潮水盆地和民和盆地中侏罗统青土井组煤系烃源岩有机地球化学特征及其意义

随着非常规油气资源开采技术进步以及勘探范围日益扩大,煤系烃源岩日益获得重视。潮水盆地和民和盆地作为甘肃陇中、河西地区的典型侏罗系含煤沉积代表,其生烃能力及其差异性特征研究相对欠缺,为此对两地区煤系烃源岩展开综合有机地球化学参数特征及其对比研究。生物标志物特征指示:潮水盆地青土井组煤系烃源岩有机质来源以混合输入为主,处于低熟-成熟阶段,沉积环境上段为弱氧化-弱还原滨、浅湖相,下段为弱咸化半深湖-深湖相,出现高伽马蜡烷优势,指示水体出现分层现象;民和盆地窑街组煤系烃源岩有机质来源上段以低等水生生物输入为主,下段为陆相高等植物优势输入,有机质处于低熟-成熟阶段,沉积环境倾向于典型沼泽相煤系沉积。有机质丰度和类型数据揭示:潮水盆地烃源岩有机质类型主要为Ⅱ型;民和盆地烃源岩有机质类型Ⅰ型、Ⅱ型及Ⅲ型均有出现。综合分析各项有机地球化学参数,指示潮水盆地和民和盆地均具有一定生烃潜力,相对来说以低等水生生物输入为主的民和盆地煤系烃源岩可能具有相对较大的生液态烃潜力。

Organic geochemical characteristics of Qingtujing Formation coal-measure source rocks in the Chaoshui Basin and Minhe Basin,and their hydrocarbon-generation significances

With the advancement of exploration technology for unconventional oil and gas resources,the coalmeasure source rocks are gradually being appreciated. Chaoshui Basin and Minhe Basin are representative of the Jurassic coal-measure sedimentary basins in the Hexi and Longzhong regions. There is a lack of research on hydrocarbon generation capacity and organic geochemical characteristics. This study contains the characteristics and comparison of organic geochemistry between the two basins. In terms of biomarkers,the source of organic matter of Chaoshui Basin may be mainly mixed input,which is at the low-mature-mature stage. The upper part of the sedimentary environment is weakly oxidized-weakly reduced,shallow lake,and the lower part is weakly salted and semi-deep. There is a high gamacerane advantage,indicating the stratification of the water. The upper part of Minhe Basin is dominated by lower hydrobiont input,and the lower is the dominant input of terrestrial higher plant. The organic matter is in the low-mature-mature stage,and the sedimentary environment is usually marsh-phase coal-sedimentation. According to the abundance and type of organic matter,Chaoshui Basin are dominated by Type II;Minhe Basin is dominated by Type I,Type II and even Type III. Comprehensive analysis shows that both basins have hydrocarbon generation potential. Minhe Basin,which is dominated by lower hydrobiont input,may have relatively large potential.