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Motivation

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In many practical cases the reservoir flow created by well is getting aligned with a  radial direction towards or away from well.

This type of flow is called radial fluid flow and a type library model provides a reference for radial fluid flow diagnostics.

Inputs & Outputs

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InputsOutputs

LaTeX Math Inline
bodyq_t

total sandface rate

LaTeX Math Inline
bodyp(t,r)

reservoir pressure

LaTeX Math Inline
body{p_i}

initial formation pressure

LaTeX Math Inline
body{p_{wf}(t)}

well bottomhole pressure

LaTeX Math Inline
bodyd

reservoir channel width



LaTeX Math Inline
body\sigma

transmissibility

LaTeX Math Inline
body\chi

pressure diffusivity


Expand
titleDetailing


LaTeX Math Inline
body\sigma = \frac{k \, h}{\mu}

transmissibility

LaTeX Math Inline
body\mu

dynamic fluid viscosity

LaTeX Math Inline
body\chi = \frac{k}{\mu} \, \frac{1}{\phi \, c_t}

pressure diffusivity

LaTeX Math Inline
bodyc_t = c_r + c

total compressibility

LaTeX Math Inline
bodyk

absolute permeability

LaTeX Math Inline
body{c_r}

pore compressibility

LaTeX Math Inline
body{\phi}

porosity

LaTeX Math Inline
bodyc

fluid compressibility



Mathematical Model

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LaTeX Math Block
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\frac{\partial p}{\partial t} = \chi \, \left[  \frac{\partial^2 p}{\partial t^2} + \frac{1}{r} \frac{\partial p}{\partial r} \right]



LaTeX Math Block
anchor1
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p(t=0,r) = p_i



LaTeX Math Block
anchor1
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p(t, r=\infty) = p_i



LaTeX Math Block
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\left[ r \frac{\partial p}{\partial r} \right]_{r=0} = - \frac{q_t}{2 \pi \sigma}


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LaTeX Math Block
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p(t,r) = p_i - \frac{q_t}{4 \pi \sigma} {\rm Ei} \left(-\frac{r^2}{4 \chi t} \right)



Approximations

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Late-time response


LaTeX Math Block
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p(t,r) = p_i - \frac{q_t}{4 \pi \sigma} \left[  
\gamma + \ln \left(\frac{r^2}{4 \chi t} \right) \right] 

= p_i - \frac{q_t}{4 \pi \sigma} \ln \left(\frac{2.24585 \, t}{r^2} \right)



See also

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Physics / Fluid Dynamics / Radial fluid flow / Line Source Solution

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