大庆长垣及以东泉三、四段扶杨油层浅水湖泊-三角洲体系沉积特征

Shallow Lacustrine-Delta System Deposition Characteristics of Fuyang Oil Bed in Daqing Placanticline and Quan3 and Quan4 Member to Its East

大庆长垣及以东泉三、四段扶杨油层沉积属浅水湖泊-三角洲体系,发育有浅水湖泊三角洲相和湖泊相。浅水湖泊三角洲相可划分三角洲分流平原和三角洲前缘两种亚相,三角洲分流平原亚相包含水上分流河道、天然堤、决口扇、泛滥平原泥等4种微相;三角洲前缘亚相包含水下分流河道、天然堤、决口扇、分流间湾泥、河口坝、前缘薄层砂等6种沉积微相。湖泊相可划分为滨湖亚相、浅湖亚相和还原湖,滨湖亚相包含泥滩、混合滩、砂滩等3种沉积微相;浅湖亚相包含浅湖砂坝、浅湖泥两种沉积微相。沉积微相以分流河道砂最为发育,是有利的储集层;由于泥质岩微相发育,常常包裹或覆盖分流河道砂、天然堤、决口扇、河口坝、薄层砂等砂体,形成良好的储盖组合,有利于形成岩性圈闭油气藏。认清沉积相的演化特点及砂体微相的分布规律,对于砂体预测、储量估算、寻找岩性圈闭油气藏等都具有重要的指导意义。

The deposition of Fuyang oil bed in Daqing placanticline and Quan3 and Quan4 Member to its east belongs to shallow lacustrine-delta system. Shallow lacustrine-delta facies can be divided into delta distributary plain subfacies and delta front subfacies. Delta distributary plain subfacies include 4 kinds of microfacies: overwater distributary channel, natural levee, crevasse spray, and flood plain mud; Delta front subfacies include 6 kinds of microfacies: underwater distributary channel, natural levee, crevasse spray, bay mud between distributary channels, mouth bar and frontal thin sand layer. Lacustrine facies can be divided into shore lacustrine subfacies, shallow lacustrine subfacies and reducing lacustrine. The distributary channel sand developed most, and it is favorable reservoir; muddy rock microfacies often form good reservoir and seal assemblage, which is favorable for the formation of lithologic trap hydrocarbon reservoir. Clear understanding of the evolution features of sedimentary facies and distribution rules of sand body microfacies is meaningful to sand body prediction, reserve estimation and lithologic trap hydrocarbon reservoir discovery.