| Patents for E21B 47 - Survey of boreholes or wells (31,352) |
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| 09/17/1991 | CA1289061C Pipe connector and method of applying same |
| 09/13/1991 | CA2037035A1 Method for the estimation of pore pressure within a subterranean formation |
| 09/10/1991 | US5047635 Down-hole probe assemblies |
| 09/10/1991 | US5047632 Method for determining dynamic flow characteristics of multiphase flows |
| 09/07/1991 | CA2037547A1 Method and apparatus for locating solvent injection apparatus within a natural gas wellbore |
| 09/04/1991 | CN1054287A Method for determining transit time for radioactive tracer |
| 09/04/1991 | CA2037394A1 Determination of magnetic interference in a borehole |
| 09/03/1991 | US5045692 Simultaneous fluid flow and fluid density measurements using rotameter and nuclear technology |
| 09/03/1991 | US5044888 Variable speed pump control for maintaining fluid level below full barrel level |
| 09/03/1991 | US5044437 Method and device for performing perforating operations in a well |
| 09/03/1991 | US5044436 Steam injection profiling with unstable radioactive isotopes |
| 09/03/1991 | US5044198 Method of predicting the torque and drag in directional wells |
| 08/28/1991 | EP0443936A1 Method and apparatus for evaluating the cement in a well |
| 08/28/1991 | EP0443689A2 Method and system for controlling vibrations in borehole equipment |
| 08/28/1991 | CN1054114A Communication device for micro computer logging and the program thereof |
| 08/27/1991 | US5043952 Monopole transmitter for a sonic well tool |
| 08/27/1991 | US5043948 Borehole televiewer system |
| 08/27/1991 | US5042297 Well-logging process and device in a non-flowing production well |
| 08/27/1991 | CA1288173C Pressure and temperature sensor |
| 08/22/1991 | WO1991012410A1 Pipework for constructing a ground water measuring point |
| 08/22/1991 | DE4004939A1 Well level measurement arrangement - has head station at top of well pipe connected to level sensor via cable |
| 08/21/1991 | EP0442813A2 Method and apparatus for detecting and quantifying radioactive material on tubing in a borehole |
| 08/21/1991 | EP0442188A1 Downhole doppler flowmeter |
| 08/20/1991 | US5040619 Wireline supported perforating gun enabling oriented perforations |
| 08/20/1991 | US5040421 Measuring method of fluctuations of ground and its apparatus |
| 08/20/1991 | US5040414 Analyzing a hydrocarbon reservoir by determining the response of that reservoir to tidal forces |
| 08/14/1991 | EP0408667A4 Acoustic data transmission through a drill string |
| 08/14/1991 | CN2082850U Portable dip gauge |
| 08/13/1991 | US5040155 Double guided mud pulse valve |
| 08/08/1991 | WO1991011736A1 Apparatus for inductively coupling signals between a downhole sensor and the surface |
| 08/08/1991 | WO1991011646A1 Utility tunneling method and apparatus |
| 08/07/1991 | CN1053655A Remote-control well signals and the receiver thereof |
| 08/06/1991 | US5038033 Method and apparatus for detecting and quantifying radioactive material on tubing in a borehole |
| 08/06/1991 | US5036945 Sonic well tool transmitter receiver array including an attenuation and delay apparatus |
| 08/06/1991 | US5036916 Method and apparatus for locating wet cement plugs in open bore holes |
| 08/06/1991 | US5036710 Multi-phase flowmeter |
| 08/06/1991 | CA1287387C Magnetic freepoint sensor utilizing spaced hall effect devices |
| 07/31/1991 | EP0438392A1 Apparatus and method for measuring borehole deviation. |
| 07/31/1991 | CN2081883U Cable bridle for well survey |
| 07/30/1991 | US5036496 Method for cement evaluation using acoustical logs |
| 07/30/1991 | US5035581 Fluid level monitoring and control system |
| 07/30/1991 | US5035292 Whipstock starter mill with pressure drop tattletale |
| 07/30/1991 | US5035285 Electrically conductive |
| 07/30/1991 | US5035146 Method and apparatus for determining steam quality and/or flow rate from impact force and flow restriction data |
| 07/30/1991 | CA1287169C Apparatus and method for determining the position of a tool in a borehole |
| 07/30/1991 | CA1287160C Method and device for the installation of seismic sensors in a producer oil well |
| 07/30/1991 | CA1287142C Method for transmitting downhole data in a reduced time |
| 07/30/1991 | CA1287141C System for transmitting signals between a receiving set lowered into a welland a control and recording central laboratory |
