松辽盆地北部卫星地区泉四段沉积相特征

Characteristics of Sedimentary Facies of the 4th Member of Quantou Formation of Weixing Area in the Northern Songliao Basin

松辽盆地北部卫星地区泉四段以泥岩、粉砂质泥岩、泥质粉砂岩和粉砂岩沉积为主,通过对岩石学特征、沉积构造和测井相特征等分析,确定研究区泉四段为一套退积型浅水三角洲沉积,主要发育三角洲平原和三角洲前缘两个亚相,进一步可划分为分流河道、决口扇、洪泛沉积、水下分流河道、水下决口扇和支流间湾等微相.高分辨率层序地层研究表明,研究区泉四段内部划分为7个V级层序：Q4-SSC1、Q4-SSC2、Q4-SSC3、Q4-SSC4、Q4-SSC5、Q4-SSC6、Q4-SSC7;Q4-SSC1～Q4-SSC7沉积期整体表现为由三角洲平原向三角洲前缘过渡的湖侵沉积过程,各层序内部砂地比值逐渐减小,有利砂体在Q4-SSC1沉积时期最为发育。

Quan-4 member of Weixing area in Songliao Basin was mainly consisted of mudstone、silty mudstone、pelitic siltstone and siltystone.Based on the petrology,sedimentary structure and logging facies etc.Quan-4 member in the studied area is confirmed as retrograding shallow delta depositional system which develops delta plain and delta front subfacies,and additional subdivided into distributary channel,crevasse splay,flood sedimentary,submerged distributary channel,submerged crevasse splay and interdistributay bay etc.Study of high resolution sequence stratigraphy shows that：Quan-4 member of study area can be divided into 7 V level sequences.Q4-SSC1、Q4-SSC2、Q4-SSC3、Q4-SSC4、Q4-SSC5、Q4-SSC6、Q4-SSC7; During the deposition of the 4th member of Quantou Formation,from Q4-SSC1 ～ Q4-SSC7,the sedimentary facies is evolved from delta plain to delta front which reflects a lake intrusion sedimentary process,meanwhile the ratio of sandstone and strata has been reduced gradually,and the favorable reservoir is most developed in Q4-SSC1.