岩性油气藏储层非均质性成因模式——以鄂尔多斯盆地榆林—米脂地区盒8段为例

Genesis modes of heterogeneity of lithologic hydrocarbon reservoir:a case study in He8 member of Xiashihezi formation,Yulin-Mizhi area,Ordos Basin

储层的非均质性是影响岩性油气藏勘探开发效益的关键因素之一。通过分析鄂尔多斯盆地榆林—米脂地区的基准面旋回层序叠加样式与砂体成因、储层物性特征和成岩相组合特征,识别出3种类型的基准面旋回叠加样式,不同位置和不同沉积体系中发育不同的基准面旋回叠加样式;主要分为压实、压实—胶结和胶结—溶蚀3种成岩相组合;建立了物性向上变化不大、物性向上变差、物性向上变好、物性向上变差后复变好、物性向上变好后复变差和物性变化复杂6种储层非均质性成因模式。基准面旋回变化和成岩作用是岩性油气藏非均质性的主要控制因素。在中期基准面旋回早期,充填在层序界面之上的进积—加积型的分流河道和水下分流河道砂体以发育物性向上变化不大、物性向上变差和物性向上变差后复变好3种成因的非均质性储层为主,非均质性相对较弱,为最有利的储层发育相带。

The heterogeneity of reservoir is a key factor which affects the exploration and exploitation.This paper analyses the characteristic of the reservoir physical property,diagenetic facies and sequence filling types of the base-level cycle,and established six modes of heterogeneity reservoir formed by base-level cycle,and then suggests that base-level cycle and diagenetic facies is the main control factor of the heterogeneity of the subtle gas-oil reservoir.In conclusion,in the early base-level cycles,the superimposed progradational-aggradational sandbody of the distributary channels and the submerged distributary channels developed theⅠ,ⅡorⅣgenesis modes of heterogeneity reservoir with relatively weak heterogeneity,which is the most favorable facies belt of reservoir.