Difference between revisions of "Mobility Ratio"

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:<math> M > 1</math> water preferentially flows in the reservoir, unstable flow, fingering.
 
:<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>
 
:<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>
  

Revision as of 17:35, 2 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

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.

See Also

References

  1. Wolcott, Don (2009). Applied Waterflood Field DevelopmentPaid subscription required. Houston: Energy Tribune Publishing Inc.