Page 128 - Fundamentals of Reservoir Engineering

PVT ANALYSIS FOR OIL 67

Pressure Formation Vol. Factor Solution GOR
(psia) B o d = v / c b d R s d = R si d − 5.615 F / c b d
o
4000 1.2734 540
3500 1.2798 540

3300 1.2830 (B ob d ) 540 (R )
si
d
3000 1.2534 479
2700 1.2329 428
2400 1.2123 378
2100 1.1930 328
1800 1.1742 281
1500 1.1576 236
1200 1.1399 118
900 1.1219 142
600 1.1038 97
300 1.0853 52
14.7 (200°F) 1.0644 0
14.7 ( 60°F) 1.0000 0
TABLE 2.5
Differential PVT parameters as conventionally presented by laboratories, in which
B o and R s are measured relative to the residual oil volume at 60°F

The conversion can be made by expressing and R s , in table 2.5, in their equivalent,
d
absolute forms of v o and F, in table 2.2, using equs. (2.8) and (2.9) and thereafter,
using equs. (2.5) and (2.6) to allow for the surface separators. This will result in the
required expressions for B o and R s. Alternatively, the required field parameters can be
calculated directly as

v v c b d B ob f
B = o = o = B o (2.11)
o
c c c d B
f b b d f b ob f
where

v/ c b d = B the differential oil formation volume factor measured relative to the
o
o
d
residual oil volume as listed in table 2.5 (rb/stb-residual);
B ob f = 1/ c is the oil formation volume factor of the bubble point oil (rb b/stb)
f b
determined by flashing the oil through the appropriate surface separators
and is measured relative to the stock tank oil volume (refer tables 2.3 and
2.4); and

B ob d = 1/ c is the oil formation volume factor of the bubble point oil determined
b
d
during the differential liberation experiment and is measured relative to
the residual oil volume (refer table 2.5) (rb b/stb-residual).

Similarly, the required solution gas oil ratio for use under field operating conditions is,
equ. (2.6)