| 摘要 |
An improved drill steering apparatus which includes a lower stabilizer assembly mounted on the drill string in close relationship to the drill bit and an upper stabilizer assembly mounted on said drill string at a position spaced above said lower stabilizer assembly. In the preferred form of the invention, the pressure responsive element of the stabilizer assemblies are pressure responsive bladders and the lower or slave bladders have a larger effective pressure area than the upper bladders. In a modified form of the invention, the pressure responsive elements are pistons and the lower stabilizer assembly includes at least one more piston in each ground than the upper stabilizer assembly.
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