南海北部天然气成藏规律与勘探领域  

Accumulation laws and exploration fields of natural gas in northern South China Sea

作　　者：吴克强 曾清波 李宏义 徐建永 郭帅 武爱俊 冯晨阳 WU Keqiang;ZENG Qingbo;LI Hongyi;XU Jianyong;GUO Shuai;WU Aijun;FENG Chenyang(CNOOC China Limited,Hainan Branch,Haikou,Hainan 570100,China;CNOOC Research Institute Ltd.,Beijing 100028,China)

机构地区：[1]中海石油(中国)有限公司海南分公司,海南海口570100 [2]中海油研究总院有限责任公司,北京100028

出　　处：《中国海上油气》2022年第5期23-35,共13页China Offshore Oil and Gas

基　　金：“十三五”国家科技重大专项“近海大中型油气田形成条件及勘探技术(编号:2016ZX05024)”“海洋深水区油气勘探关键技术(编号:2016ZX05026)”部分研究成果。

摘　　要：南海是西太平洋最大的边缘海之一,发育17个沉积盆地,中国在南海的天然气勘探主要集中在北部的莺歌海、琼东南和珠江口3个大型新生代沉积盆地,共发现天然气田30个,累计产气量占中国近海天然气总产量的75%,已发现天然气主要为煤型气。近年来南海北部天然气勘探取得了重大进展,通过总结大中型气田的地质特点和形成条件,明确了天然气成藏规律:(1)南海海盆可划分为以发育湖相沉积为主的“外盆地带”和以发育海陆过渡相-海相沉积为主的“内盆地带”,“内盆地带”煤系和陆源海相烃源岩控制南海北部天然气资源分布,大型三角洲、海相泥岩是形成大气田的基础;(2)垂向运移控制南海北部天然气富集,底辟及相关裂隙、断裂是天然气垂向运移的主要通道,南海北部各盆地存在底辟带运汇成藏、断裂垂向运汇成藏、断-脊-砂运汇成藏、源储大面积接触运汇成藏4类天然气运汇成藏模式;(3)高泥地比岩性背景控制了南海北部天然气的保存,泥包砂与厚(超压)泥岩顶盖是两类主要保存方式。南海北部各盆地剩余天然气资源量大,未来主要的勘探领域是发育煤系和陆源海相烃源岩的潜在富气新凹陷、已证实富气凹陷内具备底辟等垂向运移条件的源外浅层或近源中深层。The South China Sea, as one of the largest marginal seas in the Western Pacific, has 17 sedimentary basins. In China, natural gas exploration in the northern South China Sea is mostly concentrated within three large Cenozoic sedimentary basins, namely the Yinggehai, Qiongdongnan and Pearl River Mouth basins. There are 30 gas fields discovered, with cumulative gas production accounting for about 75% of total offshore gas production in China, and the discovered gas is mainly coal related gas. Significant strides associated with gas exploration in the northern South China Sea have been made in recent years, and the laws of gas accumulation have been clarified through summarizing the geological characteristics and forming conditions of large and medium-sized gas fields:(1)The South China Sea basin is divided into “outer basin belt” dominated by lacustrine deposits and “inner basin belt” primarily composed of marine-continental transitional facies to marine deposits. In the “inner basin belt”, gas distribution of the northern South China Sea is controlled by coal measures and terrestrial-marine source rocks. Large-scale deltas and marine mudstones provide the basis for the formation of large gas fields.(2)Gas enrichment of the northern South China Sea is controlled by vertical migration. Diapirs and associated fissures, faults offer the main pathways for the vertical migration of natural gas. There are four types of gas migration-accumulation models established among basins in the northern South China Sea, including diapiric belt dominated migration-accumulation model, fault dominated vertical migration-accumulation model, composite migration-accumulation model of “faults-structural ridges-carrier sands”, migration-accumulation model depending on extensive contact between source rock and reservoir.(3)Gas preservation of the northern South China Sea is controlled by lithological background characterized by high ratio of mudstone to strata thickness. There are two patterns for gas preservation, “sand e

关 键 词：南海北部 天然气 成藏规律 垂向运移 岩性背景 勘探领域 

分 类 号：TE122.3[石油与天然气工程—油气勘探]