# Mudcake permeability - Formation invasion

## Input(s)

\(\mu\): Viscosity \((\mathrm{cP})\)

\(h(t)\): Filtrate Height (in.)

\(x_{c}(t)\): Mudcake Growth by time (in./s)

\(\Delta p\): Pressure Change (psi)

\(t\): Time (s)

## Output(s)

\(k\): Viscous Shear Stress at the outer Mudcake boundary (lb/in. \({ }^{2}\) )

## Formula(s)

\[
k=\frac{\mu \cdot h(t) x_{c}(t)}{(2 t \Delta p)}
\]

## Reference(s)

Chin, W. C. (1995). Formation Invasion, Page: 95.