May 1 (Reuters) - The discount on Western Canada Select

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

Intermediate (WTI) tightened on Wednesday, as commercial

operations got underway on the long-anticipated Trans Mountain

pipeline expansion (TMX):

* WCS for May delivery in Hardisty, Alberta, traded at

$11.75 a barrel below WTI, according to brokerage CalRock, after

closing at $12.20 a barrel below the benchmark on Tuesday.

* The Trans Mountain pipeline expansion project (TMX) began

commercial operations on Wednesday, and tankers will be able to

load at Westridge Marine Terminal in the Port of Vancouver by

mid-May.

* TMX nearly triples the flow of crude from Alberta to the

Pacific Coast to 890,000 barrels per day.

* Many analysts expect it will help tighten heavy crude

differentials to less than $10 a barrel below WTI by removing

export pipeline bottlenecks and forcing U.S. refiners to compete

with global buyers for Canadian barrels.

* Cenovus Energy ( CVE ) reported higher-than-expected

first-quarter profit due to increased production and refinery

throughput, and executives said the start-up of TMX would open

up new markets.

* Global oil prices fell about 3% to a seven-week low on a

surprise build in U.S. crude stocks, the prospect of a Middle

East ceasefire agreement and as hopes faded for near-term U.S.

interest rate cuts that could boost oil demand.