云南禄劝地区泥盆系油苗地球化学特征及地质意义

Organic geochemistry and geological significance of oil seepage from the Devonian of Luquan area,Yunnan Province

随着四川盆地海相常规天然气和页岩气勘探开发的成功,新区、新层系的油气勘探逐渐提上议程。云南地区泥盆系泥页岩在局部地区广泛分布,有机质丰度较高,但钻井工作很少,研究较为薄弱,油气富集情况不明。通过野外调查,在云南禄劝地区中泥盆统华宁组发现了液态油苗。有机地球化学分析表明:油苗与中泥盆统华宁组三段的泥灰岩亲缘关系较好;中泥盆统华宁组三段的泥灰岩整体沉积于强还原—还原环境,生烃母质主要为藻类等低等水生生物,也有来自高等植物的贡献,已处于成熟阶段,具有较强的油气生成能力,生烃能力与Ⅱ1型烃源岩相当;康滇古陆西缘泥盆系泥灰岩有过生油气过程,生成的原油以饱和烃和芳香烃为主,且保存条件好的情况下,具有一定的页岩油气和常规油气勘探前景。

With the successful exploration and development of marine conventional natural gas and shale gas in the Sichuan Basin,the oil and gas explorations in new areas and new strata are gradually put on the agenda.Devonian shales in Yunnan are widely distributed in local areas with high abundance of organic matter;however,little drilling work and research have been done there so that the oil and gas enrichment is unknown.Through the field investigation,liquid oil seepages were found in the Huaning Formation of Middle Devonian in Luquan area of Yunnan Province.The organic geochemical analysis shows that oil seepage had a good relationship with marl in the third section of the Huaning Formation of Middle Devonian.The marls in the third section of the Huaning Formation of the Middle Devonian were generally deposited in a strong reduction-reduction environment and were in their mature stage.Hydrocarbon generation materials were mainly algaes and other lower aquatic organisms,and higher plants did contribute too.They had strong hydrocarbon generation ability,equivalent to that of typeⅡ1 source rock.The Devonian marls in the western margin of the Kangdian ancient land once produced oil and gas,and the crude oil produced were mainly saturated hydrocarbon and aromatic hydrocarbon,which has certain potential for shale oil and gas exploration and conventional oil and gas exploration under good preservation conditions。