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In this paper, a mathematical model of axial vibration of drill string near drill bit in horizontal well under natural gas is established considering the effects of gravity, load and fluid on drill string system. Based on the developed drilling string dynamic test platform, the axial vibration experiments of drilling string system under different gas content and gas flow rate are carried out. The experimental results show that the axial vibration of drill string is more serious and the vibration amplitude increases with the increase of air flow velocity and gas content.
Yuan et al. (Sun,) studied this question.