Analytical modeling of the oil steam ratio during the lifetime steam-assisted gravity drainage process in extra-heavy oil reservoirs

• Published in: Journal of petroleum science & engineering 2021-08, Vol.203, p.108616, Article 108616
• Main Authors: Shi, Lanxiang, Li, Xiuluan, Xi, Changfeng, Qi, Zongyao, Liu, Pengcheng
• Format: Article
• Language: English
• Subjects: Analytical model; Dual-horizontal well pairs; Extra-heavy oil reservoirs; Steam oil ratio (SOR); Steam-assisted gravity drainage (SAGD)
• ISSN: 0920-4105; 1873-4715
• DOI: 10.1016/j.petrol.2021.108616

An analytical model to predict the steam oil ratio (SOR) of the steam-assisted gravity drainage (SAGD) process, including the growing up, expanding and depletion of the steam chamber development, is proposed through the use of steam chamber development modes, energy balance, and mass balance. The calculated instantaneous steam oil ratio (ISOR) and cumulative steam oil ratio (ISOR) using the new analytical model are compared and validated with other analytical models results and numerical simulation results. The results showed that the new analytical model can predict the changing of SOR during the lifetime of the SAGD process more accurately than other analytical models. In addition, it had a high agreement with the numerical simulation results. Additionally, the new model could predict more parameters, including water cut, steam quality, heat proportion in different parts of a reservoir than previous models. This model could be a fast-effective guide for the design, prediction, and adjustment of field dual-horizontal SAGD well pairs. •A new analytical steam oil ratio prediction model for the lifetime SAGD process was proposed.•Key producing parameters and the heat proportion for different parts were considered and were predicted using this new model.•The new model was considered the heat distribution ahead of steam chamber, resulting in more accurate prediction results.•The applying results of the validations certified the reliability and accurateness of the new model.