全球古老油气成藏组合资源潜力、重大发现及启示

Resource potential,giant discoveries,and implications of ancient hydrocarbon plays worldwide

全球已证实存在6套优质烃源岩,发育于前中生界的3套烃源岩构成了古老油气成藏组合的主要烃源岩。已发现的前中生界古老油气成藏组合有5个特点:①盆地类型以前陆盆地、被动陆缘盆地、克拉通盆地为主;②油气资源类型以常规油气为主,页岩油气发展迅速;③油气主要富集于二叠系、泥盆系、石炭系和奥陶系;④储层岩性主要为灰岩、砂岩、页岩和白云岩;③埋深以中-浅层为主,深层勘探潜力大。古老油气成藏组合的重大发现也具有在克拉通周缘、碳酸盐岩储层、页岩油气层系和基岩潜山4个领域富集的特征。通过对重点领域的重大发现解剖,指出长期处于低纬度热带辐合带的克拉通周缘易于形成优质生-储-盖组合;全球重大事件对烃源岩发育和页岩油气富集起着重要控制作用,可在全球重大事件时序框架下,通过重建成藏要素古位置超前优选潜在成藏组合。根据已发现油气可采储量和待发现油气资源自主评价结果,明确了常规油气资源应重点关注阿拉伯盆地、扎格罗斯盆地、塔里木盆地等;基岩潜山/残留层系也是值得重点关注的勘探领域;页岩油气应重点关注俄罗斯蒂曼一伯朝拉盆地和伏尔加一乌拉尔盆地泥盆系多玛尼克组页岩、中东地区阿拉伯盆地志留系热页岩、北非地区古达米斯盆地志留系和泥盆系、中国四川盆地和准噶尔盆地的页岩层系等领域。

Six sets of high-quality source rocks have been identified globally,with three of them in the pre-Mesozoic strata serving as the primary source rocks for ancient oil and gas reservoirs.Ancient oil and gas reservoirs from the pre-Mesozoic strata exhibit five key characteristics.(1)The predominant basin types include foreland,passive continental margin,and cratonic basins.(2)Their primary type of oil and gas resources remains conventional,although shale oil and gas is developing rapidly.(3)Their oil and gas accumulations are primarily concentrated in the Permian,Devonian,Carboniferous,and Ordovician.(4)Their reservoir lithology is primarily composed of limestones,sandstones,shales,and dolomites.(5)Their burial depth is predominantly within the middle to shallow layers,indicating significant potential for deep plays.The substantial discoveries of ancient oil and gas plays demonstrate enrichment in four fields:the periphery of cratons,carbonate reservoirs,shale oil and shale gas reservoirs,and basement reservoirs.After analyzing the major discoveries in key areas,it is revealed that high-quality source-reservoir-seal combinations form readily in the peripheral regions of cratons that were historically located within low-latitude intertropical convergence zones.Global significant events have played a crucial role in shaping the development of source rocks and the enrichment of shale oil and gas.Within the temporal framework of these significant global events,potential plays can be optimized in advance by reconstructing the paleo-positions of accumulation elements.Based on independent evaluations of recoverable oil and gas reserves and yet-to-be-discovered resources,it is evident that conventional oil and gas exploration should focus on the Arabian Basin,Zagros Basin,Tarim Basin,and other basins.Basement rocks and residual strata are also important potential exploration areas.For shale oil and shale gas exploration,the focus should be on the Devonian Domanik shale in the Timan-Pechora and the Volga-Ural basins in Russia,the Silurian hot shale in the Arabian Basin in the Middle East,the Silurian and Devonian plays in the Ghadames Basin in the North Africa,and several sets of shales in the Sichuan and Junggar basins in China.