Details

Autor(en) / Beteiligte

• Yang, Zhong-Lin
• Yu, Hai-Yang
• Chen, Zhe-Wei
• Cheng, Shi-Qing
• Su, Jian-Zheng

Titel

A compositional model for CO2 flooding including CO2 equilibria between water and oil using the Peng–Robinson equation of state with the Wong–Sandler mixing rule

Ist Teil von

• Petroleum science, 2019-08, Vol.16 (4), p.874-889

Ort / Verlag

Beijing: China University of Petroleum (Beijing)

Erscheinungsjahr

2019

Quelle

EZB-FREE-00999 freely available EZB journals

Beschreibungen/Notizen

• This paper presents a three-dimensional, three-phase compositional model considering CO 2 phase equilibrium between water and oil. In this model, CO 2 is mutually soluble in aqueous and hydrocarbon phases, while other components, except water, exist in hydrocarbon phase. The Peng–Robinson (PR) equation of state and the Wong–Sandler mixing rule with non-random two-liquid parameters are used to calculate CO 2 fugacity in the aqueous phase. One-dimensional and three-dimensional CO 2 flooding examples show that a significant amount of injected CO 2 is dissolved in water. Our simulation shows 7% of injected CO 2 can be dissolved in the aqueous phase, which delays oil recovery by 4%. The gas rate predicted by the model is smaller than the conventional model as long as water is undersaturated by CO 2 , which can be considered as “lost” in the aqueous phase. The model also predicts that the delayed oil can be recovered after the gas breakthrough, indicating that delayed oil is hard to recover in field applications. A three-dimensional example reveals that a highly stratified reservoir causes uneven displacement and serious CO 2 breakthrough. If mobility control measures like water alternating gas are undertaken, the solubility effects will be more pronounced than this example.