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JamesH

Rockworks 16 stratigraphy model problem

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Hello guys,

I am a geology student and I'm working on my bachelor thesis. I need to make few models and a map in rockworks but unfortunately I have a problems which I can not solve on my own and I can't find anybody capable of helping me.

The thing is I am modeling a part of a structure and it's subsoil in the Czech Republic. The main problem in the model is (you can see it on the picture bellow) stratigraphy. For some reason the proterozoic era goes through cretaceous and whole paleozoic is also messed up... The stratigraphy is in czech langue so I will translate for you:

kvartér = quaternary

křída    =  cretaceous

paleozoikum    = paleozoic

proterozoikum = proterozoic

 

 

2nd problem is with 2d map. I need to create a 2d map with topography and litology but I can't manage to create it. I don't know If I am doing it right, but there are no topography lines and only few litilogy. 3rd picture bellow. My guess is it only takes a certain level of topography.

 

I hope someone can help me here so I can peacefuly finish my thesis.

Thank you.^_^

 

3d_model_krida_podlozi_onlap_on.png

3d_model_krida_podlozi_onlap_off.png

litology 2d map.png

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Hi JamesH. I used RW16 in the past and use RW17 now. There is not much difference between versions so I think that maybe these suggestions could be useful. Regarding the Proterozoic cutting through the Paleozoic that could be related to the grid you are using for the Proterozoic so one option would be to make more control points to tweak your grid. Also check the number next to your units. RW interprets lower numbers as overlying units. However you may be OK there because your legend is OK. As for the map try making the maps that you need separately and then doing an append. Another suggestion is to try different gridding algorithms. I generally get satisfactory results using Inverse Distance (Kriging doesn’t work well for me in RW). Another neat trick that you can try is gridding the data in SURFER or ARCGIS if you have them and importing the data to RW using Utilities.
Best of luck to you!

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Hi, thanks for the answer. The numbers in the stratigraphy table should be good cretaceous is lowest, paleozoic is middle and proterozoic has the highest value. I don't fully understand the grid thing. What do you mean by control points?

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Control points are the known depths of the formation top and bottom. You get these from borehole data, ideally although you could create an imaginary well from a good cross section. With one or more imaginary wells well you can  “define” the depth  of the Proterozoic at different locations on your grid. Also it looks like there is a gap between the Cretaceous and the Proterozoic in your block model that you may need to look at.
Best Regards.

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Hi James,

 

RockWorks 16 and 17 both have the option to allow underlying units take precedence when grids intersect when creating a Stratigraphy model. In RockWorks 16, this option is called Onlap and is set from the Stratigraphy model menu under the Interpolate Surfaces item.

 

RockWorks 17 adds the ability to allow overlying units take precedence in the Modeling Sequence tab in the Interpolate Surfaces Options.

 

In either case, the automatic Stratigraphy modeling may not produce the model you wish, especially if control is sparse for the lower units. In that case, you can build your model manually using additional control points created from the thicknesses of each unit in the Utilities datasheet, and Utilities Grid | Math to subtract the thickness from the top unit to get the top of the underlying unit.

 

You are welcome to create a backup of the project with the Borehole Manager File | Backup Database menu command and send the ZIP file to [email protected]. Include your RwGrd files in the ZIP file. Larger files may be uploaded to rockware.com/upload or you may send a link to your DropBox, Google Drive, or other shared folder.

 

Regards,

Tom B

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14 hours ago, Edward Hakanson said:

Control points are the known depths of the formation top and bottom. You get these from borehole data, ideally although you could create an imaginary well from a good cross section. With one or more imaginary wells well you can  “define” the depth  of the Proterozoic at different locations on your grid. Also it looks like there is a gap between the Cretaceous and the Proterozoic in your block model that you may need to look at.
Best Regards.

 

Hey thanks for the tip. I've checked the litology datasheet in all boreholes and triple checked stratigraphy datasheet and it looks fine so my guess is problem is somewhere else. I've also checked again the values in datasheet and lowered the value of "unknown age" so proterozoic would be last but I don't use boreholes with these since they are not needed for the model.

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9 hours ago, TomB said:

Hi James,

 

RockWorks 16 and 17 both have the option to allow underlying units take precedence when grids intersect when creating a Stratigraphy model. In RockWorks 16, this option is called Onlap and is set from the Stratigraphy model menu under the Interpolate Surfaces item.

