普光地区侏罗系大安寨段湖相混积岩储层特征及成因

Characteristics and genesis of lacustrine mixed rock reservoirs in Jurassic Da′anzhai Member,Puguang area

四川盆地侏罗系自流井组大安寨段是重要的陆相致密气勘探层系之一。基于野外露头与岩心宏观观察、薄片鉴定、X衍射及储层物性质等分析测试数据,证实普光地区大安寨段混积岩储层规模发育。研究结果表明:1)大安寨段混积岩储层岩性可划分为黏土质混积岩、砂质混积岩和灰质混积岩等3种主要类型;2)储集空间类型以晶间(溶)孔、无机孔、壳缘缝及微裂缝为主;3)混积岩储层主要发育在浅湖—半深湖相区,受湖平面波动、地形坡度与风暴、重力流的共同控制,是相混合与间断混合沉积的产物。

The Da′anzhai Member of the Jurassic Ziliujing Formation in Sichuan Basin is one of the important continental tight gas exploration strata.Based on the macroscopic observation of outcrop and core,thin section identification,X-ray diffraction and reservoir properties,it is confirmed that the mixed rock reservoir in Da′anzhai Member of Puguang area has developed in scale.The results show that:(1)The mixed rock reservoir lithology of Da′anzhai Member can be divided into three main types,namely clay,sandy and calcareous mixed rocks.(2)The main types of reservoir space are intercrystalline pores,inorganic pores,shell boundary fractures and micro-fractures.(3)The mixed rock reservoir is mainly developed in the shallow to semi-deep lacustrine facies area,which is controlled by the lake plane fluctuation,topographic slope,storm and gravity flow,and is the product of phase mixing and discontinuous mixed sedimentation.