Distribution of steam parameters along horizontal wellbore with simultaneous dual-tubing injection technique in heavy oil reservoirs

To accurately predict the steam thermophysical parameters and improve the formation heating uniformity along the wellbore during the dual tubing injection process, a coupled reservoir and wellbore model was developed based on the structural characteristics of dual tubing horizontal wellbore and simultaneous dual-tubing injection technique. The proposed model was solved by using a fully implicit difference method and iterative algorithm. With this model, the distribution of steam thermophysical parameters along the wellbore can be calculated, and the formation heating uniformity between the short tubing injection technique, long tubing injection technique and simultaneous dual-tubing injection technique was compared. The results show that the decline range of steam pressure and steam temperature mainly occur in the long tubing, and the maximum decline range of steam pressure and steam temperature are 61.74 kPa and 1.59 ℃, respectively. However, the decline range of steam quality mainly occurs in the annulus, the maximum decline range of steam quality is 21.91%. In addition, the decline range of the steam pressure, steam temperature and steam quality from the heel point to the landing position of the packer and from the toe point to the landing position of the packer in the annulus are almost equal. The best formation heating uniformity can be achieved under the condition of simultaneous dual tubing injection technique. Compared with the short tubing injection technique, the uniformity of the steam chamber can be improved by 14.75% with simultaneous dual tubing injection technique. Therefore, adopting simultaneous dual tubing injection technique can effectively improve the formation heating uniformity. © 2021, Central South University Press. All right reserved.