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Showing results for tags 'Gas fugacity'.
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Hello, I am struggling with the meaning of fugacity and the way it is defined in GWB and I appreciate if you could help me to clarify my confusion. I am simulating gas injection into a closed system (minerals and brine) that is initially at equilibrium. I found I can add the gas as a reactant substance to my system either using simple or sliding (fugacity) option. The partial pressure of the gas is needed to reach to a certain value. By doing simple calculations for my system, to have a partial pressure of 3.5 bar, I need 0.5 mole of the gas. Fugacity coefficient in my case is 1.02, so fugacity is almost equal to the partial pressure. I created two models using different reaction paths for an identical system. In the first model I added 0.5 of gas using simple option and in the second model I used sliding and set the fugacity to 3.5, the value that should be reached by adding 0.5 mole gas. Results I got from these simulations are hugely different. When I plotted the result from the first simulation I found 0.5 mole injected gas creates fugacity of order of 1e-6 in the gas phase while I was expecting a value of 3.5. I really need to understand the meaning of fugacity in GWB to be able to have a realistic model to represent operational condition for my system. It seems setting small value for fugacity through sliding modelling acts as if I added huge amount of gas (in terms of mole) and I don't understand the reason. I would greatly appreciate your help. Thanks. Best, Neda