Page 397 - Fundamentals of Reservoir Engineering

NATURAL WATER INFLUX 332

Time step = n

W e
−
p a n1 = p 1 − n1
i
−
W ei

k = 1

p k p G p n W e n 1 E
i
i
= 1 − 1 − −
Z n Z i G G

p n k

n
k
i
ei
∆ W e n k = W ei (p a − − 1 2 (p n 1 + p )) 1 e − Jp ∆ t /W
−

n
−
p

n1
i
W e k = W e + ∆ W e k p n k = p n k-1
−
+
n=n 1 n n 1 n
k k
p p G p W e n E i kk 1
=
+
i
n
= 1 − 1 −
Z n Z i G G
k
p n

k = 1
k

- +
k
p − p k n -1 − TOL
n
k = iteration counter
TOL = tolerance pressure
difference (psi)

Fig. 9.20 Prediction of gas reservoir pressures resulting from fluid withdrawal and
water influx (Fetkovitch)