Altamira, Mexico — Prices for natural gas over the border in Texas are at historic lows, so what happened earlier this month at the Gulf of Mexico port of Altamira, Mexico, might seem to defy market logic.

Huge tankers arrived from distant Yemen and Nigeria to offload liquefied natural gas at a price four times the market rate for natural gas in the United States.

At Mexico’s two other liquefied natural gas terminals, on the Pacific coast, the same phenomenon occurs, with expensive, liquefied natural gas arriving from Peru, Indonesia, and even Africa.

It’s a sign of Mexico’s enormous energy crisis, even as oil remains the mainstay of the country’s economy. Mexico has huge natural-gas reserves, yet those reserves are largely untapped, and the nation is a net importer of the fuel.

Abundant supplies of natural gas at low prices lie just across the border, but US-Mexico pipelines are already handling all they can.

So Mexico is forced into the global market, importing natural gas from the far corners of the Earth. In short, Mexico is over the barrel on natural gas, made worse by a state-owned oil company that’s desperate to hunt for "elephants" – massive oil discoveries – rather than develop more humdrum, far-less-profitable natural gas fields.

The situation has pounded factories in Mexico’s industrial heartland, where state-owned Petroleos Mexicanos, known as Pemex, has limited natural-gas pipeline capacity. Last year, Pemex sent out more than 100 critical alerts asking industrial consumers, mainly around Guadalajara, to reduce their use of natural gas, resulting in vast accumulated days of lost productivity.

"That amounted to 42 days in the last year where they did not have natural gas," said Regulo Salinas, the head of the energy commission of Mexico’s Confederation of Industrial Chambers, an umbrella group representing industry. "Since they are at the end of the pipeline, there is not much that they can do."

President Enrique Pena Nieto on August 12th announced broad revisions to Mexico’s oil and natural gas industries to boost exploration and production and allow foreign companies to invest in risk-sharing contracts. But even if Mexico’s Congress approves the changes, it will take years for them to result in greater gas production.

Mexico, with slightly more than a third of the US population, consumes only an eighth of the 62 billion cubic feet of gas a day that’s used in the United States, Salinas said. The total length of its natural gas pipelines is just 2 percent of what crisscrosses the US.

"Gas demand grew quicker than expected because of low gas prices in North America. All of a sudden, industries in Mexico wanted to take advantage of the $4 gas you are seeing and they want to expand their industries," said Tania Ortiz Mena, the vice president of IEnova, a natural-gas infrastructure operator in Mexico.

"Pemex was not prepared to meet the unexpected and growing demand," she said. "The real solution is building more pipelines from the US And of course, the long-term solution is to produce more gas in Mexico."

Mexico is largely a silent observer in the shale oil revolution that’s unfolding in the US, primarily in Texas and North Dakota, holding out the promise one day of United States energy independence.

Much of the shale oil and gas formations under Texas extend into Mexico, and oil experts argue over whether the nation should invest in drilling in the scrublands of Coahuila state, as it lacks much of the technology and drilling rigs to do so. But experts do agree on one thing: Mexico has abundant shale gas.

The US Energy Information Administration estimates that Mexico has the world’s sixth-largest shale-gas reserves, thought to be 555 trillion cubic feet.

"Look at the map. Geology tells you that the Eagle Ford plate obviously continues into Mexico," said Ernesto Marcos, a partner in Marcos y Asociados, a Mexico City consulting firm, referring to a vast natural gas and petroleum field in southern Texas.

Marcos said, however, that big, lumbering Pemex is incapable of finding and tapping into unconventional gas resources economically.

A tanker ship prepares to unload its cargo of liquified natural gas docks at the port in Altamira, Mexico

"Asking Pemex to develop shale gas reserves is like asking an elephant to eat with chopsticks," Marcos said.

While hundreds of independent operators have flooded into Texas to coax out shale gas and oil through the process of hydraulic fracturing, or "fracking," of the underground rock layers, Pemex has been cautious in taking action.

"It’s been one of those, ‘ready, aim, study’ strategies by Pemex," said George Baker, a consultant and editor of Mexico Energy Intelligence, a newsletter out of Houston.

Because Pemex, which supplies the revenue for Mexico’s government operations, must look for higher-profit oil reserves, Baker said, it "has to pass up lots of opportunities that wouldn’t be passed up in Texas and Canada."

In addition to economic and technological considerations, Pemex must deal with tougher environmental constraints in arid northern Mexico than those in Texas.

"In Coahuila, there’s no water, and that’s where our shale plays are," said Miriam Grunstein Dickter, an energy expert at Mexico City’s Center for Research and Teaching of Economics. "We’d have to transport the water in pipelines to Coahuila to do the fracking, and we’re not a water-rich country."

So as Mexico settles on a strategy of urgently building more pipelines – the first phase of a 520-mile pipeline that will stretch from Agua Dulce, Texas, to central Mexico should be completed in December – and working out new legislation to attract private companies to its energy sector, huge cargo tankers arrive steadily at its liquefied natural gas terminals. Last week, it was the LNG EDO from Nigeria and the Seri Balqis from Yemen.

"We’re importing really expensive gas from Angola and Nigeria," Grunstein Dickter said. "We’re moving the tankers through Tierra del Fuego," at the far tip of South America – a very expensive journey – because they’re too large to pass through the Panama Canal.

In announcing his plans last month to open the energy sector to foreign companies, Pena Nieto noted that Pemex had proved to be incapable of both hunting for major oil discoveries and exploring and producing more natural gas.

"In the United States in recent years more than 9,000 wells have been drilled for the extraction of gas, while in Mexico only three, because only Pemex can do it," Pena Nieto said, referring to the monopoly that the country’s constitution grants the state company on all exploration and production.

Mexico used to be self-sufficient in natural gas, but now it imports a third of its needs. Shortages have hurt the steel, cement, glass, automotive, chemical, tire, cardboard, cooking oil, and agriculture industries, Economy Secretary Ildefonso Guajardo Villarreal said last month.

Without luring outside companies that have the technology to extract natural gas from unconventional reserves, "we’re going to lose competitiveness. We’re going to lose productivity in a very ferocious way," said Marcos, the energy consultant.

The higher costs of imported liquefied natural gas have had other impacts, as well. Electricity rates have soared in Mexico, for example. "In the United States, you can find places where electricity is half the cost of what it is in Mexico," said Marcos.

If Mexico succeeds in obtaining cheaper natural gas, it will have widespread collateral effects, allowing the development of other industries. "Nobody can build a plastics company if they can’t have an assured supply of ethylene, your raw materials," said the energy consultant.

Once natural-gas production and distribution can satisfy domestic demand again, he said, some industry will roar back to life. "You could see a rebirth of the petrochemical industry," Marcos said.