EOS COMP
When in COMP mode, the EOS COMP
table is available to specify EOS properties for the various components. The equation of state used is always cubic. This replaces EOS OIL
and EOS GAS
.
An example of the table is as follows:
EOS COMP
PREOS
GCOND
CNAME CO2N2 C1 C2 C3 C46 C7P1 C7P2 C7P3
TCRIT K 215.2 186.6 305.4 369.9 396.2 572.5 630.2 862.6
PCRIT Bar 53.903 45.6 46.20 42.55 34.35 25.93 16.92 8.61
ZCRIT 0.283 0.224 0.285 0.281 0.274 0.260 0.260 0.260
ZMF Frac 0.0315 0.6599 0.0869 0.0591 0.0967 0.0472 0.0153 0.0034
ACF 0.1325 0.013 0.098 0.152 0.234 0.332 0.495 0.833
MW 36.01 16.04 30.07 44.10 67.28 110.9 170.9 282.1
BIC 0.036
BIC 0.05 0
BIC 0.08 0 0
BIC 0.1002 0.09281 0 0
BIC 0.1 0 0.00385 0.00385 0
BIC 0.1 0 0.00630 0.00630 0 0
BIC 0.1 0.1392 0.00600 0.00600 0 0 0
END
The sub-keywords in EOS COMP
are described below:
PREOS
Specify to use the Peng-Robinson equation of state [PR76].
SRKEOS
Specify to use the Soave-Redlich-Kwong equation of state.
CNAME
Followed by a set of component names. If not supplied, internal names like C1, C2 will be generated.
TCRIT
Component critical temperatures. Followed by unit (K is only option at present). Then Nch values, where Nch = Nc-1 is the number of non water components.
PCRIT
Component critical pressures. Followed by pressure unit (e.g., Bar), then Nch values.
ZCRIT
Component critical Z-factors. No unit; followed by Nch values.
ZMF
Reservoir non-aqueous phase composition. Followed by unit (Frac or Percentage), then Nch values. The composition can be over-ridden on a cell by cell basis using ZMFVD.
ACF
Component acentric factors. No unit; followed by Nch values.
PRCORR
This keyword activates a modification of the acentric factor polynomial in the Peng-Robinson equation of state [PR76]. For acentric factor w > 0.49 a cubic expression is used instead of the quadratic default.
MW
Component molecular weights. No unit; followed by Nch values.
SHIFT
Component dimensionless shift factors for the Peneloux volume shift.
OMEGAA
Non-default Omega A values for the equation of state.
OMEGAB
Non-default Omega B values for the equation of state.
BIC
Binary interaction coefficients. As series of keywords specifying the binary coefficients as a lower triangular matrix. So the first BIC will specify the binary interaction coefficient between component 2 and component 1; the next BIC will specify the two binary interaction coefficients between component 3 and components 1 and 2, and so on – a total of Nch.(Nch-1)/2 values are required.
GCOND
Specifies a gas condensate reservoir (all one phase hydrocarbon states are gas).
PARACHOR
Parachors are values which can be used in the McLeod-Sugden expression for surface tensions [Sug24]. Parachors have units of \((dynes/cm)^{1/4}cm^3/mol\) or \((mN/m)^{1/4} cm^3/mol)\), as 1 mN/m = 1 dyne/cm. Typical values are of the order of 100. This is a conventional unit for the parachor, and PARACHOR values will always be regarded as being in these units.
Parachors are entered as part of the equation of state description in COMP EOS mode, and take the form, for example, of:
EOS COMP
PREOS
CNAME C1 C3 C6 C10 C15 C20
...
PARACHOR 71 151 271 400 600 800
END
PARACHOR values are only required with the MISCIBLE option activated.