致密砂岩填隙物特征及其对储层的影响

Characteristics of Interstitial Material in Tight Standstone and Its Effects on Reservoir

鄂尔多斯盆地中北部二叠系山1—盒8段为一套富含同沉积火山物质的致密砂岩,与普通的陆源碎屑岩相比,其填隙物类型多样、成分复杂、成岩演化程度高。填隙物主要包括同沉积火山灰、黏土矿物、碳酸盐胶结和交代物、硅质胶结物和少量细云母屑、泥屑、碳屑。针对致密砂岩中填隙物与孔隙演化相关性问题,在储层岩石学特征分析的基础上,利用铸体薄片、扫描电镜及阴极发光等分析测试手段开展了填隙物的成因、特征、成岩演化等方面的研究。研究表明,孔隙中充填的同沉积火山灰物质是次生溶孔形成的主要母质,而晚成岩期的铁方解石胶结物使残留的孔隙再次遭到强烈的破坏,舍一定量淀高岭石的储层孔隙相对发育。

The Shan1-He8 Member is tight sandstone with many consedimental volcanics in the middle-north of Ordos Basin.Compared with common clastic rocks,the fillings of tight sandstone are of many types,complicated components,and intensive diagenetic evolution.The fillings consist of consedimental volcanic ash,clay mineral,carbonate cement and metasome,siliceous cement,slender glimmer,muddy debris and carbon dust.Based on the research of reservoirs,the relativity of the fillings and pore evolution was studied by using slices,scanning electron microscopy,cathode luminescence and so on.The analysis is mainly focused on genesis,character,diagenetic evolution of fillings.Research shows that consedimental volcanic ash is mother material of secondary dissolved pores;calcite cement strongly damage pore in late-diagenetic period,and certain amount of kaolinite is favorable for pore growing.