Patent ID: 6205851
Filing Date: 2001-03-27
Classification: E21B

Abstract:
A method for determining the existence of a whirling condition during the drilling of a borehole comprising:measuring acceleration of a bottom hole assembly to determine at least one acceleration value;measuring rotational speed of said bottom hole assembly to determine at least one rotational speed value;calculating, based upon said at least one acceleration value and said at least one rotational speed value, the existence and identification of a whirl condition within said bottom hole assembly;continuously determining one of computed borehole diameter and radius dimension with equations used for each of an assumed forward whirl condition and an assumed backward whirl condition over time with respect to said equations used for each of said assumed forward whirl condition and said assumed backward whirl condition;plotting said dimensions over time with respect to said equations used for each of said assumed forward whirl condition and said assumed backward whirl condition; anddetermining areas of forward synchronous whirl, with and without slip, and backward whirl, with and without slip, over time from said plot.