BOTTOMHOLE ASSEMBLY DESIGN METHOD TO REDUCE ROTATIONAL LOADS

摘要

A method for estimating a location for disposing a tool in a drill tubular having a drill bit includes performing a modal analysis of the drill tubular to determine natural eigenfrequencies and corresponding eigenmodes of torsional oscillations of the model and selecting a predominant natural eigenfrequency and corresponding eigenmode from the determined natural eigenfrequencies and corresponding eigenmodes. The method further includes performing a forced modal analysis of the drill tubular at the predominant eigenfrequency with a force or moment acting on the drill bit to provide a correlation between forced torsional deflection amplitude and position and estimating the position to be within a range of positions wherein a vibration qualification of the tool is greater or equal to the torsional deflection amplitude throughout the range.