南八仙油田第三系储层物性及其影响因素研究

Physical Property Characteristics and its Factors Controlling the Tertiary Reservoir of Nanbaxian Oilfield in Qaidam Basin

通过砂岩储层的扫描电镜观察、能谱和X-射线衍射分析,结合区域地质、钻井、测井和物性分析资料,分析了柴达木盆地南八仙油田第三系储层物性特征。研究结果表明,南八仙油田第三系储层粉砂岩-中砂岩的物性较好,而含砾砂岩物性差,且粒度与成分成熟度对物性均有影响;伊利石、伊/蒙混层和自生绿泥石矿物降低物性,高岭石改善物性;压实、硅质胶结、粘土矿物胶结作用降低物性,溶解作用有利于形成大量的次生孔隙,从而改善物性,压溶和碳酸盐岩胶结作用具有双重性;沉积相的发育控制沉积岩物性,水下分流河道砂体的储层物性较好,河口坝、远砂坝和席状砂的储层物性较差。

Through scanning electron microscopy(SEM),energy spectrum analysis of the sandstone reservoirs,X-ray diffraction,petrographic thin section and cast slice microscopicall identification of the sandstone reservoirs,in combination with regional geology,drilling,well logging and analysis of physical property,it analyzes the physical characteristics of five oil groups of reservoirs.From lithology,clay mineral,diagenesis and sedimentary facies,it puts forward that siltstone-medium sandstone,physical properties change gradually,and its gravel property is the worst due to its sorting,particle size and maturity of composition all affect the physical property;Illite,Illite/montmorillonite interlayer and authigenic chlorite reduce the property,kaolinite improves the property,Compaction,siliceous cementation,clay mineral cementation all reduce the property,dissolution effect can form a lot of secondary pores which can improve the property,pressure solution and carbonate cementation have dual nature;The development of sedimentary facies control sedimentary rock property,the physical property of sand reservoir of underwater distributary channel is good,estuary dam,far sand dam and sand sheet are relatively poor.