| 07/30/1991 | CA1286983C Restriction subs for setting cement plugs in wells |
| 07/24/1991 | CN1013288B Radioactive well measuring device |
| 07/23/1991 | US5034929 Means for varying MWD tool operating modes from the surface |
| 07/23/1991 | US5033307 Borehole "creep" displacement tool |
| 07/23/1991 | US5033297 Submersible sensor |
| 07/23/1991 | CA1286773C Apparatus and method for gravity correction in borehole survey systems |
| 07/23/1991 | CA1286772C System for surveying fluid transmission pipelines and the like |
| 07/23/1991 | CA1286598C Apparatus for monitoring a parameter in a well |
| 07/23/1991 | CA1286497C Interferometric means and method for accurate determination of fiber-optic well logging cable length |
| 07/17/1991 | CN1053124A Physical parameter collector for slurry |
| 07/16/1991 | US5031697 Method for troubleshooting gas-lift wells |
| 07/16/1991 | US5031467 Pulse echo technique for detecting fluid flow |
| 07/16/1991 | US5031466 Method and apparatus for determining steam quality and mass flow rate |
| 07/16/1991 | US5031465 Steam quality and mass flow rate measurement using critical flow choke upstream of an orifice plate |
| 07/16/1991 | US5031452 Water level probe |
| 07/11/1991 | DE3943151A1 Underground pipe laying direction monitor - has transmitter and power supply mounted in casing on drilling bit at end of pipe |
| 07/10/1991 | EP0436017A1 Analyzing a hydrocarbon reservoir by determining the response of that reservoir to tidal forces |
| 07/09/1991 | US5031158 Method and apparatus for drill bit location |
| 07/09/1991 | CA1285989C Conductor system for well bore data transmission |
| 07/03/1991 | EP0435856A2 Multi-mode testing tool |
| 07/02/1991 | US5027655 Method and apparatus for measuring liquid level in the ground |
| 07/02/1991 | CA1285471C Well testing apparatus and methods |
| 06/26/1991 | EP0433407A1 Moling system. |
| 06/26/1991 | CN2079657U Borehole compensator for sound wave meter with single emitting and double receiving function |
| 06/26/1991 | CN1052530A Pore pressure prediction method |
| 06/25/1991 | US5025857 Wellhead tubing and casing packer and installation and removal tool |
| 06/23/1991 | WO1991010132A1 A gas detection system |
| 06/23/1991 | CA2071988A1 Gas detection system |
| 06/21/1991 | CA2032418A1 Method for determining a transit time for a radioactive tracer |
| 06/19/1991 | EP0433110A1 Tubing element forming an electromagnetic borehole source |
| 06/18/1991 | US5024098 Pressure sensor useable in oil wells |
| 06/13/1991 | WO1991008373A1 Pipe system with electrical conductors |
| 06/13/1991 | CA2069438A1 Pipe system with electrical conductors |
| 06/12/1991 | CN2078797U Shockproof layer pressure-measuring tube |
| 06/12/1991 | CN2078796U Drilling borehole trace monitor |
| 06/12/1991 | CA2031944A1 Pulse echo technique for detecting fluid flow |
| 06/11/1991 | US5023450 Method for discriminating microphonic noise in proportional counters |
| 06/11/1991 | US5022484 Logging method and apparatus using a sonde equipped with measuring pads |
| 06/07/1991 | CA2031080A1 Down-hole probe assemblies |
| 06/04/1991 | US5020609 Acceleration compensating system |
| 05/28/1991 | US5019978 Depth determination system utilizing parameter estimation for a downhole well logging apparatus |
| 05/28/1991 | US5018574 Tubing conveyed wellbore fluid flow measurement apparatus |
| 05/28/1991 | CA1284426C Method and system for determining curvature in fluid transmission pipelines |
| 05/22/1991 | EP0428422A2 Method and apparatus for measurements related to fluid flow in a borehole |
| 05/22/1991 | EP0428181A1 Percussion tool for drilling holes in the soil |
| 05/22/1991 | EP0428180A1 Control system for guiding boring tools and a sensing system for locating the same |
| 05/21/1991 | US5017778 Methods and apparatus for evaluating formation characteristics while drilling a borehole through earth formations |
| 05/21/1991 | US5016712 Method and apparatus for locating solvent injection apparatus within a natural gas wellbore |
| 05/21/1991 | CA1284357C Sonde for measuring the electric formation resistivity in earth strata |
| 05/20/1991 | CA2010863A1 Water level probe |
| 05/16/1991 | WO1991007567A1 Tubing conveyed wellbore fluid flow measurement apparatus |
| 05/16/1991 | CA2045537A1 Tubing conveyed wellbore fluid flow measurement apparatus |