Page 44 - Characterization and Properties of Petroleum Fractions - M.R. Riazi

QC: IML/FFX
P1: IML/FFX
AT029-Manual
AT029-01
June 22, 2007
24 CHARACTERIZATION AND PROPERTIES OF PETROLEUM FRACTIONS
3
3
2
squared length per time (L /t). Usually it is expressed in
2
in the SI unit.
cm /s. P2: IML/FFX AT029-Manual-v7.cls T1: IML 14:26 units of scf /stft . This unit is exactly the same as sm /stm 3
2
2
2
2
1cm /s = 10 −4 m /s = 9.29 × 10 −6 ft /s = 3.3445 × 10 −4 ft /h The conversion factors between these three units for the GOR
(GLR) are given as follows:
3
3
1.7.21 Units of Surface Tension 1 scf/stb = 0.1781 scf/stft = 0.1781 sm /stm 3
3
3
3
1sm /stm = 1 scf/stft = 5.615 scf/stb
Surface tension or interfacial tension (σ) as described in Sec-
tion 8.6 (Chapter 8) has the unit of energy (work) per unit area
2
and the SI unit of surface tension is J/m = N/m. Since N/m 1.7.24 Values of Universal Constants
is a large unit the values of surface tension are expressed in
milli-N/m (mN/m) which is the same as the cgs unit of surface 1.7.24.1 Gas Constant
tension (dyn/cm). The conversion factors for this property are The universal gas constant shown by R is used in equations
as follows: of state and thermodynamic relations in Chapters 5, 6, 8, and
10. It has the unit of energy per mole per absolute degrees. As
2
2
1 dyn/cm = 1 erg/cm = 10 −3 J/m = 1 mJ/m 2 discussed in Section 1.7.17, its dimension is similar to that of
= 10 −3 N/m = 1 mN/m molar heat capacity. The value of R in the SI unit is 8314 J/
kmol · K. The energy dimension may also be expressed as the
1.7.22 Units of Solubility Parameter product of pressure and volume (PV), which is useful for ap-
plication in the equations of state. Value of R in terms of en-
Prediction of solubility parameter (δ) for petroleum fractions ergy unit is more useful in the calculation of thermodynamic
and crude oil is discussed in Chapters 4 and 10 and it has properties such as heat capacity or enthalpy. Values of this
the unit of (energy/volume) . The traditional unit of δ is in parameter in several other units are given as follows.
0.5
(cal/cm ) . Another form of the unit for the solubility pa- 3
3 0.5
rameter is (pressure) . Some conversion factors are given R = 8.314 J/mol · K = 8314 J/kmol · K = 8.314 m Pa/mol · K
0.5
3
below. = 83.14 cm bar/mol · K
3
= 82.06 cm ·atm/mol · K = 1.987 cal th /mol · K
0.5
3 0.5
3 0.5
1 (cal th /cm ) = 2.0455 (J/cm ) = 2.0455 (MPa) = 1.986 cal/mol · K = 1.986 Btu/lbmol · R
3
3 0.5
= 2.0455 × 10 (J/m ) 3 3
3 0.5
3
= 2.0455 × 10 (Pa) 0.5 = 10.6004 (Btu/ft ) = 0.7302 ft ·atm/lbmol · R = 10.73 ft ·psia /lbmol · R
3 0.5
= 31.6228 (kcal th /m ) = 1545 ft · lb f /lbmol · R
3 0.5
= 6.4259 (atm) 0.5 = 2.05283 (ft · lb f /ft ) 1.7.24.2 Other Numerical Constants
3 0.5
3 0.5
3
1 (MPa) 0.5 = 0.4889 (cal th /cm ) = 1(J/cm ) = 10 (Pa) 0.5
The Avogadro number is the number of molecules in 1 mol of
Values of surface tension in the literature are usually ex- a substance.
3 0.5
pressed in (cal/cm ) where cal represents thermochemical N A = Avogadro number = 6.022 × 10 mol −1
23
unit of calories.
For example 1 mol of methane (16 g) consists of 6.022×10 23
molecules. Other constants are
1.7.23 Units of Gas-to-Oil Ratio
Boltzman constant = k B = R/N A = 1.381 × 10 −23 J/K.
Gas-to-oil ratio is an important parameter in determining the −34
type of a reservoir fluid and in setting the optimum operating Planck constant = h = 6.626 × 10 J · s.
8
conditions in the surface separators at the production field Speed of light in vacuum = c = 2.998 × 10 m/s.
(Chapter 9, Section 9.2.1). In some references such as the Numerical constants
API-TDB [47], this parameter is called gas-to-liquid ratio and
is shown by GLR. GOR represents the ratio of volume of gas to π = 3.14159265
the volume of liquid oil from a separator under the SC of 289 K e = 2.718 281 828
and 101.3 kPa (60 F and 14.7 psia) for both the gas and liquid.
◦
10
10
10
Units of volume were discussed in Section 1.7.13. Three types lnx = log x/log e = 2.30258509 log x.
of units are commonly used: the oilfield, the metric, and the
English units. 1.7.25 Special Units for the Rates and Amounts
of Oil and Gas
• Oilfield units: standard cubic feet (scf) is used for the volume
of gas, and stock tank barrels (stb) is used for the volume of Amounts of oil and gas are usually expressed in volumetric
oil. Therefore, GOR has the unit of scf/stb. quantities. In the petroleum industry the common unit for
3
• Metric units: standard cubic meters (sm ) is used for the volume of oil is barrel (bbl) and for the gas is standard cubic
3
gas, and stock tank cubic meters (stm ) unit is used for the feet (scf) both at the conditions of 60 F (15.5 C) and 1 atm.
◦
◦
oil. The volume of liquid oil produced is usually presented The production rate for the crude is expressed in bbl/d and
under the stock tank conditions, which are 60 F (15.5 C) for the gas in scf/d.
◦
◦
3
3
and 1 atm. Therefore, GOR unit in this system is sm /stm . In some cases, amount of crude oil is expressed in the met-
• English unit: scf is used for the gas, and sock tank cubic feet ric ton. Conversion from volume to weight or vice versa re-
3
(stft ) is used for the liquid volume. Thus the GOR has the quires density or specific gravity (API) of the oil. For a light
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