Energy stocks are having their best day of the year – here are Wall Street's best buys from here

Energy stocks, one of the worst-performing sectors this year, spiked on Monday after an attack on Saudi Arabia's heart oil production.

The S & P Oil & Gas ETF Production jumped nearly 11%, posting its best day of the year, while the S & P energy sector moved out of the market and scored its best session of 2019.

An oil processing facility at Abqaiq and the nearby Khurais oil field was attacked on Saturday, knocking out 5.7 million barrels of daily crude oil production or more than 50% of the world's total daily exports. The gross disruption Brent crude oil up as much as 19%, its biggest intraday jump in history.

The rally in the energy sector is led by small-and-mid-cap explorers that are heavily shortened, according to Citi analyst Scott Gruber. These stocks include Oil & Gas Extraction and Whiting Petroleum, which are soaring 28% and 49% respectively.

Oil explorers are typically a riskier segment in the energy sector given their growing pile of debt. Investors looking to play the oil, said Goldman Sachs energy analyst Brian Singer.

Explorers with those characteristics and also rated by Goldman include Brigham Minerals, Murphy Oil and Continental Resources, Singer said.

The soaring oil are also good news for offshore oil drilling companies. Transocean, Valaris and Diamond Offshore Drilling are all climbing more than 10% on Monday.

"Long cycle offshore activity should be less severe if the tools / geopolitical risk premium is maintained for an extended period while structural oversupply remains," Gruber said. "Thus the bounce in the offshore drillers could fade before other sub-sectors."

Goldman highlighted Kosmos Energy among the drillers as it's already "silded" with a possible positive impact, Singer said. Kosmos Energy is up more than 9% Monday.

For oil majors, Goldman expects ConocoPhillips to have the worst oil price in the world. The stock is up 9% on Monday.

"We also see a positive set up in the company's November commentary on robust free cash flow at a lower crude environment," Singer said.

Canadian oil companies will also benefit, Singer added. Canadian Natural Resources may have "disproportionate stock reactions" given its elevated leverage, he noted. Its stock jumped 12% Monday.

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PBF Energy and Valero Energy, which dropped 9% and 3.6%, respectively, are among the refiners of Saudi crude, Singer said.

"For refiners, duration of Saudi output will be key to assessing the extent of the financial impact," Singer said. "Inland refiners should be more protected from domestically barrels.