| 摘要 |
<p>A casing mill for milling pipe cemented in an oil well comprises a body with a plurality of fixed milling blades having a diameter corresponding to the outside diameter of the pipe to be milled, and a second plurality of movable blades movable between a retracted position smaller than the inside diameter of the pipe to be milled, and an extended diameter corresponding to the outside diameter of a pipe coupling between adjacent sections of pipe. Means are provided for selectively moving the blades between the retracted and extended positions in response to drilling fluid flow. A stabilizer keeps the casing mill centered in the pipe to be milled. In this way, one can mill both the pipe and coupling in the vicinity of a coupling and mill only pipe between the vicinities of adjacent couplings. <IMAGE></p> |
