1. n. [Heavy Oil, Enhanced Oil Recovery]

A thermal production method for heavy oil that pairs a high-angle injection well with a nearby production well drilled along a parallel trajectory. The pair of high-angle wells is drilled with a vertical separation of about 5 m [16 ft]. Steam is injected into the reservoir through the upper well. As the steam rises and expands, it heats up the heavy oil, reducing its viscosity. Gravity forces the oil to drain into the lower well where it is produced.

Alternate Form: SAGD

See: heavy oil,  injection well