Experimental study on initial stage of SAGD process using 2-dimensional scaled model for heavy oil recovery

The experiments on initial stages of steam assisted gravity drainage (SAGD) process have been carried out using two-dimensional scaled reservoir models to investigate its production process and performance. Rising or growing process of the initial steam chamber, its shape and area, and temperature distributions have been visualized by using video and thermal-video pictures. As a drainage mechanism, the relationship between isothermal lines and chamber interface have been presented. The temperature on the interface, where the chamber was expanding, was maintained at almost constant temperature of 80 °C. Furthermore, the effect of vertical well spacing between two horizontal wells on oil recovery has been investigated. For the case of usual SAGD, oil production rate increases with increasing vertical well spacing, however the leading time to start oil production by gravity drainage becomes longer. The results show that the well spacing may be a representative length for initial stage of the process. Based on these experimental results, a modified SAGD process by adding intermittent steam injection from the lower production well have been proposed. By applying the modified process, the time to generate near breakthrough condition between two wells was relatively shorten, and oil production was enhanced at the stage of rising chamber compared with that of usual SAGD process.