Rock anti-drillability parameters are important basic parameters for making drilling plan and implementing optimal drilling. In this paper

the computational models of formation anti-drillability parameters such as rock compressive strength

rock drillability level value and rock hardness are established through the rock mechanics testing. After that

combined with the logging data and geological data

the profiles of rock anti-drillability parameters varied with the well depth of different strata for shale gas in Nanchuan are also built up. Based on the analysis of its distribution rule

the bits are selected. The study shows that the characteristic parameters of the strata above Liangshan Formation in the shale gas block of Nanchuan fluctuate greatly

which indicates that the stratigraphic heterogeneity is obvious; the lower strata change more gently

but there is a gradual upward trend from the bottom of Longmaxi Formation. According to rock anti-drillability parameters

bits with good wear resistance

5 ~ 6 blades

and 13 ~ 16 mm cutting teeth with high density should be selected in bit design. The field application shows that the recommended bit has a good effect and the drilling speed is obviously improved.