Oil Compressibility Functions
Undersaturated compressibility by Vasquez-Beggs and saturated by Villena-Lanzi.
2 functions
PO.PVT.Co.UnSat.ByVasquezBeggs(Rsb, SG_gas, API, T_degF, P)
Calculates oil compressibility using Vasquez and Beggs (1980) correlation, P > Pb, [1/psi].
PO.PVT.Co.Sat.ByVillenaLanzi(P, Pb, T_degF, Rsb, API)
Calculates oil compressibility using Villena-Lanzi (1985) correlation, P <= Pb, [1/psi].