Difference between revisions of "Prats effective well radius"

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(Skin equation for fractured wells)
 
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==Prats effective well radius equation==
 
==Prats effective well radius equation==
{{Quote| text = It appears that the behavior of vertically fractured reservoirs can be interpreted in terms of simple radial-flow reservoirs of large wellbore. | source = Prats, 1961}}
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[[File:Prats effective well radius.png|thumb|right|400px|Prats effective well radius]]
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Effective well radius is a radius value at which well is draining the reservoir under the radial flow conditions.
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*For stimulated wells the effective well radius is higher than the wellbore radius.
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*For damaged wells the effective well radius is lower than the wellbore radius.
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*For undamaged wells the effective well radius is equal to the wellbore radius.
  
 
:<math>r_{w_{eff}}=r_w e^{-S}</math>
 
:<math>r_{w_{eff}}=r_w e^{-S}</math>
  
where
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{{Quote| text = It appears that the behavior of vertically fractured reservoirs can be interpreted in terms of simple radial-flow reservoirs of large wellbore. | source = Prats, 1961}}
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===Skin equation for fractured wells===
  
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For high conductivity fracture:
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:<math>r_{w_{eff}} = \frac{X_f}{2}</math>
  
===Skin equation===
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and
  
 
:<math>S = ln \left ( \frac{r_w}{r_{w_{eff}}} \right ) = ln \left ( \frac{2 r_w}{X_f} \right )</math>
 
:<math>S = ln \left ( \frac{r_w}{r_{w_{eff}}} \right ) = ln \left ( \frac{2 r_w}{X_f} \right )</math>
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==Nomenclature==
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:<math>r_{w}</math> = wellbore radius, length
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:<math>r_{w_{eff}}</math> = effective well radius, length
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:<math>S</math> = skin factor, dimensionless
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:<math>X_f</math> = fracture half length, length
  
 
==References==
 
==References==

Latest revision as of 06:39, 28 April 2020

Prats effective well radius equation

Prats effective well radius

Effective well radius is a radius value at which well is draining the reservoir under the radial flow conditions.

  • For stimulated wells the effective well radius is higher than the wellbore radius.
  • For damaged wells the effective well radius is lower than the wellbore radius.
  • For undamaged wells the effective well radius is equal to the wellbore radius.
r_{w_{eff}}=r_w e^{-S}
It appears that the behavior of vertically fractured reservoirs can be interpreted in terms of simple radial-flow reservoirs of large wellbore.
— Prats, 1961

Skin equation for fractured wells

For high conductivity fracture:

r_{w_{eff}} = \frac{X_f}{2}

and

S = ln \left ( \frac{r_w}{r_{w_{eff}}} \right ) = ln \left ( \frac{2 r_w}{X_f} \right )

Nomenclature

r_{w} = wellbore radius, length
r_{w_{eff}} = effective well radius, length
S = skin factor, dimensionless
X_f = fracture half length, length

References

  1. Prats, M., Hazebroek, P., and Strickler, W.R. 1962. Effect of Vertical Fractures on Reservoir Behavior--Compressible-Fluid Case. SPE J. 2 (2): 87-94.