Plummeting oil prices mean that two natural gas export projects in Cameron Parish that are already underway may be among the few such planned facilities in the U.S. that experts say will actually be built, potentially leaving $31 billion or more in other proposed Louisiana projects at risk of going undeveloped.

Eleven proposed Louisiana projects are among more than three dozen U.S. liquefied natural gas export facilities for which developers have filed federal permit applications. The nine that have yet to break ground could all be at risk, experts say.

“No matter how many permits the U.S. Department of Energy issues, probably no more than five or six LNG export plants will materialize in the United States through 2020,” Harvard researcher Leonardo Maugeri wrote in a December paper.

At least one LNG project, in Texas, already has been delayed.

The 30-plus LNG projects around the nation were aimed largely at capitalizing on a yawning disparity between oil prices and natural gas prices, a gulf that has shrunk dramatically in recent months.

The plunging price of oil was also a major factor in the Wednesday announcement by the South African energy giant Sasol that its proposed $14 billion gas-to-liquids plant outside Lake Charles would be delayed. That plant, though different because it would make diesel, naphtha and other chemical products, was also predicated in part on a big split between oil and gas.

Of the 38 liquefied natural gas export projects planned across the country, only four are under construction, including Sabine Pass Liquefaction and Cameron LNG in Louisiana and one facility apiece in Maryland and Texas. Sabine Pass and Cameron LNG will have a combined cost of $24 billion. They promise a total of 540 permanent jobs, and at their peak will employ 7,500 construction workers.

“The key to these projects is that they’re first movers,” said Gregory Remec, senior director for Fitch Ratings. “They’re moving ahead, and they’ve already got their construction plans largely in order.”

The Louisiana plants have secured federal permission to export liquefied natural gas to Asia and Europe, key markets where natural gas fetches the highest prices. LNG is used primarily to fuel power generation plants. It serves as an alternative source of energy that is cleaner than coal and cheaper than oil — an advantage that has diminished considerably with crude prices dropping by more than half since the summer. Natural gas prices overseas also have fallen, making America’s relatively inexpensive gas less of a factor.

Despite those setbacks for the LNG sector, Sabine Pass and Cameron have key advantages most proposed competitors don’t, Remec said.

Most importantly, the two have signed long-term supply contracts with buyers for basically all of their LNG exports, which help secure financing for constructing the multibillion-dollar facilities.

Another advantage both share: They are being added to existing import terminals that were constructed years ago to bring LNG into the U.S., before advanced drilling techniques unleashed a glut of oil and natural gas production in this country and made importing gas unnecessary. Having most of the infrastructure needed in place lowers construction costs.

The projects that have secured supply contracts are the ones Fitch Ratings believes will be completed, Remec and others said.

“If you’re a company developing, and you’ve got long-term contracts … you may do that deal,” said David Dismukes, executive director of the LSU Center for Energy Studies. “But if you don’t have contracts now, in hand, you’re not going to do it.”

Long before oil prices collapsed, Dismukes and some other energy industry experts maintained that only a fraction of the proposed projects would actually be built because of the huge numbers being proposed internationally.

Worldwide, developers have proposed plowing $200 billion into LNG export facilities, adding roughly 220 million tons of annual LNG production, a 66 percent increase.

That looks much less likely today in a world of plunging oil and overseas natural gas prices.

LNG export economics rely on the margin between U.S. natural gas and international oil prices. In the past few years, that spread has been generous. U.S. natural gas prices have been about $4 per thousand cubic feet, with oil around $100 a barrel. That price difference meant that producing the same amount of energy from oil cost roughly four times as much as natural gas.

But as crude prices cratered over the last six months, the oil-to-gas price ratio has shrunk. Oil has dropped to under $50 per barrel, while natural gas in the U.S. is hovering near $3 per thousand cubic feet.

The LNG export picture also has been complicated by falling natural gas prices in Asia. The price has plunged to around $10 per thousand cubic feet, 50 percent less than year-ago levels and the lowest price seen in four years. Low oil prices, a mild winter in Asia and production from a number of new LNG facilities in places like Australia led to the price decrease.

That price decline to $10 has helped erode the advantage U.S. exports once had. With a U.S. natural gas price of $4 per thousand cubic feet, a number of proposed export facilities could deliver gas between $10 per thousand cubic feet to Europe and $12 per thousand cubic feet to Asia, according to Maugeri, an associate with the Geopolitics of Energy Project and the Environmental and Natural Resources Program at the Harvard Kennedy Center’s Belfer Center for Science and International Affairs.

Those prices for U.S.-exported natural gas factor in liquefaction-related costs: the gas itself, the expense to cool the gas to minus 260 degrees to make it a liquid, shipping the LNG by sea and then regasifaction by warming the liquid to turn it back into a gas.

Dismukes noted that developers found U.S. LNG projects attractive because of the expected high internal rates of return on their investments. Even if an LNG export facility could break even at current prices, that’s not the kind of return anybody wants from a multibillion-dollar investment, he said.

Maugeri says he believes the 220 million tons of announced new global production is overblown. He estimates that at most 66 million to 77 million tons of production will be added.

“Huge cost overruns, poor planning, changing market conditions and emerging skinny margins will likely kill many projects across the world, or postpone their materialization to an uncertain future,” he said. Canadian projects likely will be the hardest hit. Of the 15 proposed Canadian LNG export facilities, none have reached a final investment decision.

Maugeri also wrote: “Cheap shale gas makes U.S. export projects cost-competitive, but few will survive.”

The dominoes are already falling. In December, Houston-based Excelerate Energy placed its Lacava Bay, Texas, facility on hold. That same month, plans for an LNG export terminal in British Columbia, Canada, were abandoned by Malaysia’s state-owned oil company.

All of the factors at play could determine what happens with a third Louisiana project, Lake Charles Exports.

Like Sabine Pass and Cameron LNG, the project has already won federal approval to export to key countries not covered by free trade agreements. The other eight proposed facilities in Louisiana have yet to reach that stage.

In addition, Lake Charles Exports would be built at the site of an existing import site.

Energy Transfer Equity and Energy Transfer Partners will own and finance the project. BG Group and the Energy Transfer companies plan to market all of the LNG from the facility. The companies expect to make a final investment decision on the export facility this year.

Although some reports show the project has deals in place for its LNG, BG spokesman Kim Blomley said the company manages its LNG contracts a little differently than some competitors.

“Our LNG is not typically contracted to a destination but goes into our global flexible supply portfolio,” Blomley said. “This means our customers are not tied to the output of a single LNG plant and it gives us the opportunity to maximize the value of the overall portfolio.”

Follow Ted Griggs on Twitter, @tedgriggsbr.