Converting Gamma Counts to Uranium Equivalent Grade

RockWorks | Borehole Manager | P-Data | Analyze | Gamma to Grade

Use this program to read a P-Data column containing Gamma counts per second (or milli- or micro-second) and translate them to Uranium Grade values, which will be recorded in the I-Data or P-Data table.  The translation can be for a single well or all enabled wells.

Feature Level: RockWorks Standard and higher

Menu Options
Step-by-Step Summary
 

Menu Options

• Gamma (P-Data) Track: Click here to select the existing P-Data column that contains the Gamma measurements, in counts per second, millisecond, or microsecond.
• Output:
  • I-Data: Click in this radio button if the output data is to be recorded in the I-Data table.  
    • Equivalent Grade (I-Data) Track: Click to the right to select the I-Data track where the output measurements are to be recorded. 
      ! Note that this is an I-Data column that must already exist.
  • P-Data: Click in this radio button if the output data is to be recorded in the P-Data table. 
    • Equivalent Grade (P-Data) Track: Click to the right to select the P-Data track where the output measurements are to be recorded. 
      ! Note that this is a P-Data column that must already exist.
• Sample Interval:  Click here to type in the depth interval at which to perform resampling.  For example, if you enter "1", the Gamma measurements will be translated to Uranium Grade values at 1-foot or meter depth increments.
  ! Note:  Saving eGrade data to a new P-Data column assumes that the Sample Interval is the same as the spacing between the original gamma values.
• Apply to: All Enabled Boreholes vs. Currently Highlighted Borehole:  Choose whether the program is to perform the conversion for a single borehole (the currently-selected well) or for all of the enabled boreholes, by clicking in the appropriate radio button.
• Constants: The constants (Dead-Time, K-Factor, Water-Factor, or Casing-Factor) may be either specified within the menu (in which case the same constants will be used for all boreholes), or defined within the Location tab.
  The K-Factor can be defined with an unlimited number of decimal places.
  ! Note: If you're using the Location tab, the fields must already exist, and they must be named DeadTime, KFactor, WaterFactor, CasingFactor.  The Display label for the fields can contain spaces, but the field name itself must not.

• Dead Time Units: Choose whether they are recorded as seconds, milliseconds, or microseconds by clicking in the appropriate radio button.  This will apply to constants defined either in the Location tabs or in the menu, above.

Step-by-Step Summary

1. Access the RockWorks Borehole Manager program tab.
2. Verify that you have your Gamma data entered for one or more wells, in a P-Data track.
3. Create, if necessary, a column in the I-Data table or P-Data table where the Uranium Grade computations will be stored.  If there is any existing data in this column, it will be overwritten. See Defining the I-Data Columns or Defining the P-Data Columns for more information.
4. Select the P-Data | Analyze | Gamma to Grade menu option.
5. Enter the requested menu settings, described above.
6. Click the Process button to continue.

The program will read the contents of the input Gamma (P-Data) Track and perform the following computations, recording the output in the indicated I-Data or P-Data column.

For each depth increment (as defined by the original sampling interval):

If the dead-time input units are set to micro or milli-seconds the dead-time is converted to seconds.

The "deadtime_adjusted_counts" are computed by the following equation:

deadtime_adjusted_counts = raw_counts / abs ( 1 - ( raw_counts * deadtime ) )

Finally, the uranium grade is computed by the next equation (a variation of the 2KN equation):

uranium_grade = deadtime_adjusted_counts * k_factor * water_factor * casing_factor * ( 1 / interval_thickness )

Next, the data is resampled (via a spline algorithm) at intervals equal to the specified "Sample Interval". If not for this resampling procedure, the interval_thickness value within the preceding equation would be invalid (i.e. the interval thickness would be greater than the distance between the original points).

This approach assumes that the original raw-count data was sampled at regular intervals (i.e. via a wireline tool that sampled at a constant rate).

You can now display the Uranium grade as an I-Data bargraph or a P-Data curve on striplogs, and use the I-Data or P-Data tools to interpolate solid models of the grade data.

 Back to P-Data Menu Summary 

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