全球前寒武—寒武系含油气盆地石油地质特征及成藏主控因素

Petroleum Geological Characteristics and Main Control Factors of Oil and Gas Accumulations in the Global Precambrian-Cambrian Petroliferous Basin

前寒武—寒武系油气作为我国中西部含油气盆地未来油气勘探的重要接替领域,近年来受到广泛关注。本文以阿曼和东西伯利亚盆地为例,阐述全球典型前寒武—寒武系古老含油气盆地石油地质特征及成藏主控因素,为国内前寒武—寒武系油气勘探取得进一步突破提供参考。阿曼和东西伯利亚盆地烃源岩主要发育在盆地初始裂陷作用区,受埋深及地温梯度控制,在志留纪或泥盆纪之前就已大量生油;储集层岩性以砂岩为主,分布面积广,受表生风化淋滤、胶结物溶蚀及构造裂缝改造等后期作用影响,可形成优质区域性储层;优质的区域性盖层是前寒武—寒武系古老油气藏得以保存的关键性因素,盆地膏盐岩累计厚度都超过1 000m。塔里木盆地寒武系盐下深层含油气层系,同国外古老含油气盆地相比,同样具有多套高丰度优质烃源岩生烃、厚层区域性膏盐岩封堵及长距离运移、多层系成藏特征,具有良好的油气勘探潜力。

Since the great potential of Precambrian-Cambrian strata for oil and gas exploration in the central and western of China has been discovered,it had attracted widespread attention recent years.In this paper,the petroleum geological characteristics and main control factors for the hydrocarbon accumulation of the typical Precambrian-Cambrian basins are described,taking the Oman basin and EastSiberian basin for example.We expect to provide a meaningful reference for the oil and gas exploration breakthrough in Precambrian-Cambrian basins of China.The source rocks of Oman basin and East Siberian basin both developed in the initial rifting area,which have generated lots of hydrocarbons before Silurian or Devonian under the control of depth.Sandstone distributed widely as the main reservoir lithology,which can be transformed into high-quality regional reservoirs by post-reformation impacts,such as weathering,leaching,cement dissolution and tectonic fractures.The cumulative thickness of gypsum-salt strata is more than 1 000 m,which is the key factor of the regional seal to preserve the ancient reservoirs generated from the Precambrian-Cambrian stratum,after compared with the petroleum geological characteristics of the other Precambrian-Cambrian basins,we can find that Tarim basin Cambrian petroleum system also has the characteristics of an ancient giant fields,which mainly includes the development of several sets of high abundance of high-quality hydrocarbon source rocks,a thick layer of rock salt paste regional cap and accumulation hydrocarbon in multiple depths after longdistance migration.These indicate that the Tarim basin Cambrian has huge oil and gas exploration potential.