Estimating velocities with uncertainty

1. A method for estimating velocity in a subsurface region comprising:

receiving seismic data for the subsurface region;

calculating a distribution of one or more moveouts from one or more velocities of an initial velocity distribution;

generating, using a microprocessor, a posterior distribution representing one or more probabilities of one or more velocities for the one or more moveouts;

determining a velocity with uncertainty for the subsurface region based on the posterior distribution; and

determining a pore pressure with uncertainty based on the velocity with uncertainty.

2. The method of claim 1 , wherein the velocity with uncertainty is determined using a Monte Carlo method.

3. The method of claim 1 , further comprising:

determining a minimum stress with uncertainty based on the velocity with uncertainty; and

designing a well based on the pore pressure with uncertainty and the minimum stress with uncertainty.

4. The method of claim 1 , wherein generating the posterior distribution comprises:

determining an uncertainty of the moveouts;

determining one or more parameters with uncertainty that describe the one or more moveouts;

receiving modeling data for the subsurface region;

determining prior interval parameters distribution, based on the modeling data;

determining a likelihood distribution representing one or more probabilities of the one or more moveouts for each of the one or more velocities; and

multiplying the prior interval parameters distribution by the likelihood distribution to generate the posterior distribution.

5. The method of claim 4 , wherein the uncertainty of the moveouts is determined using a semblance analysis.

6. The method of claim 4 , wherein the one or more parameters with uncertainty comprise:

tomographic velocity;

root mean square average velocity;

anisotropy;

zero offset time; or

combinations thereof.

7. The method of claim 4 , wherein one or more prior interval parameters of the prior interval parameters distribution comprise:

tomographic velocity;

root mean square average velocity;

anisotropy;

zero offset time; or

combinations thereof.

8. The method of claim 4 , wherein the modeling data is obtained from surrounding wells.

9. The method of claim 4 , wherein determining the prior interval parameter distribution comprises determining a probability distribution representing one or more probabilities for the one or more velocities for a given depth in the subsurface region.

10. The method of claim 4 , wherein the one or more parameters with uncertainty are determined using numerical methods.

11. A non-transitory computer-readable medium comprising program instructions executable by a processor to:

receive seismic data for a subsurface region;

calculate a distribution of one or more moveouts from one or more velocities of an initial velocity distribution;

generate a posterior distribution representing one or more probabilities of one or more velocities for the one or more moveouts;

determine a velocity with uncertainty for the subsurface region based on the posterior distribution; and

determine a pore pressure with uncertainty based on the velocity with uncertainty.

12. The non-transitory computer-readable medium of claim 11 , wherein the velocity with uncertainty is determined using a Monte Carlo method.

13. The non-transitory computer readable medium of claim 11 , further comprising program instructions executable by the processor to:

determine a minimum stress with uncertainty based on the velocity with uncertainty; and

design a well based on the pore pressure with uncertainty and the minimum stress with uncertainty.

14. The non-transitory computer readable medium of claim 11 , wherein the posterior distribution is generated by program instructions executable by a processor to:

determine an uncertainty of the moveouts;

determine one or more parameters with uncertainty that describe the one or more moveouts;

receive modeling data for the subsurface region;

determine prior interval parameters distribution, based on the modeling data;

determine a likelihood distribution representing one or more probabilities of the one or more moveouts for each of the one or more velocities; and

multiply the prior interval parameters distribution by the likelihood distribution to generate the posterior distribution.

15. The non-transitory computer-readable medium of claim 14 , wherein the uncertainty of the moveout is determined using a semblance analysis.

16. The non-transitory computer-readable medium of claim 14 , wherein the one or more parameters with uncertainty comprise:

tomographic velocity;

root mean square average velocity;

anisotropy;

zero offset time; or

combinations thereof.

17. The non-transitory computer-readable medium of claim 14 , wherein the modeling data is obtained from surrounding wells.

18. The non-transitory computer-readable medium of claim 14 , wherein determining the prior interval parameters distribution comprises determining a probability distribution representing one or more probabilities for the one or more velocities for a given depth in the subsurface region.

19. A computer system, comprising:

a processor;

a memory comprising program instructions executable by the processor to:

receive seismic data for a subsurface region;

calculate a distribution of one or more moveouts from one or more velocities of an initial velocity distribution;

generate a posterior distribution representing one or more probabilities of one or more velocities for the one or more moveouts;

determine a velocity with uncertainty for the subsurface region based on the posterior distribution; and

determine a pore pressure with uncertainty based on the velocity with uncertainty.

20. The computer system of claim 19 , further comprising program instructions executable by the processor to:

determine a minimum stress with uncertainty based on the velocity with uncertainty; and

design a well based on the pore pressure with uncertainty and the minimum stress with uncertainty.