Time for matrix-to-fracture pressure stabilization (Warren-Root, 1963)
This calculator helps to illustrate the importance of fracture intensity (spacing) on matrix-fracture pressure stabilization time, i.e. how quick is the fracture pressure decline at a well impacted by matrix-to-fracture flow.
Input:
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Oil saturation, the fraction of pore volume occupied by oil
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Water saturation, the fraction of pore volume occupied by water
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Matrix and fracture porosity (pore volume % of bulk volume)
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Effective permeability of fracture network and/or matrix
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Matrix and fracture Pore Volume Compressibility (change in pore volume with pore pressure)
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Fracture spacing in x and y (assume idealized, uniform fracture spacing in 2 dimensions)
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Wellbore radius
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Effective total viscosity of fluids in the system
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Oil fluid compressibility (change in oil volume with pore pressure)
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Water compressibility (change in water volume with pore pressure)
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Gas compressibility (change in gas volume with pore pressure)
Note:
rw and kfe have no impact on inflection points
Output:
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Calculated total compressibility (pore volume plus total fluid compressibility)
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Calculated matrix shape factor (a function of fracture spacing as per equation)
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Calculated transmissivity ratio (matrix-to-fracture flow capacity relative to fracture only flow capacity as defined in equation)
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Storage ratio (fracture storage capacity relative to total system storage capacity as defined in equation)
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Inflection time (mid pressure decline inflection point between early (fracture only) and late time (fracture + matrix) in well pressure decline as defined by equation)
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End of Early St. Line (end of early time well pressure decline when matrix first impacts well pressure as given by equation )
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Start of 2nd St. Line (start of late time well pressure decline when both matrix and fracture simultaneously impact pressure decline as given by equation)
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Not designed to work on mobile devices.
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