A unified model for wellbore flow and heat transfer in pure CO2 injection for geological sequestration, EOR and fracturing operations. (February 2017)

• Record Type: Journal Article
• Authors: Li, Xiaojiang; Li, Gensheng; Wang, Haizhu; Tian, Shouceng; Song, Xianzhi; Lu, Peiqing; Wang, Meng
• Is Part Of: International journal of greenhouse gas control. Volume 57(2017)
• Page Start: 102
• Page End: 115
• Publication Date: 2017-02
• Subjects: CO2 injection -- Wellbore flow model -- Heat transfer -- Coupling solution -- Heat source/sink; Greenhouse gases -- Environmental aspects -- Periodicals; Air -- Purification -- Technological innovations -- Periodicals; Gaz à effet de serre -- Périodiques; Gaz à effet de serre -- Réduction -- Périodiques; Air -- Purification -- Technological innovations; Greenhouse gases -- Environmental aspects; Periodicals; 363.73874605
• DOI: 10.1016/j.ijggc.2016.11.030
• Languages: English
• ISSNs: 1750-5836

Abstract

Highlights: A unified model which can predict flowing pressure/temperature and analyze heat transfer mechanism during pure CO2 injection is proposed. Annular fluid is the most important thermal resistance in wellbore. The contributions of heat source/sink effects are important to wellbore heat transfer, and they vary intensely with mass flow rate. Wellbore heat transfer is dominated by formation at low flow rate and by CO2 at high flow rate. Abstract: A unified model considering heat source/sink effects is developed to investigate flow and thermal behavior of pure CO2 injection for sequestration, EOR, and fracturing. The model is based on mass conservation, momentum, and energy balance and employs a state-of-the-art equation of state and transport models of CO2 to calculate in-situ thermodynamic and transport properties, respectively for a certain section of wellbore. Temperature, pressure, and properties of CO2 are coupled in the depth direction using an iteration scheme. CO2, the annular fluid, and formation are coupled to calculate the overall heat transfer coefficient in the radial direction. The model is validated using data from both field and numerical simulation. Heat transfer mechanism involving thermal resistance and heat source/sink in wellbore is analyzed. A sensitivity study is also conducted to investigate the influence of factors on bottomhole pressure and temperature. Results indicate that annular fluid is the most important thermal resistance in the wellbore. The natural convection of liquid in annulus is much stronger than that of gas, which can greatly promote heat transfer. The heat source/sink effects consist of gas expansion, frictional heat, and Joule–Thomson effect. Their contributions to wellbore heat transfer vary intensely with mass flow rate or Reynolds number. Wellbore heat transfer is dominated by the formation at low flow rates, in which the equilibrium state can be attained at shallow depths. Both bottomhole pressure and temperature change linearly with injection pressure and temperature; there is a non-linear relationship between bottomhole pressure/temperature and time.