Downhole adjustable stabilizer

A downhole adjustable stabilizer apparatus comprising:

• a mandrel;
• a sleeve member mounted on said mandrel for limited relative rotation;
• at least three vertically arranged and circumferentially spaced sets of radially movable pistons on said sleeve member;
• means on said mandrel for supporting said pistons in extended positions in a first rotational position of said sleeve member on said mandrel;
• and means responsive to rotation of said sleeve member to a second rotational position on said mandrel for allowing movement of said sets of pistons to retracted positions in order to enable said stabilizer apparatus to have a substantially undergage size with respect to the diameter of a wellbore.

A downhole adjustable stabilizer apparatus comprising;

• a mandrel;
• sleeve means mounted on said mandrel for limited relative rotation;
• a plurality of radially movable members on said sleeve means, said members being movable between retracted and extended positions;
• means responsive to relative rotation of said mandrel and said sleeve means in one rotational direction for enabling retraction of said members and in the other rotation direction for causing extension of said members;
• and means for restraining relative rotation of said mandrel and said sleeve means in said other rotation direction.

Downhole adjustable stabilizer apparatus comprising:

• a mandrel, sleeve means mounted for limited rotational movement on said mandrel;
• a plurality of button means mounted on said sleeve means and arranged for radial movement between extended and retracted positions in response to said rotational movement;
• means forming an annular oil-filled chamber between said mandrel and said sleeve means;
• piston means mounted for longitudinal movement in said chamber;
• means for co-rotatively coupling said piston means of said sleeve means;
• cam means for converting rotation of said mandrel relative said sleeve means to longitudinal movement of said piston means;
• and means for restraining movement of said piston means in one longitudinal direction in said chamber to correspondingly restraint relative rotation of said mandrel in the direction that causes extension of said button means.