Comments on heat and mass transfer characteristics of steam in a horizontal wellbore with multi-point injection technique considering wellbore stock liquid [International Journal of Heat and Mass Transfer 127 (2018) 949–958].

Highlights • Effect of wellbore stock liquid should be re-studied. • The wellbore stock liquid can be divided into two regions. • Effect of temperature distribution in heated oil region should be considered. Abstract This paper presents some comments on "Heat and mass transfer characteristics of steam in a horizontal wellbore with multi-point injection technique considering wellbore stock liquid" that was recently published on [International Journal of Heat and Mass Transfer 127 (2018) 949–958]. Overall, the paper deserves to be published on International Journal of Heat and Mass Transfer. However, some points should be noted to improve the paper. The model presented in their model neglected the heat conduction process, which can lead to a mis-understanding of behaviors of wellbore stock liquid during the steam injection process. In fact, the wellbore stock liquid can be divided into two regions: the heated oil region (region ①) and the cold region (region ②). The oil in region ① will be injected into reservoir, while the oil in region ② cannot flow. However, they assumed that oil in both regions can flow in the horizontal direction. Their purpose of making such an assumption is to build a model. However, this assumption is unreasonable and should be questioned. Their model can be improved by taking the temperature distribution in region ① into consideration. [ABSTRACT FROM AUTHOR]