Laboratory investigation of drillstring vibrations

Abstract

Experimental investigations of drillstring dynamics are essential to complement the theoretical studies and to alleviate the complexity of such dynamic models. This article presents an experimental investigation using a specially designed drilling test rig. The test rig can simulate the drillstring vibrational response because of various excitation mechanisms, including stick-slip, well—borehole contact, and drilling fluid interaction. The test rig is driven by a variable speed motor that allows for testing different drilling speeds, while a magnetic tension brake is used to simulated stick-slip. In addition, a shaker is employed to excite the drillstring axially in order to simulate the weight-on-bit. The drillstring is instrumented for vibration measurements. The experimental measurements in conjunction with the finite-element mathematical model of the drillstring are used to characterize and tune some modelling parameters. Comparisons with published data demonstrate the reliability of the developed scheme for prediction of drillstring vibrations.