姬原西部延长组长61储层成岩作用与成岩相特征

针对姬原油田西部区块长6_1储层物性差、非均质性强、成岩作用较复杂的问题,文章通过铸体薄片、扫描电镜和物性资料分析手段,对其成岩作用和成岩相进行了研究。研究区以岩屑长石砂岩和长石岩屑砂岩为主,孔隙类型以残余原生粒间孔和次生溶蚀孔为主。主要的成岩作用有压实、胶结、溶蚀和交代作用。其中,压实作用和胶结作用是原生孔隙降低的主要原因,溶蚀作用形成的次生孔隙在一定程度上改善了储层物性。通过成岩作用、储层物性和沉积相综合研究,划分出了4种主要的成岩相:弱压实—强溶蚀相;中等溶蚀—硅质胶结—高岭石充填相;中等压实—弱溶蚀相和强压实—碳酸盐胶结相。最后结合储层常规测井特征对各成岩相在剖面上分布规律、组合模式进行分析表明,研究区长6_1储层在剖面上的岩相组合模式主要有侧向封堵式、同心环式和纵向互层式。

Diagenesis and diagenetic facies of reservoir Chang 61 in the Yanchang Formation in the western Jiyuan region

In the light of the poor physical property, strong heterogeneity and complex diagenesis of reservoir Chang 6₁ in the western JIYuan region diagenesis and diagenetic facies of this area are studied by using the casting thin section, scanning electron microscope and data analysis methods. Debris-feldspar sandstone and the feldspar-debris sandstone are main rock types. The pore is dominated by residual primary inter-grain pore and secondary dissolution pore. The main diagenesis are compaction, cementation, dissolution and replacement and the compaction and cementation are the main reasons for the decrease of the primary porosity, secondary porosity formed by the dissolution improves the reservoir property in a certain extent. Based on the comprehensive study of diagenesis, reservoir physical property and sedimentary facies the study area is divided into four main diagenetic facies:weak compaction-strong dissolution, medium dissolution-silicon cementation, kaolinite filling, medium compaction -weak dissolution and strong compaction-carbonate cementation facies. Combined with the conventional logging characteristics of reservoir Chang 6₁ we analyzed and summarized the distribution law and combination patterns of the main facies, i.e. the lateral sealing, concentric ring and interlayer distribution in the profile.