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>
  
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:<math> k_o </math> = relative oil phase permeability, function of the phase saturation, mD
 
:<math> k_o </math> = relative oil phase permeability, function of the phase saturation, mD
 
:<math> k_w </math> = water phase permeability, function of the phase saturation, mD
 
:<math> k_w </math> = water phase permeability, function of the phase saturation, mD
:<math> M = mobility ratio, fraction
+
:<math> M </math>= mobility ratio, fraction
 
:<math> \mu_o </math> = oil viscosity, cP
 
:<math> \mu_o </math> = oil viscosity, cP
 
:<math> \mu_w </math> = water viscosity, cP
 
:<math> \mu_w </math> = water viscosity, cP
 
:<math> q_o </math> = oil rate, cc/sec
 
:<math> q_o </math> = oil rate, cc/sec
 
:<math> q_w </math> = water rate, cc/sec
 
:<math> q_w </math> = water rate, cc/sec
 +
 +
Rule of thumb:
 +
:<math> M = 0.333 \mu_o</math>
  
 
==Example==
 
==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 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>
 
:<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==
 
==See Also==

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.

See Also

References

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