Changes

Follow the steps listed below for each seismic event to be mapped.

Follow the steps listed below for each seismic event to be mapped.

# Make structure contour maps for key horizons using well control only.

# Make structure [[contour]] maps for key horizons using well control only.

# Pick seismic horizons.

# Pick seismic horizons.

# Calculate depth conversion velocity at locations where both well and seismic time picks exist.

# Calculate depth conversion velocity at locations where both well and seismic time picks exist.

:<math>\upsilon = \frac{2z}{t}</math>

:<math>\upsilon = \frac{2z}{t}</math>

Depth conversion velocities are posted to a map and contoured or gridded to create ''υ''(''x, y'').

Depth conversion velocities are posted to a map and [[contour]]ed or gridded to create ''υ''(''x, y'').

[[:file:interpreting-seismic-data_fig12-13.png|Figure 2]] shows a hypothetical well with important reference points as well the average velocity map for the Wilcox Formation in the Glenn Pool survey. This map has a fairly strong lateral velocity gradient, i.e., the velocity changes from about 11,400 ft/s for velocity (NE) to 10,200 ft/s (SW) in the space of just over a mile. When this occurs, time structure and depth structure can be significantly different.

[[:file:interpreting-seismic-data_fig12-13.png|Figure 2]] shows a hypothetical well with important reference points as well the average velocity map for the Wilcox Formation in the Glenn Pool survey. This map has a fairly strong lateral velocity gradient, i.e., the velocity changes from about 11,400 ft/s for velocity (NE) to 10,200 ft/s (SW) in the space of just over a mile. When this occurs, time structure and depth structure can be significantly different.