浅水三角洲分流河道沉积模式分类

Classification of Sedimentary Models of Distributary Channels in Shallow-water Deltas

通过浅水三角洲现代沉积考察分析,结合探地雷达(GPR)资料,对浅水三角洲分类方案和对应的沉积模式进行探讨。结果表明:根据分流河道弯曲指数和分叉参数,将浅水三角洲分为分叉平直河三角洲、分叉曲流河三角洲、分汇曲流河三角洲和分汇辫状河三角洲4种类型,并建立了各类型的沉积模式;浅水三角洲沉积模式的控制因素是分流河道下蚀作用和侧蚀作用的强度。将该沉积模式应用于渤海南部海域BZ25-1油田新近系明化镇组下段砂体内部构型的研究认为:明化镇组下段4油层组2小层(NmⅣ2)时期是低位体系域早期,发育分汇曲流河三角洲,河道间为侧积隔夹层;明化镇组下段4油层组1小层(NmⅣ1)时期湖平面上升,发育分汇辫状河三角洲,河道间为垂积隔夹层。这为下一步的开发方案设计提供了指导。

Through the analysis of modern shallow-water delta sediments,combined with the ground-penetrating radar(GPR)data,the classification and sedimentary models of shallow-water delta were discussed.The results show that according to flexural indices and bifurcation parameters of distributary channel,shallow-water delta can be divided into four types,including distributary straight river delta,distributary meandering river delta,barrier meandering river delta and barrier braided river delta,and the corresponding sedimentary models are built;the controlling factors of shallow-water delta sedimentary models are the strength of distributary channel incision and lateral erosion.The sedimentary models can be applied to the research on sand body architecture of Lower Neogene Minghuazhen Formation in BZ25-1 oilfield of South Bohai.The period of single layer 2 of oil layer group 4 in Minghuazhen Formation(NmⅣ2)is the early low system tract,distributary meandering river delta is developed,and the lateral accretion interbeds are developed;the lake level rises in the period of single layer 1 of oil layer group 4 in Minghuazhen Formation(NmⅣ1),barrier braided river delta is developed,and the vertical accretion interbeds are developed.The above research provides guidance for the next development project design.