Mobility Ratio

Brief

Mobility Ratio determines the relative rate of one fluid to another (etc. water to oil).

$M \le 1$ oil is dominant flowing phase, stable flow.

$M > 1$ water preferentially flows in the reservoir, unstable flow, fingering.

Equation

$M = \frac{k_w/ \mu_w}{k_o/ \mu_o}=\frac{k_{rw}/ \mu_w}{k_{ro}/ \mu_o}=\frac{q_w B_w}{q_o B_o}$

where

$A$ = Area, m2

$B_{wi}$ = Injected water formation oil factor, m3/m3

$h$ = Net pay, oil saturated thickness, m

$HCPV$ = Hydrocarbon pore volume, m3

$HCPV_{inj}$ = Injected hydrocarbon pore volumes, fraction

$W_i$ = Cumulative water injection volume, m3

$\phi$ = Porosity, fraction

$S_o$ = Oil saturation, fraction

Related definitions

Dimensionless injected pore volume:

$W_{iD} = \frac{W_i * B_{wi}}{PV} = \frac{W_i * B_{wi}}{A * h * \phi}$

Injected movable pore volume:

$MOPV_{inj} = \frac{W_i * B_{wi}}{MOPV} = \frac{W_i * B_{wi}}{A * h * \phi *(1-S_{wc}-S_{orw})}$

where

$S_{wc}$ = Connate water saturation, fraction

$S_{orw}$ = Residual oil saturation to water, fraction

See Also

• HCPV
• STOIIP
• VRR
• Pattern
• Block
• Mature Water Flood Analysis