鄂尔多斯盆地东南部大宁—吉县区块上古生界盒8段流体包裹体特征及成藏意义  

Characteristic of Fluid Inclusions in Upper Paleozoic He 8 Member of Daning-Jixian Block,Southeastern Ordos Basin and Its Significance for Hydrocarbon Accumulation

作　　者：张佳琦 赵靖舟 李军 杨晓 ZHANG Jiaqi;ZHAO Jingzhou;LI Jun;YANG Xiao(School of Earth Sciences and Engineering,Xi’an Shiyou University,Xi’an,Shaanxi 710065,China;Key Laboratory of Shaanxi Province for Petroleum Accumulation Geology,Xi’an Shiyou University,Xi’an,Shaanxi 710065,China)

机构地区：[1]西安石油大学地球科学与工程学院,陕西西安710065 [2]陕西省油气成藏地质学重点实验室,陕西西安710065

出　　处：《西安石油大学学报（自然科学版）》2024年第3期34-41,142,共9页Journal of Xi’an Shiyou University（Natural Science Edition）

基　　金：中国博士后科学基金(2022MD713801)。

摘　　要：鄂尔多斯盆地东南部大宁—吉县区块相较于盆地内部,其构造活动强烈,地层抬升幅度大,有机质成熟度高,导致研究区与盆地内部天然气成藏存在差异。利用单偏光显微镜、激光拉曼光谱仪及冷热台等实验仪器,对研究区盒8段13块流体包裹体样品开展了岩相学显微观察、测温测盐和古压力恢复,并结合地层埋藏史—热史厘定了大宁—吉县区块盒8段天然气成藏期次及成藏过程。结果表明,烃类包裹体类型有CH_(4)+CO_(2)包裹体、CH_(4)包裹体及含碳质沥青包裹体。前两类烃类包裹体对应的共生盐水包裹体均一温度介于90~160℃,具有双峰分布特征,第3类包裹体形成时期温度较高,成岩作用阶段已达到晚期,几乎不发育与其伴生的盐水包裹体,通过计算得出含碳质沥青反射率介于2.79%~3.32%,处于高成熟阶段,为原油裂解形成。综合分析表明研究区天然气存在三期充注成藏过程:第Ⅰ期共生盐水包裹体均一温度分布区间为90~120℃,天然气充注期距今175~155 Ma,古压力系数达到1.43,对应于早侏罗世晚期-晚侏罗世早期;第Ⅱ期共生盐水包裹体均一温度区间为130~160℃,天然气充注期距今145~110 Ma,为主成藏期,充注完成时古压力系数达1.57,对应于早白垩世;第Ш期为裂解期,烃类包裹体为含碳质沥青包裹体,形成时的地层温度高于200℃,其成因为原油在早白垩世末裂解形成,古压力系数增加到2.0,距今110~100 Ma。Using single polarization microscope,laser Raman spectroscopy and microthermometry,the petrographic microscopic observation,temperature measurement,salt measurement and paleopressure recovery of the He-8 member in the Daning-Jixian block,the southeastern part of the Ordos Basin were carried out by 13 fluid inclusion samples,and the natural gas accumulation periods and process of the He-8 member were determined combined with the burial history and thermal history.The results show that the types of hydrocarbon inclusions include CH_(4)+CO_(2)inclusions,CH_(4)inclusions and carbonaceous asphalt inclusions.The homogenization temperature of the symbiotic brine inclusions corresponding to the first two types of hydrocarbon inclusions is 90~160℃.The third type of fluid inclusions were formed at high temperatures,and the reservoir diagenetic sequence had reached the late diagenetic stage,with almost no development of associated brine inclusions.The reflectivity of carbonaceous asphalt is 2.79%~3.32%,which is in the high maturity stage and is formed by crude oil cracking.The evolution process of the study area is from normal pressure,overpressure to normal pressure,and the greatest ancient pressure coefficient is 2.0.There are three stages of natural gas charging and accumulation in the study area.In the first stage,the symbiotic brine inclusions are low-salinity fluid,the homogenization temperature is 90~120℃,the natural gas charging period is 175~155 Ma ago(late Early Jurassic-early Late Jurassic),and the ancient pressure coefficient reaches 1.43.In the secondstage,the symbiotic brine inclusions are high-salinity fluid,the homogenization temperature is 130~160℃,the natural gas charging period is 145~110 Ma ago(the Early Cretaceous),and the ancient pressure coefficient was 1.57 when the charging was completed.In the third stage,hydrocarbon inclusions are carbonaceous asphalt inclusions with high asphaltene reflectivity,and the formation temperature was higher than 200℃when they were formed.They were formed by cru

关 键 词：鄂尔多斯盆地 大宁—吉县 盒8段 流体包裹体 压力演化 成藏期次 成藏过程 

分 类 号：TE122[石油与天然气工程—油气勘探]