| 摘要 |
A method and apparatus for ranging from ahead of a drill bit is described. The ranging apparatus includes a ranging probe with at least one sensor that may be deployed ahead of the drill bit. The ranging probe may be conveyed via a cable through the interior of a drill string. In an alternative embodiment, the ranging probe may be attached to a ram that is seated inside of the drill string and that may be extended and retracted. In such an embodiment, the ranging probe may be retrievable by cable. The ranging probe optionally includes collapsible arms that retract when the ranging probe is inside the drill string or drill bit and that extend when the ranging probe is deployed ahead of the drill bit. One or more ranging sensors may be coupled to the collapsible arms. Ranging measurements may be communicated to the surface using telemetry. |
