南祁连盆地碳酸盐岩储层特征与评价

通过岩石薄片、扫描电镜和物性等资料的综合分析,对南祁连盆地碳酸盐岩储层特征进行了研究。结果表明:储层岩石类型主要为鲕粒灰岩、生物碎屑灰岩、微晶灰岩和少量的白云岩,其中最佳储集体鲕粒灰岩主要发育于中三叠统大加连组;储集空间以次生孔隙为主,主要发育粒内溶孔、粒间溶孔、晶间溶孔及裂缝;储层物性差,为特低孔、低渗储层。研究认为,白云石化作用、溶蚀作用和构造作用对储层孔、渗性具有改善作用,胶结作用和压实作用对储层孔、渗性具有破坏作用,导致储层孔、渗能力变差。根据储层物性特征和孔隙结构参数将研究区储层划分为Ⅲ类和Ⅳ类储层。

Characteristics and evaluation of carbonate reservoir in the southern Qilian Basin

Based on the analysis of rock thin section,scanning electron microscope and properties,the characteristics of the carbonate reservoir in the southern Qilian Basin were studied.The result shows that reservoir rocks are dominated by oolith limestone,bioclastic limestone,micrite limestone and little dolomite,and the best oolith limestone reservoir mainly developed within Middle Triassic Dajialian Formation.The reservoir space is mainly secondary pores developed in intragranular dissolved pores,intergranular dissolved pores,intercrystal dissolved pores and fractures.The reservoir properties are poor,with ultra-low porosity and low permeability.Dolomitization,dissolution and tectonism improve the reservoir properties,while cementation and compaction play destructive roles to reservoir properties and pores of reservoir,which results in poor porosity and permeability.According to reservoir properties and pore structure parameters,the reservoirs in the study area are divided into type Ⅲ and type Ⅳ.