A new concept of enhanced SAGD process by adding intermittent stream-stimulation on lower horizontal production-well (SAGD ISSLW)

An enhanced SAGD process named SAGD-ISSLW for heavy oil recovery has been studied by experi- ments using 2-dimensional scaled physical-models, video and infra-red visualization techniques. In the usual SAGD process, oil production rate increases with increasing vertical well spacing between two horizontal wells, but the lead time to start oil production by gravity drainage is longer at the initial stage. The new process uses a lower horizontal well with both functions of intermittent steam-injection and continuous oil-production instead of the usual SAGD production-well. Meanwhile, like in the usual SAGD, the steam is also injected continuously through the upper well as same as the usual SAGD. The benefits of the new concept reported in the paper are quick buildup of warm steam chamber and higher oil production rate as compared to the usual SAGD process. The process also has advantages for setting longer vertical well spacing and keeping temperature of flowing heavy-oil in the surface-drilled SAGD wells by the single well configuration.