Skin factor for a deviated well

Input(s)

ө: Angle of Inclination (degree)

kv: Vertical Permeability $(\mathrm{mD})$

kh: Horizontal Permeability $(\mathrm{mD})$

$\mathrm{h}$ : Formation Thickness (ft)

rw: Radius of Wellbore $(\mathrm{ft})$

s: Total Skin Factor (dimensionless)

tw: Angle of Inclination due to drilling (degree) $h_{d}$ : Dimensionless Effective Thickness (dimensionless)

$s_{t h}$ : Directional Drilling Skin Factor (dimensionless)

$s_{t}$ : Skin Factor other than Directional Drilling (dimensionless)

\begin{gathered} t w=\left(\operatorname{atan}\left(\left(\frac{k v}{k h}\right)^{0.5} * \tan \left(\theta * \frac{\pi}{180}\right)\right)\right) * \frac{180}{p i} \\ h_{d}=\left(\frac{h}{r w}\right) *\left(\frac{k h}{k v}\right)^{0.5} \\ s_{t h}=-\left(\frac{t w}{41}\right)^{2.06}-\left(\frac{t w}{56}\right)^{1.865} * \log \left(\frac{h_{d}}{100}\right) \\ s_{t}=s-s_{t h} \end{gathered}

Pressure Transient Testing, Lee, Rollins & Spivey, Page: 44.