General fracturing techniques are extremely difficult to satisfy requirements of the development of shale gas

due to the highly low porosity and permeability and well developed natural fractures and horizontal beddings in shale reservoirs. Therefore

one of and key technologies is the multiple clusters staged hydraulic fracture of horizontal well

which can greatly increase the stimulation volume

the production rate of gas and final recovery efficiency. In order to locate the fracturing point and fracturing pressure of multiple clusters staged horizontal well of shale gas reservoir

a three-dimensional breaking model of multiple clusters staged horizontal well is established with finite element method

which considers cement mantle and casing. Comparing the simulation results with laboratory experiment of fracturing pressure

the good agreement indicates that the numerical model is reliable and validity. This paper further studies the effect of parameters on fracturing points and fracturing pressure of multiple perforation clusters within multi-stage hydraulic fracturing in shale gas horizontal well using the simulation model. The research results show that fracturing points are found near the roots of perforation clusters

when there is no influence of natural fractures and horizontal bedding plane around perforations. The smaller perforation cluster spacing is

the greater interference between perforation clusters is

which may induce that the perforations cluster in the middle is unable to fracture. Moreover

the fracturing pressure is reduced with the increase of perforation density and perforation length. The existence of natural fracture can reduce the fracturing pressure and change the fracturing initiation position under certain circumstance

mainly depending on the natural fracture distribution and orientation and horizontal principle stress difference. In addition

the bedding plane may reduce the fracturing pressure

but relating to the difference between vertical principal stress and minimum horizontal principal stress. The regularity of fracturing pressure can provide basis for further research on the fracture propagation in multiple clusters staged horizontal well of shale gas reservoir. This study also offer concrete advises on perforating parameters in hydraulic fracture design and hydraulic operation in shale gas reservoir.