Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor (freeing objects stuck in boreholes by flushing E21B31/03)

Child Classifications

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• E21B 21/001
• E21B 21/002
• E21B 21/003
• E21B 21/01 Arrangements for handling drilling fluids or cuttings outside the borehole, e.g. mud boxes
• E21B 21/02 Swivel joints in hose-lines
• E21B 21/06 Arrangements for treating drilling fluids outside the borehole
• E21B 21/08 Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure (valve arrangements therefor E21B21/10)
• E21B 21/10 Valve arrangements in drilling-fluid circulation systems
• E21B 21/12 using drilling pipes with plural fluid passages, e.g. closed circulation systems
• E21B 21/14 using liquids and gases, e.g. foams
• E21B 21/16 using gaseous fluids (E21B21/14 takes precedence)
• E21B 21/18 Preventing exhaust air from the drill motor from blowing-off towards the working face