Desurveying Data and Importing Drill Holes

Desurvey Drill Hole Data

The Desurvey Tool allows users to convert interval data from drill holes (in .CSV format) into data points represented as curve objects along a continuous drill hole trace. This tool interpolates the survey data (azimuth and dip) to create a 3D representation of the drill hole based on the collar, survey, and drill hole interval data. To use the Desurvey Tool, go to Drilling -> Desurvey Data

Input Data

• Downhole Data: Must contain intervals defined by from_depth and to_depthcolumns correlated to a unique hole ID... plus any numerical or categorical data columns. Remember, if your coordinate system is in meters, make sure the from_depth and to_depth columns use meters.
• Survey Data: Must contain the azimuth and dip measurements at specified depths for each hole ID. Ensure dip values are negative numbers. If coordinate system is in meters, ensure depth column is in meters.
• Collar Data: Must contain the easting (X), northing (Y), and elevation (Z) of the drill hole collars and final depth of each Hole ID. If coordinate system is in meters, ensure final depth and elevation use meters.
  • Start Depth is used for wedged drill holes, if all holes start from surface set Start Depth to None

NOTE: Ensure that each unique Hole ID has a matching Hole ID in the collars (and surveys) sheet. Most desurveying errors occur from missing or mismatched hole ids between the sheets, you will see IndexError: list index out of range

NOTE: collar data CSV can act as the survey data if you do not have survey data or do not wish to use the survey data. In this case, upload your collar sheet in place of the survey sheet and and include the azimuth and dip of each hole and use the final depth column as the survey_depth

How it Works

1. Initial Setup:

   • The tool first sorts the drill hole data by hole_id and to_depth, ensuring that the intervals are processed in sequence from shallowest to deepest.
   • Each drill hole is uniquely identified by its hole_id, and the collar data provides the initial starting coordinates (easting, northing, and elevation).

2. Interpolating Survey Data:

   • For each interval, the tool uses the survey data to interpolate the drill hole's trajectory. The azimuth and dip values are retrieved from the survey data by looking up the appropriate depth.
   • The tool approximates the x, y, and z coordinates for the next point using the depth difference between consecutive intervals and the survey data.
   • The calculation for each interval follows these steps:
     • Change in x (Δx): Calculated as the horizontal distance in the easting direction based on the azimuth and dip: $$Δx = (depth_{to} - depth_{from}) * sin(azimuth) * cos(dip)$$
     • Change in y (Δy): Calculated as the horizontal distance in the northing direction: $$Δy = (depth_{to} - depth_{from}) * cos(azimuth) * cos(dip)$$
     • Change in z (Δz): Calculated as the vertical distance based on the dip of the hole: $$Δz = (depth_{to} - depth_{from}) * sin(dip)$$
   • These calculations are performed iteratively, accumulating the coordinate changes as the tool progresses down the drill hole trace.

3. Handling Infill Rows:

   • If there are gaps between consecutive intervals, the tool automatically generates additional rows for missing intervals. These infill rows help to ensure that the drill hole trace remains continuous, especially in cases where no data is available for specific depths. (i.e. you want to desurvey assay data but only assayed a select part of the hole)

4. Error Handling:

   • The tool checks for missing data in the collar or survey files and ensures that all drill holes are represented correctly. It also warns users if a hole ID is missing from either the collar or survey data.

5. Output:

   • After completing the desurveying process, the tool offers users the option to export the desurveyed data as a CSV file which can then be used in the Import Drill Holes fucntion

Importing Drill Holes

1. Go to Drilling -> Import Drill Holes (.CSV)

2. Click Load CSV to bring up the file browser and navigate to the desurveyed data file.

3. Once the data file is selected, the drop downs will automatically populate; fill in the appropriate data columns for Hole_id, X (your desurveyed x coordinate), Y (your desurveyed y coordinate) and Z(your desurveyed elevation coordinate). Click Import Drill Holes

• The code converts the raw X and Y coordinate values to match the scene crs set up through blenderGIS when topography is added.

4. Three collections will populate into your scene and outline; Drill Hole Collection, Hole ID Collection and Drill Hole Traces

• Drill Hole Collection: This collection holds the all the interval data, i.e. each row in your CSV corresponds to a curve object along the drill trace.
• Hole ID Collection: This collection holds all the unique hole IDs. The Name is turned on so that labels are present.
• Drill Hole Traces: This collection holds the drill holes traces, this is a single curve object as line to represent the full extent of the drill hole. This is a nice light-whieght way to show the drill holes without having thousands of object visible in the scene. It also comes in handy when querying the data.

5. All your data is now brought in as custom properties under its respective interval object (the individual curve objects under Drill Hole Collection). You can access these properties by selecting the object and navigating to Object Properties and apply the drop down for Custom Properties. Scroll down to view all the custom properties.