The largest oil refinery in the US is shutting down because of flooding from Harvey

Motiva's refinery in Port Arthur, with a capacity of 603,000 barrels a day, began shutting down at around 5 a.m. CT on Wednesday "in response to increasing local flood conditions," according to The Wall Street Journal. Motiva is owned by Saudi Arabia's state oil behemoth Saudi Aramco.

The refinery began winding down production by at least 60% on Tuesday, according to the Houston Chronicle.

Eighteen refineries have been closed or partially closed in Texas as of Wednesday morning, including Port Arthur, according to analysts at BMI Research.

"The largest impact to energy markets is severe flooding, which has resulted in the closure or part-closure of nearly 25% of the United States' refinery capacity," the analysts wrote in a note to clients.

"As Harvey heads inland once again, we note a number of refineries in its current trajectory will be under threat," they added. "This could close up to another 824,000 barrels per day (b/d) of capacity, giving an additional lift to fuel prices, while further depressing crude."

Harvey has had a greater effect on refining than on production, and this is why oil prices have been trickling downward, moving opposite gasoline prices, according to a research team at LPL Financial.

Oil prices usually tick up when severe weather hits areas with heavy concentrations of oil businesses. However, prices have been moving lower over the past few days. West Texas Intermediate crude oil, the US benchmark, was down 1.1%, at $45.94 a barrel, at 10:44 a.m. ET.

US gasoline futures, on the other hand, earlier Wednesday shot up to their highest level since July 2015. Although they have since pulled back slightly, they have been on an upward trajectory since Harvey first made landfall on Friday.

The team at LPL Financial explained that discrepancy in a recent report (emphasis ours):

"As refineries have been shut down (due to damage, the inability for workers to reach them, or the inability to get gasoline out of them) a lack of demand for oil has been created. In turn, this has increased the amount of oil in storage waiting to be refined, thereby depressing prices. On the other side, refiners' inability to produce and distribute gasoline and other refined products is weighing on supply and driving those prices higher. The chart below shows the difference between the price of oil and the price of gas, which generally tend to move together, but at times — and especially now — have diverged considerably, and the impact of refinery shutdowns on the price of gasoline."