Difference between revisions of "Prats effective well radius"

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

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.

@@ Line 1: / Line 1: @@
 ==Prats effective well radius equation==
+[[File:Prats effective well radius.png|thumb|right|400px|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.
+:<math>r_{w_{eff}}=r_w e^{-S}</math>
 {{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}}
-:<math>r_{w_{eff}}=r_w e^-S</math>
+===Skin equation for fractured wells===
+For high conductivity fracture:
+:<math>r_{w_{eff}} = \frac{X_f}{2}</math>
-where
+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(\frac{r_w}{r_{w_{eff}}}) = ln(\frac{2 r_w}{X_f})</math>
+==Nomenclature==
+:<math>r_{w}</math> = wellbore radius, length
+:<math>r_{w_{eff}}</math> = effective well radius, length
+:<math>S</math> = skin factor, dimensionless
+:<math>X_f</math> = fracture half length, length
 ==References==
-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.
+# 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.
 {{#seo:

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