| 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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| 04/22/1992 | CN2102365U Automatic mud grouting apparatus |
| 04/16/1992 | WO1992006273A1 Control of lost circulation in wells |
| 04/16/1992 | WO1992006271A1 Apparatus for releasing fluid into a well |
| 04/08/1992 | EP0479585A1 Mist-spouting type drilling device |
| 04/08/1992 | CN1016202B Hammer drills for making boreholes |
| 04/07/1992 | US5101918 High pressure pipe and device for making a hole in the ground, provided with such high pressure pipe |
| 04/07/1992 | US5101913 Method and apparatus for drilling wells |
| 03/31/1992 | US5099928 Non-polluting dispersing agent for drilling fluids based on freshwater or salt water |
| 03/26/1992 | DE4030067A1 Vacuum dust collector for portable power drill - has bag compartment shaped to cause kinking of dust bag and release of adherent dust layer |
| 03/24/1992 | CA1297782C Gravel packing system for a production radial tube |
| 03/19/1992 | WO1992002707A3 A core sampling device with indicator for jammed core |
| 03/17/1992 | US5096002 Method and apparatus for enlarging an underground path |
| 03/17/1992 | US5095988 Plug injection method and apparatus |
| 03/17/1992 | CA1297587C Method for determining pore pressure and horizontal effective stress from overburden and effective vertical stress |
| 03/04/1992 | CN1059180A Solidification control system for well drilling liquid |
| 03/03/1992 | US5093008 Process and apparatus for recovering reuseable water form waste drilling fluid |
| 03/03/1992 | US5092406 Apparatus for controlling well cementing operation |
| 03/03/1992 | US5092399 Apparatus for stabbing and threading a drill pipe safety valve |
| 03/03/1992 | CA1296707C Method of controlling fluid influxes in hydrocarbon wells |
| 02/26/1992 | EP0280705B1 Process and device for producing drilling holes from an angled position in relation to the drilling axes |
| 02/25/1992 | US5091448 Suspending medium for water soluble polymer |
| 02/25/1992 | US5090498 Water wash/oil wash cyclonic column tank separation system |
| 02/25/1992 | US5090256 Method and apparatus for sampling the gaseous content of a liquid |
| 02/20/1992 | WO1992002707A2 A core sampling device with indicator for jammed core |
| 02/20/1992 | DE4131070A1 Hydraulically-driven drill hammer - has control valve sliding coaxially in striker piston |
| 02/19/1992 | EP0471065A1 Self propelled probe, particularly for penetrating a powdered material |
| 02/19/1992 | CN2096631U High-pressure waste water pump hydraulic device for oil field |
| 02/18/1992 | WO1992003633A1 Drill cuttings disposal method and system |
| 02/18/1992 | US5088521 Mud pump valve |
| 02/13/1992 | DE4027414C1 Tubular rock bore drill stem - has concentric channels for fluids and has spring-loaded control valves |
| 02/11/1992 | US5086842 Device and installation for the cleaning of drains, particularly in a petroleum production well |
| 02/11/1992 | CA1295604C Pneumatic percussion hammer |
| 02/05/1992 | EP0470046A1 Drilling device with suction cleaner |
| 02/05/1992 | EP0469317A2 Method and device for modifying the weight on an earth frill bit |
| 01/30/1992 | DE4023595A1 Continuous degassing of borehole drilling mud with air excluded - provides information on gas bearing rock formation contg. the borehole |
| 01/29/1992 | EP0468664A2 Method and apparatus for enlarging an underground path |
| 01/27/1992 | CA2047910A1 Method and apparatus for enlarging an underground path |
| 01/26/1992 | CA2047587A1 Detecting outflow or inflow of fluid in a wellbore |
| 01/22/1992 | EP0466702A1 Coupling for drilling machine with dust extractor. |
| 01/21/1992 | US5082499 Water, cement, calcium sulfate, acdelerator |
| 01/15/1992 | EP0466229A1 Method of and apparatus for detecting an influx into a well while drilling |
| 01/15/1992 | EP0465685A1 Drilling head of a horizontal drilling machine |
| 01/14/1992 | US5080721 Process for cleaning particulate solids |
| 01/14/1992 | US5080182 Method of analyzing and controlling a fluid influx during the drilling of a borehole |
| 01/11/1992 | CA2044901A1 Device for making a hole in the ground |
| 01/09/1992 | WO1991019075A3 Double-tube core drill for inclined drilling |
| 01/09/1992 | DE4021719A1 Enlarging pilot holes in soil - involves power-driven cone with linked bentonite suspension and water ducts followed by protecting tube |
