Methods and systems to boost surface detected electromagnetic telemetry signal strength

Patent metadata

Field	Value
Publication number	US-10082019-B2
Application number	US-201515536517-A
Country	US
Kind code	B2
Filing date	Dec 17, 2015
Priority date	Dec 18, 2014
Publication date	Sep 25, 2018
Grant date	Sep 25, 2018

Abstract

A method for signal communication between a well drilling instrument and the Earths surface includes generating an electromagnetic field in an instrument disposed in drill string used to drill a wellbore. The electromagnetic field includes encoded measurements from at least one sensor associated with the instrument. A signal corresponding to an amplitude and/or phase of the electromagnetic field is measured between the drill string and a surface electrode when the drill string is substantially electrically isolated from a well casing. A signal corresponding to the amplitude and/or phase is measured between the casing and a surface electrode when the casing and the drill string are in electrical contact with each other.

First claim

What is claimed is:

1. A method for signal communication between a well drilling instrument and the Earth's surface, comprising:
generating an electromagnetic field in an instrument disposed in a drill string used to drill a wellbore, the electromagnetic field comprising encoded measurements from at least one sensor associated with the instrument;
measuring a signal corresponding to an amplitude and/or phase of the electromagnetic field; and
decoding the measurements from the measured signal, wherein the measured signal comprises at least one of;
a voltage imparted across the drill string and an electrode disposed at a selected distance from the wellbore proximate the Earth's surface wherein the drill string and a wellbore casing are substantially electrically isolated from each other,
a current induced in the drill string wherein the drill string and the wellbore casing are substantially electrically isolated from each other, and
a voltage imparted across the well casing and the electrode wherein the casing and the drill string are electrically connected to each other.

2. The method of claim 1 wherein a resistivity of a drilling fluid in the wellbore is in a range between 1,000 ohm meters and 1,000,000 ohm meters.

3. The method of claim 1 wherein the generating an electromagnetic field comprises imparting a time varying voltage across in insulating gap between electrically conductive components of the instrument.

4. The method of claim 1 wherein the generating an electromagnetic field comprises imparting a time varying electric current through a toroidal coil forming part of the instrument.

5. The method of claim 1 further comprising measuring a voltage between the casing and the drill string and decoding the measurements from the voltage measured between the casing and the drill string wherein the drill string and the casing are substantially electrically isolated from each other.

6. The method of claim 1 wherein electrical isolation between the casing and the drill string is performed by at least one insulating standoff or centralizer coupled to the drill string.

7. The method of claim 1 wherein electrical connection between the casing and the drill string is performed by at least one electrically conductive standoff or centralizer coupled to the drill string.

8. A system for communication between a wellbore instrument and the Earth's surface, comprising:
an electromagnetic field generator associated with the wellbore instrument in a drill string in a wellbore, the electromagnetic field generator configured to encode measurements made by at least one sensor associated with the wellbore instrument; and
an electromagnetic field detector in signal communication with the Earth's surface, the electromagnetic field detector comprising at least one of;
a voltage measuring circuit connected between the drill string and an electrode disposed at a selected distance from the wellbore proximate the Earth's surface wherein the drill string and a wellbore casing are substantially electrically isolated from each other,
a current measuring circuit for measuring current induced in the drill string wherein the drill string and the wellbore casing are substantially electrically isolated from each other, and
a voltage measuring circuit connected between the well casing and the electrode wherein the casing and the drill string are electrically connected to each other.

9. The system of claim 8 wherein the electromagnetic field generator associated with the wellbore instrument comprises an insulating gap disposed between electrically conductive parts of the wellbore instrument.

10. The system of claim 8 wherein the electromagnetic field generator associated with the wellbore instrument comprises a toroidal coil disposed on the wellbore instrument.

11. The system of claim 8 further comprising at least one standoff or centralizer comprising an electrically insulating material coupled to the drill string.

12. The system of claim 8 further comprising at least one standoff of centralizer comprising an electrically conductive material coupled to the drill string.

13. A method for measurement in a wellbore, comprising:
moving a wellbore instrument coupled to a drill string along an interior of a wellbore, the wellbore instrument including at least one sensor;
generating an electromagnetic field in the wellbore instrument, the electromagnetic field comprising encoded measurements from the at least one sensor;
measuring a signal corresponding to an amplitude and/or phase of the electromagnetic field; and
decoding the encoded measurements from the measured signal, wherein the measured signal comprises at least one of;
a voltage imparted across the drill string and an electrode disposed at a selected distance from the wellbore proximate the Earth's surface wherein the drill string and a wellbore casing are substantially electrically isolated from each other,
a current induced in the drill string wherein the drill string and the wellbore casing are substantially electrically isolated from each other, and
a voltage imparted across the well casing and the electrode wherein the casing and the drill string are electrically connected to each other.

14. The method of claim 13 wherein a resistivity of a drilling fluid in the wellbore is in a range between 10,000 ohm meters and 100,000 ohm meters.

15. The method of claim 13 wherein the generating the electromagnetic field comprises imparting a time varying voltage across in insulating gap between electrically conductive components of the instrument.

16. The method of claim 13 wherein the generating the electromagnetic field comprises imparting a time varying electric current through a toroidal coil forming part of the instrument.

17. The method of claim 13 further comprising measuring a voltage between the casing and the drill string and decoding the measurements from the voltage measured between the casing and the drill string wherein the drill string and the casing are substantially electrically isolated from each other.

18. The method of claim 13 wherein electrical isolation between the casing and the drill string is performed by at least one insulating standoff or centralizer coupled to the drill string.

19. The method of claim 13 wherein electrical connection between the casing and the drill string is performed by at least one electrically conductive standoff or centralizer coupled to the drill string.

Assignees

• Schlumberger Technology Corp

Inventors

• Gao Guozhong
• Depavia Luis Eduardo
• Jannin Gaelle

Classifications

• G08C17/04 Primary

  using magnetically coupled devices · CPC title

• E21B47/13 Primary

  by electromagnetic energy, e.g. radio frequency · CPC title

• G08C17/02

  using a radio link · CPC title

• H04Q9/14

  Calling by using pulses · CPC title

• H04Q9/00

  Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom · CPC title