The Formation Mechanism Of Low Oil Saturation Reservoirs In Moxizhuang Oilfield,junggar Basin On Micro-scale

The main reservoir of Moxizhuang Oilfield in Junggar Basin is the second member of Sangonghe Formation.Its oil saturation is generally less than 40%,which is a low oil saturation reservoir.Based on the study of structural features,stratigraphic features and sedimentary characteristics,this paper systematically analyzes the petroleum geological characteristics of low oil saturation reservoirs.Then,micro-CT and constant-speed mercury intrusion were used to systematically study the pore structure of the reservoir and classify different pore structure types.At the same time,in order to explore the influence of oil saturation on the micro scale,this paper selects typical core samples to carry out one-dimensional physical simulation experiments,looking forward to analyzing the characteristics of oil seepage characteristics and oil saturation growth patterns as well as finding out the relationship between oil saturation and filling power,physical properties and pore structure.In addition,the paper also discusses the effects of clay minerals,irreducible water saturation,and reservoir adjustment on oil saturation.According to the research of this thesis,we can Fig.out that:(1)The microscopic pore structure of the reservoir of the second member of the Sangonghe Formation can be divided into four types: large pore with fine throat,medium pore with thick throat,small pore with fine throat and small hole with micro throat.And different types of pore structure have different oil saturation growth modes.(2)Oil saturation is weakly affected by single factor,and it is controlled by reservoir physical properties and filling power.(3)High clay mineral content,high irreducible water saturation,and reservoir adjustment are also responsible for the low oil saturation of the reservoirs in the target area.