Abstract: A dual walled pipe string structure defines an annular cavity between the walls into which hard granules may be packed to oppose wall collapse when inserted to high pressure well depths. Segments of pipe thus constructed will reduce the heat transfer across the pipe string allowing for the conveyance of drilling mud from a surface cooler to a downhole tool. The rate of cooled drilling mud transfer to the tool may be controlled to match the heat transfer rates and the heat generated at the tool. To further oppose wall pressures inert gas at opposing pressure may be introduced into the interstices between the granules.

Abstract: Disclosed herein is a transportable cooling system for cooling drilling mud in the course of drilling for geothermal sources or deep well drilling. The cooling system includes a mud carrying radiator provided with a water sprinkler assembly and fan for cooling the exterior thereof. Both the water sprinklers and the fans are controllable in their rate in response to a signal combining the well outlet temperature. In this manner cooling demands of a well bore can be anticipated, allowing for deep well drilling.