Experimental modelling of the SAGD process: Enhancing SAGD performance with periodic stimulation of the horizontal producer

Experiments on initial stages of the steam-assisted gravity drainage (SAGD) process were carried out using two-dimensional scaled reservoir models to investigate production process and performance. The rising or growing process of the initial steam chamber, its shape and area, and temperature distributions were visualized using video and thermal-video pictures. The relationship between isothermal lines and chamber interface was investigated to study the drainage mechanism. The temperature at the interface where the chamber was expanding remained nearly constant at 80deg.C. The effect on oil recovery of vertical spacing between the two horizontal wells was also investigated. For the case of conventional SAGD, oil production rate increased with increasing vertical well spacing; however, the lead time for the gravity drainage to initiate oil production became longer. The results suggest that L can be used as a governing factor to evaluate production rate and lead time in the initial stage of the SAGD process. Based on these experimental results, the SAGD process was modified by adding intermittent steam injection from the lower production well to the continuous steam injection from the upper well (named SAGD-ISSLW). Using the modified process, the time to generate near break-through condition between two wells was shortened, and oil production was enhanced at the rising chamber stage compared with that of the conventional SAGD process.