徐家围子断陷火山岩储层流体包裹体研究

FLUID INCLUSION FROM VOLCANIC RESERVOIRS IN XUJIAWEIZI FAULT DEPRESSION

为揭示徐家围子断陷深层火山岩气藏的充注期次和主成藏期,对采自12口井上侏罗统营城组火山岩储层的34块样品开展了流体包裹体研究。对流体包裹体进行系统的镜下岩相学特征观察以及显微测温分析结果表明:该区营城组火山岩储层中捕获的流体包裹体记录了6期热流体活动,其中前4期热流体活动与该储层发生的4期天然气充注密切相关,后2期热流体活动则记录了火山活动的信息。结合该区埋藏史综合分析结果得出,4期天然气充注发生于距今120～85Ma,且每次充注持续时间均小于10Ma,其中发生于泉头组沉积末期—青山口组沉积中晚期的第三次天然气充注是营城组火山岩气藏的主成藏期。

In order to reveal the stages of gas charging and the main reservoiring stage of the volcanic gas pool in Xujiaweizi fault depression,a case study was performed on the fluid inclusions in 34 samples collected from the volcanic reservoirs of the Upper Jurassic Yingcheng Formatioin in 12 wells.Systematic petrographic and microthermometric analyses showed that the fluid inclusions entrapped in the Yingcheng Formation volcanic reservoirs in the study area recorded 6 thermal fluid events,in which the former 4 thermal fluid events are closed related with the 4 natural gas charging stages in the reservoirs,while the latter 2 thermal fluid events recorded the volcanic activities.In combination with the comprehensive analysis of the burial history in the study area,it is believed that the 4 gas charging stages occurred during 120-85 Ma,and the durations of them are all smaller than 10 m.y..The third gas charging stage,which occurred during the end of deposition of the Quantou Formation-the mid-late of deposition of the Qingshankou Formation,is the main gas accumulating stage of the Yingcheng Formation volcanic gas pool.