Difference between revisions of "Mobility Ratio"

Latest revision as of 09:02, 4 April 2022

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

B_o

= oil formation volume factor, m3/m3

B_w

= water formation volume factor, m3/m3

k_{rw}

= relative water phase permeability, function of the phase saturation, fraction

k_o

= oil phase permeability, function of the phase saturation, fraction

k_o

= relative oil phase permeability, function of the phase saturation, mD

k_w

= water phase permeability, function of the phase saturation, mD

M

= mobility ratio, fraction

\mu_o

= oil viscosity, cP

\mu_w

= water viscosity, cP

q_o

= oil rate, cc/sec

q_w

= water rate, cc/sec

Rule of thumb:

M = 0.333 \mu_o

Example

Determine the Mobility Ratio using the following data^[1]:
Core is at 70% water and 30% oil saturation. Water phase permeability is 248 mD, oil phase permeability is 50 mD. Water viscosity is 1 cP, oil viscosity is 3 cP.

M = \frac{248/1}{50/3} =15

In this case the mobility of water is 15 times higher than the mobility of water.

References

↑ Wolcott, Don (2009). Applied Waterflood Field Development. Houston: Energy Tribune Publishing Inc.

[DW-1] Wolcott, Don (2009). Applied Waterflood Field Development. Houston: Energy Tribune Publishing Inc.

[1]

@@ Line 7: / Line 7: @@
 :<math> M > 1</math> water preferentially flows in the reservoir, unstable flow, fingering.
-===Equation===
+==Equation==
 :<math> 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}</math>
@@ Line 23: / Line 23: @@
 :<math> q_o </math> = oil rate, cc/sec
 :<math> q_w </math> = water rate, cc/sec
+Rule of thumb:
+:<math> M = 0.333 \mu_o</math>
 ==Example==
-Determine [[Mobility Ratio]] using the following data<ref name=DW/>:
+Determine the [[Mobility Ratio]] using the following data<ref name=DW/>:<BR>
-Core is at 70% water and 30% oil saturation. Water phase permeability is 248 mD, oil phase permeability is 50 mD. Water viscosity is 1cP, oil viscosity is 3cP.
+Core is at 70% water and 30% oil saturation. Water phase permeability is 248 mD, oil phase permeability is 50 mD. Water viscosity is 1 cP, oil viscosity is 3 cP.
 :<math> M = \frac{248/1}{50/3} =15 </math>
-Injected movable pore volume:
+In this case the mobility of water is 15 times higher than the mobility of water.
-:<math> MOPV_{inj} = \frac{W_i * B_{wi}}{MOPV} = \frac{W_i * B_{wi}}{A * h * \phi *(1-S_{wc}-S_{orw})}</math>
-where
-:<math> S_{wc} </math> = Connate water saturation, fraction
-:<math> S_{orw} </math> = Residual oil saturation to water, fraction
 ==See Also==

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