Development and Application of a Coiled Tube Fatigue Life Prediction Software

During operation, the life of coiled tubing will be shortened due to complex cyclic load effect, corrosion, mechanical damage, manufacturing defect and faulty operation etc. Therefore, a coiled tubing fatigue life calculation and analysis software was developed on the Qt platform based on the fatigue life theories and massive empirical data at home and abroad. With this software, the effect of bending radius, wall thickness and internal pressure of the coiled tubing on its fatigue life were calculated and analyzed, and a feasibility testing was also performed. The analytical results indicated that this software could be used to effectively calculate the coiled tubing fatigue life values; the increase of internal pressure of coiled tubing will lead to the decrease of its fatigue life, but the decrease tendency will slow down gradually. However, the coiled tubing will lose its loading capacity when internal pressure reached certain point; a proper reel size could improve the life of coiled tubing; coiled tubing with large or varying wall thickness shall be recommended. The development of this software is of great guidance significance to the engineering applications and safety evaluations of coiled tubing.