Patent ID: 7584788
Filing Date: 2009-09-08
Classification: E21B

Abstract:
1. A method for determining a a curvature of a subterranean borehole, the method comprising: (a) providing a downhole tool in a drill string, the downhole tool including first and second surveying devices disposed at corresponding first and second longitudinal positions in the borehole, the first and second surveying devices deployed on corresponding first and second body portions of the downhole tool, wherein the first and second body portions are configured to rotate substantially freely with respect to one another about a longitudinal axis of the downhole tool during drilling; (b) causing the first and second surveying devices to measure longitudinal directions of the borehole at the corresponding first and second positions; and (c) processing the longitudinal directions of the borehole at the first and second positions to determine the curvature of the borehole between the first and second positions.