A STUDY OF BIFURCATION OF THE COMPRESSIVE-ROTATING DRILLSTRING IN VERTICAL WELL SECTION

The present work aims to investigate the effect of the rotating speed on the buckling behavior of the drillstring in oil drilling engineering. Taking into account the rotating inertial force of the drillstring, a bifurcating differential equation is established for the rotating slender drillstring in compression in vertical well section subjected to distributed buoyant weight. The equation is solved numerically. The first four-order bifurcating value curves and the corresponding buckled configurations are shown graphically. The present work shows that the higher the rotating speed of the drillstring is, the lower the buckling weight-on-bit of the drillstring. As an example, a practical drilling case is analyzed, indicating that the rotating effect has significant influence on the buckling behavior of the drillstring.