| 摘要 |
The present invention provides methods and apparatus for reducing friction and preventing galling between surfaces in a wellbore. In one aspect of the invention, mating threads are coated with fullerene to reduce galling of the threads during make up and break down. In another aspect, a fullerene is used between surfaces of an expansion tool and a tubular to be expanded in order to reduce friction and prevent galling therebetween. Preferably, the fullerene is a spherically shaped carbon 60 molecule otherwise known as buckyball or C60. The fullerene coating provides an intermediate surface between two metal surfaces, thereby preventing galling between the two surfaces. In another aspect of the invention, the fullerene is placed between the roller of an expander tool and the surface of the tubular to be expanded in order to reduce friction and galling.
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