Abstract
The research on calculation of torque and drag in highly deviated wells has demonstrated a significant gap against oil exploration and development; with the increasingly rigorous situation, the drill string dynamics and the contact or friction of drill pipe with borehole wall under the drill string action of dynamic need more attention and urgent research work. Based on full-hole system dynamics, three-dimensional nonlinear dynamic model and dynamic torque and drag model were established in highly deviated well by using the finite element method. An application of analyzing typical torque and drag problems presented here provides a means to more accurate description of the contact relation between drill string and wellbore. The results show that those models established in this paper have complete adaptability for a complex three-dimensional borehole trajectory. For the actual well application, it will help to evaluate security performance of drill string in complex working conditions.
Highlights
With scarcity of resources, great difficulties have been confronted with oil companies during the process of exploration drilling of oil or gas and the complexity of drilling geological environment is bottlenecking the development of drilling technology
Based on nonlinear coupling vibration of drilling string, three-dimensional nonlinear dynamic model and dynamic friction torque model were established in highly deviated well with mud drilling by using the finite element method to study the vibration rule of dynamic drag and friction torque of the drill string in rotary drilling
(1) Dynamic drag and torque model established in this paper has a good adaptability under a complex threedimensional borehole trajectory in highly deviated well for real drilling; it has much less assumptions and its result is highly coincident with the actual drilling operations
Summary
Great difficulties have been confronted with oil companies during the process of exploration drilling of oil or gas and the complexity of drilling geological environment is bottlenecking the development of drilling technology. In 1984, Johancsik et al [2] assumed that both torque and drag are caused entirely by sliding friction forces that result from contact of the drill string with the wellbore. They define the sliding friction force to be a function of the normal contact force and the coefficient of friction between the contact surfaces based on Coulomb’s friction model. This paper established the models for vertical, lateral, and torsion coupled vibration of full-hole drilling strings in highly deviated well with mud drilling using the finite element method to dynamically analyze torque and drag of string drilling in operation
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