Page 42 - Handbook of Natural Gas Transmission and Processing Principles and Practices
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(1.17)
3
where is in kg/m , P is in kPa, and T is in °K.
The density can also be written as:
(1.18)
3
3
where is in lbm/ft and B is in ft /SCF. Alternately,
g
(1.19)
3
3
3
where is in kg/m and B is in m /Sm .
g
1.6.1.5. Isothermal Compressibility of Gases
The isothermal gas compressibility, which is given by the symbol c , is a useful concept that will be
g
used extensively in determining the compressible properties of the reservoir. The isothermal
compressibility is also called the bulk modulus of elasticity. Gas usually is the most compressible
medium in the reservoir. However, care should be taken so that it is not confused with the gas
deviation factor, Z, which is sometimes called the super-compressibility factor:
(1.20)
where V and P are volume and pressure, respectively, and T is the absolute temperature. For ideal
gas, we can define the compressibility as:
(1.21)
Whereas, for nonideal gas, compressibility is defined as:
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