Double-acting jar compounder

Double-cone device and pump

Double-plate control device

Double-taper slip-on drill string stabilizer

Double-tube core drill for inclined drilling

Double-wall underground container for storing liquids and...

Dovetail thread coupling for expandable tubulars

Dovetail thread coupling for expandable tubulars

Down hole apparatus for generating a pulsing action

Down hole blow out preventer and method of use

Down hole bypass valve

Down hole casing string cleaning device

Down hole drill improvement

Down hole drilling tool control mechanism

Down hole drills using spent driving fluid for flushing...

Down hole fluid heating apparatus and method

Down hole hammer assembly

Down hole hammer having elevated exhaust

Down hole induction heating tool and method of operating and...

Down hole motor with locking clutch