苏里格气田东二区二叠系山西组山2段沉积相特征及演化

摘要

为明确苏里格气田东二区二叠系山西组山2段沉积相特征及类型,采用现代沉积学理论为指导,综合岩芯观察、岩石薄片鉴定、测井曲线特征等资料进行分析,通过沉积构造识别、测井相分析及古生物标志鉴定,系统性对东二区山2段沉积微相类型及特征进行研究;在单井相及沉积序列研究基础上,结合沉积相连井剖面及砂地比特征,刻画了山32~山12沉积微相展布特征及时空演化.研究结果表明:山2沉积期东二区北部为近源砂质辫状河沉积,主要发育心滩、辫状河道、泛滥平原、洪漫沼泽等沉积微相,垂向上"砂包泥"特征明显,发育"辫状河道-河漫滩"沉积序列;南部为曲流河沉积,主要发育边滩、河道充填、漫滩、天然堤等沉积微相,垂向上"二元结构"特征明显,发育"曲流河道-河漫滩"沉积序列.山32~山12沉积期北部辫状河与南部曲流河的分界位置逐渐向北迁移,迁移距离约20 km.研究成果对该区砂体展布规律及储层综合评价研究具有指导意义,北部辫状河心滩与南部曲流河边滩是形成有效储层的有利相带.%In order to understanding the types and characters of sedimentary facies of Shanxi Forma-tion's second member(S2)East Ⅱ Block in Sulige gas field,this paper has made a systematic study and a detailed description of sedimentary distribution and evolution of S 2's three single layers S32,S22 and S12from bottom to top,based on sedimentary theory,with the methods of single well facies analysis and sedimentary sequence study,combined cross well facies and sand thickness to formation thickness ratio characters using data on cores,thin section,well logging and so on.This study shows that,in north of this block during the deposition period of S2,near-source braided river facies with developing middle channel bar,braided river channel,flood plain,flooded swamp etc.deposition microfacies developed;and in south,meandering river facies,with point bar,meandering river channel,flood plain,nature lev-ee microfacies and characterized by"dual structure"in vertical,with meandering river channel at the bottom and flood plain at the top. The boundary of braided river facies and meandering river facies transferred from south to north for about 20 km during the deposition period of S2.These achievements help us to understand the law of sand distribution and thus to make a comprehensive study and evalua-tion of reservoir.This research also indicates that northern braided river middle channel bar and the southern meandering river point bar are favorable microfacies to effective reservoirs.