 

RockWorks 17 adds the ability to allow overlying units take precedence in the Modeling Sequence tab in the Interpolate Surfaces Options.

 

In either case, the automatic Stratigraphy modeling may not produce the model you wish, especially if control is sparse for the lower units. In that case, you can build your model manually using additional control points created from the thicknesses of each unit in the Utilities datasheet, and Utilities Grid | Math to subtract the thickness from the top unit to get the top of the underlying unit.

 

You are welcome to create a backup of the project with the Borehole Manager File | Backup Database menu command and send the ZIP file to [email protected]. Include your RwGrd files in the ZIP file. Larger files may be uploaded to rockware.com/upload or you may send a link to your DropBox, Google Drive, or other shared folder.

 

Regards,

Tom B

Hi TomB,

 

I tired the onlap function many times. On the 1st picture is onlap turned on and 2nd is onlap off. It only removes paleozoic under proterozoic but still leaves proterozoic in the middle of cretaceous.

 

I've tried to downloaad the trial version of Rockworks 17 but for some reason the converting from 16 to 17 maded errors and even after fixing it the files are not suitable I guess because when I want to create model or something else everything is so small and unreadable and the model is not even showing.

 

So I shloud try to create new unreal boreholes to fix it? I've also tried adding 0 thickness of proterozoic under paleozoic and 0 thickness to paleozoic where is proterozoic right under the cretaceous but it still did not help.

 

I guess I'll try share my project here since I am pretty new in rockworks and after few months of using it it's still pretty difficult for me. 

 

The backup file is pretty small so it should be no problem. Only the stratigraphy and litology datasheets are in czech language so I hope I won't be a big problem or you can use google translator If needed. Here are the most common rocks: cretaceous slínovec = marlstone; pískovec = sandstone, písek = sand; slepenec = conglomerate; jíl = clay, jílovec = claystone and some older proterozoic slates = břidlice. 

 

 

Rockworks stratigrafie001.zip

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JamesH,

 

I suggest using the Striplogs | 2D | Section and Striplogs | 3D | Multiple Logs to look at your Stratigraphy data.

 

  • Only a few of your boreholes have the Proterozoic unit, and they are at a higher elevation relative to the base Paleozoic in the boreholes on the east side of the project. If you make grids of this unit, RockWorks does not have the control points for this unit in the wells where it is missing, so it uses the existing data to project the unit at a high elevation. Add Proterozoic tops to boreholes to control the surface.

 

.XSect01-a.pngXSect01-b.png

 

  • Some boreholes have missing tops for the Paleozoic where it has been pinched out by the Proterozoic. Add zero-thickness tops for the Paleozoic in these boreholes to control the surfaces.
  • Use the Striplogs | Pick Stratigraphic Contacts menu to add tops on a cross-section and save them to the Borehole Manager Stratigraphy table.

 

  • Another option is to create a Stratigraphy model with the Triangulation gridding method, and choose the option for No Interpolation of Un-Triangulatable Nodes. This method will truncate the surface outside the area where there is data. There are boreholes that need additional tops to prevent the surfaces from crossing with this method, but it is not as bad as with the other interpolation methods that extend to the edge of the project limits.

.image.png

  • I will address your lithology question in a separate message.

 

Regards,

Tom B

RockWare Inc

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JamesH,

 

Regarding your lithology map question:

 

Create lithology map from a lithology model RwMod file and a gridded surface RwGrd file with the Borehole Manager Lithology | Surface Map menu. If you have truncated the Lithology model with the ground surface (superface filter), and you are using the same ground surface for the Lithology Surface Map, you may need to subtract the value of the model Z spacing. The ground surface and lithology model do not overlay exactly due to the size of the lithology model voxels. If you imagine placing a board on a flight of stairs, you will notice that the board only contacts the edge of the stair steps.

 

To subtract a value from the grid used for the Lithology surface, use the Utilities Grid | Math | Grid & Constant menu.

 

Topography contours are not created using this method. You can append topography contours created in another map such as the Borehole Manager Map | Borehole Locations map or the Utilities Map | Grid-Based Map.

 

Regards,

Tom B

RockWare Inc

 

LithologySurface.png

.

 

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Hello TomB,

 

Thank you so much for your help! You literally saved me. I'll try to do this just like you described.

 

Thanks again,

James.

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