Page 333 - Fundamentals of Reservoir Engineering

REAL GAS FLOW: GAS WELL TESTING 268

.0153 .832 .605 10 6
×
×
×
p
∆= = 3.21 psi
21200
×
Assuming a depletion type material balance, equ. (1.35), then
G p
4
−
∆ G = ∆ ( ) ≈ − 8 × 10 G
p
p/ Z i Z
i
Thus the use of the flow coefficients B and F, determined using the inflow equation in
the analysis is only very slightly pessimistic and in general provides a perfectly
acceptable approximation for highly productive wells such as the one described in this
exercise.

2
2
4) For the assumed value of F = .047 psia /cp/(Mscf/d) , which was determined in the first
part of this exercise, the data for the plot of equ. (8.47) are listed in table 8.4, and the
plot itself shown as fig. 8.10.
4000
∆ m(p) − FQ 2 n F = 0.030; A = 43 ACRES
Q n
2
(psia / cp / Mscf/d)
F = 0.035; A = 60 ACRES

F = 0.040; A = 100 ACRES
3500

F = 0.047; A

∆ Q j
t ∆ j
Q n
3000
10 20 30

Fig. 8.10 Gas well test analysis assuming semi-steady state conditions and applying
equ. (8.47). Data; table 8.4