There are huge coalbed methane reserves existing in our country. These CBM reservoirs have the characteristics of low pressure

low saturation

low permeability

high heterogeneity and complex reservoir structure

with the easily broken coal rocks.The technology of the pore-creating by the hydraulic jet can avoid the collapse of the coal bed

eliminate the compaction effect caused by the conventional perforation and break the coal petrography to promote the permeability of the reservoir. By the study of the large physical models

the conclusion was that the bore diameter increases by the increasing of the nozzle diameter. The abrasive concentration and the pore diameter increases but the bore depth decreases after the increasing and the pumping pressure and the bole depth increase. Finally

the operation parameters were optimized

that is

the pumping pressure is 25 MPa

the nozzle diameter is 4 mm and the abrasive concentration is 6.6 %. These parameters are helpful for the parameter design of the site construction.