Method and apparatus for adding a tubular to drill string...
Method of and apparatus for crushing earth under the ground
Pressure core barrel
Retractable core barrel valving apparatus
Sampling drill
Sealed bearing roller cone bit having anti-plugging device
Self-contained closure mechanism for a core barrel inner tube as
Soil sampling device
Stopper for cable passages or conduits
Subterranean drilling and slurry mining
Subterranean mining apparatus
Tool actuator
Up-hole overshot and safety drilling apparatus
Up-hole pump-in core barrel apparatus
Well clean out tool
Wire line core drilling apparatus