Adjustable stabilizer for directional drilling

摘要

A drillstring carries a stabilizer sub above the drill bit for steering or directing drilling. The stabilizer body is rotatably carried by the stabilizer sub, wherein the stabilizer body remains substantially stationary relative to the borehole as the drillstring rotates. At least one stabilizer blade is carried by the stabilizer body, the stabilizer blade being radially extendable from the stabilizer body and into engagement with the sidewall of the borehole. Each stabilizer blade is extendable and retractable from the stabilizer body independently of the others. The stabilizer blades are coupled to the stabilizer body such that the blades are capable of collapse to minimum radial extension if the stabilizer assembly becomes stuck in the borehole.