Aug 8 (Reuters) - The discount on Western Canada Select

(WCS) heavy crude versus the North American benchmark West Texas

Intermediate (WTI) tightened on Thursday:

* WCS for September delivery in Hardisty, Alberta, settled

at $13.10 a barrel below WTI, according to brokerage CalRock,

having settled at $13.35 a barrel under the U.S. benchmark on

Wednesday.

* It was the fourth straight session in which the heavy

crude discount shrank, helped by Exxon Mobil ( XOM ) restarting

select units at its 251,800 barrel-per-day refinery in Joliet,

Illinois, three weeks after it lost power following a storm.

* Joliet is one of the biggest single buyers of Canadian

heavy crude, consuming about 8% of all Canadian exports, said

Rory Johnston, founder of the Commodity Context newsletter.

* Global oil prices settled higher for the third consecutive

session, after U.S. jobs data eased demand concerns and war in

the Middle East helped prices recover from an eight-month low on

Monday.

(Reporting by Nia Williams in British Columbia; Editing by Anil

D'Silva)