Import complex geological geometry

Alexandros Daniilidis

Hi all, I am trying to import geological layers from Petrel software to COMSOL. Importing the grid directly is not possible as the formats of Petrel (*.egrid, *fgrid, *gsg, ASCII) are not recognized from COMSOL and vice-versa. So my approach is to do this only with the defining surfaces and the mesh the whole domain again, this time in COMSOL. I am able to export contact surfaces in the form of points (X,Y,Z txt file) and import this into COMSOL. These are large areas of about 13km x 5km and the original mesh is 50m x 50m. However, I am not sure how to proceed. How can I convert these imported points to a "solid" surface and assign the domain between them as geological space to be populated with properties such as porosity, permeability etc? Any tips or guidance would be greatly appreciated


7 Replies Last Post 2017年10月24日 GMT-0400上午11:39
Jeff Hiller COMSOL Employee
Posted: 2 months ago 2017年9月13日 GMT-0400下午2:00
Updated: 2 months ago 2017年9月13日 GMT-0400下午2:00

Hi Alexandros, After creating an interpolation function "z=myfunction(x,y)", you'll need to use that interpolation function in a parametric surface, and then use that parametric surface to partition a solid domain, say, a cube.

See this blog post, which gives more details and uses an elevation function instead of an interpolation function but otherwise follows the approach I just mentioned: https://www.comsol.com/support/knowledgebase/838/ Best, Jeff

Hi Alexandros, After creating an interpolation function "z=myfunction(x,y)", you'll need to use that interpolation function in a parametric surface, and then use that parametric surface to partition a solid domain, say, a cube. See this blog post, which gives more details and uses an elevation function instead of an interpolation function but otherwise follows the approach I just mentioned: https://www.comsol.com/support/knowledgebase/838/ Best, Jeff

Alexandros Daniilidis
Posted: 2 months ago 2017年9月14日 GMT-0400上午4:52
Updated: 2 months ago 2017年9月14日 GMT-0400上午5:10

Hi Jeff, thanks for the reply. I had already found the knowledgebase post on this, but it wasn't very helpful. The link to the DEM file is dead, but i did manage to find it and now I am trying to reproduce the whole geometry definition of the model.

Also, it would appear that any format other than DEM is not handled as easily for this purpose. Given that points with coordinates are the easiest format to exchange between various programs, why can't I make a a surface out directly out of the point cloud data? I tried converting the polygon to a surface but I keep failing. I would expect this to be pretty straightforward. Am I missing something?

I have been able to create the parametric surface with an interpolation function for my data. However since the geological domain boundaries are not aligned to N-S and E-W axis i get a surface that is larger than it needs to be. How can I trim this to the boundaries of my geo-data?

Hi Jeff, thanks for the reply. I had already found the knowledgebase post on this, but it wasn't very helpful. The link to the DEM file is dead, but i did manage to find it and now I am trying to reproduce the whole geometry definition of the model. Also, it would appear that any format other than DEM is not handled as easily for this purpose. Given that points with coordinates are the easiest format to exchange between various programs, why can't I make a a surface out directly out of the point cloud data? I tried converting the polygon to a surface but I keep failing. I would expect this to be pretty straightforward. Am I missing something? I have been able to create the parametric surface with an interpolation function for my data. However since the geological domain boundaries are not aligned to N-S and E-W axis i get a surface that is larger than it needs to be. How can I trim this to the boundaries of my geo-data?

Jeff Hiller COMSOL Employee
Posted: 2 months ago 2017年9月14日 GMT-0400上午8:19
Updated: 2 months ago 2017年9月15日 GMT-0400上午9:20

Hello Alexandros, I am glad to hear you were able to turn your point cloud data into a parametric surface. You can trim it by using the usual geometry operations such as intersecting it with solids, etc. Before you do that, you may want to consider extending your data out a bit with fictitious values to avoid oscillations at the edges of your data. See this link for a more in depth discussion: https://www.comsol.com/forum/thread/143132/importing-odd-shape-dem-and-xyz-available?last=2017-05-03%2016:33:44 . If you need further assistance, please contact COMSOL support at support@comsol.com . Best regards, Jeff

Hello Alexandros, I am glad to hear you were able to turn your point cloud data into a parametric surface. You can trim it by using the usual geometry operations such as intersecting it with solids, etc. Before you do that, you may want to consider extending your data out a bit with fictitious values to avoid oscillations at the edges of your data. See this link for a more in depth discussion: https://www.comsol.com/forum/thread/143132/importing-odd-shape-dem-and-xyz-available?last=2017-05-03%2016:33:44 . If you need further assistance, please contact COMSOL support at support@comsol.com . Best regards, Jeff

Alexandros Daniilidis
Posted: 2 months ago 2017年9月15日 GMT-0400上午8:56

Hi Jeff, what i don't understand is why is it so difficult to create a surface from XYZ points. I don't understand this. When I try to convert the XYZ file to a surface i get an empty object. Surely there must be a way to do this. Can you please clarify? thanks Alex

Hi Jeff, what i don't understand is why is it so difficult to create a surface from XYZ points. I don't understand this. When I try to convert the XYZ file to a surface i get an empty object. Surely there must be a way to do this. Can you please clarify? thanks Alex

Jeff Hiller COMSOL Employee
Posted: 2 months ago 2017年9月15日 GMT-0400上午9:17
Updated: 2 months ago 2017年9月15日 GMT-0400上午9:41

I must have misunderstood your earlier post. I had read the first sentence of your last paragraph to mean that you had been successful.

It is a fairly straightforward approach, and it sounds like you are trying to follow it: 1/ create an interpolation function based on your data file, 2/ use that function to define a parametric surface. Since you are reporting that you are getting an empty object, my guess would be that there is something going on with your data or with the way you're calling it. Figuring things out more precisely will require a look into your data and how you're using it in the mph file. If you need further assistance, please contact COMSOL support at support@comsol.com . Best, Jeff

I must have misunderstood your earlier post. I had read the first sentence of your last paragraph to mean that you had been successful. It is a fairly straightforward approach, and it sounds like you are trying to follow it: 1/ create an interpolation function based on your data file, 2/ use that function to define a parametric surface. Since you are reporting that you are getting an empty object, my guess would be that there is something going on with your data or with the way you're calling it. Figuring things out more precisely will require a look into your data and how you're using it in the mph file. If you need further assistance, please contact COMSOL support at support@comsol.com . Best, Jeff

Alexandros Daniilidis
Posted: 4 weeks ago 2017年10月24日 GMT-0400上午11:25

Hi Jeff,

I have been able import the surfaces this time as polygons. The problem now is getting from the polygon to a surface. Converting the polygons to a surface results in an empty object. Why is that and what could be the solution? Or is there another way to do this? Greetings Alex

Hi Jeff, I have been able import the surfaces this time as polygons. The problem now is getting from the polygon to a surface. Converting the polygons to a surface results in an empty object. Why is that and what could be the solution? Or is there another way to do this? Greetings Alex

Jeff Hiller COMSOL Employee
Posted: 4 weeks ago 2017年10月24日 GMT-0400上午11:39

Hello Alexandros,

Please contact COMSOL support at support@comsol.com for further assistance.

Best,

Jeff

Hello Alexandros, Please contact COMSOL support at support@comsol.com for further assistance. Best, Jeff

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