(Adds Penn West layoffs, quote)
By Nia Williams
CALGARY, Alberta, Sept 1 (Reuters) - ConocoPhillips and Penn West Petroleum are eliminating a combined 900 jobs in Canada, the two companies said on Tuesday, as low oil prices persist.
Both companies said most of their cuts would come from their offices in Calgary, the corporate capital of Canada's 3.7 million barrel-per-day oil industry.
Global oil major ConocoPhillips is laying off 400 employees, 15 percent of its Canadian workforce, and 100 contractors.
Spokesman Rob Evans said the cuts, which staff were told about on Monday, would take effect in mid-October.
"We had previously informed staff that there would be reductions by the end of the year, so yesterday's announcement was meant to add context and clarity to that conversation," Evans said.
ConocoPhillips, which has oil sands operations as part of its international portfolio, is reducing its global workforce by 10 percent on average because of low oil prices.
News of the cuts came on the same day the company announced first oil at its new Surmont 2 thermal project in northern Alberta.
Light-oil producer Penn West said it would lay off about 400 employees and contractors that make up 35 percent of its workforce.
Many oil industry workers were bracing for a fresh round of layoffs in September after global crude benchmarks plunged to 6-1/2-year lows in August.
U.S. crude was last trading at $45.61 a barrel, down more than 50 percent since the slide started in June 2014.
The third quarter is typically the time when companies complete their spending plans and budgets for next year.
Alberta alone has lost more than 35,000 oil patch jobs this year, according to the Canadian Association of Petroleum Producers. (Reporting by Nia Williams; Editing by Lisa Von Ahn)