WLT Pseudo-steady-state: 2005 #63 (similar)

Well test problems are often pseudo-steady-state. The Guidebook covers these on 12 WLT 2-5.

Several tricks to be aware of:
1) If given reservoir volume, assume it's circular to find the radius.
           Example: A reservoir is 100 acres, re = [(43,560 ft/ac)100 ac(1/pi)]0.5 = ~1,200 ft
2) If given a range of B & viscosity, average the start and end values over flow time.
          Typical values are 1.4 and 0.5.
3) If reservoir pressure falls below the BP, remember it's no longer single phase flow. This qualifier can be used to calculate the drawdown.
4) Chose the right formula: there are three types: with skin, skin pressure drop, or adjusted k. The GB has all three on the same page.

In this example, q is requested. I'll use typical values: skin (+1) and drawdown (1,000 psi), k (50 md), h (45 ft), and rw (0.5).



Q is easily found:
1,000 = 141.2q(1.4)0.5(1/50)(1/45) [ln(0.472*(1,000/0.5)) + 1]
q = 2,900 STB/D