Heavy oil—evermore mobile

Worldʹs heavy oil and tar sands resources may yield as much hydrocarbons as conventional oil resources. Among the many processes tested for exploitation of heavy oil and tar sands, cyclic steam stimulation and steamflooding have been commercially successful. Promising new technologies, such as SAGD, are making it possible to exploit reservoirs considered to be unsuitable for commercial operations until recently. Other recovery processes, such as in situ combustion, have been far less successful, but special reservoir conditions may justify their application.