浅水三角洲相沉积构成特征--以渤中25-1南油田为例

综合各种地质信息后分析认为,渤中25-1南油田新近系明化镇组主力油层为浅水三角洲相相沉积.在岩心观察和测井相分析的基础上,把浅水三角洲相划分为分支流河道、天然堤、决口和分支流河道间四种微相.各微相平面形态为分支流河道间夹分支流河道和天然堤,有时决口也发育在天然堤外侧.根据河道形态和沉积机理,分支流河道可分成两种类型底负载型和混合负载型,阐述了这两种河道各自特征并做了比较.由于河道窄,明确分支流河道期次、类型和分布是预测有利储层及布置井网的关键.

A discussion on features of sedimentary composition of shallow water delta facies: Taking BZ25-1S oilfield as an example

Based on comprehensive analysis of various geologic data, it is believed that the major pay zones in Neocene Minghuazhen Fm in BZ25 - 1S oilfield are deposits of shallow water delta facies. The shallow water delta facies is further divided into four microfacies, including distributary channel, natural levee, avulsion and interdistribu-tary, according on core observation and electrofacies analysis. Laterally, distributary channel microfacies and natural levee microfacies lie between interdistributaries and sometimes avulsion microfacies are also developed outside natural levee microfacies. According to shapes of channels and mechanisms of deposition, distributary channel microfacies can be divided into bed load type and mix load type. The characteristics of these two types of distributary channels are introduced and compared. Determination of stage, type and distribution of distributary channel micro-faices is critical to prediction of favorable reservoirs and placement of well patterns.