Investigation on Axial-Lateral-Torsion Nonlinear Coupling Vibration Model of Drilling String in Ultra-HPHT Curved Wells

In view of the vibration failure of drilling string system in ultra-high temperature and high pressure (ultra-HPHT) curved wells, an axial-lateral-torsion coupling (ALTC) nonlinear vibration model of drilling string system was established using energy method and Hamiltonian principle, in which, the influence of wellbore trajectory change, wellbore constraint, interaction between bit and rock and ultra-HPHT of wellbore on elastic modulus and viscosity of drilling fluid were taken into account. The finite element method (FEM) is used to realize the numerical solution of the nonlinear vibration model. The correctness and validity of the ALTC nonlinear vibration model was verified by comparing the measured data of four ultra-HPHT wells with the theoretical calculation results of the proposed model. The research results provide a theoretically sound guidance for designing and practically sound approach for effectively improving rate of penetration (ROP) and the service life of drilling string in ultra-HPHT curved wells.