Authors : Jamal Zare, Seyed Jalalodin Hashemi and Gholamreza Rashed
Abstract: Lateral vibration is recognized as the leading cause of drillstring and BHA failures, shocks and severe damages to borehole wall. This study presents a finite element model using ANSYS software to investigate the drillstring lateral vibrations in slightly deviated wells. The analysis proceeds in two stages. At first, a nonlinear static analysis is performed to determine the effective length of the string where it is free to vibrate in the lateral direction. The second stage consists in modal, harmonic and transient dynamic analyses to obtain the lateral vibration modes and natural frequencies, frequency response and time dependent response, respectively. The modeling is developed in the presence of mud, friction and nonlinear contact between drillstring and wellbore wall. The effects of drilling mud, drillstring length, hole inclination and WOB are considered. The model was compared with experimental and simulated results obtained from several BHA configurations giving excellent results.
Jamal Zare, Seyed Jalalodin Hashemi and Gholamreza Rashed, 2011. Finite Element Analysis of Drillstring Lateral Vibration. Journal of Engineering and Applied Sciences, 6: 64-70.