Zeinab Taherian - Department of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
Mohsen Vafaie sefti - Department of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
Mohammadmahdi Shadman - Department of Chemical Engineering, Tarbiat Modares University, Tehran, Iran
Mohammadbagher Zare talavali - Department of Chemical Engineering, Tarbiat Modares University, Tehran, Iran

Asphaltene precipitation during natural depletion and miscible gas injection is a common problem in oilfields throughout the world. Therefore, predicting asphaltene phase behavior through thermodynamic modeling may help to control its precipitation and reduce the associated problems. In this work a new modified CPA (cubic- plus- association) equation of state was used to model asphaltene precipitation. This equation is based on a combination of a new physical part and an association term.The new physical part has an evolved cubic equation of state with a new attractive term. in this work, the results of this modified CPA equation of state were compered to experimental data of three lived oils and results of CPA equation of state base on SRK and PR in physical part. The results showed that this modified CPA equation of state can predict asphaltene precipitation with good accuracy.

Asphaltene precipitation, CPA equation of state, Attractive term, Thermodynamic modeling