Flooding from tropical storm Harvey caused ongoing large-scale US refinery outages today, while crude prices have risen on the back of supply disruptions in Colombia and Libya.

Refinery shutdowns from the storm helped push US petrol prices to $1.7799 per gallon yesterday, the most since 2015, although they receded slightly to $1.7374 per gallon by 6.32am Irish time.

US West Texas Intermediate (WTI) crude futures rose 23 cents, or 0.5%, to $46.80 a barrel, after falling more than 2% in the previous session.

International Brent crude futures were up 21 cents, or 0.4%, at $52.10 per barrel.

Massive floods caused by Harvey forced several refineries to close along the US Gulf Coast, and while some refineries were starting to prepare for re-starts, heavy rains are expected to last through Tuesday and Wednesday after already causing catastrophic flooding in Houston.

Harvey, which has been downgraded to a tropical storm from a hurricane, has affected oil refiners more than crude producers.

Sources said Motiva Enterprises will decide this morning whether to shut the 603,000 barrel-per-day (bpd) Port Arthur, Texas, refinery, the nation's largest, because of flooding.

"US government statistics and media reports indicate that around 2-3 million bpd of refining capacity is offline or in the process of shutting down," Barclays bank said.

"More than 500,000 bpd of oil production... is offline," it added.

Barclays bank said the storm's impact was "likely to linger for several more weeks".

"The shuttering of refining capacity in the Houston area will have a large impact on demand for crude for a while," said Greg McKenna, chief market strategist at futures brokerage AxiTrader, adding it would likely "see crude inventories build up."

The United States has 141 oil refineries, with a total capacity of 18.6m bpd, according to the Energy Information Administration.

Texas is home to 30 of those with a capacity of 5.7m bpd.

The expected US crude build-up widened the WTI discount to Brent to $5.64 per barrel, its widest in over two years.