SINGAPORE-The crowd gasped as the brokers swung the wooden mallets on the lid of the sake barrel, cracking it open in celebration. "Everyone please give them a hand," the MC said, as Japanese liquor was passed around.

The party, held in the Rendezvous Hotel, was hosted by BGC Group, a U.S.-listed brokerage whose fortunes have boomed since the Iran war upended global energy markets.

It isn't the only one. The Middle East is locked in an intractable conflict and oil prices are rising, bringing pain to consumers around the world. But it is good times for those who produce, trade and ship oil. Across Singapore this past week, traders and brokers toasted an industry that has faced its biggest-ever shock, yet for some is delivering a bumper year.

"What we've seen this year is the biggest crude oil supply disruption in history," said Jim Burkhard, S&P Global Energy's head of crude-oil research. "When you have big dislocations like this, there's going to be opportunities."

Executives gathered in the wealthy city-state for S&P Global Energy's Asia Pacific Petroleum Conference, or Appec. The event was dominated by discussion of the Iran conflict and partial closure of the Strait of Hormuz, a waterway through which a fifth of the world's oil passed before the war. Singapore, a centuries-old entrepôt, has leveraged its location on the main Middle East-to-Asia oil-trade route to become a major energy trading and refining hub.

But the conference is increasingly defined by its sideshow of parties: galas in rooftop bars, museum mixers and dinners held in the city's colonial-era hotels.

This year, there was much to celebrate. High oil prices are benefiting producers-even some of those dependent on the Strait of Hormuz-by offsetting lower export volumes. Traders and shippers are demanding premiums to navigate riskier waterways. From their desks, brokers are profiting as buyers of jet fuel, diesel and gasoline mitigate wild swings in prices with derivatives.

During the conference, attendees watched as Brent crude-the global benchmark of oil prices-crossed the $100-per-barrel threshold, driven by fresh fighting between the U.S. and Iran. President Trump has criticized U.S. energy companies for making too much money from the war, and attendees in Singapore were wary of brandishing their stellar year.

To be sure, not everyone in the industry is winning. Some traders have made wrong-way bets on prices, and customers in Asia have had to pay up to get their hands on oil. But for the brokers sipping sake in Singapore, the chaos is an opportunity to cash in.

The week kicked off on Sept. 6 with golf at Sentosa Golf Club, hosted by the national energy company of the United Arab Emirates. The course is located on Sentosa, an islet off the coast of Singapore that acts as a playground for billionaires, with multimillion-dollar homes and a sleek marina hosting superyachts. Memberships at the club cost up to $600,000.

Iran has fired thousands of drones and missiles across the Persian Gulf at the U.A.E. this year. But its energy firm, Abu Dhabi National Oil Co., has weathered the crisis partly by transporting more crude through a land-based pipeline that runs from Abu Dhabi in the Persian Gulf to the port of Fujairah in the Gulf of Oman, cutting out the Strait of Hormuz. Adnoc's maritime logistics company is one of a buccaneering group staging daring "shuttle runs," where tankers make short trips moving oil from the U.A.E. and other Persian Gulf terminals to ports just outside Hormuz. From there, oil is transferred onto other vessels destined for global markets.

Those flows have unexpectedly grown into a substantial supply of crude that had until recently helped cap oil prices. They have also contributed to record-breaking profits for Adnoc's maritime arm. In the second quarter, the unit reported a net profit of $951 million, a fourfold increase on the same period last year.

One of Appec's hottest parties was organized by Oil Brokerage, a small commodities broker based in London with an office in Singapore. Guests were served Champagne as they walked into a hotel ballroom, according to one guest. It had a DJ booth and the branding "House of OB" behind it, according to pictures of the event. In another room, traders drank free beer and played darts, guests said.

At a separate event across town, BGC Group-the U.S.-listed broker formed two decades ago by current Commerce Secretary Howard Lutnick-celebrated its strong year with the barrel of sake. In recent earnings statements, BGC said that the Iran shock boosted a business that was already performing strongly.

Brokers can make more money during wartime as conflicts disrupt physical supplies of energy. That forces physical buyers of crude and oil products, such as airlines or refiners, to buy financial derivatives that hedge against price spikes. Brokers take commissions for each transaction, benefiting from the increased volume caused by buyers constantly trying to manage price swings.

At BGC's dinner event, elegant women in bright-red pencil dresses handed out drinks. Japanese chefs gave a loud heave-ho before slicing up a four-foot-long tuna to be handed out as sashimi to guests.

Marex, another financial broker experiencing a strong year, organized drinks and canapés at Lavo, a stylish Italian restaurant at the top of Marina Bay Sands, Singapore's iconic building of three skyscrapers with a boat-shaped cantilever perched across.

The biggest names in oil trading also hosted events in Singapore. Privately held commodities traders such as Trafigura and Vitol make money by buying oil from producers in one location at a low price and selling it later to buyers elsewhere who are willing to pay higher prices.

Many commodities traders also manage shipping logistics. Loading a supertanker with oil, transporting it from the Middle East to Asia and offloading it is no easy feat even in peacetime. During a war it can be highly complex and risky-vessels might be hit by drones, crew members could die and insurance costs are high.

However, market upheavals like this are exactly when independent traders who shift oil, natural gas and metals around the world and are willing to take the risks get to reap giant profits. Commodity traders often profit when prices in different regions and at different times move out of whack.

Vitol's chief executive, Russell Hardy, was one of the main morning speakers at the S&P conference last week, and the company entertained clients at the historic Raffles Hotel, which has hosted celebrities, artists and heads of state over the years and where the famous Singapore Sling cocktail was invented.

In June, Vitol transported millions of barrels of Iraqi crude. The move would help the Iraqi government-which was starved of cash and offering oil at a deep discount to traders who could move its crude out of the Persian Gulf-but also benefit Vitol, which could later sell it at a much higher price.

"If you're a trader, then your kind of USP is that you are the master of the physical barrel," said Tom Reed, head of oil-markets analysis at Argus Media. "You are able to identify a discrepancy in prices between regions or across timings," he said, adding, "you can make enormous amounts of money."

Trafigura, one of the largest commodity traders in the world, reported a 173% year-over-year surge in net profit for the six months ended on March 31. Mercuria Energy Group saw its unaudited profits for the nine months ended in June surge 122% from a year earlier, according to numbers seen by The Wall Street Journal.

It isn't just independent traders. Shippers who work with the traders to move cargo are also benefiting. Higher insurance costs and a shortage of shippers willing to cross the Strait of Hormuz have pushed costs up. Sailing an oil supertanker from Oman to South Korea topped $572,000 a day in mid-September-more than double February rates, according to Clarksons Research.

In recent years, listed European energy majors such as BP and TotalEnergies have also expanded their trading operations. Guests at Appec events discussed a major trade earlier this year that paid off for TotalEnergies. The oil trading business of the French energy giant observed the U.S. Navy amassing near the Persian Gulf at the end of February, just before the U.S. and Israel started their attack on the country, Patrick Pouyanné, Total's chief executive, said during a shareholders meeting in May.

"So they took a position that wasn't an easy one to take, which was to buy oil with debt when markets were saying that oil was going to go down," Pouyanné said.

A spokesperson for TotalEnergies declined to comment on its trading unit's earnings. In July, the firm said trading in crude oil and petroleum products delivered $500 million in "overperformance" in the second quarter, beyond what was normally expected.

In Singapore, TotalEnergies entertained guests at the Clifford Pier, a chandelier-lit hall overlooking the harbor. "It offers an extraordinary setting for unforgettable occasions," according to its website.