Modeling and Avoidance of Heave-Induced Resonances in Offshore Drilling

Abstract

Summary The problem of heave-induced-pressure fluctuation during drilling is considered. The surge/swab pressures created by the vertical motion of the pipe can excite resonances that may amplify the magnitude of pressure oscillations by a factor of 10. The locations of the resonant frequencies depend on the topside-choke opening and can hence be avoided. By use of a model of the full coupled dynamics, it is shown that the elastic pipe and the mud-in-pipe can also exhibit resonant behavior significantly affecting the downhole pressure. Techniques to avoid resonances are discussed.