Numerical Investigation on Wellbore Temperature Prediction during the CO₂ Fracturing in Horizontal Wells

• Main Authors: Xinrun Lyu, Shicheng Zhang, Yueying He, Zihan Zhuo, Chong Zhang, Zhan Meng
• Format: Article
• Language: English
• Published: MDPI AG 2021-05-01
• Series: Sustainability
• Subjects: CO₂; non-isothermal flow; fracturing; horizontal wellbore; heat transfer; numerical model
• Online Access: https://www.mdpi.com/2071-1050/13/10/5672

A novel model is established to predict the temperature field in the horizontal wellbore during CO₂ fracturing. The pressure work and viscous dissipation are considered, and the transient energy, mass and momentum equations as well as the CO₂ physical properties are solved fully coupled. The model passes the convergence test and is verified through a comparison using the COMSOL software. Then, a sensitivity analysis is performed to study the effects of the treating parameters. Results illustrate that the relationship between the injection rate and the stable bottom-hole temperature (hereinafter referred to as BHT) is non-monotonic, which is different from the hydraulic fracturing. The existence of the horizontal section will increase the BHT at 2 m³/min condition but reduce the BHT at 10 m³/min condition. The problem of high wellbore friction can be alleviated through tube size enhancement, and the ultimate injection rate allowed increased from 2.7 m³/min to 29.6 m³/min when the tube diameter increased from 50.3 mm to 100.3 mm. Additionally, the open-hole completion method of the horizontal section can increase the BHT to 2.7 °C but reduce the near formation temperature to 24.5 °C compared with the casing completion method.