In-situ calibration of borehole gravimeters

Patent metadata

Field	Value
Publication number	US-11525941-B2
Application number	US-201816957009-A
Country	US
Kind code	B2
Filing date	Mar 28, 2018
Priority date	Mar 28, 2018
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

A method and system for in-sit calibration of a gravimeter. A method may comprise disposing a downhole tool in a borehole, wherein the downhole tool comprises the gravimeter attached to a linear actuator, recording a first set of measurements with the gravimeter while the linear actuator is stationary, activating the linear actuator, recording a second set of measurements with the gravimeter, and calibrating the gravimeter based on the first and second set of recorded measurements. A system may comprise a downhole tool, a conveyance, and an information handling system. The downhole tool may further comprise a hanger, a sonde, connected to the hanger, a linear actuator, connected to the hanger, and a shaft, connected to the linear actuator. The downhole tool may further comprise a linkage, connected to the shaft, a package, connected to the linkage, and a gravimeter, disposed in the package.

First claim

What is claimed is:

1. A method for in-situ calibration of a gravimeter, comprising:
disposing a downhole tool in a borehole, wherein the downhole tool comprises the gravimeter attached to a linear actuator, wherein the linear actuator is configured to drive axial movement of the gravimeter, and wherein the downhole tool further comprises a plurality of springs configured to restrain lateral movement of the gravimeter;
recording a first set of measurements with the gravimeter while the linear actuator is stationary;
activating the linear actuator to cause the gravimeter to move axially;
recording a second set of measurements with the gravimeter; and
calibrating the gravimeter based on the first and second set of recorded measurements.

2. The method of claim 1 , further comprising activating an acceleration sequence for the linear actuator in an analog mode.

3. The method of claim 2 , further comprising producing waveforms for the analog mode and energizing the linear actuator using the waveforms.

4. The method of claim 3 , further comprising sending confirmation to the information handling system that the acceleration sequence is complete.

5. The method of claim 1 , further comprising activating an acceleration sequence for the linear actuator in a stepper mode.

6. The method of claim 5 , further comprising producing a series and timing command for the stepper mode and energizing the linear actuator using the series and timing command.

7. The method of claim 6 , further comprising sending confirmation to the information handling system that the acceleration sequence is complete.

8. The method of claim 1 , wherein the recording a first set of measurements with the gravimeter while the linear actuator is stationary comprises a time delay to allow the gravimeter to be powered and stabilized.

9. The method of claim 1 , further comprising specifying a calibration parameter.

10. The method of claim 9 , wherein the calibration parameter is a number of constant acceleration intervals, a magnitude and sign of acceleration for each interval, an acceleration sample rate, or an acceleration to be produced in an analog mode or a stepper mode.

11. The method of claim 1 , further comprising rotating the gravimeter and measuring a bias.

12. A system comprising:
a downhole tool, wherein the downhole tool comprises:
a hanger;
a sonde connected to the hanger;
a linear actuator disposed within the sonde and having a proximal end connected to the hanger;
a shaft extending from a distal end of the linear actuator;
a package connected to the shaft via a linkage, wherein activating the linear actuator is configured to extend and retract the shaft along a central axis of the sonde to drive axial movement of the package;
a gravimeter disposed in the package such that axial movement of the package moves the gravimeter axially; and
a plurality of springs disposed within the sonde and configured to restrain lateral movement of the package such that lateral movement of the gravimeter is restrained;

a conveyance attached to the downhole tool; and
an information handling system, wherein the information handling system is in signal communication with the downhole tool, and configured to initiate a calibration sequence, send commands to a linear actuator module and a gravimeter module, record a first set of measurements while the linear actuator is stationary; activate the linear actuator; record a second set of measurement while the linear actuator is moving; calibrate the gravimeter based on the first and second set of recorded measurements; and store the calibration results.

13. The system of claim 12 , wherein the information handling system is configured to activate an acceleration sequence for the linear actuator in an analog mode.

14. The system of claim 13 , wherein the information handling system is configured to produce waveforms for the analog mode and energizing the linear actuator using the waveforms.

15. The system of claim 14 , wherein the information handling system is configured to send confirmation to the information handling system that the acceleration sequence is complete.

16. The system of claim 12 , wherein the information handling system is configured to activate an acceleration sequence for the linear actuator in a stepper mode.

17. The system of claim 16 , wherein the information handling system is configured to produce a series and timing command for the stepper mode and energizing the linear actuator using the series and timing command.

18. The system of claim 17 , wherein the information handling system is configured to send confirmation to the information handling system that the acceleration sequence is complete.

19. The system of claim 12 , wherein gravimeter is a three axis gravimeter.

20. The system of claim 12 , further comprising a plurality of gravimeters.

21. A downhole tool, wherein the downhole tool comprises:
a hanger;
a sonde connected to the hanger;
a linear actuator disposed within the sonde and having a proximal end connected to the hanger;
a shaft extending from a distal end of the linear actuator;
a package connected to the shaft via a linkage, wherein activating the linear actuator is configured to extend and retract the shaft along a central axis of the sonde to drive axial movement of the package; and
a gravimeter disposed in the package such that axial movement of the package moves the gravimeter axially;
a plurality of springs disposed within the sonde and configured to restrain lateral movement of the package such that lateral movement of the gravimeter is restrained.

Assignees

• Halliburton Energy Services Inc

Inventors

• Rodney Paul F
• Stark Daniel Joshua

Classifications

• G01V7/02

  Details · CPC title

• E21B23/00

  Apparatus for displacing, setting, locking, releasing or removing tools, packers or the like in boreholes or wells (setting of casings, screens or liners E21B43/10) · CPC title

• G01V13/00 Primary

  Manufacturing, calibrating, cleaning, or repairing instruments or devices covered by groups G01V1/00 – G01V11/00 · CPC title

• E21B49/00

  Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells · CPC title

• E21B47/12

  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 title