The example given here is the interval between Upper Fayetteville SH and the Boone LS in the Desoto 3D seismic survey of NE Conway County, AR (data credit: SWN). Horizon tracking by Daniel Moser.
Definitions
Isochron map: Seismic two-way interval time between two horizons
Isopach map: Thickness interval between two geological or seismic horizons
- In the project tree add two horizons A and B, here A=U_Fay_Smooth (Fig 1) and B=Boone_Smooth (Fig 2). The A horizon is shallower than B.
- Right click on shallower horizon U_Fay_Smooth and select Workflows > Calculate Isochron ...
- In the isopach parameter window set Calculate to menu to Boone_Smooth use default attribute name I:Boone_Smooth, and output result in msec.
- You will see there is a new attribute I:Boone_Smooth in the U_Fay_Smooth tree list.
- Right click on the I:Boone_Smooth attribute and select Tools > Set Z Values ...
- In the parameter window select: Values are Relative (deltas), Units are msec, Save Horizon As new, output horizon name UFay_Boone_iso and check the Display after create box. This will generate a horizon representing the isochron between the horizons. Contours can be added to show the isochron between these two horizons (Fig 3).
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| U_Fay_smooth horizon time structure with 2 ms contours |
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| Boone_smooth horizon time structure with 2 ms contours |
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| Fay-Boone isochron with 2 ms contours |
Not yet... generate isopach from isochron (CL)
- Choose menu item Scene>New[Depth]. In the parameter box select Linear Velocity and set the Vint parameter to 12000 ft/s (from averaging of sonic velocity between U Fay and Boone) and set gradient to zero. This forces a constant velocity depth conversion. Select OK.
- A new project tree window appears below the previous project tree along with the new scene window. Minimize the original scene window and maximize the new one.
- In the depth scene add the UFay_Boone_iso horizon
