Patent ID: 7845061
Filing Date: 2010-12-07
Classification: E21B,Y10T

Abstract:
1. A method of making a bow spring centralizer having extendable collars, comprising: cutting elongate portions from the center portion of a tube intermediate the first and second tubular ends to form a generally elongate cage with a plurality of generally angularly distributed ribs intermediate the first and second tubular ends; forming a first extendable collar from the first tubular end by cutting the first tubular end into first and second interlocking tubular members and by removing portions of a wall of the first tubular end along the interlocking interface to form a first stop collar that is rotatably locked to, but slidably interlocked with, a first moving collar; forming a second extendable collar from the second tubular end by cutting the second tubular end into first and second interlocking tubular members and by removing portions of a wall of the second tubular end to form a second stop collar that is rotatably locked to, but slidably interlocked with, a second moving collar that is opposite the elongate cage from the first moving collar, with both moving collars intermediate the first and second stop collars; and displacing the angularly distributed ribs radially outwardly from the axis of the tube to form a plurality of bow springs; wherein the moving collars are integral with the plurality of bow springs, and wherein a bore of the first extendable collar and a bore of the second extendable collar are generally aligned for receiving a casing.