. In Eq. (4-23) and other deliverability expressions, the product is at the average pressure between Pe and Pwf. Temperature is constant. With the data in Appendix C, show the difference in the production rate if the is calculated at the initial pressure rather than the average. Flowing bottomhole pressures are 1000 and 3000 psi. p - P f = re 1424qZT (In+s) kh