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CALCULATING
fLuid Properties
The log analysis results can be transformed into
reserves if the fluid properties are known or can be estimated.
Use measured values if available, otherwise try these US DOE
correlations.
STEP 1: Calculate fluid properties
1: PF = KP1 *
DEPTH
2: PS = KP2
Where: KP1 = 0.46 psi/foot for English units
(use measured pressures where available)
KP1 = 10.4 KPa/meter
for Metric units
KP2 = 14.7 to
600 psi for English units
KP2 = 100 to
4000 KPa for Metric units
3: DENShy =
8829.6 / (131.5 + API) / 62.4 * KD2
Where: KD2 = 1.00 for English units
KD2 = 1000 for
Metric units
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4A: SGx = SGd * (1.0 + 0.00005912 * API * FT *
log(PF / 114.7))
4B: GOR = (KG1 * SGx * PF ^ KG2) * EXP ((KG3 * API) / (FT +
KT2))
Where: KG1 = 0.0362 for API < 30
KG1 = 0.0178
for API > 30
KG2 = 1.0937
for API < 30
KG2 = 1.1870
for API > 30
KG3 = 25.7242
for API < 30
KG3 = 23.9318
for API > 30
KT2 = 460'F
SGd = gas specific gravity downhole (unitless)
SGx =
gas specific gravity at 100psi (unitless)
NOTE: PF is in psi and FT in Fahrenheit for
Equation 4.
5: Bo = 1 + KC1
* GOR * (KC2 + KC3 * GOR) * (FT – 60) * (API / DENShy)
 Where: KC1 = 0.000 467 700 for API < 30
KC1 = 0.000 467
000 for API > 30
KC2 = 0.000 017
510 for API < 30
KC2 = 0.000 011
000 for API > 30
KC3 = 0.000 000
018 for API < 30
KC3 = 0.000 000
0013 for API > 30
NOTE: DENShy is in gm/cc and FT in Fahrenheit for
Equation 5. GOR is in scf/bbl.
6: Bg = (PS *
(TF + KT2)) / (PF * (TS + KT2)) * ZF
Where: KT2 = 460 for English units
KT2 = 273 for
Metric units
7: VISd = 10^(10^(3.0324 – 0.02023 * API) / (FT^1.163)) – 1
8: VISo =
(10.715 / (GOR +100) ^ 0.515) * VISd
^ (5.44 / (GOR + 150) ^
0.338)
Where:
Bg = gas formation volume factor (fractional)
Bo = oil formation volume factor (fractional(
DEPTH = formation depth (ft or m)
GOR = gas oil ratio (ocf/bbl or m3/m3)
PF = formation pressure (psi or KPa)
PS = standard surface pressure (psi or KPa)
TF = formation temperature (degrees C or degrees F)
TS = standard surface temperature (degrees C or degrees F)
COMMENTS:
These fluid properties equations are derived from a US Department
of Energy publication. Measured values should be used if available.
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