Difference between revisions of "Relative Permeability"

From wiki.pengtools.com
Jump to: navigation, search
(Created page with "__TOC__ ==Brief== Relative Permeability is the ratio of the effective permeability to base oil permeability measured at irreducible oil saturation. :<math> k_{ro} = k_o...")
 
 
(36 intermediate revisions by the same user not shown)
Line 3: Line 3:
 
==Brief==
 
==Brief==
  
−
[[Relative Permeability]] is the ratio of the effective permeability to base oil permeability measured at irreducible oil saturation.
+
[[Relative Permeability]] is the ratio of the effective permeability to base oil permeability measured at connate water saturation<ref name=DW/>.
  
−
:<math> k_{ro} = k_o/k_{oS_{wir}}</math>  
+
:<math> k_{ro}(S_w) = k_o(S_w)/k_o(S_{wc})</math>  
−
===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> k_{rw}(S_w) = k_w(S_w)/k_o(S_{wc})</math>  
  
 
where
 
where
  
−
:<math> B_o </math> = oil formation volume factor, m3/m3
+
:<math> k_{ro}(S_w) =</math> Oil relative permeability at the given water saturation Sw, fraction
−
:<math> B_w </math> = water formation volume factor, m3/m3
+
:<math> k_{rw}(S_w) =</math> Water relative permeability at the given water saturation Sw, fraction  
−
:<math> k_{rw} </math> = relative water phase permeability, function of the phase saturation, fraction
+
:<math> k_o(S_w) =</math> Effective oil permeability at the given water saturation Sw, mD
−
:<math> k_o </math> = oil phase permeability, function of the phase saturation, fraction
+
:<math> k_w(S_w) =</math> Effective water permeability at the given water saturation Sw, mD
−
:<math> k_o </math> = relative oil phase permeability, function of the phase saturation, mD
+
:<math> k_o(S_{wc}) =</math> Effective oil permeability at the connate water saturation, mD
−
:<math> k_w </math> = water phase permeability, function of the phase saturation, mD
+
:<math> S_{wc} =</math> Connate water saturation, fraction
−
:<math> M </math>= mobility ratio, fraction
+
 
−
:<math> \mu_o </math> = oil viscosity, cP
+
==Related definitions==
−
:<math> \mu_w </math> = water viscosity, cP
+
'''Relative permeability curves''' are the relationships between the k<sub>ro</sub> and k<sub>rw</sub> vs S<sub>w</sub>. Corey correlation is a useful approximation for the rel. perm. curves.
−
:<math> q_o </math> = oil rate, cc/sec
+
 
−
:<math> q_w </math> = water rate, cc/sec
+
'''Effective permeability''' - oil, water, gas phase permeability when more than one phase is present. Depends on fluids saturations.
 +
 
 +
'''Absolute permeability''' - permeability of the core sample when saturated with one liquid. Independent of fluid. Dependent on pore throat sizes.
  
 
==Example==
 
==Example==
−
Determine the [[Mobility Ratio]] using the following data<ref name=DW/>:<BR>
+
Determine the [[Relative Permeability]] 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 1 cP, oil viscosity is 3 cP.  
+
Core dimensions: A=2 cm2, L=3 cm. PVT: water viscosity = 1 cP, oil viscosity = 3 cP, Bw=1 cc/cc, Bo=1.2 cc/cc.
 +
 +
===Absolute permeability===
 +
 
 +
Core is at 100% water and qw=0.553 cc/sec:
 +
 
 +
Using [[Darcy's law]]:
  
−
:<math> M = \frac{248/1}{50/3} =15 </math>
+
:<math> k_{abs} = \frac{0.553*1*1*3}{2*2} = 0.415 D = 415 mD </math>
  
−
In this case the mobility of water is 15 times higher than the mobility of water.
+
Same core at 100% oil and qo=0.154 cc/sec:
 +
 
 +
:<math> k_{abs} = \frac{0.154*1.2*3*3}{2*2} = 0.415 D = 415 mD </math>
 +
 
 +
=== Effective permeability===
 +
 
 +
Same core at 70% water and 30% oil and qw=0.332 cc/sec and qo=0.0184 cc/sec:
 +
 
 +
:<math> k_w(S_w=0.7)= \frac{0.332*1*1*3}{2*2} = 0.249 D = 249 mD </math>
 +
:<math> k_o(S_w=0.7)= \frac{0.0184*1.2*3*3}{2*2} = 0.049 D = 50 mD </math>
 +
 
 +
Same core at 30% connate water and 70% oil and qw=0 cc/sec and qo=0.123 cc/sec:
 +
 
