Importance

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Abstract

A flow stream of drilling gas in a gaseous drilling fluid circulation drilling system is separated from that drilling gas supplied to the drill string, and the flow stream is reduced in temperature prior to supplying the flow stream to a drilling tool component to be cooled. A heat exchanger is employed to remove heat from the flow stream, and a second separate flow stream of drilling gas is directed over the heat exchanger to remove the heat. The temperature of the second cooling stream is reduced by thermodynamic effects. Various drilling tool components may be cooled, including bearing means operative between two relatively movable parts, a seal assembly operative to seal lubricant between two relatively moving parts, and cutter elements of a drag-type drill bit. The seal assembly includes a flange-like projection member and a fluid conducting conduit in thermal transferring relationship with the projection member. Flexible flank members form a movable sealing relationship with the projection member and the reduced-temperature flow stream is forced through the conduit. The drag-type drill bit includes a plurality of cooling jet means which direct jets of reduced-temperature drilling gas from the flow stream into thermal transferring relationship with each of the cutter elements.

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First Claim