<p>Assuming the boreholes are all drilled at the same angle they effectively form an artificial surface that is 70° off horizontal with a 40° bearing. To rectify the data gained from them one rotates that surface to the horizontal, making the bores vertical, to get the correct relative depths of the data points. This also rotates the apparent dip and strike, you <em>could</em> use the <a href="https://www.geological-digressions.com/stereographic-projection-poles-to-planes/" rel="nofollow noreferrer">stereographic approach</a> plot the existing points and then move them through the appropriate angles, but honestly I'd find that not only, literally, a headache but the slow method. I'd spreadsheet the data, work out the transforms, and get the software to crunch it for me, numbers make more sense to me than visuals and stereonets in particular take way too much processing.</p>

CC BY-SA 4.0
2024-07-26T09:05:28.580Z
Thanks Ash, for this scenario what would be the appropriate angles and in what order would the rotations need to be done on the stereonet?
MJ_Wales
CC BY-SA 4.0
2024-07-26T09:50:37.610Z
@MJ_Wales Like I said this stuff hurts my brain but I'm pretty sure you only need one transform, a 20° tilt to bring the bores to the vertical, this will alter the observed dips by an equal amount in the same direction.
Ash
CC BY-SA 4.0
2024-07-26T00:55:28.700Z
2024-07-26T09:49:16.003Z
2024-07-26T09:49:16.003Z
Ash
<p>Scenario: I have dips (in the form dip and strike) which have been defined from borehole image data. The orientation of these dips (apparent orientation) is relative to the borehole axis, however, I am interested in their true orientation. For arguments sake, the borehole plunges at 70 degrees from horizontal with a plunge direction of 40 degrees.</p>
<p>I have read that it is possible to use a stereonet to rotate these apparent dips based on the borehole orientation to get their true orientation, can someone please tell me how that would be done?</p>

<structural-geology>
Using a stereonet to account for borehole orientation
MJ_Wales
# Using a stereonet to account for borehole orientation

(Asked by: username_0 on 2024-07-25)

Scenario: I have dips (in the form dip and strike) which have been defined from borehole image data. The orientation of these dips (apparent orientation) is relative to the borehole axis, however, I am interested in their true orientation. For arguments sake, the borehole plunges at 70 degrees from horizontal with a plunge direction of 40 degrees.

I have read that it is possible to use a stereonet to rotate these apparent dips based on the borehole orientation to get their true orientation, can someone please tell me how that would be done?

**Tags:** structural-geology


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## 1 answers

### Answer by username_1 on 2024-07-26. Score: 0

Assuming the boreholes are all drilled at the same angle they effectively form an artificial surface that is 70° off horizontal with a 40° bearing. To rectify the data gained from them one rotates that surface to the horizontal, making the bores vertical, to get the correct relative depths of the data points. This also rotates the apparent dip and strike, you *could* use the [stereographic approach](https://www.geological-digressions.com/stereographic-projection-poles-to-planes/) plot the existing points and then move them through the appropriate angles, but honestly I'd find that not only, literally, a headache but the slow method. I'd spreadsheet the data, work out the transforms, and get the software to crunch it for me, numbers make more sense to me than visuals and stereonets in particular take way too much processing.

> **Comments:**
> **username_0**: Thanks Ash, for this scenario what would be the appropriate angles and in what order would the rotations need to be done on the stereonet?  
> **username_1**: @username_0 Like I said this stuff hurts my brain but I'm pretty sure you only need one transform, a 20° tilt to bring the bores to the vertical, this will alter the observed dips by an equal amount in the same direction.  

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