U.S. Oil Warehouses Swell 6.2 Million Barrels in Biggest Weekly Build Since 2023

U.S. Crude Stockpiles Leap 6.2 Million Barrels, Largest Weekly Gain Since November 2023

• Commercial inventories jumped to 449.3 million barrels in the week ended March 13.
• The build was the mirror opposite of the 0.9 million-barrel draw analysts expected.
• Front-month WTI futures promptly fell $1.54 to $66.80/bbl, erasing a two-week rally.
• Stocks are still 1 % below the five-year average, but the gap is narrowing fast.

Sudden surplus rekindles oversupply talk as refinery maintenance peaks.

EIA WEEKLY DATA—U.S. crude-oil stockpiles surged by 6.2 million barrels last week, the Energy Information Administration reported Wednesday, confounding Wall Street’s consensus for a modest decline and sending futures prices into a tailspin.

The weekly build pushed commercial inventories to 449.3 million barrels—the highest level since early January and the steepest one-week increase since late 2023.

Within minutes of the 10:30 a.m. ET release, front-month West Texas Intermediate tumbled more than 2 % to settle below $67 per barrel while the Brent-WTI spread widened to $4.20 in favor of the global benchmark.

Analyst Consensus Missed the Mark—What Went Wrong?

Every Tuesday a poll of 30-plus analysts conducted by Reuters, Bloomberg and S&P Global Commodity Insights sets the market’s baseline expectation for EIA data. Ahead of the March 13 release, the median forecast called for a 0.9 million-barrel draw, with individual estimates ranging from a 3.0 million-barrel decline to a 1.5 million-barrel build. None anticipated a 6.2 million-barrel surge.

Claudio Galimberti, senior vice-president of oil markets at Rystad Energy, told clients the miss stemmed from “an overestimation of refinery demand and an underestimation of import resilience.” U.S. crude imports averaged 6.7 million barrels per day (bpd) during the week, up 340 000 bpd from the prior seven days and the highest since late December. At the same time, refinery utilization slipped 0.6 percentage points to 87.4 % of capacity, trimming crude runs by 185 000 bpd.

The divergence flipped the implied supply-demand balance into a 7.1 million-barrel surplus, the widest since last October. “Markets priced for a deficit were forced to recalibrate risk premiums within minutes of the release,” Galimberti said. Historical data show similar consensus misses occur roughly once a quarter, but a miss of this magnitude has not happened since April 2023, when a 5.9 million-barrel build blindsided traders and sent WTI below $70.

Part of the surprise can be traced to fog-related delays in Houston ship channel loadings the prior week, which pushed about 3 million barrels into the latest survey period. Add weaker-than-expected runs at Midwest refineries undergoing spring turnarounds, and the physical balance quickly loosened. “It’s a reminder that the margin for error in weekly data is still plus or minus 5 million barrels,” said Jenna Delaney, senior oil analyst at Energy Aspects.

Implication: The scale of the forecast error underscores how opaque weekly supply chains have become after years of pandemic disruptions, sanctions reshuffling and export-policy shifts. With implied volatility at a three-month high, expect choppy trading to persist through summer as investors reassess physical balances and the Federal Reserve’s rate path.

Strategic Petroleum Reserve Stays on the Sidelines

The EIA figures exclude the 395 million barrels held in the Strategic Petroleum Reserve (SPR), focusing instead on commercially held stocks. Since the Biden administration ceased emergency releases in mid-2023, the SPR has become a static line item, but traders still monitor it for policy signals. Energy Secretary Jennifer Granholm reiterated last month that refilling the reserve is “not imminent” while prices hover above $65.

Analysts at ClearView Energy Partners estimate the government would need to purchase 1.0–1.5 million bpd over six months to return the SPR to pre-2022 levels, a pace that could tighten global markets by 3 %. Instead, Congress has authorized only marginal 3-million-barrel test buys, leaving the reserve 45 % below 2021 levels and the lowest since 1983.

Meanwhile, the law requires any future SPR purchases to be priced at or below the five-year average—currently around $62.50 for WTI. With front-month futures settling at $66.80 after the inventory data, the window for cheap refills has yet to reopen. “Politically, there is little appetite to buy high after selling low,” said Kevin Book, managing director at ClearView.

Market purists argue the SPR should be reserved for genuine supply disruptions, not price management. Yet the absence of a buffer means weekly commercial swings carry more weight. “Every million-barrel surprise today moves futures twice as much as it did in 2019 because the SPR cushion is gone,” Book added.

Bottom line: With the SPR sidelined, weekly swings hinge almost entirely on commercial stock movements, amplifying the market impact of today’s 6.2 million-barrel build and raising the probability of more violent price spikes should geopolitical risk escalate.

