Changes

[[file:mapping-with-two-dimensional-seismic-data_fig5.png|left|thumb|{{figure number|5}}Velocity map with velocities marked at grid intersections.]]

[[file:mapping-with-two-dimensional-seismic-data_fig5.png|left|thumb|{{figure number|5}}Velocity map with velocities marked at grid intersections.]]

Approximate velocities can be calculated using the stacking velocities that were picked during processing<ref name=pt07r9>Dix, C. H., 1955, Seismic velocities from surface measurements: Geophysics, v. 20, p. 68–86., 10., 1190/1., 1438126</ref> ([[:file:mapping-with-two-dimensional-seismic-data_fig4.png|Figure 4]]). This is the poorest source of velocity information, but it may be the only source in areas where no wells have been drilled. Stacking velocities are usually printed at the top of each seismic line. Use the nearest shotpoint printed under the stacking velocities as the “ground position” for your calculated average velocities. Keep in mind that stacking velocities are not true velocities; they are just the velocities that the processor interpreted as the best at tuning events during processing. Occasionally, these velocities can vary from true velocities by more than 20%. However, they generally approximate the root mean square velocities from which average velocities can be calculated.

Approximate velocities can be calculated using the stacking velocities that were picked during processing<ref name=pt07r9>Dix, C. H., 1955, Seismic velocities from surface measurements: Geophysics, v. 20, p. 68–86, DOI: [http://library.seg.org/doi/abs/10.1190/1.1438126 10.1190/1.1438126].</ref> ([[:file:mapping-with-two-dimensional-seismic-data_fig4.png|Figure 4]]). This is the poorest source of velocity information, but it may be the only source in areas where no wells have been drilled. Stacking velocities are usually printed at the top of each seismic line. Use the nearest shotpoint printed under the stacking velocities as the “ground position” for your calculated average velocities. Keep in mind that stacking velocities are not true velocities; they are just the velocities that the processor interpreted as the best at tuning events during processing. Occasionally, these velocities can vary from true velocities by more than 20%. However, they generally approximate the root mean square velocities from which average velocities can be calculated.

[[file:mapping-with-two-dimensional-seismic-data_fig6.png|thumb|{{figure number|6}}(a) Block diagram showing the time that Is mapped for a time slice map. (b) Interval that is mapped on time interval map. (c) Time interval map.]]

[[file:mapping-with-two-dimensional-seismic-data_fig6.png|thumb|{{figure number|6}}(a) Block diagram showing the time that Is mapped for a time slice map. (b) Interval that is mapped on time interval map. (c) Time interval map.]]