南祁连盆地三叠系碎屑岩储层特征及综合评价

Reservoir characteristics and comprehensive evaluation of Triassic clastic reservoir in southern Qilian Basin

对南祁连盆地三叠系碎屑岩储层特征及储层发育的控制因素进行了研究。结果表明,研究区三叠系碎屑岩储层以中-细粒长石砂岩为主,砂岩的结构成熟度和成分成熟度均较低。主要储集空间为填隙物内孔隙、溶蚀孔隙和裂缝,具有孔喉细小、分选极差、连通性及渗流能力普遍较差的孔隙结构特征。储层物性条件较差,整体表现为低孔低渗的特点,储层的发育状况主要受沉积作用、成岩作用及构造运动的影响。综合分析,将南祁连盆地三叠系碎屑岩储层划分为Ⅴ类、Ⅵ类和Ⅶ类储层,整体属于特低孔渗的致密储层。

On the basis of thin section,scanning electron microscopy,physical property analysis and mercury injection analysis,the reservoir characteristics and main control factors of Triassic clastic reservoir in Southern Qilian Basin were studied.The results indicate that the clastic reservoir sandstone is mainly composed of medium to fine grained feldspar sandstone and the textural and compositional maturation of the reservoir is low.The main reservoir space types are interstitial content pores,dissolution pores and fractures.In additional,the reservoir pore structure is characterized by mini pore throat,poor sorting,poor connectedness and poor infiltrating ability.The reservoir physical properties are poor,with low porosity and low permeability.Moreover,the development of reservoir is mainly controlled by sedimentation,diagenism and favorable tectonic condition.Comprehensively considering above analysis,the Triassic clastic reservoirs have been divided into type Ⅴ,type Ⅵ and type Ⅶ,overall belonging to tight reservoirs with ultra-low porosity and permeability.