时期的古地貌,探讨了物源和古地貌(坡折、沟谷)等对沉积砂体富集差异性的控制作用,明确了古地貌控制作用下的沉积相类型和展布规模。研究表明:渤南低凸起为陡坡型物源,母岩岩性以前寒武系花岗岩为主,易于风化剥蚀,沟谷发育,砂体富集程度高,物源规模大,砂体范围广;莱北低凸起为缓坡型物源,主要发育前寒武系花岗岩、中生界安山岩和中生界凝灰岩,有效物源区面积小,供源能力弱,沟谷不发育,发育的辫状河三角洲规模较小。母岩类型是寻找优质富砂储层的关键,水流携带富砂沉积物通过古沟谷通道富集于地貌低势的洼陷区,富砂的辫状河三角洲是勘探的有利区带。

According to the latest 3D seismic data,combined with drilling,core,wall core and other data,the paleo topography of the provenance area of Bonan low uplift and Laibei low uplift in the east of Huanghekou was analyzed,the control effect of provenance,slope break,gully and other paleo topography on the enrichment difference of sedimentary sand body was discussed,and the sedimentary facies type and distribution scale under the control of paleo topography was defined.The results show that Bonan low uplift is of a steep slope type provenance,and its parent rock is mainly Precambrian granite,which is easy to be weathered and eroded,with developed gullies,high enrichment of sand body,large scale of provenance and wide range of sand body.Laibei low uplift is of a gentle slope type provenance,which mainly develops Precambrian granite,Mesozoic andesite and Mesozoic tuff.The effective provenance area is small,the supply capacity is weak,the gullies are not developed,and the braided river delta is small.The type of parent rock is the key to find high-quality sand rich reservoirs.The sand rich sediments through the paleo-ravine carried by water flow are enriched in low depression area,and the braided river delta rich in sand is a favorable area for exploration.