How Does 449.3 Million Barrels Compare Historically?

While 449.3 million barrels sounds large, context matters. The EIA benchmarks weekly data against a trailing five-year average for the same calendar week. On March 13, commercial stocks were 1 % below that average, meaning the market is still working off a modest structural deficit accumulated during 2022–23 refinery outages and record export surges.

Looking further back, the all-time high of 535 million barrels was set in March 2020 when pandemic lockdowns crushed demand and floating storage ballooned. Conversely, the 2022 low of 413 million barrels coincided with post-Ukraine invasion price spikes and the largest SPR drawdown in history. Today’s level sits roughly in the 55th percentile of the past decade’s range.

Seasonality also plays a role. Between mid-February and mid-April, refineries typically conduct turnarounds ahead of summer driving season, so crude stocks normally build by 15–20 million barrels. The current trajectory is tracking the upper end of that band, suggesting another 8–10 million barrels could be added before draws begin in May.

Forward curves reinforce the point. The WTI Dec-25/Dec-26 spread has softened to a 90-cent backwardation from $1.40 last month, indicating traders expect looser balances later this year. Yet if inventories breach 460 million barrels—a level last seen in July 2021—contango could deepen, incentivizing onshore storage plays in Cushing, Oklahoma.

Forward outlook: If refinery maintenance peaks this month as scheduled, inventories could climb another 10–15 million barrels before drawing down during summer driving season, according to Wood Mackenzie analyst Alan Gelder. That trajectory would push stockpiles toward the upper end of the five-year band, capping rallies in Brent and WTI unless OPEC+ intervenes.

What the Build Means for Gasoline and Diesel Prices

Crude is only half the story. Refinery yields determine how much of that oil reaches motorists. The same EIA report showed gasoline inventories fell 2.1 million barrels to 226.4 million, tightening supplies ahead of spring-break travel. Distillate stocks—diesel and heating oil—also dipped 1.4 million barrels to 117.2 million, 8 % below the five-year average and the lowest for March since 2014.

“Refiners are choosing to maximize diesel margins, which are trading $20 per barrel above gasoline in the Gulf Coast,” said Robert Campbell, head of oil products at Energy Aspects. The result: pump prices may not fall as quickly as crude futures. AAA data put the national average for regular gasoline at $3.28 per gallon on Wednesday, down only half a cent despite the 2 % slide in crude.

Ultra-low-sulfur diesel on the Gulf Coast averaged $2.76 per gallon, up 4 cents week-over-week, and forwards suggest summer spreads could widen further if European imports stay thin. The East Coast is particularly exposed; inventories there are 15 % below normal after the Phillips 66 Bayway refinery ran at reduced rates during February maintenance.

Consumer-facing metrics reinforce the stickiness. Gasoline demand, measured by product supplied, rose 450 000 bpd to 9.1 million, the highest since late 2022, even as refiners produced 90 000 bpd less. That divergence whittled days-of-cover down to 25.3 from 27.1 the prior week.

Consumer takeaway: Expect limited relief at the pump unless crude builds persist long enough to compress crack spreads and incentivize refiners to swing output toward gasoline rather than diesel.

Could OPEC+ Respond to the U.S. Surplus?

OPEC+ ministers next meet on April 3 to review output quotas. The 6.2 million-barrel U.S. build, combined with similar stock increases in Europe and Singapore, strengthens the case for the group to extend current 2 million bpd cuts through mid-2025. Saudi Energy Minister Prince Abdulaziz bin Salman has repeatedly flagged OECD commercial stocks as a key metric for policy tweaks.

Yet internal divisions complicate action. The UAE has capacity to raise output by 0.6 million bpd and has lobbied to use it, while Russia’s compliance with agreed cuts has slipped to 40 % in February versus 80 % a year ago. A survey by S&P Global found traders now assign a 55 % probability that OPEC+ rolls over existing curbs, down from 70 % before today’s data dump.

Market positioning adds urgency. Money managers have cut net-long Brent positions to 210 000 lots, the lowest since 2020, implying limited downside cushion if physical oversupply snowballs. “Another surprise build next week could force OPEC+ into an emergency teleconference,” said Helima Croft, head of commodity strategy at RBC Capital Markets.

Logistics also matter. Saudi Aramco has already trimmed April official selling prices to Asia, a move seen as pre-empting market-share defense. Meanwhile, Iraqi exports through Ceyhan are resuming after a three-week pipeline outage, potentially adding 400 000 bpd to Mediterranean supply.

Market signal: If U.S. inventories post another 5-million-barrel-plus gain next week, expect a flurry of ministerial phone calls aimed at jaw-boning prices back above $70 or risk unraveling the year-long stability that underpinned Saudi fiscal planning.