| 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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| 03/29/1988 | CA1234540A1 Drill pipe inside blowout preventer |
| 03/23/1988 | CN87104321A Displacement of free fluid accumulations in pipelines |
| 03/22/1988 | US4733233 Method and apparatus for borehole fluid influx detection |
| 03/22/1988 | US4733232 Method and apparatus for borehole fluid influx detection |
| 03/22/1988 | US4732226 Drilling machine |
| 03/15/1988 | US4730806 Gate valve |
| 03/15/1988 | CA1234094A1 Rotary drill bit |
| 03/08/1988 | US4730234 Pipe assembly module with internal electrical circuitry |
| 03/08/1988 | US4729432 Activation mechanism for differential fill floating equipment |
| 03/08/1988 | CA1233841A1 Foam process for recovering underground rock fragments |
| 03/02/1988 | EP0257944A2 Milling tool |
| 02/24/1988 | EP0256601A1 Method and device for making a hole in the ground |
| 02/23/1988 | US4726429 Percussion down hole drilling tool with central fluid flushing passage |
| 02/23/1988 | US4726301 System for extracting contaminants and hydrocarbons from cuttings waste in oil well drilling |
| 02/16/1988 | US4725362 Treatment techniques for drill fluids, cuttings and other oil field wastes |
| 02/11/1988 | WO1988001007A1 Enhanced circulation drill bit |
| 02/11/1988 | WO1988000274A3 Adjustable mechanism for stabbing and threading a drill pipe safety valve |
| 02/03/1988 | EP0255269A2 Poppet valve |
| 02/03/1988 | CN86105305A 钻井液 Drilling |
| 02/02/1988 | US4722403 Annular air-hammer apparatus for drilling holes |
| 02/02/1988 | CA1232264A1 Continuous, undisturbed sampling of hard bottom till by means of a rotating core drill |
| 01/28/1988 | WO1988000584A1 Organophilic polyphenolic acid adducts |
| 01/26/1988 | CA1231891A1 Apparatus and method for inserting flow control means into a well casing |
| 01/19/1988 | US4719937 Marine riser anti-collapse valve |
| 01/19/1988 | CA1231706A1 Drilling apparatus |
| 01/14/1988 | WO1988000274A2 Adjustable mechanism for stabbing and threading a drill pipe safety valve |
| 01/14/1988 | DE3622934A1 Drill tool of compact design |
| 01/13/1988 | CN87202889U Conical launder device for drilling fluid shaking screen |
| 01/12/1988 | US4718503 Method of drilling a borehole |
| 01/12/1988 | US4718289 Drill cuttings sample collector |
| 01/07/1988 | EP0251394A1 A method of separating and recovering a granulate from a viscous suspension containing said granulate, and apparatus for carrying out said method |
| 01/06/1988 | CN87202418U Drilling fluid purifying equipment |
| 01/05/1988 | CA1230979A1 Rotary cutter for cable following apparatus |
| 12/29/1987 | US4715128 Curvature probe and method |
| 12/23/1987 | EP0250162A2 Displacement of free fluid accumulations in pipelines |
| 12/22/1987 | US4714376 Hillslope landslide stability drain |
| 12/15/1987 | US4712619 Float device for use in a well bore cementing operation |
| 12/15/1987 | US4712613 Down-hole blow-out preventers |
| 12/09/1987 | EP0248615A2 Improvements in drilling apparatus |
| 12/08/1987 | US4711310 For a drilling machine |
| 12/01/1987 | US4709900 Choke valve especially used in oil and gas wells |
| 12/01/1987 | US4709768 Annular air hammer apparatus for drilling wells |
| 11/24/1987 | US4708212 Method and apparatus for optimizing determination of the originating depth of borehole cuttings |
| 11/19/1987 | EP0245341A1 Valve for use in well bores. |
| 11/18/1987 | CN87103385A Borehole drill construction |
| 11/11/1987 | EP0244986A2 Borehole drill construction |
| 11/10/1987 | US4705120 Drilling machine |
| 11/10/1987 | US4705119 Annular air-hammer apparatus for drilling holes |
| 11/10/1987 | US4705118 Hammer for use in a bore hole and apparatus for use therewith |
| 11/04/1987 | EP0244076A2 Downhole circulation pump |
| 11/03/1987 | US4703664 Fluid flow measurement system sensor mounting block |
