(Bloomberg) -- Even in the closely knit energy industry they are virtually unknown. On the streets of Geneva, London and Houston they go unrecognized. Yet a handful of executives were oil-industry standouts in 2015. They thrived because of — not despite — plunging crude prices.

From Total SA to Trafigura Group Pte, trading emerged as the industry’s cash cow.

Take Vitol Group BV, the world’s largest independent energy-trading operation. The 50-year-old company reported net profit of $1.6 billion last year  the fourth highest ever, buoyed in part by the strategies employed by the teams headed by Mark Couling, chief oil trader.

“The oil trading industry as a whole enjoyed the best year since 2008-09,” said Damian Stewart, managing director at Human Capital, a commodities-focused headhunter.

Oil traders were rewarded by a surge in volatility. They also capitalized by holding onto crude to take advantage of the market contango  a situation where future prices are higher than current prices  allowing them to buy oil cheap, store it in tanks to sell later and locking in a profit via derivatives.

Vitol hired one of the world’s largest tankers, the Overseas Laura Lynn  a 380-meter-long vessel (about equal to the Empire State Building laid on its side) capable of carrying 3 million barrels of oil  to store crude offshore of Dubai. Competitors including Glencore Plc prospered by hiring capacity on land from St. Lucia in the Caribbean to Saldanha Bay in South Africa.

Glencore Profit

Look also at Glencore Plc, the world’s largest commodities trader. While its mining business suffered, Alex Beard, head of oil, saw its energy trading earnings before interest and tax rising to $778 million last year, up 49% from 2014. The company profited from "high market volatility, entrenched contango, a decent refinery margin environment and promising returns on tanker freight," Glencore said.

“A combination of low prices and contango is great for traders,” said Olivier Jakob, managing director of Petromatrix AG, an oil consultant based in Zug, Switzerland. “It is a profitable environment.”

It wasn’t just the independent houses. Although better known for their oil fields, refineries, and petrol stations, BP Plc, Royal Dutch Shell Plc and Total SA are also the world’s biggest oil traders.

While the companies disclose little about their trading performance, BP Chief Financial Officer Brian Gilvary offered a glimpse in February of the 2015 riches. He said that the in-house trading arm enjoyed "one of the highest results we have seen for some time.” Key was Donald Porteous, the departing head of crude oil and a dominant trader in West Texas Intermediate.

Trading Surge

In the first quarter of last year alone, BP’s trading profits surged $350 million above what the company considers the “normal” level, Gilvary said. The sum was equal to almost 15% of the company’s total quarterly adjusted profit.

Thomas Waymel, the head of Total Trading SA, a Geneva-based unit of the French company, oversaw an increase of almost 8% in crude and refined products trading volumes -- in the 2015 market, more volumes may have easily translated into higher profits. At Shell, the trading teams lead by Mike Conway, head of Shell’s trading and supply business, contributed healthy profits as the rest of the business suffered under the weight of lower oil and gas prices.

It was at the independent oil trading houses where the good times were most visible.

At Singapore-based Trafigura, the oil-trading team lead by Jose Laroca had its best year ever. Their gross profit soared 50% to $1.7 billion in the year through September. Other top traders there include Ben Luckock, global head of crude, and Rob Gillon, global head of middle distillates.

Former Marine

At Mercuria Energy Group Ltd., global head of oil trading Kurt Chapman  a Harvard University economics graduate and former U.S. Marine  had his best year since 2009, according to a person with knowledge the situation. Overseeing a team of about 10 people in Geneva and colleagues positioned across the globe, Chapman profited from storage opportunities and price volatility, particularly in North Sea oil, they said.

Gunvor Group, where Jose Orti is head of crude oil trading, reported its best ever year, boosted by asset sales. But underlying trading and refining profits were also strong, up 10% from 2014. "Gunvor had a number of desks that did very well in 2015, in addition to refining and other areas,” said Seth Pietras, a Gunvor spokesman in Geneva.

Jeff Frase and Mitch Rubinstein at Noble Group oversaw a banner year in oil and energy trading from the U.S.  a rare bright spot for Asia’s largest commodity trader, which spent much of the year reeling from allegations of aggressive accounting as well as dismal results from its coal and metals-trading units.

As always, though, each trader began 2016 with a blank slate and this year may prove more challenging. Contango, for example, is diminishing. And volatility isn’t as high. Yet, despite the obstacles, Ian Taylor, Vitol CEO, said: "Opportunities in the physical market continue to exist."