Why are shallow heavy oil reservoirs suited to steam recovery methods?

Shallow heavy oil reservoirs are particularly well-suited to steam recovery methods primarily due to the economic and physical constraints associated with depth. Because generating steam is a costly process—often requiring the consumption of energy equivalent to 25 to 35 percent of the produced oil—the depth of a reservoir significantly influences the viability of thermal recovery techniques.12

In general, shallower reservoirs are preferred for steam cycling (steam soak) and steam flooding because the heat loss during the transport of steam from the surface to the formation is minimized. Conversely, deeper reservoirs are typically considered better candidates for in situ combustion, where heat is generated directly within the reservoir.32

Steam recovery works by injecting heat to reduce the viscosity of heavy crude oils, which can be up to one million times more viscous than water. By raising the reservoir temperature, the oil's mobility is markedly improved, allowing it to flow into the wellbore for extraction.34