Skin Factor for a Deviated Well Formula
Skin Factor for a Deviated Well calculates directional-drilling skin factor for well performance workflows in production engineering.
How engineers use this formula
Use this formula when the listed inputs (theta, k_v, k_h, h, r_w, s_total) are known and the assumptions behind the cited well performance relationship match the engineering case being checked.
Assumptions
- Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
- The declared units match the field-unit constants used in the formula.
- The cited formula applies to the selected petroleum engineering workflow.
Limitations
- The calculation does not replace a full engineering model or operating procedure.
- Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.
Common mistakes
- Mixing unit systems without converting the inputs.
- Using default example values as field recommendations.
- Applying the formula outside the source assumptions.
Default example
Using the default inputs, s_theta equals -0.222382 dimensionless.
30
25
100
100
0.33
5
Inputs
theta
degWell Inclination from Vertical
k_v
mDVertical Permeability
k_h
mDHorizontal Permeability
h
ftFormation Thickness
r_w
ftWellbore Radius
s_total
dimensionlessTotal Skin Factor
Outputs
s_theta
Directional-Drilling Skin Factor
theta_w
Effective Deviation Angle
h_d
Dimensionless Effective Thickness
s_other
Skin Factor Other Than Directional-Drilling Skin
Source and review
reviewedPressure Transient Testing, Lee, J., Rollins, J.B., Spivey, J.P. (2003)
Lee, J., Rollins, J.B., and Spivey, J.P. Pressure Transient Testing, SPE Textbook Series Vol. 9, Page 44.