Changes

==Step 2: Pick seismic horizons==

==Step 2: Pick seismic horizons==

 

[[file:interpreting-seismic-data_fig12-12.png|300px|thumb|{{figure number|1}}(a) Representative line from the Glenn Pool data volume with sonic overlay and tracked events; (b) Horizon amplitude and time structure maps for the Wilcox. From Liner.<ref name=Liner_1999>Liner, Chris, Elements of 3-D Seismology: Tulsa, PennWell.</ref> Courtesy PennWell.]]

interpreting-seismic-data_fig12-12.png|{{figure number|1}}(a) Representative line from the Glenn Pool data volume with sonic overlay and tracked events; (b) Horizon amplitude and time structure maps for the Wilcox. From Liner.<ref name=Liner_1999>Liner, Chris, Elements of 3-D Seismology: Tulsa, PennWell.</ref> Courtesy PennWell.

For 2-D data, only the traveltime to each event of interest is recorded with its coordinate along the line ''t''(''x''). For 3-D data, both traveltime and amplitude at each (''x, y'') are available from the seismic data cube, ''t''(''x, y'') and ''a''(''x, y''). The traveltimes form a time structure map, and the amplitudes are a horizon slice. [[:file:interpreting-seismic-data_fig12-12.png|Figure 1A]] shows a representative line from the Glenn Pool data volume with sonic overlay and tracked events. Horizon amplitude and time structure maps for the Wilcox are shown in [[:file:interpreting-seismic-data_fig12-12.png|Figures 1B, C]].

For 2-D data, only the traveltime to each event of interest is recorded with its coordinate along the line ''t''(''x''). For 3-D data, both traveltime and amplitude at each (''x, y'') are available from the seismic data cube, ''t''(''x, y'') and ''a''(''x, y''). The traveltimes form a time structure map, and the amplitudes are a horizon slice. [[:file:interpreting-seismic-data_fig12-12.png|Figure 1A]] shows a representative line from the Glenn Pool data volume with sonic overlay and tracked events. Horizon amplitude and time structure maps for the Wilcox are shown in [[:file:interpreting-seismic-data_fig12-12.png|Figures 1B, C]].

==Step 3: Calculate depth conversion velocity==

==Step 3: Calculate depth conversion velocity==

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

==Step 4: Convert time to depth==

==Step 4: Convert time to depth==

Convert time to depth by multiplying the time structure map and the depth conversion velocity map, i.e.,

Convert time to depth by multiplying the time structure map and the depth conversion velocity map, i.e.,