鄂尔多斯盆地乌审召地区盒8、山1段储层流体包裹体特征及其意义

运用普通显微镜、荧光显微镜观察,冷热台均一温度、冰点温度测定,激光拉曼成分分析等方法,对乌审召地区盒8、山1段储层砂岩流体包裹体的形态、温度、盐度及成分等特征进行了系统研究,探讨了自生矿物形成条件及次生孔隙成因,识别出盐水包裹体、烃类包裹体以及CO_2包裹体3种包裹体类型。研究认为,研究区存在低温低盐度、高温高盐度两期流体充注过程,并伴有中-低成熟度、高成熟度两期明显的烃类充注过程。结合埋藏史研究认为,烃类进入储层的时间主要在中侏罗世末—早白垩世末。烃类成熟过程中产生的有机酸以及CO_2是造成砂岩次生孔隙形成的主要原因,后期发生的构造热事件有利于原生孔隙的保存与次生孔隙的形成。

Characteristics of fluid inclusions in reservoirs in the eighth member of the Shihezi Formation and the first member of the Shanxi Formation in Uxin Ju area, the Ordos Basin and their significance

W ith methods such as ordinary m icroscopic observation，fluorescence m icroscopic observation，homoˉgeneous temperature and ice point temperaturemeasurement and LaserRoman spectroscopic analysis of composiˉtion，a systematic study is conducted on the geometry，temperature，salinity and compositions of the fluid incluˉsions in reservoirs in the eighth member of the Shihezi Formation and the firstmember of the Shanxi Formation in theUxin Ju area，Ordos Basin.The development conditions of autogeneticm inerals and the origin of secondary pores are also discussed.Three types of fluid inclusions are identified:saline water，hydrocarbon and CO 2 incluˉsions.According to the study，it is believed that the study area experienced two stages of fluids charging process.One stage was with low temperature and low salinity and the other stage was with high temperature and high salinity.Accompanying the two stages was two phases of hydrocarbon charging process:one with moderateˉlow maturity and the other onewith highmaturity.Combinedwith burialhistory，we believe thathydrocarbon charged the reservoirsmainly from the end ofMiddle Jurrassic to the end ofEarly Cretaceous.The organic acid and CO 2 generated during thematuration ofhydrocarbon are themain causes of secondary pore development in the sandˉstone reservoirs.Later tectonic thermal activities are favorable for the preservation of primary pores and the