准噶尔盆地中部4区块头屯河组成藏要素配置关系及控藏作用

摘要

在对准噶尔盆地中部4区块头屯河组烃源岩及充注期次、超压及油源断层等成藏要素配置关系分析的基础上,利用断层输导有效性评价系数和断层启闭系数定量评价研究区断层输导的有效性、断层与砂体的有效配置,认为研究区油气输导呈“工”字型分布,油源断层和圈闭的有机耦合是头屯河组油气成藏的基础,构造运动使断层开启,生烃增压,油气沿油源断层向上运移,是其成藏的关键,据此建立早期充注—超压驱动—断层沟通—幕式成藏的油气成藏模式.综合分析认为,头屯河组油气来自八道湾组,且发生2期油气充注,油气成藏过程可分为3幕.头屯河组油气成藏与分布受八道湾组烃源岩生烃范围和油源断层控制,且距油源断层越近越容易成藏.%Based on analysis of matching relationship among oil reservoiring factors of source rock in the Toutunhe Formation,hydrocarbon infilling times,overpressure and oil source faults in the 4th Block of central Junggar Basin,effectiveness of fault transportation and effective configuration between fault and sandbodies were evaluated quantitatively by effective evaluation coefficient and fault open and closure coefficient.It is considered that hydrocarbon transports in a I-shape way.Reasonable match of effective faults and traps is the basic condition for the accumulation of oil and gas in the Toutunhe Formation.Tectonic movement leads to fault opening.Hydrocarbon generation increases the stratigraphic pressure.The pressure transfer causes oil and gas to migrate upward along the effective fault.This is the key for the accumulation of oil and gas in the Toutunhe Formation.As a result,a hydrocarbon reservoiring mode is built,which describes a mode of hydrocarbon early filling-overpressure driving-fault connecting-episodic hydrocarbon accumulation.The comprehensive analysis shows that the hydrocarbon in the Toutunhe Formation are from the Badaowan Formation,and hydrocarbon charging occurred two times.The hydrocarbon accumulation process can be divided into three episodes.Hydrocarbon accumulation and distribution are controlled by the scale of hydrocarbon generation in the Badaowan Formation and the distribution of oil source faults,and hydrocarbon accumulation is more likely to happen where reservoir is adjacent to the oil source faults.