Page 267 - Fundamentals of Reservoir Engineering

OILWELL TESTING 204

= 4464 hours. The early linear trend of the observed data, for 1.5 < t < 6 hours has
been extrapolated to determine

t +∆ t
p* = 3020 psi for log = 0
t ∆

and p ws(LIN) = 2727 psi for ∆t = 1 hour

The slope of buildup is m = 80 psi/log cycle from which k can be calculated as

162.6q B 162.6 400 1 1.23
µ
× ×
×
k = o = = 50 mD
mh 80 20
×
and using equ. (7.52), the skin factor is
p ws
(psi)
p* = 3020 psi
3000

p (DIETZ)
= 2944 psi
2900

p = 2820 psi
d
2800 p =
ws (1 - hr)
2727
x
2700 t +∆ s t
log t +∆ d t = 2.51 log = .942
∆ d t ∆ s t

2600
4 3 2 1 0
t +∆t
log
∆t

Fig. 7.25 Pressure buildup analysis to determine the average pressure within the no-
flow boundary, and the dynamic grid block pressure (Exercise 7.7)