连续油管疲劳寿命的预测及模糊优选

连续油管的失效主要是弯曲疲劳失效。疲劳寿命是衡量其可靠性的关键指标。而目前连续油管疲劳寿命预测理论还很不成熟。现文利用等效应力建立了连续油管的疲劳寿命估计模型；并根据理论模型，综合考虑连续油管使用的实际条件和有关因素，对连续油管的疲劳寿命预测模型进行了模糊处理，得到了连续油管的模糊可靠性寿命，并用现场实例进行了验证说明。

The prediction and fuzzy optimal selectionof the coiled tubing fatigue life

The bending fatigue is the main failure of the coiled tubing, so the fatigue life becomes the key index for appraising the coiled tubing's reliability. The coiled tubing fatigue belongs to over low cycle fatigue at multi-axial stress state. The prediction theory of this field is far more complete. The coiled tubing fatigue study method was outlined in this paper. Based on the equivalent stress formula of the coiled tubing, the life prediction model was put forward and a semi-empiric formula for prediction was obtained. Based on the theoretical model, considering the real working conditions of the coiled tubing, the prediction life was optimal selected and the fuzzy reliability life of the coiled tubing was obtained. In the end, the results were verified by experimental data and oilfield application.