Test device for simulating longitudinal-lateral-torsional coupled nonlinear vibration of drill string of deepwater riserless drilling and method therefor

The present invention discloses a testing device and method for simulating longitudinal-transverse-torsional coupled nonlinear vibration of a drill string in deep-water riser-free drilling. The testing device comprises a pool (1), a motor (2) and a hook load adjustment device (3), wherein a guide wheel (4) is provided on the top of the pool (1); a support seat A (5) and a support seat B (6) are fixed on the bottom surface of the pool (1); an organic glass tube (8) is fixed between the support seat A (5) and the support seat B (6); a casing (9) is respectively provided on the top surface of the support seat B (6) and the top surface of the trailer (7); the left end of the plastic tube (10) extends into the organic glass tube (8) along the axis of the organic glass tube (8). The present invention further discloses a simulation method. The present invention has the following beneficial effects: the structure is compact; the longitudinal-transverse-torsion coupled vibration responses of the drill string under different rotating speeds of the drill string, ocean flow rates, flow rates of the drilling fluid, torsional excitations and longitudinal excitations at the bottom of the formation section is simulated, thereby filling up the blank in the riser-free drilling system.