ICP=2 Function of Pickens

Function of Pickens et al. (1979)

$P_{cap}=-P_0\left\{ln\left[\frac{A}{B}\left(1+\sqrt{1-\frac{B^2}{A^2}}\right)\right]\right\}^\frac{1}{x}$

with

$A = (1 + S_l/S_{l0})(S_{l0} - S_{lr})/(S_{l0} + S_{lr})$

$B = 1 - S_l/S_{l0}$

where

$P_0$= CP(1) $S_{lr}$= CP(2) $S_{lo}$= CP(3) x = CP(4)

Restrictions: 0 < CP(2) < 1 ≤ CP(3); CP(4) ≠ 0