琼东南盆地低熟煤型气地球化学特征及勘探前景

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R_O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。

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

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 R_O is 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 large-scale. 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.