【作者】 王振峰； 孙志鹏； 朱继田；

【Author】 WANG Zhenfeng;SUN Zhipeng;ZHU Jitian;Zhanjiang Branch of China National Offshore Oil Corporation (CNOOC) Limited;

【机构】 中海石油(中国)有限公司湛江分公司；

【摘要】 南海西部深水区位于南海北部琼东南盆地中南部,是近年油气勘探的热点地区。"十一五"以来,中国海油以自主创新为主导,依托国家科技重大专项,"产学研"联合攻关。综合利用大面积三维地震、测井、钻井岩芯/屑和地化分析等资料,以构造-热体制为抓手,系统研究深水区沉积过程、烃源岩形成和生排烃过程,明确资源潜力,优选富烃凹陷。查明了深水区天然气地质条件,取得了"烃源条件优越"、"储集条件良好"、"大型勘探目标成群成带"三大创新性认识,指明了大中型气田勘探方向,获得深水区超千亿方级大气田的重大发现,创造了良好经济与社会效益。琼东南盆地的形成受印支-欧亚板块碰撞与喜山隆升、南海扩张等多重构造事件控制,经历了古近纪裂陷和新近纪的拗陷期。始新世断裂活动强烈并伴有湖泊沉积;早渐新世裂陷继续发育,沉积环境为海陆过渡相和滨-浅海相。分析认为存在以生油为主的始新统湖湘泥岩和以生气为主的下渐新统海陆过渡相煤系地层等两套主力烃源岩。根据热演化、生烃量及生烃强度指标分析,研究区乐东、陵水、宝岛和长昌等四大凹陷属于潜在富生烃凹陷,其中乐东和陵水凹陷的良好生烃潜力已得到钻探证实。深水沉积学和成藏动力学研究发现,研究区纵向上发育古近系和新近系两大成藏组合,横向上发育中央峡谷岩性圈闭带(群)、长昌环凹圈闭带(群)和宝岛南部断阶带等三大有利成藏区带。其中,中央峡谷岩性圈闭带成藏要素是处于陵水-乐东潜在富烃凹陷、煤系源岩生烃、新近系浊积水道砂岩和海底扇储集、裂隙沟源、垂向运移、晚期聚集、岩性圈闭控藏,因而成藏条件优越,勘探潜力巨大。作为首选目标实施钻探,一举发现了南海北部最大天然气田—中央峡谷气田,探明天然气地质储量超过两千亿立方米,取得了南海西部深水区天然气勘探的重大突破。坚定了南海深水区勘探开发的信心,展现了深水区油气开发的巨大潜力,具有重大的经济与社会效益。更多还原

【Abstract】 The deep water area of the northwestern South China Sea is located in the central south of Qiongdongnan Basin.,which is the hydrocarbon exploration hotspot in recent years.By integration of all available information and data of gravity-magnetic,the large areal 3D seismic,core or cuttings,paleontology and geochemical index,the forming geological conditions of natural gas pools in the deepwater area were studied.Then,the paper divided petroleum system and established hydrocarbon accumulation model.Physical simulation of basin structure has clarified that,the formation of QDN Basin was controlled by multiple tectonic movements,such as Indo Chinese-Eurasian Plate collision,Himalayan uplift,Red River fault and the expansion of the South China Sea etc.,which experienced the Paleogene rifting period and Neogene depression period.Eocene Epoch had intense fault activities and was accompanied by lake sediments.Based on the drilling results,this area has mainly developed marine-continental transitional facies,neritic-bathyal sedimentary environment from the early Oligocene.The source rock of Yacheng Formation is rich in organic matter and mainly generates gas.According to the geological-geochemical data from the lastest drilling wells,Lingshui Sag,Baodao Sag,Changchang Sag are abundant hydrocarbon-generating depressions or potential hydrocarbon-generating depressions,which develop the Paleogene and Neogene reservoir-forming combinations in vertical and central canyon lithologic-structural trap zone,Changchang marginal trap zone and south fault terrace of Baodao Sag in lateral.Among them,central canyon trap zone has great potential for exploration because reservoir-forming elements are well matched,i.e.,good coal-measure source rocks,sufficient reservoirs from the Neogene turbidity sandstone and submarine fan,faults connecting source rock and reservoirs,effective vertical migration,late stage aggregation and favorable structural – lithological composite trap.These results hence offer an important scientific basis for hydrocarbon exploration in this area.The discovery of Gas Reservoir LS-A in the central canyon of Lingshui Depression was a good example recently.更多还原