火山碎屑岩储层特征及敏感性——以塔木察格盆地塔南凹陷为例

为了研究火山碎屑岩的储层特征及储层敏感性机理,以塔木察格盆地塔南凹陷铜钵庙组)南屯组火山碎屑岩为对象,运用普通薄片、铸体薄片和扫描电镜等技术,结合储层敏感性实验资料,根据《储层敏感性流动实验评价方法》(SY/T5358-2002),分析火山碎屑岩储层特征及其水敏、盐敏、速敏、碱敏、酸敏的特征和形成机理.结果表明:岩石类型包括凝灰岩、沉凝灰岩和凝灰质砂(砾)岩,主要敏感性黏土矿物有蒙脱石、伊利石、高岭石、绿泥石和伊/蒙混层,属于中低孔特低渗型储层;水敏性强弱与岩石类型关系密切,凝灰质砂(砾)岩水敏为中等偏强)强,凝灰岩和沉凝灰岩水敏为中等偏弱)中等偏强;盐敏程度绝大多数为中等偏强,临界盐度为5.126g/L;速敏为中等偏弱)弱速敏;碱敏为中等偏弱)中等偏强碱敏,临界碱度为7.43;酸敏程度范围较广;水敏程度与黏土矿物总量呈正相关;酸敏程度主要受绿泥石含量影响,酸敏指数与绿泥石含量呈正相关.该研究可为火山碎屑岩油气勘探提供借鉴.

Reservoir characteristics and its sensitivity mechanism of pyroclastic rock of Tanan depression in Tamtsag basin,Mongolia

Reservoir characteristics and its sensitivity mechanism of pyroclastic rock were investigated by casting thin sections and scanning electron microscope,according to the industrial standard of SY/T 5358-2002 Method for Reservoir Sensitivity Evaluation,taking the pyroclastic rock of Tongbomiao Formation and Nantun Formation from Tanan Depression in Tamtsag Basin for example.The study indicates that: the pyroclastic rock is mainly composed of tuff,sedimentary tuff,and tuffaceous sandstone(conglomerates);the main sensitivity clay minerals are montmorillonite,illite,kaolinite,chlorite and iraq/shuffle layer;the pyroclastic rock belongs to medium-low porosity,extra low permeability reservoir;the water sensitivity differs when rock types changes;the water sensitivity of tuffaceous sandstone is moderate-strong,the water sensitivity of tuff and sedimentary tuff is moderate-weak to moderate-strong;salinity sensitivity is moderate-strong,critical salinity is 5 126 mg/L;velocity sensitivity is moderate-weak to weak;alkaline sensitivity is moderate-weak to moderate-strong,critical alkalinity is 7.43;acid sensitivity changes widely.There is a positive correlation between water sensitivity degree and the total amount of clay minerals;chlorite absolute content and acid sensitivity index have a good linear relationship.