新构造运动期断裂活动对油气的控制作用——以渤中地区为例

Controlling of hydrocarbons by Neotectonics and Tectonics fault activities:a case study of Bozhong area

新构造运动调整和控制了渤中地区油气的成藏和最终分布.本文将定性评价与半定量刻画相结合,系统分析了渤中地区的断裂系统特征和62条Ⅰ,Ⅱ级断裂活动速率(FAR)的差异,探讨了晚期断裂活动对成藏条件和油气成藏过程的控制作用.结果表明:强烈活动(FAR>25m/Ma)断裂对油气主要起输导作用,微弱活动(FAR<10m/Ma)断裂主要起封闭作用,中等活动(10m/Ma<FAR<25m/Ma)断裂则对油气起封闭与输导共同作用;断层沿走向对油气的输导与封闭呈现"分段式"特点,"分段式"断裂活动控制了多层系油气富集;远源凸起的缓坡带油气优势运移路径上的圈闭,凸起末端烃源岩发育、断裂活动中-弱的古近系的圈闭,以及断裂活动中-强的断裂与"活跃"烃源岩最佳组合区域的圈闭是有利的油气勘探领域.

Neotectonism controlled and adjusted the accumulation and distribution hydrocarbon in Bozhong area. Combining the qualitative appraisement with semi-quantitative description method, this paper discusses the controlling action on hydrocarbon forming conditions and its accumulation effect in late-stage fault activity based on the analyses of the fault system charac- teristics and the fault activity rate （FAR） difference between 62 Ⅰ and Ⅱ faults. The results show that strong active faults （FAR〉25 m/Ma） have a transportation role, however, weak active faults （FAR〈10 m/Ma） mainly restrict hydrocarbon migration. Medium active faults （10 m/Ma〈FAR〈25 m/Ma） have hydrocarbon sealing and transportation dynamic equilibri- um role. Faults having transportation or sealing role along the strike show ＂segmentation＂ fea- ture, and the multi-layer enrichment pools form under the controlled ＂ segmented＂ active faults. The traps located at the dominant migration path of the gentle slope of the uplift are farfrom hydrocarbon kitchen. The paleocene strata of the medium-weak active fault and ＂active＂ source rocks at the end of uplift area, or regional combination of medium-strong active fault and ＂active＂ source rocks are the most interesting hydrocarbon exploration areas.