Analysis of wall closure rate of oil wells due to the creep phenomenon in salt formations

Salt domes are one of the most important oil traps. More over salt minerals can be present in other oil traps. Drilling in salt formations can result in many problems such as stuck pipe of drilling strings and casings، closure of borehole’s wall and therefore bad cementing and casing failure. These problems occur as the result of creep phenomenon which is the time dependent deformation of salt under constant stress. The aim of this paper is to study the mechanical behavior of salt rock. Based on obtained results، appropriate drilling fluids، the time for running the casing in the borehole، and the collapse pressure on the casing can be determined. The effect of drilling fluid’s weight on reducing the rate of borehole’s wall closure is evaluated by FLAC codes. Considering that drilling of oil and gas wells is an expensive operation، optimization of the drilling fluid''s weight can ensure oil well integrity. Heavier drilling fluids can reduce the rate of borehole’s wall closure and therefore the running of casing can be postponed.