琼东南盆地低熟煤型气地球化学特征及勘探前景  

Geochemical characteristics and exploration prospect of low mature coal-derived gas in Qiongdongnan Basin

作　　者：梁刚 甘军 游君君 李兴 雷明珠 LIANG Gang;GAN Jun;YOU Jun-jun;LI Xing;LEI Ming-zhu(Zhanjiang Branch of CNOOC Ltd.,Zhanjiang 524057,China)

机构地区：[1]中海石油(中国)有限公司湛江分公司,广东湛江524057

出　　处：《天然气地球科学》2020年第7期895-903,共9页Natural Gas Geoscience

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)资助~~。

摘　　要：琼东南盆地近年来发现的Y8等气田的天然气碳同位素值异常偏低,与以往发现的成熟—高成熟煤型气大不相同。在深入理解低熟气概念及进行详细地球化学分析后,认为研究区δ13C1值分布在-47‰^-42‰之间,δ13C2值分布在-28‰^-25‰之间的天然气是与吐哈盆地类似的低熟煤型气,天然气成熟度RO值介于0.5%~0.8%之间,主要来自凹陷斜坡、凸起区低成熟演化阶段的崖城组烃源岩及盆地内大范围发育的中新统烃源岩。低熟煤型气的发现极大拓展了琼东南盆地烃源岩的研究范围,为盆地下一步勘探提供了新的思路。In recent years,the carbon isotope of natural gas from Y8 and other gas fields in Qiongdongnan Basin is relatively low,which is quite different from the mature & high mature coal-derived gas discovered in the past.After in-depth investigation of the concept of low mature gas and detailed geochemical analysis,it is considered that δ13C1 is distributed between -47‰ and -42‰,δ13C2 is distributed between -28‰ and -25‰,which is similar to the low mature coal-derived gas in Turpan-Hami Basin,and the maturity of natural gas ROis between 0.5% and 0.8%,which mainly comes from the source rocks with low maturity of the Yacheng Formation distributing in the depression slope and the uplift,and the Miocene source rocks developed in the basin with largescale. The discovery of low mature coal-derived gas has greatly expanded the research scope of source rock in Qiongdongnan Basin and provided a new research idea for future exploration in the basin.

关 键 词：低熟气 煤型气 碳同位素 琼东南盆地 

分 类 号：TE122.113[石油与天然气工程—油气勘探]