Patent ID: 7472761
Filing Date: 2009-01-06
Classification: E21B,G01V

Abstract:
1. In a system for tracking a boring tool which is moved in an underground region using a drill string having a length that extends to the boring tool and said boring tool having an overall orientation that is characterized by a pitch orientation, a yaw orientation and a roll orientation and which is steerable underground in the region using said roll orientation, a method comprising: determining a maximum curvature of the drill string; monitoring an advance of the boring tool over a path segment from a known, start position to an end position, where the path segment forms a portion of an overall drill path that is taken by the boring tool and includes a segment length; concurrently with said monitoring, measuring the pitch orientation and the roll orientation of the boring tool; and establishing a resulting position of the boring tool at an endpoint of said path segment based on the measured pitch orientation, the measured roll orientation, the monitored advance of the drill string and the maximum curvature of the drill string.