Patent EA-000595-B1 (EA)
Title: Adjustable stabilizer for directional drilling
Inventor: SCHUH FRANK J
IPC: E21B17/10
Filed: 1996-05-20
Abstract: 1. An improved assembly for steering a rotating drillstring in a borehole (1), the assembly having a stabilizer sub (9) for attachment into a drillstring (3), a stabilizer body (13) rotatably carried by the stabilizer sub, wherein the stabilizer body remains substantially stationary relative to the borehole as the drillstring rotates, characterized in that: at least one stabilizer blade (11) 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, the stabilizer blade being carried by the stabilizer body such that it will collapse to minimum radial dimension upon application of sufficient axial force to the drillstring if the stabilizer sub should become stuck in the borehole. 2. An improved assembly for steering a rotating drillstring in a borehole (1), the assembly having a stabilizer sub (9) for attachment into a drillstring (3), a stabilizer body (13) rotatably carried by the stabilizer sub, wherein the stabilizer body remains substantially stationary relative to the borehole as the drillstring rotates, characterized in that: at least a pair of generally opposed stabilizer blades carried by the stabilizer body, the stabilizer blades being independently radially extendable from the stabilizer body and into engagement with the sidewall of the borehole, the stabilizer blade the sidewall of the borehole the stabilizer blade being carried by the stabilizer body such that it will collapse to minimum radial dimension upon application of sufficient axial force to the drillstring if the stabilizer sub should become stuck in the borehole. 3. An improved assembly for steering a rotating drillstring in a borehole (1), the assembly having a stabilizer sub (9) for attachment into a drillstring (3), a stabilizer body (13) rotatably carried by the stabilizer sub, wherein the stabilizer body remains substantially stationary relative to the borehole as the drillstring rotates, characterized in that: at least one longitudinal slot (17) is formed in the exterior of the stabilizer body, the slot having an inclined bottom (17A); at least one stabilizer blade (11) carried in the slot in the stabilizer body, the stabilizer blade being independently radially extendable from the stabilizer body and into engagement with the sidewall of the borehole by longitudinal movement in the slot having the inclined bottom, the stabilizer blade being carried in the slot such that it will collapse to minimum radial dimension upon application of sufficient axial force to the drillstring if the stabilizer sub should become stuck in the borehole; a motor (19) carried by the stabilizer body and coupled to the stabilizer blade to cause longitudinal movement of the stabilizer blade in the slot; a source of electrical power carried by the stabilizer sub and in electrical communication with the motor. 4. The assembly according to Claim 1 or 2, wherein each stabilizer blade is carried in a longitudinal slot in the stabilizer body, the slot having an inclined bottom and relative longitudinal movement between the stabilizer blade and stabilizer body causes extension or retraction of the stabilizer blade. 5. The assembly according to Claims 1, 2 or 3 further comprising: at least three stabilizer blades spaced apart on the circumference of the stabilizer body. 6. The assembly according to Claims 1 or 2, further comprising: a motor (19) coupled between each stabilizer blade and the stabilizer body to cause relative longitudinal movement therebetween. 7. The assembly according to Claims 1, 2, or 3, wherein the stabilizer sub includes a fixed stabilizer (7) at an end opposite the drill bit. 8. The assembly according to Claim 1, 2, or 3 further comprising: four stabilizer blades spaced apart on the circumference of the stabilizer body. 9. The assembly according to Claim 3 further comprising: four stabilizer blades spaced apart in four longitudinal slots in the circumference of the stabilizer body; and four motors carried by the stabilizer body. 10. The assembly according to Claim 3 wherein a lead screw (21) couples the motor to the stabilizer blade, rotation of the lead screw by the motor causing longitudinal movement of the stabilizer blade in the slot.