摘要
西湖凹陷杭州斜坡埋深近5000 m、温度179.4℃地层发现商业天然气藏,但深埋、高温条件下规模性优质气藏成因与发育模式不明确。基于铸体薄片、扫描电镜照片、物性测试、油气地化测试等基础资料,结合构造演化及沉积充填特征分析,总结了杭州斜坡深层—超深层气藏特征、优质储层成因及气藏成藏模式。结果表明,杭州斜坡深层—超深层发育低渗—中渗气藏,巨厚辫状河道砂体、绿泥石包膜及近洼早期油气充注共同控制了杭州斜坡优质储层的发育;大断裂下降盘可容纳空间增大有利于富砂背景下规模盖层的形成,中成岩B期河道侧缘粉、细砂岩演化至致密层也能成为有效盖层;高地温促使控洼断裂下降盘平湖组烃源岩快速生烃,有利于近源、近断、强充注成藏。明确了深层—超深层优质储层形成条件及富砂背景下储盖组合特征,理清了油气成藏过程与富集规律。西湖凹陷深层—超深层油气资源丰富,杭州斜坡天然气藏成功发现的经验及成藏规律新认识为西湖凹陷下一步在深层—超深层的勘探提供了借鉴。
A commercial natural gas reservoir has been identified in the strata at a burial depth of nearly 5000 m and a temperature of 179.4℃in Hangzhou Slope,Xihu Sag.However,the genesis and development mode of large-scale,high-quality gas reservoirs under large burial depth and at high temperature remain unclear.Based on basic data including casting thin sections,scanning electron microscopy(SEM)images,physical property tests,and hydrocarbon geochemical tests,the characteristics of deep-to-ultra-deep gas reservoirs,the genesis of high-quality reservoirs,and the accumulation mode of gas reservoirs in Hangzhou Slope were studied and summarized by combining structural evolutionary and sedimentary filling characteristics.The results indicate that low-to-medium permeability gas reservoirs develop in deep-to-ultra-deep strata of Hangzhou Slope,and thick braided river sand bodies,chlorite grain coatings,and early hydrocarbon charging from nearby sags collectively control the development of high-quality reservoirs in Hangzhou Slope.Large-scale fault-controlled downthrown blocks undergo increased accommodation space,facilitating the formation of extensive caprock systems in sand-rich settings.Additionally,the siltstone and fine-grained sandstone at the channel margins which evolved into tight layers during the middle diagenetic stage B can also become effective caprock systems.High ground temperatures promote rapid hydrocarbon generation in the source rocks of the Pinghu Formation within the downthrown block of sag-controlling faults,which is beneficial to near-source,faultproximal,and high-intensity hydrocarbon charging.The formation conditions of high-quality reservoirs in deep-to-ultra-deep strata and characteristics of reservoir-caprock assemblages in sand-rich settings were clarified,thereby sorting out the hydrocarbon accumulation processes and enrichment patterns.Xihu Sag is proved to have abundant deep-to-ultra-deep oil and gas resources.The successful discovery of a natural gas reservoir in Hangzhou Slope and new insights into accumulation patterns provide reference for future exploration efforts targeting deep-to-ultra-deep strata in Xihu Sag.
作者
李宁
张武
覃军
肖晓光
丁飞
王皖丽
LI Ning;ZHANG Wu;QIN Jun;XIAO Xiaoguang;DING Fei;WANG Wanli(CNOOC China Limited,Shanghai Branch,Shanghai 200335,China)
出处
《中国海上油气》
北大核心
2026年第1期54-65,共12页
China Offshore Oil and Gas
基金
中国海洋石油集团有限公司“十四五”重大科技项目“海上深层/超深层油气勘探技术”课题二“弧后盆地深层/超深层油气成藏条件与成藏机制研究——西湖凹陷(编号:KJGG2022-0402)”
中海石油(中国)有限公司重大科技项目“东海西湖凹陷大中型气田勘探方向及关键技术研究(编号:KJZX-2023-0101)”部分研究成果。
关键词
天然气
深层—超深层
成藏过程
成藏模式
杭州斜坡
西湖凹陷
natural gas
deep-to-ultra-deep
accumulation process
accumulation mode
Hangzhou Slope
Xihu Sag
