Nonlinear analysis of axial-torsional vibration of drill string based on a 3 DOF model

Based on a model with three-degree-of-freedom, the nonlinear coupled axial-torsional vibration of drill string is numerically studied considering modified contact bit-rock interaction. The effects driving angular velocities, nominal drilling pressures, and formation stiffness response are discussed. simulation results show that can be periodic, quasi-periodic or chaotic motion variation system parameters. Increasing velocity helpful to reduce duration sticking even make stick-slip free. However, bit-bounce may occur if too large. pressure cause more prone stick-slip, but it has dampening effect bit-bounce. larger is, smaller amplitude axial corresponding maximum also larger, whereas torsional smaller. Compared from two-degree-of-freedom model, present remarkable greater. Meanwhile, than one two-degree-of-freedom, not easy bit bounce.