Dynamic characteristics analysis of drillstring in the ultra-deep well with spatial curved beam finite element

Based on the spatial curved beam element, a new finite element model for drillstring dynamics was presented to understand the dynamic characteristics of the drillstring in a curved borehole. In view of the contact between drillstring and borehole, an iterative solution for the model was given to analyze drillstring dynamic characteristics, such as whirl orbit, whirl speed, lateral and axial accelerations. The results show that the proposed model is correct and reliable. Furthermore, the drillstring dynamic characteristics can be effectively calculated by using spatial curved beam finite element method. The proposed method can be used to improve the efficiency of dynamic analysis of drillstring with ultra-slenderness ratio in the ultra-deep well. It can be concluded that the proposed method could provide a new way and theoretical support for analyzing dynamic characteristics of the drillstring in the curved borehole.

► We model drillstring dynamics characteristics by using spatial curved beam element.
► We present an iterative method which effectively solves the nonlinear equation.
► Fewer elements are needed when spatial curved beam finite element method is used.
► We find that spatial curved beam finite element method can save time of calculation.