Method for converting seismic data from the time domain to the depth domain

1. A method for converting seismic data between bounding upper and lower surfaces in the time domain to the depth domain, said method comprising:

determining an upper depth surface corresponding to the upper time surface;

generating an interval velocity value for each seismic sample between the upper and lower time surfaces from velocity data generated from well logs; and

converting the seismic times between the bounding time surfaces to the depth domain by adding the thickness of each seismic sample to the upper depth surface, wherein the thickness of each seismic sample is a function of the seismic sample rate and interval velocity value for each seismic sample.

2. The method of claim 1 further comprising the subsequent step of interpolating seismic attribute values from the converted seismic data to a linear depth sampling.

3. The method of claim 1 wherein the upper depth surface is determined by converting the upper time surface to the depth domain.

4. The method of claim 3 further comprising the subsequent step of adjusting the upper depth surface to match well data concerning geologic formations.

5. The method of claim 1 wherein the upper depth surface is generated from well data concerning geologic formations.

6. The method of claim 1 wherein the interval velocity values are generated by kriging.

7. The method of claim 1 wherein the interval velocity values are generated by inverse distance weighting.

8. The method of claim 1 wherein the step of converting the seismic times to the depth domain further comprises:

Depth

n

=

Depth

Surf

+

∑

j

=

1

n

⁢

Velocity

j

*

SampleRate

/

2

wherein:

Depth n =Depth at the n th seismic sample below the upper depth surface at that trace location;

Depth Surf =Depth at the upper depth surface at that trace location;

Velocity j =Interval velocity of the j th sample below the upper depth surface at that trace location; and

SampleRate=Sample rate.

9. A method for converting seismic data between bounding upper and lower surfaces in the time domain to the depth domain, said method comprising:

determining an upper depth surface by time-depth conversion of the upper time surface;

adjusting the upper depth surface to match well data concerning geologic formations;

generating an interval velocity value for each seismic sample between the upper and lower time surfaces from velocity data generated from well logs; and

converting the seismic times between the bounding time surfaces to the depth domain by adding the thickness of each seismic sample to the upper depth surface, wherein the thickness of each seismic sample is a function of the seismic sample rate and interval velocity value for each seismic sample.

10. The method of claim 9 further comprising the subsequent step of interpolating seismic attribute values from the converted seismic data to a linear depth sampling.

11. The method of claim 9 wherein the interval velocity values are generated by kriging.

12. The method of claim 9 wherein the interval velocity values are generated by inverse distance weighting.

13. The method of claim 9 wherein the step of converting the seismic times to the depth domain further comprises:

Depth

n

=

Depth

Surf

+

∑

j

=

1

n

⁢

Velocity

j

*

SampleRate

/

2

wherein:

Depth n =Depth at the n th seismic sample below the upper depth surface at that trace location;

Depth Surf =Depth at the upper depth surface at that trace location;

Velocty j =Interval velocity of the j th sample below the upper depth surface at that trace location; and

SampleRate=Sample rate.

14. A method for converting seismic data within a seismic volume to the depth domain, said seismic volume being defined by a plurality of zones, with each zone having bounding upper and lower surfaces in the time domain, said method comprising:

determining an upper depth surface corresponding to the uppermost time surface;

generating an interval velocity value for each seismic sample between the upper and lower time surfaces for each zone from velocity data generated from well logs; and

converting the seismic times between the bounding time surfaces to the depth domain by adding the thickness of each seismic sample to the upper depth surface, wherein the thickness of each seismic sample is a function of the seismic sample rate and interval velocity value for each seismic sample within each zone.

15. The method of claim 14 further comprising the subsequent step of interpolating seismic attribute values from the converted seismic data to a linear depth sampling.

16. The method of claim 14 wherein the upper depth surface is determined by converting the upper time surface to the depth domain.

17. The method of claim 16 further comprising the subsequent step of adjusting the upper depth surface to match well data concerning geologic formations.

18. The method of claim 14 wherein the upper depth surface is generated from well data concerning geologic formations.

19. The method of claim 14 wherein the interval velocity values are generated by kriging.

20. The method of claim 14 wherein the step of converting the seismic times to the depth domain further comprises:

Depth

n

=

Depth

Surf

+

∑

j

=

1

n

⁢

Velocity

j

*

SampleRate

/

2

wherein:

Depth n =Depth at the n th seismic sample below the upper depth surface at that trace location;

Depth Surf =Depth at the upper depth surface at that trace location;

Velocity j =Interval velocity of the j th sample below the upper depth surface at that trace location; and

SampleRate=Sample rate.