Dope-free type premium connection for oil country tubular goods

Customarily, compound grease is doped when tightening oil country tubular connections. Eliminating the compound grease attempts to improve environmental and working conditions and a dope-free (grease is not doped) premium joint was developed with the objective of eliminating overall drilling cost. A solid lubricating film was used as a galling resistance processing that can withstand high surface pressures that exist when the screws are tightened. There was no degradation of the lubricating function even in endurance testing that simulated actual use in the field and we were able to ensure usage performance such as shielding equivalent to customary connections. Furthermore, we proved that use in an actual oil well can shorten the casing running time.