Exporting faults issue

[s-pearsongrant]

I have a 3D geological model and I am exporting faults for use in a reservoir model. If I only have faults offsetting formations it works fine, but if I have faults offsetting everything the fault surfaces become really random! I am using

rocktypes = [
geo_data.input_transform.apply_inverse(meshes.vertices)
for meshes in geo_data.solutions.dc_meshes
].

Am I doing something wrong, or is there more going on when the faults offset each other (hence why they have a double line in the attached cross-section)?
geological_model.html
geological_model_old.html

Many thanks,
Sophie

[NilsChudalla]

Hi @s-pearsongrant ,
that looks like a cool model! Would you mind sharing the structural frame with the fault matrix?

[s-pearsongrant]

@NilsChudalla
Thank you, I'm excited to get to grips with GemPy! Here is the structural frame - ohaaki and fault_h should truncate against other faults.
StructuralFrame(.txt

[NilsChudalla]

Have you tried only setting those faults to "True" in the fault relations matrix, if they actually are in proximity to each other and have an effect on each other within the model extent? I have the feeling that the scalarfield of the faults is off because it tries to consider all layers. Maybe could you also share a screen shot of the scalarfields of the faults in X direction, if the problem still persists?

[s-pearsongrant]

I tried to just set those faults to True, but the ones below in the matrix set to all False including the formation. One of the faults should be truncated against 2 faults, the other should be truncated against one fault (which also truncates the other one). They don't intersect each other. I don't know if I am setting it wrong?

These figures show the fault surfaces and I've mapped onto a grid for my modelling software.
Only offset formation

Offset all

The geological model with faults colour-coded

[NilsChudalla]

That second screenshot looks a lot different than the surfaces though... Interesting. Would you mind sharing the python script of the geomodel (only the Gempy part) including in the input? I would like to try a few different settings.

[s-pearsongrant]

I plotted the data points as well as the surfaces, and realised the surface reconstructions are so crazy because the faults don't actually truncate against other faults, they bend to follow the whole length of the other fault as well. Is there a way to make them truncate, or do I manually need to delete any that run alongside the fault they truncate against? This is causing issues when I try to map the faults onto my grid and make them continuous as well.

Many thanks,
Sophie

[NilsChudalla]

I think the refinement, which is setup in the model initialisation or before computation, is the required screw to turn. I might be able to give it a try, if you share the gempy Modeling steps with me. You can either upload a zip file here or invite me to a private repo if you are not comfortable putting it out in the open.

[s-pearsongrant]

Thank you very much! I have shared a private repo with you. This is my first time making a GemPy model so any help gratefully received.

[NilsChudalla]

I am having a go at it and I am experiencing some odd behaviour, trying to control the faults. I am trying to understand it, but I doubt that this on you, rather than Gempy :D

The doubling however is simply an artefact of the mesh extraction and Gempy being an implicit modeling software (example). Finite faults are tricky in many modeling approaches. However, this behaviour is consistent, so I do not understand, how behaviour from your screen shot "Offset all" could be explained.

Since your workflow seems to work as intendet for the "non-finite" faults (not affecting each other) and I do not see any urgency for the addition of this behaviour I would propose a intermediate solution: you could utilize the voxels from fault masking to clean up the cells in your final output. You can retrieve them in the order of the structural frame here:

fault_mask = geo_model.solutions.raw_arrays.mask_matrix[i]
# if you have to you can reshape it according to the models resolution
fault_mask_reshaped = fault_mask.reshape((geo_model.grid.regular_grid.resolution))

If possible in your simulation software, I would try adding the faults iteratively, starting with the minor ones, merging into the bigger ones (e.g. fault 4 and 5 before fault 1). Then, I would apply the mask of fault 1 to remove the values overlapping.

Let me know, if this workflow works for you.

Furthermore, I am really intrigued by your usecase. I would like to encourage you to contribute it to our examples. Especially, if the other software you are using is open source as well. Many other geoscientists may highly appreciate this!