鄂尔多斯盆地北部杭锦旗地区上古生界砂岩储层特征

CHARACTERISTICS OF UPPER PALEOZOIC SANDSTONE RESERVOIR IN HANGJINQI AREA OF ORDOS BASIN

以岩心及铸体薄片观察、扫描电镜鉴定、碳氧同位素测试、测井交会解释等为研究手段,系统研究了鄂尔多斯盆地北部杭锦旗上古生界储层特征.结果表明,研究区上古生界储层岩性复杂,存在岩屑长石砂岩、石英砂岩及岩屑砂岩等,北区东部见蒙脱石、高岭石及地开石等粘土矿物.储集空间以剩余原生粒间孔隙和次生孔隙组合为主,孔隙度中等,渗透率较低,排驱压力及饱和度中值压力较高,孔喉半径小且分选较差,孔隙结构总体较差,构造裂缝及微裂缝较发育,对油气运移成藏及储渗均有重要意义.根据储层岩性、物性及孔隙结构等参数特征,评价出4类储层.Ⅰ类储集岩是研究区最好的储集岩,Ⅱ、Ⅲ类储集岩是研究区主要储集岩,是勘探开发的主力储层.

The characteristics of upper paleozoic sandstone reservoir in Hangjinqi area of north Ordos Basin were investigated by the methods of core analysis, scaning electron microscope, isotope analysis and log data.The lithology of upper paleozoic sandstone reservoir is complicated which the litharenite arkose sandstones, quartz sandstone,and lithic sandstones are founded. And there are some clay minerals such as montmorillonite, dickite, etc in the northeast of area.The pore space of reservoir mainly includes the primary residual intergranular pores and secondary intergranular pores. The porosity of upper paleozoic sandstone reservoir is medium and the permeability is low, and the pore texture is not preferable, which with high displacement and saturation median point pressure, small pore throat radius, poor pores sorting and coarse-fine skewness. Structural fractures and microfractures formed well which played important role in gas migration and accumulation or reserving and permeating. According to the lithology and petrophysical properties of reservoir and pore texture parameters,upper paleozoic reservoir was classified into four types.The type Ⅰis the best reservoir in researched area,and the type Ⅱand Ⅲ are the main reservoir, which are chief reservoir for exploration and production.