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

A general term for injection processes that introduce heat into a reservoir. Thermal recovery is used to produce viscous, thick oils with API gravities less than 20. These oils cannot flow unless they are heated and their viscosity is reduced enough to allow flow toward producing wells. During thermal recovery, crude oil undergoes physical and chemical changes because of the effects of the heat supplied. Physical properties such as viscosity, specific gravity and interfacial tension are altered. The chemical changes involve different reactions such as cracking, which is the destruction of carbon-carbon bonds to generate lower molecular weight compounds, and dehydrogenation, which is the rupture of carbon-hydrogen bonds. Thermal recovery is a major branch of enhanced oil recovery processes and can be subdivided in two types: hot fluid injection such as steam injection (steamflood or cyclic steam injection) and hot waterflooding and in-situ combustion processes.

Alternate Form: TEOR

See related terms: API gravity,  chemical flooding,  miscible displacement