Abstract:The electric submersible pump is widely used in high production oil wells, but frequent overhaul increases the operation cost, and the insulation breakdown of joint is the most common fault. In order to analyze the failure of the submersible cable and extend the time free period, an electromagnetic and heat conduction coupling model is established and the thermal effect of the cable is analyzed. The electric field of the cable joint is analyzed for reason of insulation breakdown of joint. The Tafel formula is used to analyze the armored layer corrosion in tensile stress. The grey correlation method is used to analyze the relationship between the various factors and the repair period of the cable. Results show that if the annular space is full of gas, the heat generated by cable inductance is not easy to distribute, the temperature can be 10 degrees higher than environment. The unsmooth surface at joint is most likely to produce non-uniform electric field lead to insulation breakdown. Stronger tension in cable brings higher corrosion rate at the defective position, especially, if plastic strain appears the corrosion rate is greatly accelerated. The correlation factor between temperature and repair period is the highest, so the ultimate temperature of cable should be appropriate and the joint is as smooth as possible, and the tensile stress is reduced as much as possible. After the pertinent measures taken, the repair period has been extended by more than 30%in X oilfield.