Abstract: Fracturing practice shows that hydraulic fractures in shale reservoir present complex extending models of non-planar and multiple branches，which is essentially different from traditional symmetry plane bi-wing fractures in forming mechanism. Based on the research results of indoor experiments，field fracturing practice，theory analysis and numerical simulation etc，this paper has systematically analyzed the controlling factors of hydraulic fractures extending into network in shale formations. Research shows the extending shape of fractures in shale reservoir is influenced by both geological factors and engineering factors：according to reservoir geological attributes，higher brittle mineral contents of rock，stronger elastic characteristic of rock mechanical properties，smaller horizontal differential stress and better developed natural fractures will be constructive to better extension and propagation for hydraulic fractures extending into network；according to engineering conditions of
fracturing operations，higher operation net pressure，lower fluid viscosity and larger fracturing scale will be more helpful to the formation of fully propagated fracture-network. This study has important theoretical value and practical significance to the understanding of shale reservoir fracture-network propagation mechanism and can improve the science of shale reservoir fracturing design.

Key words: shale, fracture-network, brittle mineral, natural fractures, net pressure