Crude oil and energy-sector exchange traded funds rallied Wednesday after an unexpected fall in U.S. oil inventories.

On Wednesday, the United States Oil Fund (NYSEArca: USO), which tracks West Texas Intermediate crude oil futures, gained 4.0% and the Energy Select Sector SPDR (NYSEArca: XLE) and rose 3.9% as WTI crude oil futures increased 3.9% to $37.5 per barrel.

Leading the charge in the energy sector, smaller companies and oil services surged, with the Market Vectors Unconventional Oil & Gas ETF (NYSEArca: FRAK) up 7.1%, SPDR S&P Oil & Gas Exploration & Production ETF (NYSEArca: XOP) 6.9% higher and PowerShares S&P SmallCap Energy Portfolio (NasdaqGM: PSCE) up 6.5% Wednesday.

Crude oil and the energy industry were advancing after the Energy Information Administration revealed crude oil inventories declined by 5.9 million barrels in the past week, compared to expectations of a 1.1 million barrel draw, Reuters reports.

The energy sector, notably oil explorers and more unconventional shale companies, have taken the brunt of the hit from falling crude oil prices. For instance, PSCE plunged 48.2%, FRAK fell 40.8% and XOP plummeted 38.4% so far this year, whereas the broader XLE fell 22.5%.

With oil prices recently hitting 11-year lows, oil companies have been cutting back on expanding projects, which have hurt the explorers and producers space. Meanwhile, the depressed prices have weighed heavily on unconventional oil producers, like the nascent shale oil industry, which have much higher overhead costs that require higher prices to break even.

U.S. WTI crude oil futures are also trading above Brent crude oil for the first time in five years. Brent settled below U.S. crude for the first time since August 2010 Tuesday and was hovering around $37.5 per barrel, its lowest since 2004.