| 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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| 10/11/1994 | US5354956 Ultrasonic measurement apparatus |
| 10/04/1994 | US5351764 For removing cuttings from a borehole |
| 09/28/1994 | EP0616660A1 Method of propagating a hydraulic fracture using fluid loss control particulates |
| 09/27/1994 | US5350024 Drill pipe |
| 09/27/1994 | CA2114176A1 Top drive cementing manifold |
| 09/20/1994 | US5348351 Coupling apparatus |
| 09/13/1994 | CA2007428C Hydraulic jackhammer |
| 09/07/1994 | EP0613992A1 Method for driving pipes into the ground |
| 09/07/1994 | EP0613991A1 Apparatus and for driving pipes into the ground |
| 09/07/1994 | EP0613514A1 Mud check valves in drilling apparatus (wells). |
| 09/06/1994 | US5344570 Entrainment of solids, centrifuging, pumping and separation of solids |
| 09/06/1994 | US5343968 Downhole material injector for lost circulation control |
| 09/06/1994 | US5343943 Portable oil-drilling waste recovery system |
| 08/31/1994 | EP0612913A1 Connector assembly for coiled tubing |
| 08/31/1994 | CN1091493A Low-displacement double-layer anti-sand method for well wall of plastics and almond shells |
| 08/30/1994 | US5341887 Directional multi-blade boring head |
| 08/30/1994 | US5341882 Well drilling cuttings disposal |
| 08/25/1994 | DE4324434C1 Process and apparatus for dewatering tailings |
| 08/25/1994 | DE4306333A1 Method and apparatus for producing stable trenches in the earth, loose rock or the like on the basis of hydraulic extraction |
| 08/25/1994 | CA2116301A1 Flow control assembly for coiled tubing |
| 08/23/1994 | US5339912 Cuttings disposal system |
| 08/23/1994 | US5339899 Drilling fluid removal in primary well cementing |
| 08/23/1994 | US5339864 Safety sub for retaining drilling fluids |
| 08/17/1994 | EP0610366A1 Gravel-packed pipeline and method and apparatus for installation thereof |
| 08/17/1994 | CN2174561Y Self-regulating flow-spliting and collecting type water-search instrument |
| 08/16/1994 | US5337966 Method and apparatus for the reduction and classification of solids particles |
| 08/16/1994 | US5337824 Coal slag universal fluid |
| 08/04/1994 | WO1994017278A1 Means and method to displace a logging tool to the bottom of a well for withdrawal through the well |
| 07/21/1994 | WO1994015690A1 System for removing solids from a liquid |
| 07/20/1994 | EP0531336B1 Double-tube core drill for inclined drilling |
| 07/19/1994 | US5330017 Method of processing drilling mud in earth-boring operations |
| 07/13/1994 | EP0605562A1 Apparatus and method for removing drillhole debris. |
| 07/12/1994 | US5327984 Method of controlling cuttings accumulation in high-angle wells |
| 07/12/1994 | US5327980 Drill head |
| 07/12/1994 | US5327979 For use in a machine tool |
| 07/12/1994 | CA2094884C Cementing apparatus |
| 07/07/1994 | WO1994015062A1 Anti-rotation devices for use with well tools |
| 07/07/1994 | WO1994014918A1 Rheologically controlled, pumpable, fluid aqueous preparations for use for instance as water-based drilling fluids |
| 07/07/1994 | CA2152778A1 Rheology-controlled flowable and pumpable aqueous preparations, for example for use as water-based drilling muds |
| 07/06/1994 | EP0502938B1 Drilling bit irrigated by a fluid distributed by a fluidic oscillator |
| 07/06/1994 | CN1088955A Pretreated clays, their preparation and use in formulating drilling muds not aggressive to layer clays |
| 07/05/1994 | US5325922 Restoring lost circulation |
| 07/05/1994 | US5325921 Method of propagating a hydraulic fracture using fluid loss control particulates |
| 06/28/1994 | US5323860 Apparatus for connecting a diverter assembly to a blowout preventer stack |
| 06/28/1994 | US5323858 Case cementing method and system |
| 06/23/1994 | WO1994013925A1 A device for drilling holes in the crust of the earth, especially for drilling oil wells |
| 06/15/1994 | EP0601724A2 Method and apparatus for reducing size of particulate solids in fluid medium |
| 06/15/1994 | EP0500609B1 Converter |
| 06/15/1994 | CN1087967A Slurry parameter auto-testing device in use for oil and/or gas field well drilling and cementing |
