中扬子北缘京山二叠系古油藏特征及石油地质意义

通过详细的野外地质调查和有机地球化学、流体包裹体、(U-Th)/He、裂变径迹及盆地模拟等测试分析手段，深入系统地探讨了中扬子北缘京山雁门口二叠系古油藏源岩、原油有机地球化学特征及古油藏形成-改造过程。研究结果表明：区内二叠系烃源岩有机质丰度高、类型好，属于优质烃源岩；区内油气显示主要为黄绿色或褐黄色轻质油苗，产状以晶洞型、裂缝型和缝洞型为主；源岩和原油的有机质主要来源于海相还原环境，推测原油可能主要来源于二叠系烃源岩，为自生自储；古油藏油气显示保存至今的最主要因素可能是保存条件或封闭条件较好。通过流体包裹体和地层埋藏史分析认为，区内二叠系烃源岩生油时间主要在早三叠世初期；而在晚三叠世-晚侏罗世(203~159 Ma)有一期或多期与油气运移有关的热流体活动，同时也是古油藏形成的关键期。裂变径迹和(U-Th)/He热年代学证据则显示古油藏形成后主要经历3期构造叠加改造(晚侏罗-早白垩世的强烈构造抬升-冷却、晚白垩世-古近纪早期的缓慢抬升-冷却及古近纪中后期以来的相对强烈的抬升-冷却),其中晚侏罗世-早白垩世的构造抬升剥蚀-冷却事件可能是古油藏被改造，乃至完全破坏的主要因素。通过对该古油藏系统分析认为，在中扬子燕山期构造活动较弱地区，二叠系裂缝、晶洞发育带内上古生界海相油气勘探潜力较大。

Characteristics and Its Petroleum Geological Significance of the Permian Paleo-Oil Reservoir of Jingshan Area,the North Edge of the Central Yangtze Block

Field investigation, organic geochemistry, fluid inclusion and low temperature thermochronology analysis were carried out for further understanding characteristic, formation and destroy process of the Permian paleo-oil seepage in Jingshan area, the north edge of the central Yangtze block. The Permian source rock with high organic abundance and type I organic matter is considered to be the best source rock. The hydrocarbon are mainly preserved in hole, crack or crack-hole, show olivine or brown yellow color, are easy-volatizing light oil, and are expulsed from the Permian source rock. The preservation conditions may be the key factor for the paleo oil seepage. Based on fluid inclusion analysis and basin modeling, Permian hydrocarbon source rock started to generate oil during the Early Triassic, there must exist one or more thermal fluid activities which were related to petroleum migration or redistribution in the Late Triassic-Late Jurassic. By low temperature thermochronology analysis, the reservoir experienced three stages of tectonic movement after its formation: 1)Strong uplift and rapid cooling during Jurassic-Early Cretaceous stage; 2)Slow uplift stage during the Late Cretaceous-Early Paleogene； 3)Strong uplift and cooling since the Middle Paleogene, and the first event applies the greatest impaction on the reservoir and maybe even destroy it. Through the paleo-oil seepage analysis, the central Yangtze region may be gets primary oil or gas reservoirs reserved in cracks or/and hole developed within Permian strata, especially where the Yanshanian tectonic influence is weak.