| 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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| 05/09/1990 | EP0367240A1 Adaptor for drilling strings with a controllable air passage |
| 05/09/1990 | CN1041987A Automatic clearance pot |
| 05/08/1990 | US4923018 Percussion drill |
| 05/08/1990 | US4923011 Drill stem mud wiping apparatus |
| 05/03/1990 | WO1990004699A2 Float collar and plug for use in wells |
| 05/03/1990 | WO1990004467A1 Drilling mud separation system |
| 05/01/1990 | US4921057 Method and device for making a hole in the ground |
| 05/01/1990 | US4921056 Hammer drills for making boreholes |
| 05/01/1990 | US4921052 Downhole recirculating hammer |
| 05/01/1990 | US4921046 Horizontal hole cleanup tool |
| 04/25/1990 | CN1007744B Method and apparatus for automatically pouring mud during pulling out the drill |
| 04/24/1990 | US4919349 Dust seal for gyratory rock crushers |
| 04/24/1990 | US4919218 Process for reestablishing circulation in a lost return zone |
| 04/19/1990 | DE3905699C1 Drilling method for producing a large-diameter hole in rock with extendable drill stem and indirect compressed-air flushing |
| 04/18/1990 | EP0245341B1 Valve for use in well bores |
| 04/17/1990 | US4917194 Improved downhole hammer |
| 04/17/1990 | CA1267777A1 Non-polluting fluidising agents for drilling fluids having soft or salt water base |
| 04/11/1990 | CN2055857U Lossless spiral-flow grit catcher |
| 04/10/1990 | US4915850 Filtration of drilling mods |
| 04/05/1990 | WO1990003488A1 Improvements in pneumatic percussion hammers |
| 04/04/1990 | CN2055532U Monitor for well gushing and leaking |
| 04/03/1990 | US4913585 Method of treating solids containing waste fluid |
| 04/03/1990 | US4913245 Wellbore drilling cuttings treatment |
| 03/28/1990 | EP0360321A1 Process for laying a pipeline through an earth mass |
| 03/28/1990 | CN2055177U Switching type double insurance oil drainer |
| 03/28/1990 | CN2055176U Working truck for separating operation by precipitation |
| 03/28/1990 | CN2055175U Wheel type well dredge machine |
| 03/27/1990 | US4911834 Drilling mud separation system |
| 03/27/1990 | US4911253 Core and water collector |
| 03/27/1990 | US4911250 For rock drilling |
| 03/27/1990 | US4911243 Method for disconnecting a marine drilling riser assembly |
| 03/21/1990 | EP0358786A1 Superimposing drilling device |
| 03/13/1990 | US4907660 Interchangeable sectional mining drill and bolt driver system |
| 03/08/1990 | WO1990002244A1 A drill for rock and concrete |
| 03/07/1990 | EP0357235A1 Self-lubricating centrifugal drilling mud degasser |
| 03/06/1990 | US4905958 Blowout preventer |
| 03/06/1990 | US4905777 Device for producing drilling holes from an angled position with respect to the drilling axis |
| 03/06/1990 | US4905775 Drilling system and flow control apparatus for downhole drilling motors |
| 02/20/1990 | US4901761 Closure apparatus with pressure test device |
| 02/20/1990 | US4901563 System for monitoring fluids during well stimulation processes |
| 02/20/1990 | EP0327575A4 A pneumatic percussion hammer. |
| 02/20/1990 | CA1265994A1 Valve for use in well bores |
| 02/14/1990 | EP0128206B1 Flow diverter |
| 02/13/1990 | US4899837 Mud saver valve |
| 02/13/1990 | US4899833 Downhole drilling assembly orienting device |
| 02/08/1990 | WO1990001102A1 Drilling device and method for the study and exploitation of the underground |
| 02/07/1990 | CN1039464A Drill pipes and casings utilizing multi-conduit tubulars |
| 02/06/1990 | CA1265528A1 Water soluble polymers and compositions containing them |
| 01/31/1990 | EP0353168A1 Method and drilling machine for examination and exploitation of the subsoil |
| 01/31/1990 | EP0353152A1 Device for withdrawing dug material for making deep trenches |
| 01/31/1990 | EP0352390A1 Apparatus for the treatment of industrial sludge |
| 01/31/1990 | EP0207136B1 Diverter/bop system and method for a bottom supported offshore drilling rig |
