Lithologies Outside the Model
Good morning,
When I look at the statistics in the evaluation of the drillholes against the geological model, I see that some lithologies appear “outside the model”.
I tried removing the topography from the model, and it seems that some drillholes may be above the topography, which could be why those lithologies appear outside.
I am trying to detect them, but I can’t find where the issue is.
I make cross-sections to see which drillhole might be responsible, but I can’t locate it.
I don’t want to adjust all the drillholes to fit the topography to fix this, because I have an old topography and some drillholes are in mined areas, and I don’t want to modify their Z values.
Any suggestions on how I could detect the area where the lithology that falls outside the model is located?
When the lithology is labeled as “unknown,” I can apply a filter and detect where it is, but in the case of “outside the model,” it doesn’t allow filtering.
I was thinking that maybe in the calculation area it might be possible to generate some kind of script, but I don’t know how to do it.
Thank you very much in advance.Best regards.
Best Answer
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Hi Alejandro,
Actually, you don't need to make a copy of your project, just your GM. I made a copy of my project because I wanted to manipulate\raise the drillhole collar elevations.
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Answers
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Maybe you could hide all of the lithologies except for the most recent ones. Another idea may be to create a topography from the wellbore locations and combine it with the topographic surfacet that you already have.
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You could always check your clipping boundaries to see if topography is used as a clipping surface to the model and adjust accordingly. So I'd try to play around with the model boundaries and see where the topography sits in relation to the collars.
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thank you so much .
I will try the second one .
I have already tried the first one without solving the problem
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Hi Alejandro,
I have another suggestion. Make a copy of your Leapfrog project. In the copied project, untick 'Use Topography' for the Boundary in your GM. Add a new Lithology and call it 'Air'. Add topography as an Erosion surface with Air as the younger lithology and Unknown as the older lithology. Activate the GM with Air as the most recent surface. Evaluate the new GM onto your drillholes as a New Evaluation Table.
The Air intervals in the drillhole evaluation table should be similar to the drillhole intervals flagged as 'outside the model' from your original GM.
Good luck!
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wow! This sounds very solid!
I’ll try this for sure ! Thank you so much1 -
Hey Alejandro, a couple of ideas:
- Create a model with the same extents as your existing one, and use the topography as an erosional surface defining two lithologies 'AboveTopo' and 'BelowTopo'. Evaluate this onto your drilling database, create a merged table with these results and your lith table, and then you can easily filter for intervals which are above your topo.
- I rarely use the topo as a project boundary, because, as you have learned, it can generate all sorts of odd problems in how it interacts with the collars. What I do is remove it as a lateral extent, add a lithology of 'Air' to my model, and add the topo as an erosional surface>from mesh, with the younger side specified as air to the model. This sidesteps many common issues. I wrote a short article discussing it here: https://www.linkedin.com/pulse/topography-data-interactions-3d-geological-modelling-comments-fraser-lgpge/?trackingId=xbI8A7sUQUmh3uSmxZm0Gg%3D%3D
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thank you so much
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