In-situ calibration of borehole gravimeters

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.