| 摘要 |
A traveling top drive sheave system includes in one embodiment a rig carrier, a mast assembly pivotally attached to the rig carrier comprising guide rails and a crown block, a top drive fixture, and a traveling sheave block. The mast assembly is moveable to a generally perpendicular position with respect to the rig carrier, providing the top drive access to a wellhead. The top drive is mounted within the mast assembly and is supported along guide rails to be vertically moveable along a same axis as the wellhead. In one embodiment, the traveling sheave block has an axis offset from the crown block to enhance the reeving of a drilling line between both blocks. In another embodiment, the system contains guide rails and rollers whereby at least one of the rollers or guide rails has a groove and the other is sized to mate with said groove for facilitating vertical movement along said mast assembly. |
