CALGARY, Alberta, Feb 8 (Reuters) – Oil inventories at Canada’s largest storage site are on the rise as discounts for the crude plumb new depths, a company that tracks tank volumes across North America said on Wednesday.

Oil volumes at the Hardisty, Alberta, storage site have climbed 350,000 barrels on the week to 8.2 million, which puts capacity use at 48 percent, said Abudi Zein, senior vice-president at Genscape.

That is about midway between the 2011 highs and lows, but the trend is up as production volumes rise in Western Canada and volumes also grow at the Cushing, Oklahoma, storage hub, depressing prices for land-locked crude supplies in many parts of the continent, Zein said.

Last year’s high was about 11 million barrels in August and the low was about 5.8 million in December, he said.

Over the past week, Western Canada Select heavy blend for March deliver has fallen past $35 a barrel under benchmark West Texas Intermediate and has lately hovered in the low $30s per barrel under WTI.

Light synthetic has fallen into the low $20s per barrel under WTI, reaching record discounts. It sold for a premium as recently as December.

“My impression is that one of the guiding factors is basically absence of disruption. There have been no accidents in an industry that has been accident-prone and that has built up supplies and they have to go somewhere,” Zein said.

CALGARY, Alberta, Feb 7 (Reuters) – Tight oil pipeline capacity, surging output in Canada and in North Dakota and reported refinery outages have pushed discounts for Canadian crude to new depths, but the painful spreads for producers won’t likely be permanent.

Light synthetic crude for March delivery was selling for a bargain-basement $20 a barrel under benchmark West Texas Intermediate crude on Tuesday, compared with a record of $22 a barrel under WTI a day earlier.

Reports of an unscheduled outage at Canadian Natural Resources Ltd’s Horizon oil sands plant tightened spreads a bit on Tuesday, but as recently as December the crude sold for a premium to WTI.

At today’s U.S. price, the crude wrung from the Alberta oil sands and upgraded into refinery-ready feedstock was fetching around $78.50 a barrel on an absolute basis, or just 68 percent of the international benchmark Brent oil price.

Western Canada Select heavy crude was hit too. It sold for $31.25 a barrel under WTI, representing a gain from Monday when it sank to $35.50 under. It was worth $17.70 under WTI a month ago.

The drops are steep, and analysts see many of the reasons as short-term. But they are indicative of a coming squeeze in pipeline capacity for Canadian oil, as politicians, the industry and environmental groups battle over building new pipelines into the United States and to the Pacific Coast.

Meanwhile, the price difference between WTI and international benchmark Brent has also ballooned again due to clogged pipeline and storage capacity in the U.S. Midwest and Midcontinent regions, where much of the Canadian supply gets refined or stored.

CALGARY, Alberta, Feb 7 (Reuters) – Canadian Natural Resources Ltd’s Horizon oil sands plant in northern Alberta is shut down for unplanned repairs and could be off line for two to three weeks, a source with knowledge of the situation said on Tuesday.

The outage pushed up U.S. oil prices and pressured Canadian Natural shares, which fell as much as 5.2 percent. By early afternoon they were down C$1.69, or 4.2 percent, at C$38.59 on the Toronto Stock Exchange.

“It’s off, and probably for two to three weeks,” the source said.

The shutdown of the 110,000 barrel a day plant, the fourth-largest Canadian tar sands mining and crude processing venture, came as discounts for the synthetic oil had been deepening due to booming industry-wide supplies.

The work, which is said to be concentrated on one of the fractionation towers, follows weekend maintenance at the site. The plant was down for seven months in 2011 following a fire early that year.

Canadian Natural officials were not immediately available for comment.

Talk of the disruption helped prompt a spike in benchmark West Texas Intermediate of nearly $3, narrowing the Brent-WTI spread from a three-month low under $20 to around $18 a barrel.