Hello,
I am working on stratigraphy and lithogeochemistry of a VMS-hosting sequence of Paleoproterozoic volcanic rocks and would like to plot drillcore samples that I collected into IoGas and Geoscience Analyst. I only have the collar location, drillhole orientation and sample depth, however both softwares require the ZYX coordinates to display the sample accurately. I know these calculation can easily be done with Gocad, Target or other 3D mining softwares, but I am wondering if there is another (cheaper) option where I could process small batch of data on a need basis. It does not have to be something that takes into account all the drillhole deviation, I am not looking for that kind of precision. Thank you.
Simon
Simple trigonometry and direction cosines.
The z-coordinate of your sample = z(collar) - depth(sample)*sin(DHdip), where
depth(sample) = halfway point between top and bottom of sampling interval and
DHdip = drillhole inclination angle from horizontal.
Sample x (Easting) and y (Northing) are given by:
x = x(collar) + depth(sample)*cos(DHdip)*sin(DHazi)
y = y(collar) + depth(sample)*cos(DHdip)*cos(DHazi)
As you know, I guess, you have to express the angles in radians for the trigonometric functions in Excel, so divide angles in degrees by 180 and multiply by pi.
You can correct for DH deviation using one of the common correction formulas. I have made an Excel spreadsheet that does that using the minimum curvature algorithm. I can send you a copy when I get back to my office computer on Monday. Haven’t checked the link William sent you above, but I guess you should find your answer there too.
Dear Mr. Simon Gagne : I attached for you a spreed sheet that you ask.
best regards
sincerely
Haithem A. Minas
Thank you Prof. Minas and Mr. Dickie for the spreadsheet and website suggestion. Both contains a lot of useful information.
Thank you Andre. Your explanation helped me a lot. I also got a suggestion to use nested conditional formulas in Excel which together with your comments allowed me to create a speadsheet that works to calculate the xyz coordinates of samples from non-deviated holes (straigth holes) in the UTM system. For most of my samples deviation is not an issue, however I would like to find an effective way to include deviation is in my spreadsheet. If you have any suggestion, I would appreciate. Thank you.
If anyone would like a copy of the spreadsheet, just message me.
Regards,
Simon
Hello Simon,
See attached a spreadsheet that contains the formulas for calculating the vertical, east and north displacements of the drillhole survey points. Online research for ‘minimum curvature borehole desurveying’ will give you a number of pages where the formulas and terms, used in the spreadsheet, are explained. Essentially, it turns around computing the intercept angle between the two survey directions (the dog’s leg angle DL) and the ratio factor RF, which is the ratio between the subscribed chord of the best-fit great circle between the two survey points and the length, subtended by the extended survey lines between the survey points. Note that the ‘Inclination’ in the formulas is the angle between the vertical and the drillhole / survey line, equal to the complement of the measured drillhole / survey dip.
plz have a look on this:
https://exceltable.com/en/analyses-reports/abc-xyz-analysis-in-excel
https://www.maclab.sk/clanky/en-3d-graph-excel.php
https://faculty.fuqua.duke.edu/~pecklund/ExcelReview/2001_Documents/2001XLScatterPlotMono.pdf
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