| 01/30/1990 | CA1265123A1 Mechanically actuated whipstock assembly |
| 01/30/1990 | CA1264934A1 Curvature probe and method |
| 01/23/1990 | US4895665 Method for treating and reclaiming oil and gas well working fluids and drilling pits |
| 01/16/1990 | US4893684 Method of changing well fluid |
| 01/16/1990 | CA1264413A1 Self-breaking foamed oil in water emulsion for stimulation of wells blocked by paraffinic deposits |
| 01/10/1990 | CN2050879U Pressing air countercirculatory sludging device |
| 01/09/1990 | US4891887 Hand held drill drive |
| 01/03/1990 | CN1038490A New method for stratified logging ecentric water-distributing well |
| 12/26/1989 | US4889645 Quaterized with dicocodimethyl ammonium chloride |
| 12/26/1989 | US4889199 Downhole valve for use when drilling an oil or gas well |
| 12/26/1989 | US4889196 Diverter apparatus |
| 12/22/1989 | EP0274523A4 Organophilic polyphenolic acid adducts. |
| 12/20/1989 | EP0347172A1 Pressurised check valve |
| 12/19/1989 | US4887676 Device for closing a core barrel installed in a drilling rig |
| 12/14/1989 | WO1989012156A1 Method for improving drill cuttings transport from a wellbore |
| 12/14/1989 | DE3818998A1 Process and apparatus for laying supply lines |
| 12/13/1989 | EP0345896A2 Device for driving a drilling and/or percussion tool |
| 12/13/1989 | CN2049261U Vibration screen with eccentric motor |
| 12/06/1989 | EP0344818A2 A method of using polymeric compositions |
| 12/05/1989 | CA1263596A1 Surging fluids downhole in an earth borehole |
| 11/29/1989 | EP0343689A2 Method for plugging lost circulation areas |
| 11/28/1989 | US4883133 Combustion operated drilling apparatus |
| 11/22/1989 | CN2048108U Wear-resisting slurry pump value for drilling |
| 11/21/1989 | US4881473 Method and apparatus for treating oil-water-solids sludges and refinery waste streams |
| 11/15/1989 | CN1037187A Oil in water liquid for repairing well |
| 11/14/1989 | US4880468 Waste solidification composition and methods |
| 11/14/1989 | US4880065 Air motor operated rotary earth drilling tool |
| 11/09/1989 | DE3907637A1 Rodless drilling, pressure or cleaning implement |
| 11/08/1989 | CN2047299U Sand remover with automatic bottom-flow controller |
| 11/08/1989 | CN2047298U Under-ground blocking preventive by-passs circulating joint |
| 11/07/1989 | US4879654 Drilling fluid |
| 11/07/1989 | US4878382 Method of monitoring the drilling operations by analyzing the circulating drilling mud |
| 11/02/1989 | EP0339752A1 Pore pressure formation evaluation while drilling |
| 11/02/1989 | EP0198853B1 Marine riser well control method and apparatus |
| 11/01/1989 | CN2046921U Rotational flow drilling speeder |
| 11/01/1989 | CN2046920U Gas lift counter-circulating simple drill |
| 10/31/1989 | US4877095 Stopper for cable passages or conduits |
| 10/19/1989 | WO1989009869A1 An apparatus for, and method of, filling well casings |
| 10/19/1989 | WO1989009638A1 A method in treating solid material to remove vaporizable matter from it |
| 10/11/1989 | EP0336010A1 Percussion drill with interchangeable downhole or sideways discharging cutting or drilling head |
| 10/10/1989 | US4872949 Using shell in tube heat exchanger |
| 10/10/1989 | US4872530 Self-lubricating centrifugal drilling mud degasser |
| 10/10/1989 | US4872510 Subterranean well casing float tool |
| 10/10/1989 | US4872509 Oil well production system using a hollow tube liner |
| 10/05/1989 | WO1989009091A1 Process and arrangement for treating recirculated drilling mud in drilling for oil and gas |
| 10/04/1989 | EP0335543A1 Drilling apparatus |
| 10/04/1989 | EP0334944A1 Apparatus and method for removing and recovering oil and/or other oil-based drilling mud additives from drill cuttings |
| 09/26/1989 | US4869810 Method of recovering evaporable liquids from mud comprising fine grained particles and the evaporable liquids |