EXPANDABLE CENTRALIZER FOR EXPANDABLE PIPE STRING

摘要

A close-tolerance expandable bow spring centralizer (8) having a first expandable collar (10A) coupled to and spaced apart from a second expandable collar (10B) through a plurality of bow springs (30) wherein expandable collars (1OA, 10B) comprise a plurality of slidably coupled links (16) that separate to expand the diameter of the collars (1OA, 10B), e.g., upon expansion of an expandable pipe string (80) on which the centralizer (8) is received. Expandable bow spring centralizer (8) may grip the expandable pipe string (80) when in the collapsed configuration to eliminate the need for a stop collar. Additionally or alternatively, a fin (32) may be connected to each bow spring (30), and then connected to one or more adjacent fins (32) upon collapse of the bow springs (30) to form a restraining band (39) that may be ruptured, e.g., upon expansion of the expandable pipe string (80).