Fracture porosity when using MINC in Tough2

Hi All,

When we choose MINC in tough2, we need to input the porosity of fracture in the material data as in the following screen shot. What is the definition of the fracture porosity here?  Is it the total fracture volume divided by the total reservoir volume?  How will this parameter taken into account into the simulation? To me it seems like the fracture spacing and the volume fractions under global properties will have larger impact.  Thanks a lot!

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  • Wendy,

    (1)  Fracture volume fraction is the volume assigned to the fracture continuum divided by the total volume; it determines the element volumes.

    (2) Fracture porosity is the fracture pore volume divided by the fracture continuum volume.

    (3) Therefore, the volume of open fractures in a given gridblock is the product of fracture porosity, fracture volume fraction, and element volume of the primary mesh.

    (4) Fracture spacing affects fracture-matrix interface area and nodal distances.

    (5) Which of these parameters has the highest impact depends on the application; I suggest you do a simple sensitivity analysis to find out.

    Stefan

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  • Thanks Stefan!  It is clear to me now.  However, is there any guideline how to choose the combination of the fracture porosity and fracture volume fraction?  For example, for a given fracture opening aperture and spacing system, we can have different combination of fracture porosity and fracture volume fraction that can satisfy the condition.  From simulation conversion and speed point of view, is there any suggestion?  Thanks! 

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  • The only guideline I can give is to consider that local thermodynamic equilibrium is assumed within the fracture and matrix continuum.

    Stefan

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