This document discusses vertical lift relationships and working charts used to determine production parameters like PWF given other known values. It provides an example of using a working chart for a 1.5" tubing to calculate a PWF of 1600 psi given a PTH of 200 psi, flow rate of 500 bbl/day, well depth of 5000 ft, and GLR of 200 scf/bbl. It also demonstrates using vertical flow performance curves and an IPR curve to determine an allowable flow rate of 820 bbl/day at a PWF of 1450 psi.