| 06/14/1994 | US5320188 Underground mining system |
| 06/14/1994 | US5320181 Combination check valve & back pressure valve |
| 06/14/1994 | US5320178 Sand control screen and installation method for wells |
| 06/14/1994 | US5319959 Air lubricated penetrometer rod system |
| 06/10/1994 | CA2110956A1 Method and apparatus for reducing the size of solids recovered from a wellbore |
| 06/07/1994 | US5318132 Retrievable whipstock/packer assembly and method of use |
| 06/01/1994 | CN2167184Y Driving apparatus for vibration sieve for drilling mud |
| 05/31/1994 | US5317111 Ultrasonic measurement apparatus |
| 05/26/1994 | WO1994011610A1 Case cementing method and system |
| 05/25/1994 | EP0598378A1 Blended drilling fluid thinner |
| 05/25/1994 | CN2166215Y Device for removing solid-phase corpuscles by electric field method |
| 05/25/1994 | CN1087108A Blended drilling fluid thinner |
| 05/24/1994 | US5314267 Horizontal pipeline boring apparatus and method |
| 05/18/1994 | EP0466702B1 Coupling for drilling machine with dust extractor |
| 05/18/1994 | EP0440825B1 Method of re-using slurry in ground improving construction work |
| 05/18/1994 | EP0437588B1 Assembly comprising an extension tube and a sleeving conduit inside it |
| 05/18/1994 | CN2165223Y Swivel for engineering driller |
| 05/17/1994 | US5311955 Installation for cleaning the zone near the drill hole |
| 05/17/1994 | CA1329495C System for monitoring fluids during well stimulation processes |
| 05/11/1994 | WO1994010420A1 Retrievable whipstock/packer assembly and method of use |
| 05/10/1994 | US5310005 Flapper valve assembly with floating hinge |
| 05/10/1994 | US5309996 Methods of primary cementing of wells |
| 05/10/1994 | US5309989 Oil well fire extinguishing apparatus |
| 05/10/1994 | CA1329319C Oil removal from hydrocarbon contaminated cuttings |
| 05/04/1994 | CN2163864Y 旁通阀 Bypass valve |
| 05/04/1994 | CN2163863Y Cyclone separator |
| 05/03/1994 | US5307881 Flushing system for a percussive, fluid-activated apparatus |
| 04/28/1994 | WO1994009254A1 Method of propagating a hydraulic fracture using fluid loss control particulates |
| 04/28/1994 | WO1994009088A1 Separation of oils from solids |
| 04/27/1994 | CN2163230Y Dual-function sword-like back-pressure valve |
| 04/26/1994 | US5305836 System and method for controlling drill bit usage and well plan |
| 04/20/1994 | EP0593122A2 Blow-out prevention device for shutting off an annulus between a drill column and a well wall |
| 04/20/1994 | CN2162528Y Sand removing device for drilling liquid |
| 04/19/1994 | US5303786 Earth drilling cuttings processing system |
| 04/19/1994 | US5303582 Pressure-transient testing while drilling |
| 04/17/1994 | CA2108487A1 Blow-out prevention device for shutting off an annulus between a drill column and a well wall when drilling for oil or gas |
| 04/14/1994 | WO1994008127A1 Method for calculating sedimentary rock pore pressure |
| 04/12/1994 | US5302052 Underground work chamber assembly and method for the construction thereof |
| 04/12/1994 | US5301759 Method and apparatus for core-sampling subsurface rock formations |
| 04/12/1994 | CA1328399C Process and means for measuring geological formations properties in a horizontal borehole drilled from an underground patch |
| 04/05/1994 | CA1328254C Drill pipes and casings utilizing multi-conduit tabulars |
| 04/05/1994 | CA1328252C Hammer drills for making boreholes |
| 03/31/1994 | WO1994006881A1 Pretreated clays, their preparation and use in formulating drilling muds not aggressive to layer clays |
| 03/31/1994 | EP0678149A4 Masonry coring system. |
| 03/31/1994 | CA2145090A1 Pretreated clays, their preparation and use in formulating drilling muds not aggressive to layer clays |
| 03/29/1994 | US5297629 Drill stem testing with tubing conveyed perforation |
| 03/23/1994 | EP0588373A1 Double-tube core taking apparatus for inclined drilling |
| 03/23/1994 | CN1084244A Prodn. method for lead filled high gravity valve ball |
| 03/22/1994 | US5295536 Drilling mud container apparatus |
| 03/22/1994 | US5295317 Apparatus for excavating earthen material by evacuation of same |
| 03/16/1994 | CN2158913Y Vibrating sieve for drilling fluid |