An analytical model is presented in detail which pre- dicts the oscillatory motions and forces at the top of a drillstring due to forward whirl of the BHA (bottom hole assembly) at a BHA lateral resonance. The geometry and amplitude of the BHA mode shape are used in a scheme which converts the lateral motions to sinusoidally varying axial forces and tangential impulses acting on the BHA. The entire string is then analyzed for wave propagation of the axial forces and torsional impulses. In this manner, the dynamic axial and torsional response at the top of the drillstring can be used to predict BHA forward whirl at each of the BHA lateral resonances. The model has been incorporated in a computer program for practical analyses.

Keywords:
resonance, natural frequency, amplitude, upstream oil & gas, detection, axial force, lateral critical speed, spe 24583, rotary speed, bha lateral resonance
Subjects:
Drillstring Design, Drilling Operations, Drilling Equipment, Torque and drag analysis
Copyright 1992, Society of Petroleum Engineers
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