Abstract:The development of structural fractures changes the mechanical properties of the reservoir rock, directly affecting the efficiency of dense reservoir exploration and development. Therefore, the development characteristics of the fractures is of very important theoretical significance and practical value. We analyze the characteristics of the fracture from geological outcrop and the underground in the Jiyuan-Yuancheng area of the Ordos basin, and combine the tectonic stress field background getting the following results in this paper: (1) the structural fracture is given priority oblique to the maximum principal stress of a single fracture, with the trend of SWW-NEE or nearly E-W and NNE-SSW or nearly S-N, and a small amount of the corresponding conjugate fracture NW-SE and NE-SW fracture develops; (2) according to the cutting relationship between the fracture system in the outcrop area, the trends of NE-SW and nearly S-N latter develop, and SWW-NEE or nearly E-W fracture develop early; (3) in the background of pressure stress field in the north west and south east of Yanshan period, the principal stress difference caused by the early cretaceous tectonic uplift is the main reason for the formation of early conjugate fractures. The stress extrusion of north east-south west in the Himalaya period is the main reason for the fracture.
GAO Jindong,ZHOU Lifa,FENG Qiao. The Characteristics and Formation Phase of Structural Fracture of the Jiyuan-Yuancheng Area in the Ordos Basin[J]. jgg, 2018, 38(8): 811-817.