南海大气田天然气是煤型气  

Natural gas in large gas fields in the South China Sea is mainly coal-type gas

作　　者：张功成 李增学 兰蕾 陈莹 李友川 刘世翔 ZHANG Gongcheng;LI Zengxue;LAN Lei;CHEN Ying;LI Youchuan;LIU Shixiang(College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao,Shandong 266590,China;CNOOC Research Institute Co.,Ltd.,Beijing 100029,China)

机构地区：[1]山东科技大学地球科学与工程学院 [2]中海油研究总院有限责任公司

出　　处：《天然气工业》2021年第11期12-23,共12页Natural Gas Industry

基　　金：国家自然科学基金项目“琼东南盆地渐新统海相沉积组合中陆源有机质聚集机制”(编号:41872172);“泥炭与泥炭沼泽的持续性和间歇性比较沉积学演化机制”(编号:42072188);国家科技重大专项“海洋深水区油气勘探关键技术(三期)”(编号:2016ZX05026)。

摘　　要：中国南海海域天然气资源丰富,已发现数百个气田,是我国海域天然气勘探开发的主要领域。为了进一步明确南海海域天然气勘探的方向、寻找更多的大气田,基于该区已发现的储量规模大于300×10^(8)m^(3)的37个大气田烃源岩样品,采用有机地球化学的实验测试技术,系统开展了南海大气田形成的烃源岩条件和生烃模式研究,并预测了下一步大气田的勘探方向｡研究结果表明:①南海大气田天然气主要为煤型气,烃源岩主要为煤系烃源岩及陆源海相烃源岩,煤系烃源岩发育于河流入海口,陆源海相烃源岩发育于浅海;②煤系烃源岩形成于三角洲､扇三角洲和潮坪-潟湖3大沉积体系,三角洲是其中主要的沉积体系,三角洲发育于凹陷缓坡,规模差异大,大型煤系三角洲发育的煤系烃源岩规模大;③陆源海相烃源岩发育规模受三角洲规模、古地形尤其是坡度等的控制,有机质类型以高等植物来源为主;④南海外陆架及陆坡区属于热盆地,源热共控是南海大型油气田形成的重要机制,其烃源岩具有生烃持续时间长､生烃高峰期晚､多阶段生烃的特征｡结论认为,煤系烃源岩及陆源海相烃源岩发育区背景下的烃源岩高熟区是南海海域下一步寻找大气田的勘探方向。The South China Sea is the main field of natural gas exploration and development in China,for there is abundant natural gas resource and hundreds of gas fields have been discovered there.In order to further determine the natural gas exploration direction and discover more large gas fields in the South China Sea,this paper systematically studies the source rock conditions and hydrocarbon generation models of large gas fields in the South China Sea by means of organic geochemical test technologies,based on the source rock samples of 37 large gas fields with a reserve scale larger than 300×10^(8)m^(3)that have been discovered.In addition,the exploration direction of large gas fields in the next step is predicted.And the following research results are obtained.First,natural gas in the large gas fields of the South China Sea is mainly coal-type gas,and its source rocks are mainly coal-measure source rocks and terrigenous marine source rocks.Among them,the coal-measure source rocks are developed at the estuary of rivers and the terrigenous marine source rocks are developed in shallow seas.Second,coal-measure source rocks are formed in three sedimentary systems,i.e.,delta,fan delta and tidal flat-lagoon,among which delta is the main sedimentary system.Delta is developed in the gentle slope of the depression and its scale varies greatly.The large coal-measure delta has a large scale of coal-measure source rocks.Third,the development scale of terrigenous marine source rocks is controlled by delta scale,paleotopography and especially slope,and the organic matter is mainly derived from higher plants.Fourth,the outer continental shelf and continental slope of the South China Sea are thermal basins.The joint control of source rock and thermal evolution degree is an important mechanism for the formation of large oil and gas fields in the South China Sea,and the source rocks are characterized by long hydrocarbon generation duration,late peak hydrocarbon generation and multi-stage hydrocarbon generation.In conclusion,the high-m

关 键 词：中国南海 大气田 煤系烃源岩 陆源海相烃源岩 煤系三角洲 热演化程度 勘探方向 

分 类 号：P618.13[天文地球—矿床学]