Page 266 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Material Balance and Volumetric Analysis 235

Table 5-31
Material Balance Equations
Gas reservoir with active water drive

G,B, - 5.615(Wn - W,)
G=
B, - Bd
Gas reservoir; no active water drive (We = 0)

G,B, + 5.615WP
G=
- 'd
Oil reservoir with gas cap and active wafer drive
&[e, + 0.1781 B,(R, - Rd)] - (W, - W,)
N=

Oil reservoir with gas cap; no active water drive (We = 0)
N,[B, + 0.1781 B,(R, - R,)] + W,

Initially undersaturated oil reservoir with active water drive (rn = 0)
1. Above bubble point

2. Below bubble point
N, [B, + 0.17818, (R, - R, )] - (We - W, )
N=
Bt - Bai
Initially undersaturated oil reservoir; no active water drive (rn = 0, We = 0)
1. Above bubble point

2. Below bubble point

N,[B, +0.1781B,(RP -Rd)]+ W,
N=
B, -B,
From Reference 180.
Note: In this table, 8, is expressed in W/SCF.