We start with reservoir pressure diffusion outside wellbore:
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where
well-reservoir contact of the -th well | |
normal vector of differential area on the well-reservoir contact, pointing inside wellbore | |
mass rate at -th well |
Then use the following equality:
d(\rho \, \phi) = \rho \, d \phi + \phi \, d\rho = \rho \, \phi \, \left( \frac{d \phi }{\phi} + \frac{d \rho }{\rho} \right) = \rho \, \phi \, \left( \frac{1}{\phi} \frac{d \phi}{dp} \, dp + \frac{1}{\rho} \frac{d \rho}{dp} \, dp \right) = \rho \, \phi \, (c_{\phi} \, dp + c \, dp) = \rho \, \phi \, c_t \, dp |
to arrive at:
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where
We start with :
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and neglect the non-linear term for low compressibility fluid or equivalently to a constant fluid density: .
Together with constant pore compressibility this will lead to constant total compressibility .
Assuming that permeability and fluid viscosity do not depend on pressure and one arrives to the differential equation with constant coefficients:
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See also
Physics / Mechanics / Continuum mechanics / Fluid Mechanics / Fluid Dynamics / Pressure Diffusion / Pressure Diffusion @model / Single-phase pressure diffusion @model