Spring bow, centralizer, and related methods

A centralizer for well casing to function in an annular space between the casing and a wellbore, the centralizer having a longitudinal central axis, the wellbore having an upper edge at an upper wellbore opening, the centralizer comprising

• a pair of spaced-apart and aligned collar means adapted to encircle the casing,
• a plurality of spring bows extending between and secured to the collar means, each bow having two ends and a bow mid-portion curved outwardly from the longitudinal central axis of the centralizer, the bows disposed so that a bow part of the bow mid-portion is at a bow angle with respect to the upper edge of the wellbore upon insertion of the centralizer into the wellbore,
• at least one of said bows having at least one contact angle reduction member, the contact angle reduction member comprising a member protruding from the bow part, the contact angle reduction member protruding outwardly with respect to the longitudinal central axis of the centralizer, the contact reduction member contacting the upper edge of the wellbore at a contact angle which is smaller than the bow angle, and
• at least one tubular abutment member for abutting the casing on at least one of said bows, the tubular abutment member comprising an extending member having two ends only one of which is secured to the bow, the tubular abutment member protruding inwardly from the bow toward the centralizer's central axis, the tubular abutment member increasing the bow's restoring force by contacting the casing as the bow is moved into the casing during insertion of the centralizer into the wellbore.

A spring bow for a well casing centralizer, the centralizer to function in the annular space between a casing and a wellbore, the centralizer having a longitudinal central axis and a pair of spaced-apart and aligned collar means adapted to encircle the casing, the wellbore having an upper edge at an upper wellbore opening, the bow comprising

• a body member having two ends and a mid-portion disposed between the two ends,
• the mid-portion curved outwardly from the centralizer's longitudinal central axis, the mid-portion of the bow having a bow part which is at a bow angle with respect to the upper edge of the wellbore upon insertion of the centralizer into the wellbore,
• the bow having a contact angle reduction member protruding outwardly from the bow part with respect to the longitudinal central axis of the centralizer, the contact angle reduction member contacting the upper edge of the wellbore and a contact angle less than the bow angle, and
• a tubular abutment member for abutting the casing, the tubular abutment member comprising an elongated extending member having two ends only one of which is secured to the bow, and the tubular abutment member protruding inwardly from the bow toward the centralizer's central axis to increase the bow's restoring force by contacting the casing as the bow is moved into the casing during insertion of the centralizer into the wellbore.

A method for employing casing in a wellbore, the method including the steps of

• disposing a centralizer on the casing, the centralizer comprising
• a pair of spaced-apart and aligned collar means adapted to encircle the casing,
• a plurality of spring bows extending between and secured to the collar means, each bow having two ends and a bow mid-portion curved outwardly from the longitudinal central axis of the centralizer, the bows disposed so that a bow part of the bow mid-portion is at a bow angle with respect to the upper edge of the wellbore upon insertion of the centralizer into the wellbore,
• at least one of said bows having at least one contact angle reduction member, the contact angle reduction member comprising a member protruding from the bow part, the contact angle reduction member protruding outwardly with respect to the longitudinal central axis of the centralizer, the contact angle of reduction member contacting the upper edge of the wellbore at a contact angle less than the bow angle,
• inserting the casing into the top of the wellbore, and
• moving the casing so that it is contained within the wellbore.

A method for employing casing in a wellbore, the method including the steps of

• disposing a centralizer on the casing, the centralizer comprising
• a pair of axially spaced-apart and aligned collar means adapted to encircle the well casing,
• a plurality of spring bows extending between and secured to said collar means, each bow having two ends and a mid-portion curved outwardly from the central axis of the centralizer, the ends secured to the collar means, the bows exerting a restoring force upon emplacement of the centralizer within the wellbore,
• at least one tubular abutment member for abutting the casing on at least one of said bows, the tubular abutment member comprising an extending member having two ends only one of which is secured to the bow, the tubular abutment member protruding inwardly from the bow toward the centralizer's central axis, the tubular abutment member increasing the bow's restoring force by contacting the casing as the bow is moved into the casing during insertion of the centralizer into the wellbore,
• inserting the casing into the top of the wellbore, and
• moving the casing so that it is contained within the wellbore.

A method for employing casing in a wellbore, the method including the steps of

• disposing a centralizer on the casing, the centralizer comprising
• a pair of spaced-apart and aligned collar means adapted to encircle the casing,
• a plurality of spring bows extending between and secured to the collar means, each bow having two ends and a bow mid-portion curved outwardly from the longitudinal central axis of the centralizer, the bows disposed so that a bow part of the bow mid-portion is at a bow angle with respect to the upper edge of the wellbore upon insertion of the centralizer into the wellbore,
• at least one of said bows having at least one contact angle reduction member, the contact angle reduction member comprising a member protruding from the bow part, the contact angle reduction member protruding outwardly with respect to the longitudinal central axis of the centralizer, the contact reduction member contacting the upper edge of the wellbore at a contact angle which is smaller than the bow angle, and
• at least one tubular abutment member for abutting the casing on at least one of said bows, the tubular abutment member comprising an extending member having two ends only one of which is secured to the bow, the tubular abutment member protruding inwardly from the bow toward the centralizer's central axis, the tubular abutment member increasing the bow's restoring force by contacting the casing as the bow is moved into the casing during insertion of the centralizer into the wellbore,
• inserting the casing into the top of the wellbore, and
• moving the casing so that it is contained within the wellbore.