Hydraulic well derrick with cable lifts

DETAILED DESCRIPTION OF THE INVENTION In the following descriptions, the same or similar items are given the same numerical designation in each of the several views.
In FIG.
1 particularly, there is shown a foundation structure 4, above which is mounted a derrick framework comprising an upper derrick 19, and a main derrick 17, the upper derrick being mounted on rollers not detailed within the main derrick 19, whereby the upper derrick may telescope within the main derrick.
Means not shown are provided to enable the clamping of the upper derrick at any desired height within the main derrick.
The main derrick 17 is attached at its base through diagonal compressive brace members 21 to a set of primary skid beams 22, having lugs 25 by which the primary skid beams may be drawn into any desired location.
In the drawing of FIG.
1, the primary skid beams are mounted upon supplemental skid beams 23, which are stretched across the girders 26 of an off-shore drilling platform.
In setting up the well drilling apparatus, the skids are pulled into a position surrounding the well centerline 3, so oriented that the centerline extends vertically in front of the center of the derrick's working face, as will shortly become apparent.
Hydraulic cylinders 2a and 2b are arranged in pairs at the outer corners of the derrick's working face, with the cylinder centerlines all being in the same plane as the well centerline.
In FIG.
2, it may be seen particularly clearly that the two cylinders labelled 2a constitute one pair and the two cylinders labelled 2b constitute a second pair, of somewhat larger diameter than the first pair.
The bottom ends of each of the cylinders rest upon a cross member in the skid beam structure.
The rams 1a and 1b are forced upward by hydraulic fluid supplied from an undetailed source to the chambers of the cylinders.
At or near the bottom of the inner pair of cylinders 2b is a pair of lugs 12, by which the lower ends of a set of cables 11 may be fixed.
For clarity in presentation, this attachment is detailed only in FIG