Mathematical Model and Experimental Investigation of Bit-Bounce in Horizontal Oil Well Drillstring

The bit-bounce is detrimental to the service life of drillstring and bit. This study highlights the influence of axial excitation and torsional excitation on the bit-bounce in horizontal well. Because of the complicated surroundings of downhole, Hamilton principle, a kind of energy method, is employed in this paper to derive the motion equation of the drillstring, which is discreted through finite element method. The impact–friction between the drillstring and borehole wall, and bit–rock and fluid–structure interaction are also modeled in this paper. The research results show that both axial excitation and torsional excitation greatly affect the dynamic behavior of the drillstring. Both the amplitude and the intensity of bit-bounce reduce with the development of the axial excitation and torsional excitation. And the test results are in agreement with the numerical simulation. The results of both have been mutually verified.