鄂尔多斯盆地镇北油田长8油层组储层影响因素分析

Influential Factors of Chang 8 Oil Reservoir of Yanchang Formation in Zhenbei Area of Ordos Basin

结合岩性观察、薄片鉴定、电镜扫描、阴极发光和物性分析等资料,研究了鄂尔多斯盆地镇北油田长8油层组储层特征及影响因素。研究表明,镇北油田长8油层组储层处于三角洲沉积交汇处,主要发育三角洲前缘亚相砂体。岩性以岩屑质长石砂岩为主,平均孔隙度9.64%,渗透率0.68mD,属低孔-特低孔、低渗-特低渗储层。储集性能主要受沉积环境和成岩作用的影响,水下分流河道、河口坝和远砂坝砂体是有利的储集空间。压实-压溶作用、胶结作用是导致孔隙度减小的主要原因,使储集层物性变差;溶解作用形成大量次生孔隙,极大程度上改善了储层的储集性能。

The characteristics and the influential factors of Chang 8oil reservoir of Yangchang Formation in Zhenbei Area of Ordos Basin were studied by core observation,core slice identification,scanning electron microscope,cathodoluminescence and physical properties analysis.Study result indicates that Chang 8oil reservoir is at the intersection of delta deposit,where delta front subfacies is mainly developed.It is mainly composed of lithic arkose sandstone with an average porosity of 9.64% and permeability of 0.68mD,it is classified into low-ultra low porosity and low-ultra low permeability reservoir.Reservoir performance is mainly affected by sedimentary environment and diagenesis.Underwater distributary channel,mouth bar and distal bar are the favorable reservoir spaces.Compaction-presolution and cementation are the major causes of porosity decrease,by which poor reservoir physical property is caused.Moreover,a large amount of secondary pores are formed by dissolution,it greatly improves reservoir property.