Spring mechanism for downhole steering tool blades

A steering tool comprising:

• a tool body having an outer surface;
• at least one blade deployed in a recess on the outer surface of the tool body, the blade configured to displace between radially opposed retracted and extended positions;
• the blade including first and second sprung ends, the sprung ends located proximate to first and second longitudinally opposed ends of the blade, the sprung ends disposed to elastically spring bias the blade radially inward towards the retracted position, each of the sprung ends in floating contact with the tool body, the floating contact substantially restraining a contact portion of the sprung end from translating radially outward relative to the tool body, the contact portion further substantially free to pivot about a portion of the tool body;
• and
• at least one actuation module disposed, upon actuation, to extend the blade radially outward from the tool body towards the extended position, said elastic spring bias disposed to retract the blade radially inward towards the retracted position upon deactuation of the actuation module.

A downhole steering tool comprising:

• a tool body having an outer surface;
• at least one blade deployed in a recess on the outer surface of the tool body, the blade configured to displace between radially opposed retracted and extended positions;
• at least one sprung member configured to elastically spring bias the blade radially inward towards the retracted position, the sprung member including at least one floating end, the floating end in floating contact with one of the blade and the tool body, the floating contact restraining the floating end from translating radially with its elastic spring bias relative to one of the blade and the tool body, the floating end substantially free to pivot about a portion of one of the blade and the tool body;
• and
• at least one actuation module disposed, upon actuation, to extend the blade radially outward from the tool body towards the extended position, said elastic spring bias disposed to retract the blade radially inward towards the retracted position upon deactuation of the actuation module.

A downhole steering tool comprising:

• a tool body having an outer surface;
• at least one blade deployed in a recess on the outer surface of the tool body, the blade configured to displace between radially opposed retracted and extended positions;
• at least one hairpin sprung member disposed to elastically spring bias the blade radially inward towards the retracted position, the sprung member including first and second leg portions located on opposing sides of a sprung hairpin portion, the first leg portion engaged with the blade, the second leg portion in floating contact with the tool body, the floating contact substantially restraining a contact portion of the second leg from translating radially outward relative to the tool body, the contact portion further substantially free to pivot about a portion of the tool body;
• and
• at least one actuation module disposed, upon actuation, to extend the blade radially outward from the tool body towards the extended position, said actuation opening the hairpin sprung member against its elastic spring bias, the elastic spring bias disposed to close the hairpin sprung member and thereby retract the blades radially inward towards the retracted position upon deactuation of the actuation module.

A method for changing the drilling direction of a drill bit deployed in a subterranean borehole, the method comprising:

• (a) deploying a drill string in the subterranean borehole, the drill string including a drill bit and a steering tool, the steering tool comprising:
• a steering tool body having an outer surface;
• at least one blade deployed in a recess on the outer surface of the tool body, the blade configured to displace between radially opposed retracted and extended positions;
• at least one hairpin sprung member disposed to elastically spring bias the blade radially inward towards the retracted position, the hairpin sprung member including first and second leg portions located on opposing sides of a sprung hairpin portion, the first leg portion engaged with the blade, the second leg portion engaged with the tool body;
• and
• at least one actuation module disposed, upon actuation, to extend the blade radially outward from the tool body towards the extended position, said actuation disposed to open the hairpin sprung member against its elastic spring bias, the elastic spring bias disposed to close the hairpin sprung member and thereby retract the blade radially inward towards the retracted position upon deactuation of the actuation module;
• (b) actuating the actuation module to extend the blade radially outward from the tool body into engagement with a wall of the subterranean borehole, the engagement with the wall displacing a longitudinal axis of the steering tool from a borehole axis, said displacement of the longitudinal axis changing an angle of approach of the drill bit;
• and
• (c) deactuating the actuation module so as to allow the elastic spring bias to urge the blade radially inwards towards the tool body, said urging of the blade radially inwards also changing the angle of approach of the drill bit.