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Move the cursor over the Cross-correlation track and a read out will appear just below the track/column header is a read out indicating the Current position and the Max correlation that can be achieved with the suggested bulk shift to be applied. Take note of these values. The phase shift can later also be included once the phase mistie is computed (see below).
Back in the Seismic well tie window, the remaining tabs for refining the synthetic seismogram are activated.
6. Time shift tab
From the suggested time shift to maximize correlation, enter the value for the bulk shift and check the align box to adjust the vertical position of the synthetic seismogram (Figure 5). Alternatively, this can also be implemented using a button in the Well tie editing toolbar.
Figure 5: Time shift tab
7. Correlation
The upper (and bottom) segments of a log and a synthetic seismogram are often problematic and should be excluded in the analysis. In calculating the correlation between the synthetic seismogram generated, with a trace or set of traces from the seismic profile, the user can define the start and end time window for the calculation (Figure 6. ).
In the Trace section, the default is to calculate the correlation to all the seismic traces displayed in the Well section window. Alternatively, the user can define only the trace or a few traces around the actual well/borehole. In a default setting of 10 traces around the well, set the start and end traces to 10 in order to correlate only with the trace corresponding to the well; 9 to 11 if the adjacent two traces should be included.
The Phase mistie section in the Correlation tab enables this parameter to be computed. If you hover over a trace in the Correlation track, the readout will show the suggested rotation angle for the wavelet used. To apply this, open the Wavelet toolbox > Phase manipulation tab (Figure 7).
Figure 6: Correlation tab
8. Alignment points
Credits
This guide is largely derived from the Petrel 2017 Geophysics training manual:
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