Generally there exist a large number of ineffective perforation clusters in multistage hydraulic fracturing of horizontal wells of shale gas reservoirs. So improving the effectiveness of perforation and maintaining the long-term conductivity of fractures are the main challenges to increase production and reduce costs for shale gas horizontal wells. Based on previous research results

the main reasons for low production of perforation clusters include: ① Fracture does not initiate or propagate effectively due to mechanical heterogeneity of shale reservoir

stress shadow between fractures

or difference of perforation erosion rate; ② The distribution of proppant is non-uniform between clusters and in fractures due to the difference of perforation displacement distribution within the stage

weak sand suspension ability of low viscosity fracturing fluid

and fracture bending

inclination and roughness; ③ The fracture conductivity is lost due to the breakage and embedding of proppant

diagenesis

formation and migration of formation particles. In order to solve the above problems

the optimization and technical solutions to facilitate the balanced initiation of fractures

the uniform distribution of proppants

and the improvement of fracture conductivity are proposed. They include new-type limited entry fracturing technique

degradable temporary plugging diversion

optimization of perforation parameters and sand-adding sequence

high-speed channel fracturing

high viscosity friction reducers and new-type proppants

etc.

which are expected to provide benchmark for improving the effectiveness of perforation cluster fracturing of horizontal wells.