松辽盆地大庆长垣上白垩统姚家组震积岩的发现及其地质意义

Discovery of seismites in the Upper Cretaceous Yaojia Formation in Daqing Placanticline of Songliao Basin and its geological significance

大庆长垣上白垩统姚家组发育与地震相关的震积岩。通过岩心观察,在大庆长垣上白垩统姚家组识别出2种震积岩的主要类型:软沉积物变形构造(液化砂岩脉、砂球—砂枕构造、液化卷曲构造和重荷构造)和硬岩层脆性变形构造(阶梯状微断层、角砾状构造和地层破裂构造),共计7小类。通过对取心井(DQ-N1井、DQ-N2井、DQ-N5井和DQ-N7井)的系统观察,总结了松辽盆地大庆长垣软沉积物变形垂向组合序列,并讨论了震积岩在三角洲沉积体系中的发育情况。在阶梯状微断层现象(见于DQ-N2井)和地层破裂现象(见于DQ-N5井)发育的井段中均发现油迹显示,说明震积岩本身确实可以作为潜在的油气储集体,地震活动可以有效地提高储集层的孔渗性、增加新的油气运移通道,对油气资源的勘探与开发提供了新的切入点。

A great deal of seismites, which are related with earthquakes, were found in the Yaojia Formation of the Upper Cretaceous, Daqing Placanticline. By observation of cores, two major categories of seismites are identified, which are deformational structures of soft sediments （including liquefaction sand dyke, ball-and-pillow structure, vibration-induced liquefaction structure and load structure） and hard rock （including step micro-fault, autoclastic brecciated structure and structure）. These deforma-tional structures can be divided into 7 subclasses. Based on the data of core observation （Well DQ-N1 , DQ-N2, DQ-NS, DQ-N7）, the vertical sequence of seismites was drawn, at the same time, different development of seismites in the sedimentary system of delta was discussed. The oil trace, which was found in the step micro-fault （Well DQ-N2） and formation breakdown （Well DQ-N5）, shows that the seismites themselves were a kind of potential reservoir, and seismic activity can efficiently enhance the po- rosity and permeability of the reservoir and increase new pathways for oil and gas migration. It will provide a breakthrough point to analyze the exploration and development of oil and gas resource.