利用储集砂岩微观特征进行物源分析--以吐哈盆地鄯勒地区为例

岩石组构和重矿物微观特征分析认为,鄯勒地区J2x^1-2砂岩储集层成分成熟度较好,为以英安岩岩屑、英安斑岩岩屑、中基性喷出岩岩屑、中基性凝灰岩岩屑等为主的岩石标型组合;砂岩结构成熟度和分选性较差,石英碎屑的磨圆度呈棱角-次棱角状;砂岩中重矿物为不稳定的矿物标型组合,成岩环境为弱还原环境.结合宏观精细地层对比和沉积环境条件分析,明确了鄯勒地区J2x^1-2砂岩储集层属于北物源沉积体系,指出了在前陆盆地进行物源分析时必须与微观特征、环境条件等多方面研究相结合.这种分析方法为今后同类物源分析提供了借鉴.

Source Analysis of Reservoir Sands in Microscopic Feature--An example of Shanle area in Tuha basin

The petrologic inake-up and the heavy mineral feature analyses show that J2x^1-2 reservoir sands of Shanle area in Tuha basin are good in sand compositional maturity with a typical rock assemblage dominated by dacite, dacite liparite, intermediate-basic extrusive rock and intermediate-basic tuff debris, but poor in sand structural maturity and sorting with angular-subangular quartz clasts; the sand heavy minerals appear in an unstable typical mineral association, and the diagenetic environment is weak. Integrated with macro- and fine- formation correlation and depositional setting analysis, it is clarified that the J2x^1-2 reservoir sands belong to sedimentary system of the north sources. This paper suggests that the source analysis of foreland basin should be made considering micro-stratigraphic feature, environment conditions, etc., which could be as a guide for similar source supply studies in the future.