琼东南盆地松南-宝岛凹陷梅山组碎屑岩储集性及成岩作用研究

Physical properties and diagenesis of the clastic rocks from the Meishan Formation in the Songnan-Baodao depression, Qiongdongnan Basin

通过岩石铸体薄片和扫描电镜观察,结合压汞测试、微米CT扫描技术、X射线衍射、流体包裹体分析等,刻画琼东南盆地凹陷梅山组碎屑岩的岩石学面貌和物性特征,研究成岩作用以及对储集性能的影响,并通过成岩岩相分析预测了有效储层的可能发育区带。研究表明,琼东南盆地凹陷梅山组碎屑岩岩性以长石质石英细砂岩、粉砂岩为主,点-线接触,颗粒支撑结构。胶结物类型主要是黏土矿物和碳酸盐矿物。孔隙类型主要是粒间溶孔,其次为残余粒间孔和粒内溶孔,孔隙大小中等,以细-特细喉道为主,具有中孔、低渗-特低渗特征。破坏性成岩作用主要是压实作用,其次为胶结作用,主要的建设性成岩作用是溶蚀作用。三角洲前缘可能是研究区梅山组碎屑岩中有效储层发育的有利区带。

In terms of the examination of thin sections and scanning electron photomicrographs,combined with mercury injection test,micron-scale CT Scanning technique,X-ray diffraction analysis and fluid inclusion analysis,the present paper deals with the petrological features,physical properties of the clastic rocks,diagenesis and its effects on the reservoir quality,and prediction of the potential favourable zones based on the diagenatic facies analysis for the Meishan Formation in the Songnan-Baodao depression,Qiongdongnan Basin.The clastic rocks in the study area consist dominantly of fine-grained feldspathic quartz sandstone and siltstone,with point-line contacts and grain-supported textures.The cement types contain clay minerals and carbonate minerals.The porosity types are composed of intergranular solution openings,residual intergranular solution openings and intragranular solution openings,with fine-to extra-fine throats,and mesopores and low-to extra-low permeability.The destructive diagenesis is represented by compaction and cementation while the constructive diagenesis includes dissolution.The delta front may be the potential favourable zone for the development of the effective reservoir rocks in the Meishan Formation in the study area.