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amykrice

EOS7C initial conditions

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Hello,

I'm have trouble figuring out the EOS7C initial condition options. For two-phase modeling, the options are pressure (Pa); Brine Mass Fraction; NCG Mass Fraction; Tracer Mass Fraction; Gas Saturation; and Temperature © (Properties/Initial Conditions menu).

Is the idea that pressure is used to control water saturation? Also, what exactly is "gas" saturation? Does it include NCG and methane combined? I tried trial and error to figure it out, and was confused when I input a gas saturation of 0.01 and my model started with a methane mass fraction near 0.98. I would like to get zero methane, residual water saturation, and mostly nitrogen (NCG) for initial conditions.

Thank you,

Amy

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Amy,

I have also had a hard time initializing a model with very little methane and mostly NCG using EOS7C. If you would like to send me your SIM file, I can experiment a bit with that, but think that this might be a better question for the LBNL TOUGH2 forum.

It is my understanding that you would want to make the NCG mass fraction very large. Whatever part of the gas phase that is not make up of water vapor or NCG will be methane.

Best Regards,

Alison

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If you don't mind looking, I'd appreciate it. The parameters and geometry of the model are based on the second example in the EOS7C User's Guide. I'll email you the sim file. I'm planning to inject methane through the injection cell, but not until I get initialization with very little methane figured out.

I've posted on the LBNL forum, too.

Best,

Amy

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I wanted to post a PDF discussion of this topic on the forum for others to look at. The initial mass fraction of NCG is in the aqueous phase. The equation of state will calculate the equilibrium value in the gas phase. The remaining gas will be methane. Because a very small mass fraction of aqueous N2 leads to a much larger equilibrium mass fraction of gas, you have to use very low initial NCG values during initialization.

Thanks to Dan Swenson at Thunderhead for putting this together.

If anyone would like to see the spreasheet or SIM files used here, please contact me at alison @ rockware.com.

Thanks,

Alison

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