松南地区下白垩统九佛堂组沉积相特征

Characteristics of Sedimentary Facies in Cretaceous Jiufotang Formation in Songnan Area

松南地区白垩纪断陷层九佛堂组是该区基底大断裂剧烈活动时期沉积的主要含油气层段。为明确该组含油气前景,通过对测井、岩心、地震剖面等资料的系统研究,发现该区九佛堂组发育近岸水下扇、扇三角洲、三角洲、湖泊和浊积扇5种沉积相类型,其中近岸水下扇和扇三角洲多分布在断陷盆地陡坡区,三角洲多分布在断陷盆地缓坡区,湖泊分布在扇三角洲、三角洲周边及深凹带中央地带。平面上从断陷边缘至中心,沉积相由近岸水下扇、扇三角洲相或三角洲相渐变为滨浅湖相至深湖相。

Cretaceous Jiufotang Formation in Songnan Area was the main oil and gas reservoir development staged in the basement faults with intense activity.To clarify the hydrocarbon potential of Jiufotang Formation,based on the research of well logging,core and seismic section from the studied area,nearshore subaqueous fan facies,fan delta facies,delta facies,turbidite fan facies,lacustrine facies were found out,of which the near-shore subaqueous fan facies and fan delta facies were mainly distributed in the steep slope zones of the faulted basin.The delta facies was mainly developed in the gentle slope belt and lacustrine facies was organized around the fan delta and delta facies and in the central zone of the deep area.From the margin to the centre of the depression,the sedimentary facies is gradually turned from near-shore subaqueous fan,fan delta or delta facies to lacustrine facies.