准噶尔盆地阜康凹陷芦草沟组烃源岩地球化学特征与生烃潜力研究

Geochemical characteristics and hydrocarbon generation potential of Lucaogou Formation source rocks in Fukang Sag,Junggar Basin

准噶尔盆地阜康凹陷作为盆地内最大的富烃凹陷,其烃源岩地球化学特征、沉积环境和生烃母质等研究不足,限制了对该区探明资源量较低问题的理解。基于阜康凹陷东斜坡新钻揭的烃源岩样品实验分析结果,对阜康凹陷芦草沟组源岩进行了地质地球化学分析研究。阜康凹陷芦草沟组烃源岩总体属于中—很好质量的烃源岩,有机质类型为Ⅱ—Ⅲ型,主体处于低熟—成熟演化阶段;生物标志物特征显示,芦草沟组烃源岩的有机质为陆源高等植物和水生菌藻类的混合,可能具有类杜氏藻的绿藻贡献,总体沉积于贫氧—次富氧、淡水—半咸水的间歇性分层水体环境中,泥岩沉积特征明显。阜康凹陷芦草沟组烃源岩平面上地球化学特征变化较大,阜中凹槽和阜北凹槽显示出更大的生烃潜力。

As the largest hydrocarbon-rich sag in the Junggar Basin,the limited research on geochemical characteristics,sedimentary environment and bio-precursors of source rocks in the Fukang Sag has seriously restricted the understanding of the poor proven oil and gas resources in the sag.A combined geological and geochemical analysis on the Lucaogou Formation source rocks in the Fukang Sag was conducted based on the experimental analysis results of the newly drilled source rock samples on the Fudong Slope.The results show that the Lucaogou Formation source rocks in the Fukang Sag generally belong to source rocks of medium to very good quality,with organic matter of typeⅡto typeⅢ,and mainly in the thermal maturity of early mature to mature stage.Biomarker characteristics show that the organic matter of Lucaogou Formation source rocks in the Fukang Sag is a mixture of terrestrial higher plants and aquatic algae and bacteria and maybe some Dunaliella-like green algae,which is generally deposited in the anoxic to oxic,fresh to brackish,intermittent stratified water environment,showing obvious mudstone sedimentary characteristics.The geochemical characteristics of the Lucaogou Formation source rocks in the Fukang Sag vary greatly on the plane,among which,the central and northern subsags show great hydrocarbon generation potential.