Thanks to the creep behavior of salt rock

drilling hole in the salt deposit of deep stratum is a very important and difficult problem in petroleum engineering. The creep of salt deposit often causes oil borehole losing stability

blocking aiguille and demolishing oil well casing

and brings huge economic loss. Based on the measured result of the drilling hole diameter between the different time in Shengke 1 borehole drilling engineering

the creep velocities of the rock layer in the deep stratum are obtained. The exponent creep constitutive law is employed to analyze the creep velocity of rock layer in the three dimension numerical method. The creep parameters of salt rock and soft mudstone are obtained. The creep velocities of rock layer under different drilling mud densities and salt layer depth are also analyzed based on the obtained creep parameters. Considering the permissive stratum creep velocity during drilling

the optimum drilling mud densities under different salt layer depths are obtained. The research result can be used in drilling engineering.