扭张断层活动性评价及其对油气成藏的控制作用——以东营凹陷新生代为例

Transtensional fault activity evaluation and its control on hydrocarbon accumulation:a case study in Cenozoic Dongying Sag

基于断层滑动速率法,文中提出了扭张盆地中断层活动性的评价参数——扭张系数,依据扭张系数,分析了东营凹陷新生代扭张构造的活动性特征及其控藏规律。研究表明:东营凹陷新生代不同扭张构造样式活动性特征差异明显,帚状扭张构造具有先张后扭的活动性特征,平面上具有明显的分带特征,收敛端以走滑作用为主,发散端以拉张作用为主;雁列式扭张构造以走滑作用为主,在演化过程中表现为边张边扭、以扭为主的活动特征;侧接型扭张构造具有先扭后张的活动性特征。活动性差异也影响并控制了不同的油气成藏模式。

Based on the method of fault slip rate,the transtensional coefficient is proposed to evaluate the transtensional fault activity in the torsion basin.According to the transtensional coefficient,the paper analyzes the activity characteristics of the Cenozoic transtensional structure in Dongying sag and its reservoir control law.The results show that there are obvious differences in the activity characteristics of different transtensional tectonic styles of the Cenozoic in Dongying sag.The broom-shaped transtensional structure is characterized by early extension and later torsion,and has obvious zoning characteristics in the plane.The strike slip action is dominant at convergence end,while the tension action is dominant at divergence end.The en echelon transtensional structure is dominated by strike slip,which is characterized by simultaneous extension and torsion during evolution and torsion activity as the dominance.The side connected transtensional structure is characterized by early torsion and later extension.The difference of activity influences and controls different oil and gas accumulation models.