Abstract:

Basing on the principles of geomechanics and rock texture mechanics, this paper discusses the important role of horizontal shear stress in the formation, transformation and distribution of large fracture systems and its physical model. The paper holds that a large fracture system is the product of a larger straight press type fracture network and a shear type fracture network, and is mainly distributed over the zone on which horizontal shear stress and straight press stress jointly act. Horizontal shear stress is the most important factor of transformation and controling the incongruity of large fracture network strueture.So it provides new patterns of forming reservoirs and theoretical basis for researching and finding relatively large concealed fracture system.

Key words: Horizontal shear stress, Fracture system, Texture analysis, Distribution of fracture