| 01/02/1992 | DE4020773A1 Drilling and chisel hammer - incorporates fluid container, fluid being activated by compressed air or pump for spraying against dust produced |
| 01/01/1992 | CN1057412A Process and apparatus for cleaning particulate solids |
| 01/01/1992 | CN1057411A Process and apparatus for cleaning particulate solids |
| 12/31/1991 | US5076921 Filtering screens |
| 12/27/1991 | CA2019947A1 Variable weir assembly for drilling rig sump systems and method of use thereof |
| 12/11/1991 | EP0460902A2 Drill pipe bridge plug and method of use |
| 12/10/1991 | US5072404 Method of tracking fluids flowing along a flow path |
| 12/10/1991 | US5070951 Drill for water wells |
| 12/10/1991 | US5070950 Remote controlled actuation device |
| 12/10/1991 | US5070949 Method of analyzing fluid influxes in hydrocarbon wells |
| 12/10/1991 | US5070943 Apparatus and method for perforating a well |
| 12/03/1991 | US5069285 Dual wall well development tool |
| 12/01/1991 | WO1991019075A2 Double-tube core drill for inclined drilling |
| 12/01/1991 | CA2083827A1 Double-tube core drill for inclined drilling |
| 11/27/1991 | CN1056553A Method and apparatus for drilling and coring |
| 11/26/1991 | US5067570 Auger and retaining shell assembly |
| 11/26/1991 | US5067569 Auger and sweeper assembly |
| 11/21/1991 | EP0457650A2 Ultrasonic measurement apparatus and method for boreholes |
| 11/20/1991 | CN2089170U Automatic recorder for pressure |
| 11/19/1991 | US5065820 Treatment Mixture Of A Non-Aqueous Carrier Liquid And A Sponge-Like Material |
| 11/14/1991 | WO1991017339A1 Method and apparatus for drilling and coring |
| 11/12/1991 | US5063776 Method and system for measurement of fluid flow in a drilling rig return line |
| 11/06/1991 | EP0454947A1 Boring ram |
| 11/05/1991 | US5062481 Control of `U` tubing in the flow of cement in oil well casings |
| 10/31/1991 | WO1991016521A1 Percussive drilling arrangement |
| 10/30/1991 | EP0454057A2 A suspending medium for water soluble polymer |
| 10/30/1991 | CN2087782U Rubber cup type antifreezing device for pressure gage |
| 10/30/1991 | CN1055793A Cement tank vehicle |
| 10/23/1991 | CN1055573A Solid controlling and water treating technology for drilling slurry |
| 10/22/1991 | US5058686 Sliding-weight operated hole boring tool |
| 10/22/1991 | US5058684 Drill pipe bridge plug |
| 10/22/1991 | US5058672 Landing collar and float valve assembly |
| 10/22/1991 | US5058671 Pipe insert assembly |
| 10/16/1991 | CN2086789U Flushing-type water distributer with internally dividing flow |
| 10/15/1991 | US5056609 Valve assembly for a downhole to remove bore hole subsidence |
| 10/09/1991 | EP0334944A4 Apparatus and method for removing and recovering oil and/or other oil-based drilling mud additives from drill cuttings |
| 10/03/1991 | WO1991013232A3 Process and apparatus for cleaning particulate solids |
| 10/02/1991 | EP0448646A1 Use of selected diester oils as drilling fluids, in particular for exploiting off-shore petroleum or natural gas deposits (ii) |
| 10/02/1991 | EP0448579A1 Use of selected ester oils in bore-flushing fluids, particularly for the development of offshore oil and gas fields (i) |
| 10/02/1991 | DE4109079A1 Dust removal plant for rock drilling - has facility for taking dust samples, and involves fan feeding drill waste in air current |
| 10/02/1991 | DE4006320C1 Straight line tunnel borer - has guide tube to which casing is connected with load-out conveyor |
| 10/02/1991 | CN2085851U Bidirectional cleaner for high-pressure drilling fluid |
| 10/01/1991 | US5053082 Using cyclone separator and/or centrifuge |
| 10/01/1991 | US5052497 Apparatus for driving a drilling or percussion tool |
| 10/01/1991 | US5052219 Procedure and cell for measuring coefficients of adhesion and friction of a drilling fluid |
| 10/01/1991 | CA1289908C Wellbore drilling cuttings treatment |
| 09/25/1991 | CN2085413U Hydraulic starting oil drainer |
| 09/19/1991 | WO1991014076A1 Well clearing and cleaning device |
| 09/19/1991 | WO1991014075A1 Process and apparatus for cleaning particulate solids |
| 09/17/1991 | US5048620 Method for air rotary drilling of test wells |
| 09/17/1991 | US5048611 Pressure operated circulation valve |
| 09/13/1991 | CA2037035A1 Method for the estimation of pore pressure within a subterranean formation |
| 09/10/1991 | CA1288660C Poppet valve |