琼东南盆地深水区新近系大气田群“多级接力”成藏主控因素  

Main controlling factors of"multi-stage relay"hydrocarbon accumulation in Neogene large gas fields of deep-water area in Qiongdongnan Basin

作　　者：甘军 梁刚 庹雷 肖鸿议 GAN Jun;LIANG Gang;TUO Lei;XIAO Hongyi(CNOOC China Limited,Hainan Branch,Haikou,Hainan 570100,China)

机构地区：[1]中海石油(中国)有限公司海南分公司,海口570100

出　　处：《中国海上油气》2025年第2期61-69,共9页China Offshore Oil and Gas

基　　金：“十三五”国家科技重大专项“琼东南盆地深水区大中型气田形成条件及关键勘探技术(编号:2016ZX05026-002)”;中国海洋石油有限公司“十四五”重大科技项目“南海深水盆地油气运聚成藏分析与突破方向(编号:KJGG2022-0103)”部分研究成果。

摘　　要：琼东南盆地深水区上中新统峡谷—第四系海底扇已发现多个大气田,其成藏过程、动力及运移通道有待进一步厘清。综合应用油气源对比、构造-沉积充填及成藏动力分析方法,深入剖析大气田群形成的时空演化关系及其有序分布的主控因素。结果表明:(1)中央峡谷L17-y、L18-x、L25-x气田与陵南低凸起L36-x气田气源相同,均主要来自乐东-陵水凹陷渐新统陆源海相烃源岩;(2)乐东-陵水凹陷富生气高压凹陷成藏动力强,黄流组—乐东组发育的多期峡谷水道砂、水道壁及海底扇组成多级复合优势输导体系,控制天然气“多级穿层接力”运移,形成中浅层—超浅层多个大型气田;(3)盖层质量及地层坡度控制天然气聚集的场所和规模,在相同气柱高度条件下,地层平缓区的圈闭有利于形成大气田。研究成果为类似盆地富油气区向浅层拓展勘探提供借鉴。Several large gas fields have been discovered in the Upper Miocene canyon-Quaternary submarine fan systems of the deep-water area in the Qiongdongnan Basin.However,their accumulation processes,dynamics,and migration pathways remain to be further clarified.This study integrated hydrocarbon-source correlation,structural-sedimentary filling analysis,and reservoir formation dynamics to systematically investigate the spatiotemporal evolutionary relationships of the gas fields and the key controlling factors driving their orderly distribution.The results are as follows.①The gas fields L17-y,L18-x,and L25-x in the central canyon,along with the gas field L36-x in the Lingnan Low Uplift,share the same gas source,which primarily derives from the Oligocene terrestrial-marine source rocks of the Ledong-Lingshui Sag.②The Ledong-Lingshui Sag,characterized by abundant gas generation and high-pressure conditions,exhibits strong reservoir formation dynamics.The multi-stage canyon-channel sands,channel walls,and submarine fans developed in the Huangliu and Ledong Formations form a multi-level composite migration system.This system controls the“multi-stage relay”gas migration across stratigraphic layers,facilitating the formation of multiple large gas fields in the middle-shallow to ultra-shallow layers.③The quality of the caprock and the slope of the strata significantly influence the location and scale of natural gas accumulation.Under similar gas column height conditions,traps in gently dipping strata are more favorable for forming large gas fields.This study provides valuable insights for extending exploration in similar hydrocarbon-rich basins,particularly in shallower stratigraphic intervals.

关 键 词：琼东南盆地 深水区 新近系 大气田 成藏主控因素 

分 类 号：TE122.1[石油与天然气工程—油气勘探] P744.4[天文地球—海洋科学]