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| * Discriminate against invalid data. Using this technique, the user specifies minimum and/or maximum value limits for a primary trace. Then, instead of modifying actual trace values, the trace is scanned, and at depths where data occur outside the limits, flags are set in a separate discriminator trace. When applying the discriminator trace during data displays or calculations, any depths containing flags will either be eliminated from the display or be assigned default calculation values. | | * Discriminate against invalid data. Using this technique, the user specifies minimum and/or maximum value limits for a primary trace. Then, instead of modifying actual trace values, the trace is scanned, and at depths where data occur outside the limits, flags are set in a separate discriminator trace. When applying the discriminator trace during data displays or calculations, any depths containing flags will either be eliminated from the display or be assigned default calculation values. |
| * Apply depth corrections. These fall into two categories: | | * Apply depth corrections. These fall into two categories: |
− | | + | *#Depth shifting traces against each other. To do this, the user visually compares base and unshifted traces, marks corresponding data points (Figure 1), and then shifts the off-depth data to the base trace depths. |
− | <list-item>Depth shifting traces against each other. To do this, the user visually compares base and unshifted traces, marks corresponding data points (Figure 1), and then shifts the off-depth data to the base trace depths.</list-item><list-item>Correct for true vertical depth (TVD), true vertical thickness (TVT), and/or true stratigraphic thickness (see “Preprocessing of Logging Data”).</list-item>
| + | *#Correct for true vertical depth (TVD), true vertical thickness (TVT), and/or true stratigraphic thickness (see “Preprocessing of Logging Data”). |
| * Baseline the spontaneous potential (SP). Interactively flattening the SP to a shale baseline at a single value (Figure 2) allows the user to look at SP values quantitatively in order to calculate water resistivity (''R''<sub>w</sub>) and estimate shale content. | | * Baseline the spontaneous potential (SP). Interactively flattening the SP to a shale baseline at a single value (Figure 2) allows the user to look at SP values quantitatively in order to calculate water resistivity (''R''<sub>w</sub>) and estimate shale content. |
| * Convert data scales (both ways): conductivity to resistivity, raw data to porosities, neutron porosities to a different matrix, metric to English depth units, percent to decimal, and so on. | | * Convert data scales (both ways): conductivity to resistivity, raw data to porosities, neutron porosities to a different matrix, metric to English depth units, percent to decimal, and so on. |
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| | | |
| where | | where |
| + | ** ''y'' = corrected trace |
| + | ** ''a'' = constant (distribution) multiplier value |
| + | **''x'' = trace to be normalized |
| + | **''b'' = constant (range) value (Figure 3) |
| | | |
− | <list-item>''y'' = corrected trace</list-item><list-item>''a'' = constant (distribution) multiplier value</list-item><list-item>''x'' = trace to be normalized</list-item><list-item>''b'' = constant (range) value (Figure 3)</list-item>
| |
| * Rename, copy, and delete curves. | | * Rename, copy, and delete curves. |
| * Test and set curve values. If a trace value satisfies a criterion (such as ), then modify the value as specified. | | * Test and set curve values. If a trace value satisfies a criterion (such as ), then modify the value as specified. |