鄂尔多斯盆地西南缘三叠系延长组流体包裹体特征及对油气充注调整的指示  

Characteristics of fluid inclusion and its indication to hydrocarbon charge and adjustment of the Triassic Yanchang Formation in southwestern margin of Ordos Basin

作　　者：梁正中 许红涛 高超利 肖荣[3] 杨红新[3] 边延河 王彩霞[3] Liang Zhengzhong;Xu Hongtao;Gao Chaoli;Xiao Rong;Yang Hongxin;Bian Yanhe;Wang Caixia(School of Chemistry&Chemical Engineering,Yulin University,719000;College of Petroleum Engineering,Xi’an Shiyou University;Exploration and Development Technology Research Center,Yanchang Oil Field Co.,Ltd.)

机构地区：[1]榆林学院化学与化工学院,719000 [2]西安石油大学石油工程学院 [3]延长油田股份有限公司勘探开发技术研究中心

出　　处：《中国石油勘探》2023年第2期81-91,共11页China Petroleum Exploration

基　　金：国家自然科学基金项目“异常低压盆地压力场演化对页岩气富集的影响机理研究”(42062011);陕西省科学技术厅重点研发计划“神府地区煤系非常规天然气共生聚集机制及开发潜力评价”(2020SF-369);榆林市科技局项目“神木地区致密气富集主控因素与勘探技术对策研究”(CXY-2022-73);榆林市高新区科技计划“双碳目标下榆林及周缘地区煤层气和页岩气清洁能源协同勘探开发研究”(CXY-2021-09)。

摘　　要：随着鄂尔多斯盆地西南缘彭阳地区三叠系延长组长8段油藏的发现,证实该区具有较大勘探潜力,但整体研究程度薄弱,其油水关系异常复杂、油气充注规律不明确。油气充注过程中形成的流体包裹体可为研究油气充注过程提供依据,通过系统的流体包裹体显微鉴定、均一温度测试和热动力学模拟等包裹体分析手段,结合颗粒荧光定量测试技术,探讨了盆缘长8段油气充注—调整的过程并比较了盆内外成藏差异性。结果表明:研究区油气包裹体较为发育,原油成熟度不高,含油显示级别和今古含油饱和度均低于湖盆内部,整体充注强度较低。油气较大规模充注主要发生在早白垩世末期和晚白垩世早期,有限源储压差为研究区近源短距离运移提供了动力;但成藏动力不及盆内主体区块,限制了边缘地区油气富集饱满程度。同时,颗粒荧光定量分析(QGF)和颗粒萃取物荧光定量分析(QGF-E)得出的数据变化趋势不一致,指示了研究区古油水界面的位置变化或油藏遭受调整的特征。盆地西南缘断裂附近后期构造运动对油气藏的调整/破坏影响大,由此进一步减弱长8段油藏充注规模。深化研究盆缘油气的充注成藏规律和演化过程,对于认识不同构造背景下的低渗致密砂岩油气勘探潜力具有较强指导意义。With the deepening of petroleum exploration,new discoveries have been made in tight reservoirs in the eighth member of the Triassic Yanchang Formation(Chang 8 member)in Pengyang area in the southwestern margin of Ordos Basin,indicating a great exploration potential.However,the overall research level is low,such as the extremely complex oil-water contact and the unclear law of hydrocarbon charging.The fluid inclusions provide a basis for analyzing the process of hydrocarbon charging.By using fluid inclusion testing methods such as microscopic observation,homogenization temperature measurement and PVT simulation,as well as the quantitative grain fluorescence(QGF)experimental technology,the process of hydrocarbon accumulation and adjustment in Chang 8 member is discussed and the difference of hydrocarbon accumulation in the interior of the basin and basin margin is analyzed.The study results show that oil and gas inclusions are relatively developed in the study area,the maturity of crude oil is low,the oil display grade and modern/paleo oil saturation are lower than those in the interior of the lake basin,showing an overall low intensity of hydrocarbon charging.The large-scale hydrocarbon charging events mainly occurred at the end of Early Cretaceous and the early stage of Late Cretaceous.The limited pressure difference between source rock and reservoir provided driving force for the short-distance hydrocarbon migration,but it was lower in the study area than that in blocks in the main basin,which led to a low oil saturation in the basin marginal area.The relationship between quantitative grain fluorescence(QGF)and quantitative grain extract fluorescence(QGF-E)indexes shows an inconsistent trend,indicating the change of the paleo oil-water contact or the adjustment of oil reservoir in the study area.The later tectonic movements greatly adjusted/destroyed oil reservoir near the faults in the southwestern basin margin,which further decreased the scale of oil charging in Chang 8 member.The deep research on oil charging

关 键 词：延长组 流体包裹体 油气充注 成藏动力 鄂尔多斯盆地 

分 类 号：TE122.1[石油与天然气工程—油气勘探]