Synchronizing downhole communications using timing signals

Patent metadata

Field	Value
Publication number	US-10400587-B2
Application number	US-201515539743-A
Country	US
Kind code	B2
Filing date	Mar 11, 2015
Priority date	Mar 11, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A system that is positionable in a wellbore can include a transceiver that is positionable external to a casing string. The transceiver can be remotely programmable while in the wellbore to set an internal clock using a timing signal wirelessly transmitted from a source and a position of the transceiver in the wellbore relative to the source. The transceiver can use the internal clock for controlling a timing of the transceiver for transmitting a wireless signal.

First claim

What is claimed is:

1. A system that is positionable in a wellbore, the system comprising:
a transceiver that is positionable external to a casing string and remotely programmable while in the wellbore to set an internal clock to a reference time that is calculated using (i) a timing signal wirelessly transmitted from a source and (ii) a position of the transceiver in the wellbore relative to the source, wherein the transceiver is configured to transmit a wireless signal at a time that is offset from the reference time by a predetermined amount.

2. The system of claim 1 , wherein the source of the timing signal is a computing device positioned at a surface of the wellbore.

3. The system of claim 1 , wherein the transceiver configured to determine the reference time using the timing signal and the position in the wellbore, the reference time being usable by a plurality of transceivers to synchronize wireless communications among the plurality of transceivers.

4. The system of claim 1 , wherein the transceiver comprises:
a processing device; and
a memory device in which instructions executable by the processing device are stored for causing the processing device to:
receive the timing signal at a particular time;
determine (i) the position of the transceiver relative to the source and (ii) a temperature in the wellbore, based on data from sensors;
determine a time delay by applying the position of the transceiver, the temperature in the wellbore, and a speed of sound to an algorithm usable to compare the speed of sound to the position of the transceiver to determine the time delay between the particular time and the reference time; and
determine the reference time by subtracting the time delay from the particular time.

5. The system of claim 1 , further comprising a plurality of transceivers positioned external to the casing string and programmable to receive the timing signal and synchronize respective internal clocks in the plurality of transceivers using the timing signal for determining when to transmit wireless signals.

6. The system of claim 1 , wherein the source comprises a closer transceiver that is positioned closer to a surface of the wellbore than the transceiver.

7. The system of claim 6 , wherein the transceiver is operable to transmit another timing signal to a farther transceiver that is positioned farther from the surface of the wellbore than the transceiver.

8. The system of claim 1 , wherein the transceiver is programmable to include a known position of the transceiver relative to the source prior to the transceiver being positioned in the wellbore.

9. A communication system that is positionable in a wellbore, the communication system comprising:
a first transceiver that is positionable external to a casing string and remotely programmable while in the wellbore to set a first internal clock to a reference time that is calculated using (i) a first timing signal wirelessly transmitted from a source and (ii) a first position of the first transceiver in the wellbore relative to the source, wherein the first transceiver is configured to transmit a first wireless signal at a first time that is offset from the reference time by a first predetermined amount; and
a second transceiver that is positionable external to the casing string and remotely programmable while in the wellbore to set a second internal clock to the reference time, wherein the second transceiver is configured to calculate the reference time using (i) a second timing signal wirelessly transmitted from the first transceiver and (ii) a second position of the second transceiver in the wellbore relative to the first transceiver, and wherein the second transceiver is configured to transmit a second wireless signal at a second time that is offset from the reference time by a second predetermined amount that is different from the first predetermined amount.

10. The communication system of claim 9 , further comprising a computing device positioned at a surface of the wellbore and operable to transmit the first timing signal to the first transceiver.

11. The communication system of claim 9 , wherein the first transceiver and the second transceiver are configured to synchronize wireless communications between the first transceiver and the second transceiver based on the reference time.

12. The communication system of claim 9 , wherein the first transceiver comprises:
a processing device; and
a memory device in which instructions executable by the processing device are stored for causing the processing device to:
receive the first timing signal at a particular time;
determine (i) the first position of the first transceiver relative to the source of the first timing signal and (ii) a temperature in the wellbore, based on data from sensors;
determine a time delay by applying the first position of the first transceiver, the temperature in the wellbore, and a speed of sound to an algorithm usable to compare the speed of sound to the first position of the first transceiver to determine the time delay between the particular time and the reference time; and
determine the reference time by subtracting the time delay from the particular time.

13. The communication system of claim 9 , further comprising a third transceiver that is positioned closer to a surface of the wellbore than the first transceiver and the second transceiver, the third transceiver being operable to transmit the first timing signal to the first transceiver.

14. The communication system of claim 9 , wherein the first transceiver and the second transceiver are each programmable to include known respective positions relative to the source prior to being positioned in the wellbore.

15. A method comprising:
receiving a timing signal by a programmable transceiver positioned external to a casing string in a wellbore;
determining, by the programmable transceiver, a position of the programmable transceiver in the wellbore relative to a source of the timing signal;
setting, by the programmable transceiver, an internal clock to a reference time that is calculated using the timing signal and the position; and
transmitting, by the programmable transceiver, a wireless communication at a time that is offset from the reference time by a predetermined amount.

16. The method of claim 15 , further comprising:
synchronizing wireless communications among a plurality of transceivers positioned external to the casing string in the wellbore using the reference time.

17. The method of claim 15 , wherein determining the reference time comprises:
receiving the timing signal at a particular time;
determining the position of the programmable transceiver relative to the source and a temperature in the wellbore based on data from sensors;
determining a time delay by applying the position of the programmable transceiver, the temperature in the wellbore, and a speed of sound to an algorithm that compares the speed of sound to the position of the programmable transceiver relative to the source to determine the time delay between the particular time and the reference time; and
determining the reference time by subtracting the time delay from the particular time.

18. The method of claim 15 , further comprising:
receiving the timing signal from a closer programmable transceiver that is positioned closer to a surface of the wellbore than the programmable transceiver.

19. The method of claim 18 , further comprising:
transmitting another timing signal to a farther programmable transceiver that is positioned farther from

Assignees

• Halliburton Energy Services Inc

Inventors

• Roberson Mark W

Classifications

• E21B47/07

  Temperature · CPC title

• E21B47/13 Primary

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

• G01V1/46

  Data acquisition · CPC title

• G01V2200/12

  Clock synchronization-related issues · CPC title

• E21B4/00

  Drives for drilling, used in the borehole · CPC title