Spring bow, centralizer, and related methods

Abstract From the Canadian patent

A centralizer for well casing functions in an annular space between the casing and a wellbore. It comprises a pair of axially spaced-apart and aligned collars adapted to encircle the well casing and a plurality of spring bows extending between and secured to the collars. Each spring bow has two ends and an outwardly convex curved mid-portion. In a first form of the invention starting force is reduced by providing spring bows having outwardly projecting contact angle reduction members that engage the upper edge of the wellbore as the casing is moved into the wellbore to reduce the effective contact angle of the spring bows with respect to the wellbore and thereby reduce the force required to …