 +
:<math> k_w(S_{wc}=0.3)= \frac{0*1*1*3}{2*2} = 0 D = 0 mD </math>
 +
:<math> k_o(S_{wc}=0.3)= \frac{0.123*1.2*3*3}{2*2} = 0.332 D = 332 mD </math>
 +
 
 +
SInce Sw=0.3 is connate water saturation, ko=332mD is the effective base permeability.
 +
 
 +
=== Relative permeability===
 +
 
 +
Core at 70% water and 30% oil:
 +
 
 +
:<math> k_{rw}(S_w=0.7) = \frac{249}{332} = 0.75 </math>
 +
:<math> k_{ro}(S_w=0.7) = \frac{50}{332} = 0.15 </math>
 +
 
 +
Core at 30% connate water and 70% oil:
 +
 
 +
:<math> k_{rw}(S_w=0.3) = \frac{0}{332} = 0 </math>
 +
:<math> k_{ro}(S_w=0.3) = \frac{332}{332} = 1 </math>
  
 
==See Also==
 
==See Also==
−
*[[HCPV]]
+
*[[Mobility Ratio]]
−
*[[STOIIP]]
+
 
−
*[[VRR]]
 
−
*[[Pattern]]
 
−
*[[Block]]
 
 
*[[Mature Water Flood Analysis]]
 
*[[Mature Water Flood Analysis]]
  

Latest revision as of 17:35, 2 April 2022

Brief

Relative Permeability is the ratio of the effective permeability to base oil permeability measured at connate water saturation[1].

k_{ro}(S_w) = k_o(S_w)/k_o(S_{wc})
k_{rw}(S_w) = k_w(S_w)/k_o(S_{wc})

where

k_{ro}(S_w) = Oil relative permeability at the given water saturation Sw, fraction
k_{rw}(S_w) = Water relative permeability at the given water saturation Sw, fraction
k_o(S_w) = Effective oil permeability at the given water saturation Sw, mD
k_w(S_w) = Effective water permeability at the given water saturation Sw, mD
k_o(S_{wc}) = Effective oil permeability at the connate water saturation, mD
S_{wc} = Connate water saturation, fraction

Related definitions

Relative permeability curves are the relationships between the kro and krw vs Sw. Corey correlation is a useful approximation for the rel. perm. curves.

Effective permeability - oil, water, gas phase permeability when more than one phase is present. Depends on fluids saturations.

Absolute permeability - permeability of the core sample when saturated with one liquid. Independent of fluid. Dependent on pore throat sizes.

Example

Determine the Relative Permeability using the following data[1]:
Core dimensions: A=2 cm2, L=3 cm. PVT: water viscosity = 1 cP, oil viscosity = 3 cP, Bw=1 cc/cc, Bo=1.2 cc/cc.

Absolute permeability

Core is at 100% water and qw=0.553 cc/sec:

Using Darcy's law:

k_{abs} = \frac{0.553*1*1*3}{2*2} = 0.415 D = 415 mD

Same core at 100% oil and qo=0.154 cc/sec:

k_{abs} = \frac{0.154*1.2*3*3}{2*2} = 0.415 D = 415 mD

Effective permeability

Same core at 70% water and 30% oil and qw=0.332 cc/sec and qo=0.0184 cc/sec:

k_w(S_w=0.7)= \frac{0.332*1*1*3}{2*2} = 0.249 D = 249 mD
k_o(S_w=0.7)= \frac{0.0184*1.2*3*3}{2*2} = 0.049 D = 50 mD

Same core at 30% connate water and 70% oil and qw=0 cc/sec and qo=0.123 cc/sec:

k_w(S_{wc}=0.3)= \frac{0*1*1*3}{2*2} = 0 D = 0 mD
k_o(S_{wc}=0.3)= \frac{0.123*1.2*3*3}{2*2} = 0.332 D = 332 mD

SInce Sw=0.3 is connate water saturation, ko=332mD is the effective base permeability.

Relative permeability

Core at 70% water and 30% oil:

k_{rw}(S_w=0.7) = \frac{249}{332} = 0.75
k_{ro}(S_w=0.7) = \frac{50}{332} = 0.15

Core at 30% connate water and 70% oil:

k_{rw}(S_w=0.3) = \frac{0}{332} = 0
k_{ro}(S_w=0.3) = \frac{332}{332} = 1

See Also

References

  1. ↑ 1.0 1.1 Wolcott, Don (2009). Applied Waterflood Field DevelopmentPaid subscription required. Houston: Energy Tribune Publishing Inc. 


Retrieved from "https://wiki.pengtools.com/index.php?title=Relative_Permeability&oldid=7492"