EOS7 - Specifying initial conditions

Hi all,

I want to specify this initial condition using EOS7:

• Reservoir temperature: 240 degC
• Chloride concentration: 600 ppm weight = 0.06%-wt
• CO2 concentration: 0.5%-wt
• Steam fraction: 0.1  

I know that EOS7 in a strict sense handles NaCl brine and air, but in the TOUGH2 user's manual it is stated that (Sec. 6.6, pg. 40):

"(In EOS7) The brine is modeled as NaCl solution, while the non-condensible gas is air, although the treatment could be adapted, with minor modifications, to other brines and gases."

For 2 phase conditions the primary variables are (gas phase pressure, brine mass fraction, gas saturation+10, temperature). My questions are:

1. How do I specify an air mass fraction that represents a 0.5%-wt of CO2?  Is it by using an air mass fraction that has the same partial pressure as 0.5%-wt of CO2, adding this partial pressure to Psat(T=240 degC of pure water) and setting this sum as the gas phase pressure (PV1)?

2. For the chloride, EOS7 default brine has 24.98%-wt NaCl, so I guess to get 0.06%-wt I need to specify a brine mass fraction of 0.06/24.98 = 0.0024, right?

Thanks in advance

Manuel