| 10/27/1987 | US4702325 Apparatus and method for driving casing or conductor pipe |
| 10/22/1987 | WO1987006300A1 Improvements in drilling using downhole drilling tools |
| 10/22/1987 | DE3612801A1 Stone drill |
| 10/22/1987 | DE3611747A1 Hand-held machine tool with suction device |
| 10/21/1987 | EP0242307A1 Device for the under water drilling of foundations |
| 10/21/1987 | EP0242256A1 Process and device for measuring characteristics of geological formations in a horizontal borehole coming from an underground tunnel |
| 10/20/1987 | US4700924 For controlling fluid flow |
| 10/20/1987 | US4700739 Pneumatic well casing pressure regulating system |
| 10/06/1987 | US4698380 Polymonoallylamine and a sulfonated polymer |
| 09/30/1987 | EP0238675A1 Improved well cementing process |
| 09/29/1987 | US4696802 Drilling geothermal wells with removal of H2 S |
| 09/29/1987 | US4696353 Drilling mud cleaning system |
| 09/23/1987 | EP0081562B1 Process and apparatus for recovering usable water and other materials from oil field mud/waste pits |
| 09/22/1987 | US4694911 Drilling assembly for percussion drilling of deep wells |
| 09/22/1987 | US4694855 Drill pipe inside blowout preventer |
| 09/22/1987 | CA1227024A1 Fluid loss control agents for drilling fluids containing divalent cations |
| 09/15/1987 | US4693327 Earth well drilling apparatus |
| 09/08/1987 | US4691790 Method and apparatus for removing the inner conduit from a dual passage drill string |
| 09/08/1987 | US4691789 Process for establishing a clear horizontal borehole in a subterranean formation |
| 09/08/1987 | US4691407 Liquid recovery unit |
| 09/08/1987 | CA1226515A1 Contamination removal system and method |
| 08/26/1987 | EP0233209A1 Drop ball sub-assembly for a down-hole device. |
| 08/25/1987 | US4688831 Threaded or push-type coupling |
| 08/25/1987 | US4688650 For use in the drilling of a well with a drill bit |
| 08/25/1987 | CA1225824A1 Method for liquifying chloride-based heavy brine well completion fluids |
| 08/19/1987 | EP0233038A2 Down-the-hole-drill |
| 08/19/1987 | EP0232268A1 Device for controlling the locking of a sampling tube. |
| 08/19/1987 | CN86201038U Vibrating sieve made with special-shaped steel rod for oilwell slurry |
| 08/18/1987 | US4687019 For use in oil well cementing operations |
| 08/18/1987 | CA1225519A1 Clarification of high density brine fluids |
| 08/11/1987 | US4685520 Open hole pipe recovery circulation valve |
| 08/05/1987 | CN86201041U Oil-well mud shaker with quickly demountable sieve plate |
| 08/04/1987 | US4683963 Drilling cuttings treatment |
| 08/04/1987 | US4683955 Automatic fill-up floating apparatus |
| 08/04/1987 | US4683953 Water in oil emulsion containing expandable hydrophilic clay |
| 08/04/1987 | US4683944 Drill pipes and casings utilizing multi-conduit tubulars |
| 07/28/1987 | US4682661 Drilling apparatus |
| 07/28/1987 | CA1224728A2 Dust conveying and collecting system |
| 07/28/1987 | CA1224682A1 Downhole drilling hammer |
| 07/22/1987 | EP0229434A1 Process for the improvement of the conditioning of gasification agents utilized in an underground coal-gasification process |
| 07/07/1987 | CA1223807A1 Method and apparatus for determining formation pressure |
| 07/01/1987 | EP0227456A2 Earth well drilling apparatus |
| 07/01/1987 | EP0227193A2 Method of drilling a borehole |
| 06/30/1987 | CA1223525A1 Casing structures having core members under radial compressive force |
| 06/23/1987 | US4675852 Apparatus for signalling within a borehole while drilling |
| 06/23/1987 | CA1223247A1 Well drilling assembly |
| 06/16/1987 | US4673312 Method and apparatus for the underground installation of pipelines |
| 06/16/1987 | US4673045 Enhanced circulation drill bit |
| 06/16/1987 | CA1222933A1 Method of determination of weighting materials and low gravity solids in drilling fluids |