Seismic surveys with optical communication links

1. A system to perform a seismic survey in a marine environment, comprising:

a seismic data acquisition unit disposed on a seabed in the marine environment, the seismic data acquisition unit including a local pressure sensor, an optical transmitter and an optical receiver to determine one or more pressure values; and

an extraction vehicle including a reference pressure sensor, an optical transmitter, an optical receiver to establish an optical communications link with the seismic data acquisition unit and generate reference pressure data, and one or more processors to determine a distance between the extraction vehicle and the seismic data acquisition unit, the extraction vehicle to instruct the reference pressure sensor to obtain the reference pressure data based on the distance between the extraction vehicle and the seismic data acquisition unit and a threshold; and

at least one of the local pressure sensor and the one or more pressure values calibrated based on the reference pressure data generated by the extraction vehicle.

2. The system of claim 1 , comprising:

the extraction vehicle to transmit, via the optical communication link, the reference pressure data to the seismic data acquisition unit; and

the seismic data acquisition unit configured to calibrate, based on the reference pressure data received from the extraction vehicle, the local pressure sensor, the local pressure sensor configured to provide the one or more pressure values as calibrated pressure values.

3. The system of claim 1 , comprising:

the extraction vehicle to transmit, via the optical communication link, the reference pressure data to the seismic data acquisition unit; and

the seismic data acquisition unit configured to calibrate, based on the reference pressure data received from the extraction vehicle, the one or more pressure values measured by the local pressure sensor to generated one or more calibrated pressure values.

4. The system of claim 1 , comprising the extraction vehicle to:

receive, via the optical communication link, the one or more pressure values measured by the local pressure sensor; and

calibrate the one or more pressure values based on the reference pressure data.

5. The system of claim 1 , comprising:

the extraction vehicle to transmit, via the optical communication link, the reference pressure data to the seismic data acquisition unit; and

the seismic data acquisition unit configured to adjust a pressure parameter of the local pressure sensor based on the reference pressure data received from the extraction vehicle.

6. The system of claim 1 , comprising:

the extraction vehicle to instruct the optical transmitter to transmit, to the seismic data acquisition unit via the optical communication link, the reference pressure data based on the distance between the extraction vehicle and the seismic data acquisition unit.

7. The system of claim 1 , wherein the seismic data acquisition unit comprises one or more processors to:

determine the distance between the extraction vehicle and the seismic data acquisition unit.

8. The system of claim 7 , comprising:

the extraction vehicle to transmit, via the optical communication link, the reference pressure data to the seismic data acquisition unit; and

the seismic data acquisition unit to calibrate, based on the distance, at least one of the local pressure sensor and the one or more pressure values based on the reference pressure data received from the extraction vehicle.

9. The system of claim 1 , comprising:

a plurality of seismic data acquisition units disposed on a seabed; and

the extraction vehicle configured to establish separate optical transmission links with the plurality of seismic data acquisition units.

10. The system of claim 1 , comprising:

the extraction vehicle configured to provide, to the seismic data acquisition unit via the optical communication link, the reference pressure data including a pressure value, a time stamp corresponding to detection of the pressure value by the reference pressure sensor, and an indication of the distance between the extraction vehicle and the seismic data acquisition unit.

11. The system of claim 1 , comprising the extraction vehicle configured to:

determine a plurality of reference pressure values;

generate a reference pressure metric based on a statistical technique applied to the plurality of reference pressure values; and

transmit the generated reference pressure metric to the seismic data acquisition unit to cause the seismic data acquisition unit to calibrate the local pressure sensor.

12. The system of claim 1 , comprising:

a data processing system to:

retrieve the one or more pressure values calibrated based on the reference pressure data determined by the extraction vehicle; and

determine, based on the calibrated one or more pressure values, a depth of the seismic data acquisition unit.

13. The system of claim 1 , comprising:

the seismic data acquisition unit comprising a gravimetric sensor; and

a data processing system to:

retrieve the one or more pressure values calibrated based on the reference pressure data determined by the extraction vehicle; and

calibrate gravimetric data detected by the gravimetric sensor based on the one or more pressure values.

14. The system of claim 1 , comprising:

the seismic data acquisition unit comprising a gravimetric sensor; and

a data processing system to:

retrieve the one or more pressure values calibrated based on the reference pressure data determined by the extraction vehicle; and

determine, based on the one or more pressure values, a depth of the seismic data acquisition unit;

calibrate gravimetric data detected by the gravimetric sensor based on the one or more pressure values; and

determine a subsidence value based on at least one of the determined depth or the calibrated gravimetric data.

15. A method of performing a seismic survey in a marine environment, comprising:

deploying a seismic data acquisition unit on a seabed in the marine environment, the seismic data acquisition unit including a local pressure sensor, an optical transmitter and an optical receiver;

establishing, by an extraction vehicle including a reference pressure sensor, an optical transmitter, and an optical receiver, an optical communications link with the seismic data acquisition unit;

providing, by the extraction vehicle to the seismic data acquisition unit via the optical communication link, reference pressure data;

calibrating, by one or more processors of the extraction vehicle based on the reference pressure data, the local pressure sensor or one or more pressure values measured by the local pressure sensor;

determining, by one or more processors of the extraction vehicle, a distance between the extraction vehicle and the seismic data acquisition unit; and

instructing, by the extraction vehicle, the reference pressure sensor to obtain the reference pressure data based on the distance between the extraction vehicle and the seismic data acquisition unit.

16. The method of claim 15 , comprising:

transmitting, by the extraction vehicle via the optical communication link, the reference pressure data to the seismic data acquisition unit; and

calibrating, by the seismic data acquisition unit based on the reference pressure data received from the extraction vehicle, the local pressure sensor; and

providing, by the local pressure sensor calibrated based on the reference pressure data, the one or more pressure values.

17. The method of claim 15 , comprising:

transmitting, by the extraction vehicle via the optical communication link, the reference pressure data to the seismic data acquisition unit; and

calibrating, by the seismic data acquisition unit based on the reference pressure data received from the extraction vehicle, the one or more pressure values measured by the local pressure sensor to generate one or more calibrated pressure values.