− | Residual hydrocarbons occur as dead oil or as water displacement residual hydrocarbons. Dead oil forms as a result of water washing, thermal cracking, or [[biodegradation]]. Water displacement residual hydrocarbons form in reservoirs as a result of a leaky or breached trap or as a result of production. | + | Residual hydrocarbons occur as dead oil or as water displacement residual hydrocarbons. Dead oil forms as a result of water washing, thermal [[cracking]], or [[biodegradation]]. Water displacement residual hydrocarbons form in reservoirs as a result of a leaky or breached trap or as a result of production. |