Calculating flow rate in a well on deliverability model

Hello everyone,

I am trying to figure out the best way to calculate gas flow rate in a well. my approach is to first print out a COFT file and then sum up the values of flow rate between cells. I am attaching a schematic of what I am trying to do so please take a look and let me know if I am on the right path.


Thanks and best regards,


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  • Dear Alborz,

    looking at your grid and at the "wellbore" P and porous medium P, it seems you are actually modeling a trench to be used for soil gas extraction. 

    One possible way to simulate your problem with a constant trench P of 92 kPa could be to:

    - assign very large permeability to the trench elements, so that P gradients between trench elements are negligible;

    - include a single wellbore on deliverability in one of the trench elements, let say one  in the middle of the trench;

    - assign a wellbore pressure of 0.92 kPa to the well on deliverability and a very large productivity index (PI), so that the pressure gradient between the trench and the "wellbore" is negligible.

    - use GOFT to have the total mass extraction for the well on deliverability at each time step, which gives the total mass extracted by the trench. It should also give you the composition of extracted fluid (air + ?, may be VOCs?)

    - use COFT if you want the details of gas flows entering from the different  faces of the trench.



  • Dear Alfredo Battistelli ,


    Thank you for  your guidance.

    To be more specific, yes I am modeling soil gas extraction but, not trying to simulate a trench.

    The gas extraction system that I am trying to simulate is basically a piping with a diameter of ~ 10 inches and extraction rate of 10 ft^3/min. The slot length of the piping (aka, well screen length) is ~50 ft.

    The challenging part of this simulation for me, is to choose the correct form of gas extraction. I assume one might suggest using the simple form of mass sink from a grid block in GENER but it would not be a fit representative of the real gas well and that's why I am trying to do this using DELV option. 

    side note, I only have assigned DELV option to the grid blocks that are actually interfering with well screen length. I have not assigned any high permeability to these grids and/or very small volume.

    Anyhow, I would really appreciate if you could guide me.


    thanks and best regards,


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