准噶尔盆地南缘古近系安集海河组砂岩普遍存在碳酸盐胶结作用,是导致储层物性变差的重要因素.利用镜下观察、碳氧同位素分析等方法,在分析碳酸盐胶结物岩石学特征的基础上,探讨了碳酸盐胶结物形成环境、时期及其对储层物性的影响.安集海河组砂岩碳酸盐胶结物主要为含铁方解石,形成于成岩晚期.受有机质演化及其流体运移的影响,δ13 CPDB值大多为-10‰～-3‰,δ18OPDB值多为-15‰～-10‰.古盐度计算结果表明碳酸盐胶结物形成于淡水环境；大部分方解石为晚期较高温度下形成的.有机酸溶蚀形成的次生孔隙发育带对应于δ13 CPDB值负偏移的井段.碳酸盐胶结物充填粒间孔隙,使储层的有效孔隙度大大降低.%Carbonate cementation is the most important type of cementation for sandstone reservoir of the Anjihaihe formation Palaeozoic in the south of Junggar Basin. The distribution of calcite cement has great influence on reservoir characteristics. The results of cement generation, fluid inclusion homogenization temperature inclusion, and O/C isotope analysis prove that the main type of carbonate cement is ferrous calcite, most of the calcite cements are formed in the late diagenesis stage under high temperature (85 to 120 °C ). Stable-isotopic composition of most carbonate cements (Δ13c PDB -10‰ to -3‰,δ18 OODB-15‰ to -10‰) suggests that calcites are intimately related to the organic evolution and fluid activities. The depth intervals of secondary porosity zones are in accordance with the depth ranges of apparent positive shift of the Δ118opdb value of carbonate cements in Anjihaihe formation. The calcite cement is mainly filled in the intergranular pores, which leads to a great decrease of the effective porosity.
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