甘蒙地区北山盆地群中口子盆地侏罗系烃源岩特征及评价

北山盆地群侏罗系是我国西北地区潜在的油气勘探新领域,为深化其石油地质认识,进一步明确资源潜力,优选北山盆地群中勘探程度相对较高的中口子盆地侏罗系为研究对象,以有机质丰度、类型及成熟度等有机地球化学分析数据为基础,分析了侏罗系烃源岩基础特征,并基于生物标志化合物资料,探讨了该区侏罗系烃源岩的有机质来源及沉积环境。结果表明,中口子盆地侏罗系烃源岩有机质丰度较高,生烃潜力较好,主要为中等-好烃源岩,干酪根类型以Ⅱ2型为主,生烃母质主要是陆源高等植物,主要形成于氧气量适中的弱氧化-弱还原古环境,靠近或位于凹陷中心的烃源岩形成环境还原性稍强,较有利于有机质保存。区内黑帐房凹陷烃源岩已经成熟,而南泉凹陷烃源岩主要为低熟。因此建议黑帐房凹陷中心或者临近中心区域,寻找保存条件好的油藏是取得下步油气勘探突破的重点。这些认识可供西北地区侏罗系沉积古环境和资源潜力研究时对比参考。

Characteristics and Evaluation of Jurassic Source Rocks in Zhongkouzi Basin,Beishan Basins,Gansu-Inner Mongolia Area

On the basis of systematic sample collection,this papper studies in detail the characteristics of organic matter and biomarker characteristics of Jurassic hydrocarbon source rocks in Zhongkouzi Basin, located at the junction of Gansu and Inner Mongolia , with geochemical analysis and testing technology as the main means.The paper also discusses the sedimentary environment, the source of organic matter, the evolution degree of organic matter and the potential of hydrocarbon generation of the source rocks.The resarch results show that the abundance of organic matter of the Jurassic hydrocarbon source rocks in Zhongkouzi Basin is high, with the kerogen dominated by type Ⅱ 2, and the excellent potential of hydrocarbon generation.The main sources of organic matter are terrestrial plants, supplemented by mixed sources of algae and aquatic organisms.The source rocks are mainly formed in the weak oxidation weak-reduction paleoenvironment with the moderate amount of oxygen.The hydrocarbon source rocks near or in the center of the depression enhance the environmental reduction, which is beneficial to the preservation of organic matter. The maturity of hydrocarbon source rocks in Heizhangfang Depression is high and the degree of thermal evolution is in the stage of thermally catalyzed oil generation or major oil generation.The maturity of hydrocarbon source rocks of Nanquan Depression in the western of Zhongkouzi Basin is mainly characterized by low maturity. It is considered that the key to the exploration breakthroughs in Zhongkouzi Basin is to find oil reservoirs with good preservation conditions near or in the center of the Heizhangfang Depression.This study defines the characteristics of source rocks and the potential of hydrocarbon generation further, deepened the understanding of petroleum geology, and provides a detailed and reliable basis for achieving exploration breakthroughs in Zhongkouzi Basin.