The Recognition of Potential Fault Zone in Ordos Basin and Its Reservoir Control

Potential fault zone refers to the weak deformation fault trend zone reflected by the fracture development zone or a series of geological body alignment before the formation of the main section in the early stage of fault development. In order to study the formation mechanism of potential fault zones in Ordos basin and their control on hydrocarbon migration and accumulation, basin-level, depression-level, sag-level and trap-level potential fault zones were identified in Ordos basin by fully utilizing the data of oil and gas exploration and field investigation on the basis of gravity, magnetism and regional geology analysis. These potential fault zones can be divided into east-west, north-west and north-east directions according to their strike. According to the sequence from recessive to dominant, the evolution of the potential fault zone can be divided into five basic stages: the development period of dense caprock fractures, the linear distribution period of echelon faults, the intermittent formation period of fracture surface, the successive connection period of fracture surface and the connection of fracture surfaces period. It is concluded that the potential fault zone has important impact on hydrocarbon generation and accumulation, regulating the structural pattern of basin, dividing depressions and uplifts, accelerating the development of source rocks, controlling the distribution of sedimentary systems, and improving reservoir and transport system. The development area of potential fault zone is often the target area for hydrocarbon accumulation.