辽西凹陷辽西1号断裂体系特征及其控藏作用

辽西凹陷是位于渤海海域东北部的一个新生代凹陷,勘探证实辽西南洼陡坡带发育受辽西1号断裂体系控制的断块圈闭,且各个断块油气富集程度具有差异性。通过对辽西凹陷南部辽西1号断裂及其派生断裂静态特征和动态演化分析,文章重点解析了不同类型断裂对油气成藏的控制作用。研究结果表明:辽西1号断裂体系包括辽西1号断裂及其派生调节断裂,两者分别具有"早断晚衰"和"中断晚衰"活动特征;东营期,辽西1号断裂"S"增弯段诱发陡坡带隆起效应及其调节断裂的发育,两者共同控制了挤压型构造圈闭的发育;调节断裂对油气运聚具有分段控制作用,调节断裂陡坡段具有压扭性质,断裂结构带相对致密,利于油气的封堵,调节断裂洼槽段具有拉张性质,断裂结构带相对疏松,利于油气运移;调节断裂压扭段与主走滑位移带夹角控制油气富集程度,夹角大小与油气富集程度呈负相关性。 

THE CHARACTERICTICS OF LIAOXI NO.1 FAULT SYSTEM AND ITS CONTROL ON RESERVOIR IN LIAOXI SAG

Liaoxi sag is a Cenozoic marginal sag, which is located in the northeast of the Bohai sea. Exploration proved that a series of fault block traps developed in the role of No.1 fault system in the steep slope of the southern sub-sag of Liaoxi, with different oil and gas enrichment degree. Based on the analysis of the static characteristics and dynamic evolution of No.1 fault and its regulative faults in the south of Liaoxi sag, and the controlling roles of different types of faults on hydrocarbon accumulation are mainly analyzed. The study shows that the No.1 fault system include the No.1 fault and its regulative faults, and they have the characteristics of "early break and late decline" and "middle break and late decline" activity, respectively. The "S" increasing section caused the uplift effect of the steep slope and the development of the regulative faults in the stage of E3d, both of which control the development of the compressive structural trap. The regulative fault has a piecewise control effect on oil and gas migration and accumulation, and the slope segment of the fault has the properties of compression and torsion, and the fracture structure is relatively compact, which is beneficial to the sealing of oil and gas; The sag segment of the fault has the tensile property, the fracture structure is relatively loose and is beneficial to the migration of oil and gas. The hydrocarbon enrichment degree is controlled by the angle between the compressive segmentation of regulative fault and the main strike-slip displacement zone, which has a negative correlation with the angle size.