Abstract:Salt rock can make borehole close in the effect of creep,which often leads to stuck. However,many analytical models for creep of salt rock are based on the two-dimensional models currently,which are hard to analyze the problems of stuck because of creep in controlled directional well. Based on space coordinate transformation,the 3D model of creep of controlled directional well is established,and the variations of stresses with the actual deviation and azimuth angle are transformed to the hole axis. The established model analyses the influence of the variation of deviation and azimuth angle on creep under certain stress,and also propounds the concept that the “sensitive zone”of creep exists in parameters of some borehole of the directional well,which offers references to optimize the design of some parameters to drill out the salt formation successfully. Through actual example,it is verified that the security mud density based on the 3D numeral model is suitable during drilling the salt layer,which gives instruction of security mud density in practicing directional drilling in salt formation.