An efficient method for locating potential contact points within a wellbore for the dynamics modeling of drillstrings

With the development of oil and gas exploration to deeper layers, the slenderness ratio of the downhole drillstring system increases significantly, and the contact status becomes more complex. For drillstring systems with a large slenderness ratio, the conventional dynamic analysis method has limitations in calculation accuracy and efficiency. Moreover, the traditional bounding box method can lead to missing or recalculation of some contact points. In this paper, the dynamic equation of the downhole drillstring system is established by using the absolute nodal coordinate formulation, and a new method is developed for detecting the located wellbore segment of potential contact points. The measured depth of the contact points is used to solve the problem of missing or recalculating contact points, and the efficiency of the downhole drillstring system dynamics simulation is improved. Typical working conditions are simulated and analyzed to verify the validity of the proposed method, and the results indicate that the proposed method can be used to predict the drilling process of deep wells.