DOWNHOLE TELEMETRY SIGNALLING APPARATUS

• US 20130063276A1
• Filed: 07/19/2012
• Published: 03/14/2013
• Est. Priority Date: 07/19/2011
• Status: Active Grant

• Current Assignee: Mariusz Thomas Zientarski
• Original Assignee: Mariusz Thomas Zientarski
• Inventors: ZIENTARSKI, Mariusz Thomas
• Granted Patent: US 9,181,797 B2
• Time in Patent Office: Days
• US Class Current: 340/854.4
• CPC Class Codes: E21B 47/12 Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
• CPC Class Codes: E21B 47/13 by electromagnetic energy, e.g. radio frequency
• CPC Class Codes: H04B 13/02 Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy

Abstract

A data logging sub is mounted at the downhole end of a drill string, and a receiver, or detector is mounted at the top of the drill string at the well-head. The downhole logging sub includes a digital signal transmitter that is operatively connected to the drill string, such that it can send a series of charge pulses along the drill string. The receiver is mounted to detect changes in electrical charge on the drill string. The drill string leaks charge to the surrounding geological formation, but the time constant of the leakage is large compared to the quantity of charge of the charge pulses, and the low resistance of the drill string as compared to the resistivity of the surrounding formation. The leakage is high enough that the charge leaks off the drill string fast enough to permit a useful baud rate.

Claims

1. A well-bore downhole data logging signal transmission apparatus comprising:

a signal transmitter sub mounted to an electrically conductive drill string adjacent to a drill bit thereof;

a receiver mounted at a drill bore head location;

said signal transmitter operatively connected to place coded electrical signal pulse sequences on the electrically conductive drill string;

said receiver mounted in operative connection to sense the presence of transmitted electrical pulses; and

said signal transmitter being operable to cause pulses of charge to be placed on the drill string, said pulses having a duration of less than 10 ms.

2. The signal transmission apparatus of claim 1 including sensors for observing any of (a) compass direction;

(b) azimuth angle;

(c) temperature;

(d) acidity;

(e) salinity;

(f) gamma radiation; and

(g) resistivity, and said signal transmitter sub being operable to send data obtained from any of said sensors.

3. The signal transmission apparatus of claim 1 wherein said apparatus emits a pulse train having a mean power consumption of less than 5w.

4. The signal transmission apparatus of any claim 3 wherein said apparatus has a power consumption of between 0 and 2.5w.

5. The signal transmission apparatus of claim 1 wherein said signal transmitter is operable to release a charged signal onto the drill string.

6. The signal transmission apparatus of claim 1 wherein said charges signal has a pulse time duration of less than 5 ms.

7. The signal transmission apparatus of claim 1 further comprising a signal repeated mounted along the drill string intermediate said signal transmitter and said signal receiver.

8. The signal transmission apparatus of claim 1 wherein said signal transmitter has a baud rate in the range of 20 to 200 pulses per second.

9. A method of transmitting well-bore down hole data comprising using the apparatus of claim 1 to transmit data from said signal transmitter to said receiver.

10. The method of claim 9 wherein said method includes spacing pulses of data, said spacing including inhibiting transmission of a subsequent pulse until electrical voltage potential on an said drill string next adjacent to said signal transmitter has decayed to less than 37% of said peak voltage.

11. The method of claim 10 wherein said method includes inhibiting transmission of subsequent pulses until voltage potential on said drill string next adjacent to said signal transmitter has fallen to less than 13.5% of said peak voltage.

12. The method of claim 11 wherein said method includes inhibiting transmission of subsequent pulses until voltage potential on said drill string next adjacent to said signal transmitter has fallen to less than 5% of said peak voltage.

13. The apparatus of claim 1 wherein the electrically conductive drill string is free of electrical isolators between (i) successive sections the drill string;

and (ii) between the drill string and the surrounding geological formation.

14. The signal transmission apparatus of claim 1 wherein the apparatus is mounted in a drill string, and the drill string is free of an electrically isolated gap between the transmitting sub and the drill string more generally.

15. The signal transmission apparatus of claim 1 wherein a carrier current is placed onto the drill pipe in a polarity and form aiding transmission of the charge pulses.

16. The signal transmission apparatus of claim 1 wherein pulses of noise are imposed on the drill string over controlled pulse periods, with controlled spacing between the pulses.

17. A downhole telemetry apparatus that includes a signal source connected to place a series of controlled duration electrical charge pulses on a drill string, and apparatus mounted to detect ringing in the drill string caused by such pulses.

18. The downhole telemetry apparatus of claim 17 wherein the signalling apparatus includes a coil connected to conduct the pulses onto the drill string.

19. The downhole telemetry apparatus of claim 17 wherein the apparatus and the drill string forms and LRC decaying resonance system.

20. A method of use of the downhole telemetry apparatus of claim 17 wherein said method includes imposing a train of pulses on such drill string, and sensing the ringing in the natural frequencies of the drill string associated with such a train of pulses.