Patent ID: 7383899
Filing Date: 2008-06-10
Classification: E21B

Abstract:
1. A self-centralizing spearhead assembly for a tool passed through a drill pipe having an inner surface, comprising: a base having a longitudinal axis and an outer surface composed of a plurality of contiguous surface portions where mutually adjacent surface portions lie in, or have, relatively inclined planes or relatively inclined tangential planes, a first of said surface portions lying in a first plane perpendicular to said longitudinal axis and a second of said surface portions lying in a second plane inclined at an acute angle to the first plane, the first plane being contiguous with the second plane; a slot formed in one of said base and opening onto said plurality of surface portions; a spearpoint having a proximal end located in said slot and pivotally coupled to said base and a distal end projecting from said slot and beyond said surface portions; and a spearpoint positioning system for urging said spearpoint toward one of a plurality of angularly spaced positions, respective ones of said positions characterized by said spearpoint extending perpendicular to the plane or tangential plane of an adjacent surface portion wherein a first of said positions is a central position where said spearpoint lies parallel to said longitudinal axis when said spearpoint extends perpendicular to said first plane and a second of said positions is an inclined position where said spearpoint is pivoted through an angle θ from the longitudinal axis when the spearpoint extends perpendicular to the second plane; and wherein said spearpoint is configured to contact the inner surface of the drill pipe prior to pivoting through the angle θ from the longitudinal axis, whereby the spearpoint is self maintained in the central position while disposed in the drill pipe.