准噶尔盆地南缘博格达山前带二叠系芦草沟组烃源岩地球化学特征及生烃潜力研究

Geochemical characteristics and hydrocarbon generation potential of Permian Lucaogou formation source rocks in Bogda piedmont belt,the southern margin of Junggar basin

二叠系芦草沟组烃源岩在准噶尔盆地南缘呈区域分布,是一套重要烃源岩,在盆地内部已经得到充分的认识。但随着油气勘探难度增大,山前带新区的研究成为新热点,由于山前带钻探资料少,构造、沉积条件复杂,缺乏深钻与露头的资料相互制约和盆山结合评价,目前研究较为薄弱。为了探讨山前带油气勘探潜力,2014—2019年中国地质调查局油气资源调查中心在准噶尔盆地南缘博格达山前带部署多口钻井,通过盆地与山前带的烃源岩对比,探索了博格达山前带二叠系芦草沟组烃源岩分布和厚度,评价了烃源岩地球化学特征,研究结果表明博格达山前带二叠系芦草沟组中下部发育巨厚、连片分布的优质湖相烃源岩,沉积中心可能更靠近博格达山;博格达山前带二叠系芦草沟组发育一套丰度中等-高、有机质类型以Ⅰ-Ⅱ_(1)型为主,已达到成熟阶段,具有较高的生烃潜力,是下一步油气勘探的新方向。

The source rocks of the Permian Lucaogou formation are distributed regionally in the southern margin of the Junggar basin,they are a set of important source rocks.They have been fully understood and finely evaluated in the basin.But with the development of oil and gas exploration,the difficulty has increased,and marching into new areas and strata has become a new direction for oil and gas exploration.The exploration of the piedmont zone has also received more attention.Due to the complex structure and depositional conditions of the piedmont zone,there is a lack of deep drilling and outcrops.The current research is relatively weak because of the mutual restriction of the data and the fine evaluation of basin-mountain integration.In order to explore the oil and gas exploration potential in the piedmont zone,a number of wells have been deployed in the Bogda piedmont zone on the southern margin of the Junggar basin from 2014 to 2019.The distribution and thickness of the high-quality source rocks of the Permian Lucaogou formation in the study area have clarified the geochemical characteristics of the source rocks.The research results show that the middle and lower parts of the Permian Lucaogou formation in the Bogda piedmont zone are very thick and contiguous.The distribution of high-quality lacustrine source rocks,the deposition center is close to the Bogda mountain;the Permian Lucaogou formation source rocks in the Bogda piedmont have medium-high abundance,and the organic matter types are mainlyⅠ-Ⅱ_(1) types.It has reached a mature stage and has high hydrocarbon generation potential;the research area has the ability to form large-scale oil and gas reservoirs,which is a new direction for the next step in oil and gas exploration.