Determining seawater conductivity for the compensation of electromagnetics-based survey data

1. A method comprising:

obtaining acoustic reflection data, such as that acquired during a seismic survey in the seawater;

based on the acoustic reflection data, determining a conductivity of the seawater; and

processing data obtained from an electromagnetics-based survey based on the determined conductivity.

2. The method of claim 1 , wherein the electro-mnagnetics based survey comprises a controlled source electromagnetics survey.

3. The method of claim 1 , wherein the act of determining the conductivity comprises determining elastic properties of the seawater.

4. The method of claim 3 , wherein the elastic properties comprise a velocity.

5. The method of claim 3 , wherein the elastic properties comprise a density.

6. The method of claim 3 , wherein the act of determining the elastic properties comprise determining spatially varying elastic properties.

7. The, method of claim 3 , wherein the act of determining the elastic comprises determining temporally varying elastic properties.

8. The method of claim 3 , further comprising evaluating the determination of the elastic properties based on calibration data.

9. The method of claim 1 , wherein the act of determining the conductivity comprises determining a temperature of the seawater.

10. The method of claim 1 , wherein the act of determining the conductivity comprises determining a pressure of the seawater.

11. The method of claim 1 , wherein the act of deternilning the conductivity comprises determining a salinity of the seawater.

12. The method of claim 1 , further comprising processing data obtained in a controlled source electromagnetic survey based at least in part on the determined conductivity.

13. The method of claim 1 , further comprising evaluating the determined conductivity based on calibration data.

14. A system comprising:

an interface to receive seismic data. acquired during a seismic survey in seawater; and

a processor to detennine a conductivity of the seawater based on the seismic data.

15. The system of claim 14 , wherein the processor is adapted to determine elastic properties of the seawater.

16. The system of claim 15 , wherein the elastic properties include n velocity.

17. The system of claim 15 , wherein the elastic properties comprise a density.

18. The system of claim 14 , wherein the processor is adapted to determine a temperature, pressure or salinity of the seawater based on the seismic data.

19. The system of claim 14 , fruther comprising:

a surface vessel; and

at least one sensor towed by the survey vessel to obtain the seismic data.

20. The system of claim 14 , further comprising:

a survey vessel; and

at least one sensor towed by the survey vessel to obtain controlled source electromagnetic data.

21. The system of claim 14 , wherein the processor is adapted to provide an indication of an evaluation of the determined conductivity based on calibration data.

22. An article comprising a computer accessible storage medium to store instructions that when executed cause a processor-based system to: obtain seismic data acquired during a seismic survey in seawater; and based on the seismic data, determine a conductivity of the seawater.

23. The article of claim 22 , the storage medium comprising instructions that when executed cause the processor-based system to determine elastic properties of the seawater based on the seismic data.

24. The article of claim 23 , the storage medium storing instructions that when executed by the processor-based system cause the processor-based system to determine spatially varying elastic properties of the seawater based on the seismic data.

25. The article of claim 23 , the storage medium storing instructions that when executed by the processor-based system cause the processor-based system to determine temporally varying elastic properties of the seawater based on the seismic data.