Function of Pickens et al. (1979)
Pcap=−P0{ln[AB(1+1−B2A2)]}1xP_{cap}=-P_0\left\{ln\left[\frac{A}{B}\left(1+\sqrt{1-\frac{B^2}{A^2}}\right)\right]\right\}^\frac{1}{x}Pcap=−P0{ln[BA(1+1−A2B2)]}x1
with
A=(1+Sl/Sl0)(Sl0−Slr)/(Sl0+Slr)A = (1 + S_l/S_{l0})(S_{l0} - S_{lr})/(S_{l0} + S_{lr})A=(1+Sl/Sl0)(Sl0−Slr)/(Sl0+Slr)
B=1−Sl/Sl0B = 1 - S_l/S_{l0}B=1−Sl/Sl0
where
P0P_0P0= CP(1) SlrS_{lr}Slr= CP(2) SloS_{lo}Slo= CP(3) x = CP(4)
Restrictions: 0 < CP(2) < 1 ≤ CP(3); CP(4) ≠ 0
