二连盆地哈南油田伸展构造体系裂缝及其油气地质意义

哈南油田构造断裂十分复杂,受伸展构造体系裂缝及断层的控制,形成有与断层共生的裂缝组系和断层活动派生的裂缝组系。裂缝与NE向断层平行或与其斜交或横交。裂缝力学性质表现为张裂缝、剪裂缝和张剪裂缝,以张裂缝为主。无论是何种力学性质的裂缝,如果裂缝没有被充填,则会对油气聚集和开发产生影响。有效裂缝可以为储层提供油气运移通道和油气储集空间,在油田开发中,裂缝与断层组成裂缝网络形成的断裂导水,会致使注水层系混乱,形成非同层注水局面,影响着层系开发的效果。

FRACTURES OF EXTENSIONAL TECTONIC SYSTEM AND THEIR INFLUENCE ON OIL RESERVOIR IN HANAN OIL FIELD, ERLIAN BASIN

The structural fractures are very complex in Hanan oil field, the Erlian basin. There are two types of fractures under the extensional action, and they are associated and induced fracture systems. During the formation of faults, nearly vertical extension fractures and oblique conjugate shear fractures are deve loped. The extension fractures are small in scale and the fracture faces are rough. Only one group of the conjugate fractures is developed into a fault and the other groups exist in the form of fractures. After the action of faults, the redistribution of in situ stress generates new fractures near the faults. They are mainly extensional fractures. Controlled by the extensional faults, fractures extend along the direction of NE, which are parallel to most faults. And also there are some NW or EW fractures. Microfractures orientations are aligned with those of macrofractures, indicating that they are probably formed at the same stress field. Tensile, shear and compound fractures are developed in Hanan reservoir. Controlled by the faults, fractures are mainly distributed in such places as the neighbouring of the faults, the intersection and the end of faults.Fractures play important roles on the oil accumulation and development. Connected fractures provided the moving paths and storage rooms for oil. In the waterflooding, the network of fractures and faults, which forms the water conduction, leads to disorder of waterflooding formation and has the bad effects on deve lopment.