琼东南盆地深水大气田地质特征、成藏模式及勘探方向研究

发布时间：2018-08-26 17:58

【摘要】：琼东南盆地深水领域获得天然气勘探重大突破,但对深水天然气成藏特征的认识存在不少疑点,亟需开展天然气成因、来源及成藏过程与模式的系统分析。研究认为L17深水大气田天然气以烃类气为主,二氧化碳含量低。天然气甲烷、乙烷碳同位素特征表明天然气为有机成因、高成熟煤型气。天然气轻烃C_6、C_7系列中异构烷烃、环烷烃含量高,表明天然气生源母质以陆源高等植物为主。结合本区始新统、渐新统烃源岩成熟史综合分析认为,L17深水大气田天然气来源于渐新统崖城组烃源岩。盆地深水区晚中新世黄流期发育大型限制型块体搬运沉积,形成了优质砂岩储集体;因高密度砂质块体搬运沉积被周边深海泥岩封闭及"西低东高"的构造格局等条件配置,形成了上中新统黄流组岩性圈闭群;约4.9Ma以来渐新统崖城组烃源岩生成的成熟—高成熟天然气,在源-储压差的驱动下,沿深部被超压再次活化、开启形成的早期地质结构内的断裂或微裂隙,向上运移到上中新统黄流组岩性圈闭群中聚集成藏,具有"烃源岩、大型砂质块体搬运沉积砂岩储层、优质深海泥岩封盖和断裂/微裂隙输导"四要素耦合控藏特征。指出深水区中中新统梅山组盆底扇构造-岩性圈闭群、南斜坡-凸起生物礁、古近系滨岸带陵水组断裂圈闭带等领域具备形成深水大气田的优越条件。
[Abstract]:A great breakthrough has been made in the deep water exploration of Qiongdongnan Basin, but there are many doubtful points in understanding the characteristics of deep-water natural gas accumulation. It is urgent to carry out systematic analysis of the origin, source, process and model of natural gas accumulation. It is considered that natural gas in L 17 deep water gas field is mainly hydrocarbon gas and low carbon dioxide content. Natural gas methane and ethane carbon isotope characteristics indicate that natural gas is organic and highly mature coal type gas. The high content of naphthenic hydrocarbons in the series of natural gas light hydrocarbon C _ 6 and C _ S _ 7 indicates that the natural gas source materials are mainly terrestrial higher plants. Based on the comprehensive analysis of the maturation history of the Oligocene source rocks in the Eocene in this area, it is concluded that the natural gas of the L17 deep water gas field is derived from the source rocks of the Yacheng formation of the Oligocene. During the late Miocene Yellow current period in the deep water area of the basin, large confined block transport deposits were developed, resulting in the formation of high quality sandstone reservoirs, and the high density sand mass transport deposits were enclosed by the surrounding deep-sea mudstone and the structural pattern of "west low east high", and so on. The mature and highly mature natural gas generated by the source rocks of the Yacheng formation of the Oligocene has been reactivated by overpressure along the deep layer driven by the pressure-source differential, and formed a lithologic trap group of the Huangliu formation in the Upper Miocene, and the source rocks of the Yacheng formation of the Oligocene have been reactivated by overpressure. The faults or microcracks in the early geological structure, which were opened and formed, migrated upward to the lithologic trap group of the Huangliu formation of the Upper Miocene to form a reservoir, with "source rock, large sand block transport and sedimentary sandstone reservoir," High quality deep-sea mudstone seal and fault / microfissures transport "four elements of coupled reservoir control characteristics." It is pointed out that the areas of Mesocene Meishan formation in the deep water area have favorable conditions for forming deep water large gas fields, such as the subbasin fan tectonic-lithologic trap group, the southern slope and uplift reef, and the Paleogene riparian Lingshui formation fault trap.
【作者单位】：中海石油(中国)有限公司湛江分公司南海西部石油研究院;
【基金】：国家重大科技专项"琼东南盆地深水区大中型气田形成条件与勘探关键技术"课题(编号2016ZX05026-02)资助成果
【分类号】：P618.13

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