Survey File

The Survey File tab of the Import Drillholes form is used to configure the Survey file for the import where added to the form.

Information in the Survey file selected on the Input Files tab (such as the Hole ID and Depth fields) will be autofilled to the fields on the Survey File tab where available.

You can use the Clear button to clear the contents of the fields on the tab. The Calculate button will attempt to autofill the fields based on the information in the corresponding file.

Hole ID field

Where required, double-click to select the name of the field that contains an identifier for each hole. Only one Hole ID field is available for Survey files.

Depth field

Double-click to select the name of the field that contains the total depth of each drillhole in the survey.

Azimuth and Inclination

Azimuth and Inclination values are stored in the Survey file. Double click to select the fields that contain the Azimuth and Inclination information in the Survey.

Desurvey Options

The Desurvey options are used to configure the desurvey process by specifying any required Azimuth correction, selecting a desurvey method and configuring curve and inclination options.

Azimuth Correction

Optionally apply an Azimuth Correction.

Apply to 1st azimuth

Select this option to apply the azimuth correction to the first and all subsequent azimuths.

Do not apply the azimuth correction to the first azimuth when collar surveys have an azimuth taken in terms of grid North and subsequent downhole azimuths are taken in terms of magnetic bearings.

Desurvey method

Use the drop down list to select the required desurvey method for the database.

  • Spherical Arc (Standard Accuracy) - Standard method with an accuracy of 0.05m.

  • Spherical Arc (High Accuracy) - Default method with extended accuracy of 0.001m.

    Note: Drillhole Databases created prior to Micromine Origin & Beyond v26.5 will default to Standard Accuracy.

  • Spherical Arc (Very High Accuracy) - Advanced accuracy of (0.0005m)

  • Balanced Tangent - Uses a calculation method which treats half of a measured distance as tangent to the first survey point Inclination and Azimuth and the remainder of a second measured distance as being tangent to the next survey point Inclination and Azimuth. This is the least accurate method, but is best for backward compatibility with legacy applications.

For more information on the calculation of curves, see Trace Calculation and How is the trajectory of a hole calculated?.

Continue curve past last survey

Select this option to extend the trace by the trend of the calculated curve to the full depth of the survey.

Straight holes are always depicted with two points – one at the collar, and another at the end of hole. Curved holes are given a trace interval that varies according to the curvature of the hole; the more curved the hole, the shorter the trace interval and the more points required to draw it.

If the deepest survey point is not at the end of the hole, a new inclination and azimuth is calculated, consistent with the way those angles have been changing down the drillhole and the curve is continued on the calculated trajectory to the end.

If this option is OFF, the last inclination and azimuth survey in the Survey file is used from the point of the last survey to the end of the hole and the trace will extend straight to the full depth. No curve will be calculated.

Negative inclinations point down

The Negative inclinations point down option is selected by default. This is because Micromine Origin & Beyond considers negative inclinations in a drillhole survey file to mean that the hole points downward.

Files from other sources can in some instances can be the opposite - i.e when drillholes are first imported, they can come in upside down. Deselect the option to treat positive inclinations as downward.

Use the Interval Files tab of the form to configure the details of any Interval file for the import.

Interval Files

Run

To begin the import process, click the Run button. If the specified output file already exists, you will be given the option of overwriting the file, or appending data to the file.