Constructing 1D Cartesian Grid Equivalent to Radial System

[ahmadreza shojaee]

Dear all,

I’m currently working on representing a radial system using a 1D Cartesian grid in MRST. I understand that in radial systems, both the cell volume and face area increase with distance from the well.

In this case, I’ve generated a model in Eclipse with dimensions Nx = 50, Ny = 1, Nz = 1, where dy and dz are constant (constant perm and porosity), and dx increases by a factor of 2 for each successive cell. I then imported this model into MRST using the deck format. Since the Eclipse input already accounts for variable cell sizes, I assume MRST computes the correct cell volumes automatically, so there’s no need to manually modify model.operators.pv.

However, I have some questions regarding transmissibility. It appears that:

1. T is defined per cell
2. T_all is defined per face

In a 1D grid along the x-direction, how should I go about modifying the transmissibility vector (if needed) to reflect the increasing face area or radial scaling? Does MRST handle this automatically based on the imported geometry, or is manual adjustment of T_all (or T) required in this case?

Any clarification would be greatly appreciated.

Kind regards,
Ahmad

[Knut-Andreas Lie]

Hi Ahmad,

MRST does not have direct support for cylinder coordinates, and to set up a 1D mesh, like you describe, you would have to compute the cell volumes and the transmissibilities yourself. However, I think most parts of the solution can be found inside the near-well module (nwm), which uses cylinder symmetry near the well.

Best regards,

Knut-Andreas

PS. If you decide to make a general solution to creating operators for cylinder coordinates, I think this would be a valuable contribution that can be included in a future release.

--

Knut-Andreas Lie, Professor, PhD
Chief Scientist, SINTEF Digital, Mathematics & Cybernetics, Oslo
Phone: +47 930 58 721 (mobile)
http://folk.ntnu.no/andreas

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Subject: [MRST Users] Constructing 1D Cartesian Grid Equivalent to Radial System

 

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[ahmadreza shojaee]

Dear Knut-Andreas,

Thank you very much for your response and for pointing me toward the near-well module — I’ll definitely explore that further.

As a follow-up, could you please clarify how face numbering works in MRST? Specifically, for a 1D grid along the x-direction, how are the faces ordered and indexed?

I appreciate your guidance.

Kind regards,
Ahmad

[Knut-Andreas Lie]

Hi Ahmad,

MRST can construct 1D grid, but my advice is instead to use a row of 2D or 3D cells, which will ensure that your grid works well with most routines in the software. To understand the numbering and ordering of faces, you can look at one of the elementary grid tutorials, e.g., as shown online: https://www.sintef.no/projectweb/mrst/documentation/tutorials/grid-factory-tutorial/

I hope that this helps.

Knut-Andreas

--

Knut-Andreas Lie, Professor, PhD
Chief Scientist, SINTEF Digital, Mathematics & Cybernetics, Oslo
Phone: +47 930 58 721 (mobile)
http://folk.ntnu.no/andreas

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From: sinte...@googlegroups.com <sinte...@googlegroups.com> on behalf of ahmadreza shojaee <ashoj...@gmail.com>

Sent: Tuesday, May 13, 2025 3:34 PM

To: MRST-users: The Matlab Reservoir Simulation Toolbox User Group <sinte...@googlegroups.com>

Subject: Re: [MRST Users] Constructing 1D Cartesian Grid Equivalent to Radial System

 

To view this discussion visit https://groups.google.com/d/msgid/sintef-mrst/cac2c29e-59a4-4f06-8595-50768b11a1f9n%40googlegroups.com.