准噶尔盆地南缘环博格达山中二叠统黑色泥页岩生烃动力学研究:对周边探区油气勘探启示

Kinetic and Hydrocarbon Generation of Middle Permian Black Shale Around the Bogda Mountain,Southern Junggar Basin:Implications for Petroleum Exploration

为了探究准噶尔盆地南缘环博格达山中二叠统富有机质泥页岩的生烃潜力,对该地区不同构造单元的烃源岩进行生烃动力学研究,并讨论不同研究结果的物理化学意义以及影响活化能分布的化学反应机理。研究结果显示,受控于加热温度,含水体系恒温裂解模拟结果侧重于揭示干酪根生油的过程,而Rock-Eval开放体系的结果反映烃源岩产生所有烃类的过程。位于博格达山东北麓的中二叠统黑色泥页岩生烃活化能主峰约为55 kcal/mol,在北麓泉子街地区的活化能主峰约为60 kcal/mol,在西部的井井子沟地区和南部柴窝堡凹陷的活化能主峰约分布在65~70 kcal/mol之间。I型有机质表现出的高热解活化能可能与高峰度的链烷烃组分相关,因为链烷烃环化所需要的活化能高于其他脱氢反应。环博格达山地区,逆冲断层下盘的深部地层存在一定规模的油气聚集。

To explore the hydrocarbon potential of Middle Permian organic-rich mudstone around the Bogda Mountain,the hydrocarbon generation kinetics were studied in different tectonic units.Furthermore,we discussed the physicochemical significance of kinetic results from different methods and the chemical mechanism affecting activation energy.The results show that:controlled by heating temperature,the isothermal hydrous pyrolysis was mainly focused on the oil generation from kerogen,while Rock-Eval experiments show bulk hydrocarbon generation from the source rocks;major peaks of hydrocarbon generation activation energy of source rocks are~55 kcal/mol(northeast of Bogda Mountain),~60 kcal/mol(Quanzijie section,northern Bogda Mountain),and 65 to 70 kcal/mol(Jingjingzigou and Chaiwobu);activation energy required for alkane cyclization(higher than that of other dehydrogenation)may be the driving force of high pyrolysis activation energy of type-I organic matter,with abundant alkane components;large-scale hydrocarbon accumulation may have occurred in deep strata under thrust faults.