Apparatus and methods for determining whirl of a rotating tool

摘要

In one aspect, a method of determining the presence of whirl for a rotating tool is disclosed that in one embodiment includes obtaining measurements (ax) of a parameter relating to the whirl of the tool along a first axis and measurements (ay) of the parameter along a second axis of the tool, determining a first whirl in a time domain for the tool using ax and ay measurements, determining a second whirl rate for the tool in a frequency domain from ax and ay measurements and determining the presence of the whirl from the first whirl rate and second whirl rate. The method further quantifies the whirl of the tool from the first and second whirl rates.

主权项

1. A method of drilling a wellbore, comprising:
obtaining measurements of an acceleration (ax(t)) relating to a whirl of a rotating tool in the wellbore along a first axis and measurements of an acceleration (ay(t)) along a second axis; determining a first whirl rate using calculations in a time domain for the rotating tool using the ax(t) and ay(t) measurements; determining ax(f) and ay(f) in a frequency domain from a Fourier transform of ax(t) and ay(t), respectively; confirming a presence of whirl when ax(f) has a dominant frequency and ay(f) has a dominant frequency and when a difference between the dominant frequency of ax(f) and the dominant frequency of ay(f) is within a tolerance; and using the confirmation of the presence of whirl to control the whirl of the rotating tool.