Changes

==Step 3: Calculate depth conversion velocity==

==Step 3: Calculate depth conversion velocity==

[[file:interpreting-seismic-data_fig12-13.png|thumb|{{figure number|2}}Hypothetical well with important reference points; average velocity map for the Wilcox Formation in the Glenn Pool survey. From Liner.<ref name=Liner_1999 /> Courtesy PennWell.]]

[[file:interpreting-seismic-data_fig12-13.png|300px|thumb|{{figure number|2}}Hypothetical well with important reference points; average velocity map for the Wilcox Formation in the Glenn Pool survey. From Liner.<ref name=Liner_1999 /> Courtesy PennWell.]]

Calculate depth conversion velocity at locations where both well and seismic time picks exist. The wells used as control do not need velocity or density logs but must penetrate the event of interest. The event depth ''z'' (measured from seismic datum) is known from well control, and the vertical reflection time ''t'' is known from the previous item. The depth conversion velocity is given by

Calculate depth conversion velocity at locations where both well and seismic time picks exist. The wells used as control do not need velocity or density logs but must penetrate the event of interest. The event depth ''z'' (measured from seismic datum) is known from well control, and the vertical reflection time ''t'' is known from the previous item. The depth conversion velocity is given by