博兴洼陷沙四上亚段滩坝砂岩成岩作用及其与储层质量的关系

Relation between beach bar sandstones diagenesis and reservoir quality in the upper Es_4 of the Palaeogene in Boxing sag

根据砂岩铸体薄片、扫描电镜、X-衍射、电子探针和包裹体测温分析,对博兴洼陷沙四上亚段滩坝砂岩成岩作用进行了研究。结果表明,该区沙四上亚段滩坝砂岩储层处于中成岩A期,压实和胶结作用破坏了砂岩的原生孔隙结构,大大降低了砂岩的储集物性;后期有机酸溶蚀作用促使砂岩次生孔隙发育,改善了部分滩坝砂岩的储集性能。该区沙四上亚段滩坝砂岩可划分为压实、方解石胶结、不稳定碎屑溶蚀和压实-弱溶蚀4种成岩相类型,其中不稳定碎屑溶蚀成岩相控制的储层物性最好,方解石胶结和压实-弱溶蚀成岩相控制的储层物性较差。

Based on the data analysis of casting lamella, scan electron microscope, X-ray diffractions, electron-microprobe and homogeneous temperature of fluid inclusions ,the diagenesis of the upper Es4 reservoir in Boxing sag was investigated. The results show that the upper Es4 reservoir in Boxing sag is belong to the＂ A＂ middle diagenesis. The compaction and cementation damage the primary porosity which affects the reservoir quality. And the reservoir properties of part beach bar sandstone are improved by sec- ondary porosity developed by organic acid dissolutions. According to diagenesis ,the upper Es4 beach bar sandstone reservoir can be divided into four types including compaction facies, calcite cementation facies, unstable clastic dissolution facies and compaction and weak dissolution facies. The reservoir properties of sandstone controlled by unstable clastic dissolution facies are the best, and the reservoir properties of sandstone controlled by cementation facies and compaction and weak dissolution facies are poor.