| Patents for E21B 21 - Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor (13,780) |
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| 06/14/1977 | US4029160 Drilling machine |
| 06/07/1977 | US4028009 Jet pump |
| 06/07/1977 | US4027407 Jet flow alternator |
| 05/10/1977 | US4022349 Mud heater and pump therefor |
| 05/10/1977 | US4022285 Drill bit with suction and method of dry drilling with liquid column |
| 04/26/1977 | US4019592 By-pass tool |
| 03/01/1977 | US4010012 Removing gas from drilling mud, prevention of air pollution |
| 02/22/1977 | US4008775 Method of using a porous Fe3 O4 drilling mud additive |
| 01/18/1977 | US4003441 Method of opening carbon-bearing beds with production wells for underground gasification |
| 01/04/1977 | US4000645 Apparatus for pneumatically monitoring conditions of a well circulating system |
| 12/28/1976 | US3999965 Liquid treating apparatus |
| 12/14/1976 | US3997010 Downhole forward and back scuttling tool |
| 12/14/1976 | US3997009 Well drilling apparatus |
| 12/14/1976 | US3997008 Drill director |
| 12/07/1976 | US3995692 Continuous orifice fill device |
| 11/30/1976 | US3994166 Apparatus for eliminating differential pressure surges |
| 11/23/1976 | US3993146 Apparatus for mining coal using vertical bore hole and fluid |
| 11/16/1976 | US3991834 Sampling airhammer apparatus |
| 11/16/1976 | US3991817 Geothermal energy recovery |
| 11/09/1976 | US3990522 Rotary percussion drill |
| 11/02/1976 | USRE29021 Underground mining system |
| 11/02/1976 | US3989330 Electrical kelly cock assembly |
| 11/02/1976 | US3989114 Circulation sub for in-hole hydraulic motors |
| 10/26/1976 | US3987855 Lost circulation control |
| 10/19/1976 | US3986964 Method of well drilling and composition therefor |
| 10/12/1976 | US3985667 Process and composition for drilling shale formation in sea water |
| 09/28/1976 | US3982596 Drill bit |
| 09/28/1976 | US3982432 Well monitoring and analyzing system |
| 09/21/1976 | US3981371 Core sampling drill |
| 09/21/1976 | US3981368 Coupling means in a drilling machine |
| 09/07/1976 | US3978923 Injection sub for dual tube drilling |
| 08/31/1976 | US3977478 Method for laser drilling subterranean earth formations |
| 08/24/1976 | US3976148 Method and apparatus for determining onboard a heaving vessel the flow rate of drilling fluid flowing out of a wellhole and into a telescoping marine riser connecting between the wellhouse and the vessel |
| 08/17/1976 | US3975171 Apparatus and method for degassing drilling fluids |
| 08/10/1976 | US3973930 Drilling mud degasser apparatus and method |
| 08/10/1976 | US3973633 Hammer device |
| 08/10/1976 | US3973587 Check valve assembly |
| 08/03/1976 | US3972799 Apparatus for removing solids from drilling mud |
| 07/20/1976 | US3970877 Power generation in underground drilling operations |
| 07/20/1976 | US3970335 Dual concentric pipes |
| 07/13/1976 | US3968847 Wellpoint jetting head |
| 07/13/1976 | US3968845 Apparatus and method for geological drilling and coring |
| 07/13/1976 | US3968844 Determining the extent of entry of fluids into a borehole during drilling |
| 07/06/1976 | US3967680 Method and apparatus for actuating a downhole device carried by a pipe string |
| 07/06/1976 | US3967679 Mud saver valve |
| 06/29/1976 | US3965998 Dust control hood and dust control system |
| 06/29/1976 | US3965997 Method and apparatus for guiding and sealing a drill string |
| 06/29/1976 | US3965987 Method of sealing the annulus between a toolstring and casing head |
| 06/29/1976 | US3965980 Mud saver valve |
| 06/22/1976 | US3964557 Treatment of weighted drilling mud |
| 06/22/1976 | US3964556 Downhole signaling system |
| 06/22/1976 | US3964551 Pneumatic impact drilling tool |
| 06/15/1976 | US3963605 Polyarylene sulfide, polytetrafluoroethylene, drilling fluids |
| 06/15/1976 | US3963077 Method of preventing well bore drilling fluid overflow and formation fluid blowouts |
| 05/25/1976 | US3958651 Vacuum, vacuum-pressure, or pressure circulation bit having jet-assisted vacuum |
| 05/25/1976 | US3958650 Drilling system using weight of mud |
| 05/25/1976 | US3958648 Drilling equipment |
| 05/25/1976 | US3958642 Quick latching drill pipe blowout preventer and method of use thereof |
| 05/18/1976 | US3957114 Well treating method using an indexing automatic fill-up float valve |
| 05/11/1976 | US3955411 Method for measuring the vertical height and/or density of drilling fluid columns |
| 04/27/1976 | US3953337 Method of drilling wells employing water base drilling fluids |
| 04/27/1976 | US3952799 Apparatus for borehole drilling |
| 04/20/1976 | US3951823 Foam well cleanout using oligomeric sulfonates |
| 04/20/1976 | US3951220 Archimedes spiral drill bit |
| 04/13/1976 | US3949818 Hydraulic drilling rig and power swivel |
| 04/06/1976 | US3948588 Swivel for core drilling |
| 04/06/1976 | US3948330 Vacuum, vacuum-pressure, or pressure reverse circulation bit |
| 03/30/1976 | US3946948 Ejector |
| 03/30/1976 | US3946818 Dust controlling device for rock drilling |
| 03/30/1976 | US3946605 Apparatus and method of measuring fluctuations of excavated mud amount in a slurry line |
| 03/23/1976 | US3945613 Vibrating device |
| 03/16/1976 | US3943997 Rotary drilling apparatus and method |
| 03/09/1976 | US3942594 Drill pipe monitoring system |
| 03/02/1976 | US3941348 Safety valve |
| 03/02/1976 | US3941196 Percussive air hammer and core bit apparatus |
| 03/02/1976 | US3941190 Well control apparatus |
| 02/17/1976 | US3938589 Drilling tool |
| 02/03/1976 | US3935910 Method and apparatus for moulding protective tubing simultaneously with bore hole drilling |
| 01/27/1976 | US3934662 Core bit |
| 01/27/1976 | US3934661 Dust cup |