BHA Lateral Vibrations: Case Studies and Evaluation of Important Parameters

Abstract

Abstract Recent efforts to compute and measure drillstring and bottom hole assembly vibrations have shown that vibrations occur in the BHA which do not coincide with computed natural frequencies for axial and torsional vibrations. Analysis of BHA failures has indicated that lateral vibrations in the BHA was the probable cause of some failures. This paper presents a collection of bottom hole assembly failures. The possibility of lateral vibrations being the cause of a failure has been evaluated by considering circumstances surrounding the failure and making comparisons to a lateral vibration computer model. Similarities between lateral vibration failures are analyzed to determine what parameters are important in identifying the susceptibility of a bottom hole assembly to large lateral vibrations. The parameters include depth, hole size, ratio of hole size to drill collar diameter, and stabilizer placement. The results of this paper allow the drilling engineer to avoid BHA designs which have been shown to be susceptible to lateral vibration failures and identify designs which should be evaluated in more detail such as with a lateral vibration analysis.