青平川油田延长组长2沉积微相与油气分布

Characteristics of the sedimentary microfacies and the oil & gas distribution of Chang 2 reservoir of Yanchang Formation in Qingpingchuan Oilfield

根据地表露头、钻井岩心、测井资料以及粒度分析,并结合前人对鄂尔多斯盆地陕北斜坡东部延长组长2油层组沉积微相研究成果,指出青平川油田长2油层组为辫状河沉积,主要的沉积微相类型有心滩、河道充填以及漫滩和漫滩沼泽等,其中心滩为研究区微相类型的显著特点.对研究区长2油层组的试油试采数据、含油井段岩心观察以及测井相分析研究表明,厚度较大、连通性较好的河道砂体为主要的油气富集相带,但同时受到储层非均质性、构造和水动力等因素的影响,油层被分割成不规则的块状,形成构造-岩性油藏或构造-水动力油藏等;长2辫状河河道砂体是良好的储层,下部长7烃源岩是直接的油气来源,上部长1含煤地层对其起到区域盖层作用,从而在纵向上形成良好的生储盖组合.

Based on the outcrop,core and logging data and grain-size analysis result,being combined with the research works of the predecessors on the sedimentary facies of Chang 2 reservoir of the Yanchang Formation in the east of Shanbei Slope of Ordos Basin,it is held that the Chang 2 reservoir of Qingpingchuan oilfield belongs to braid river deposition,consisting of channel bar,channel filling,flood plain,back swamp and so on.According to the research of well testing,production testing,core analysis in the hydrocarbon bearing interval and electrofacies analysis,it is shown that the thick channel sand bodies with better connectivity are the main hydrocarbon enrichment facies belts,but at the same time,they are influenced by reservoir heterogeneity,structure and hydrodynamic pressure.The reservoir is divided into irregular blocks to form a structural-lithological pool or structural-hydrodynamic pool,etc.Chang 2 braided river channel sand body is believed to be good reservoir,and the Chang 7 hydrocarbon source rock below it is its direct hydrocarbon source,the Chang 1 coal-bearing strata above it plays a role of regional caprock,and therefore a good source-reservoir-cap assemblage is formed in vertical direction.