Joule-Thompson coefficient calculation

**kochichiro** · 02-01-2011, 09:00 PM

Hello guys, I am needed to calculate Joule-Thompson coefficient for reservoir gas. I have tuned EoS for this gas, so I can generate Z vs Pressure under constant T and vice versa plots, I also have specific heat capacity function so I can generate it for any pressure or temperature.

So, the question is how I can calculate Joule-Thompson coefficient, what plots should I generate and how I must use the data. Also, under which conditions I must perform the calculation – constant pressure with changing temperature or changing pressure with constant temperature.

I completely lost in this subject, so it would be nice if someone can help me out.

**insult2injury** · 02-01-2011, 10:55 PM

mu = (dT/dP) @ Constant H = - (dH/dP) @ Constant T / (dH/dT) @ Constant P

H = Enthalpy
P = Pressure
T = Temperature

**kochichiro** · 02-02-2011, 07:55 PM

Thank you very much, but there one more question I would like to ask. I’ve calculated Joule-Thompson coefficients with the help of PVTsim, but strangely it allocates negative coefficient values to liquid phase and positive ones to vapor phase. I also checked this in different versions of PVTsim and on several fluids from demo database. And everywhere negative coefficient values were allocated to liquid phase. Why can it be?

**mohsen2396** · 04-03-2011, 10:19 AM

Dear Brother

The Joule-Thomson Coefficient for liquid should be negative and for gas it should be positive.That's correct. because as it is well known , gas temperature decreases by pressure drawdown . but liquid warm when its pressure decreases. thats why liquid temperature in the sandface is greater than geothermal temperature in a reservoir because it become heated while flowing to through porous media.But gas temperature in sandface in usually less than geo T. you can compare these tow value from static and flowing data. in an oil well static temperature is less than flowing temperature.