CHARACTERISTICS OF FAULT AND ITS SIGNIFICANCE IN HYDROCARBON ACCUMULATION IN ORDOS BASIN

With the deepening research of oil-gas exploration, the faults in Ordos Basin have been identified continuously. On the basic analysis of the basement faults of heavy, magnetic and regional geology with fully applied the oil-gas exploration and field investigations and combined with previous studies, this paper conducts research on the cap rock fracture in Ordos Basin. The results show as follows: firstly, the fault of the cap rock is very developed, and the location can be divided into four groups: East-West, North-South, North-East and North-West. Secondly, based on the scale, they can be divided into four categories: basin level, depression level, zone level and trap level. Thirdly, according to the mechanical properties, they can be divided into tension shear type (East-West fault), extrusion type (North-South fault) and shear type (North-West and North-East trending faults). Most of these fault dip angles are steep and have many strike slip properties. The seismic profiles are not obvious in the same phase axes, and are more concealed. Besides, a large number of joints and fractures are developed in the Yishan slope in the central part of the basin. More and more evidences show that cap rock faults and fracture zones play an important role in hydrocarbon migration and accumulation. The fault not only provides the channel for the vertical migration of oil-gas, but also forms a trap for oil-gas accumulation, and the fracture zone formed by the fault activity improves the physical property of the low permeability reservoir and provides the precondition for the oil-gas accumulation, and the distribution of the fault zone controls the spatial distribution of the oil-gas reservoirs.