河西务东主断层的扭动特征及与油气勘探的关系

河西务东主断层的断面,在地震剖面上呈现直立状,断层的上部断开上第三系至第四系地层的反射波,下部断过基底古生界地层的反射波;其伴生的断层呈叠瓦状,朝上向两侧撇开,在锥状形变区,断层的落差深层大、浅层小,整体表现为花状结构。在河西务构造带各地质层位的构造图上,走向北东的断层呈雁行斜列排布,与北北东向延伸的东主断层斜交,而且东主断层附近地层中的辉绿岩被断层搓碎,这说明东主断层是一条右旋扭动基底断层。受东主断层的制约,河西务构造带各层系的油气藏也呈雁行斜列带状分布。根据这种构造特征寻找新油气藏,可大大提高该区的石油勘探效率。

Wrench characteristic of Hexiwu east master fault and its ralation to hydrocarbon exploration.

Hexiwu east master fault is nearly vertical in a seismic section. It cuts off the shallow reflections from Neogene-Quaternary systems and the deep reflections from Paleozoic erathem (the basement). The secondary faults, upward radiating, appear as imbricate arrangement; and the cone deformation zone is characterized by big fault throws in deep formations and small fault throws in shallow formations, showing overall a "flower structure". On the structural map of each geological horizon in this area, the echelon faults trending in NE direction intersect obliquely the east master fault trending in northeast by north; and the diabase which penetrated in the formations nearby the east master fault has been broken by later wrench-faulting. All of these indicate that Hexiwu east master fault is a basement-involved dextral fault. Under the control of the master fault, hydrocarbon traps in each formation in this area also occur in echelon belts. Applying this structural style to hydrocarbon exploration, we can greatly improve exploration efficiency.