通过观察岩石及铸体薄片和常规物性分析等方法，对鄂尔多斯盆地镇北地区长4＋5油层组储层砂体的岩石学特征、成岩作用、储集类型和主要控制因素进行了分析。研究表明：长4＋5油层组储层砂体的孔隙主要以粒间孔和长石溶孔为主，粒间溶孔次之；成岩作用包括建设性成岩作用和破坏性成岩作用，建设性成岩作用包括溶蚀作用、绿泥石黏土膜形成作用，破坏性成岩作用包括机械压实作用、石英及长石的次生加大、碳酸盐胶结作用，其中压实作用和碳酸盐胶结是造成本区砂岩原生孔隙大量丧失的主要原因。以成岩作用为基础，建立了镇北地区长4＋5油层组5种成岩相类型。储层的发育受沉积相、成岩作用和成岩相的影响。有利储层发育的沉积微相砂体类型为三角洲平原分流河道和三角洲前缘水下分流河道砂体，有利的成岩作用和成岩相为长石溶孔相、高岭石弱溶蚀相和绿泥石环边残余孔相。%Based on the comprehensive analysis of rocks,cast thin sections and conventional physical property,this paper analyzes the lithology characters,lithogenesis, storage category and main controlling factors of the Chang 4+5 oil layer group in the Zhenbei area of Ordos Basin.The result shows that among the several kinds of pores in Chang 4+5 oil layer group,the feldspar dissolved pore occupies first place and the intergranular dissolved pore comes second.This oil layer group has two types of lithogenesis.One is the constructive lithogenesis which contains denudation and chlorite argillan neogenesis and the other is the destructive lithogenesis which includes the secondary enlargement of quartz and feldspar,mechanical compaction and carbonate cementation.The last two kinds of lithogenesis play the main role in causing the loss of the sandstone primary pore in this area. Based on these lithogenesis,this paper builds 5 types of lapidofacies of Chang 4+5 oil layer group in the Zhenbei area.Sedimentary facies,diagenesis and diagenetic facies are affected by the development of reservoirs.The delta plain distributary channel and the delta frontal subaqueous distributary channel sand bodies are the categories of the sand body of sedimentary microfacies which are beneficial to the development of reservoirs.The favorable diagenesis and lapidofacies consist of the feldspar dissolved pore phase,the kaolinic thin corrosion phase,and the chlorite rim residual pore phase.
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