鄂尔多斯盆地延长组长9小层致密砂岩含油性控制因素

Research on Oil-bearing Control Factors of the Chang 9 Tight Sandstone of Yanchang Formation in the Ordos Basin

综合分析鄂尔多斯盆地延长组长9小层典型的致密砂岩储集层物性、岩心照片及荧光照片等资料,研究长9小层致密砂岩含油性控制因素。研究表明,鄂尔多斯盆地延长组长9小层致密砂岩含油性主要受物性、非均质性、岩性等因素的影响,具体表现为:(1)高塑性岩屑含量影响砂岩含油性,高塑性岩屑含量越高,砂岩物性越差,其含油性也越差;(2)碳酸盐胶结物含量越高,砂岩物性越差,其含油性也越差;(3)物性与其含油性正相关;(4)非均质性,其对含油性的影响巨大,容易造成纵横线油气运移的"隔断",油气难以进入储集层成藏;(5)岩性,水下分流河道砂体岩性以灰白色含泥砾中砂岩或中-细砂岩为主,而水下分流河道间以深灰色泥岩、粉砂质泥岩或泥质粉砂岩为主,水下分流河道砂在该层段含油性好;(6)裂隙,其对储层的运聚具有极大的改善作用。结合安定组沉积末期长9输导层顶面石油优势运移路径的模拟结果,优选出杏河地区向镰刀湾东方向、西河口-安塞-下坪、沿河口-冯庄北有利勘探区带。

The oil-bearing control factors of the Chang 9 tight sandstone was studied in this paper based on the analysis of reservoir physical property,the core pictures and fluorescent image. The results are as followings:( 1) The higher content of high plastic rock debris is,the worse sandstone physical property is,and the worse oil-bearing is;( 2) The higher content of carbonate cement correlates negatively with oil-bearing;( 3) The physical property correlates positively with the better oil-bearing;( 4) Heterogeneity had a huge impact on oil-bearingled to petroleum partition in vertical and horizontal lines;( 5) The lithology of sand bodies in underwater distributary channel mainly are gray mud gravel medium sandstone or middle-fine sandstone with good oil-bearing but that in interdistributary bay is dark grey mudstone,silty mudstone or argillaceous siltstone;( 6) Fractures play a good role in improving the reservoir property. The simulated results also indicated the migration path of Chang 9 reservoir and the favorable exploration areas was selected that areas of Xinghe region to eastern Liandaowan,Xihekou-Ansai-Xiaping,Yanhekou-north of Fengzhuang.