Qatar, the world's largest exporter of liquefied natural gas, is having to rethink its sales strategy because of a recent surge in U.S. natural gas production and focus on the Far East, where demand is growing.

This should pick up the slack from declining demand in the United States, a key customer, and be a major factor in building gas exports by the Arab producers in the Persian Gulf.

The U.S. Energy Information Administration reported recently that Qatar, Iran, Saudi Arabia and the United Arab Emirates account for 85 percent of the Middle East's gas production.

With more than 40 percent of the world's proven reserves, the Middle East is expected to account for a production increase of 15 tcf a year by 2035, the EIA noted.

This will be due largely to the growing demand in energy-hungry Asia, particularly China and India.

The boost in U.S. gas production stems largely from once inaccessible reserves of shale gas that can now be reached by advanced drilling technology.

In 2008, U.S. shale production soared by more than 70 percent to 2 trillion cubic feet a year. Five years ago the gulf supplied about 20 percent of U.S. gas. Today that's fallen to 9 percent and will likely slide further.

Qatar's export strategy had been built around the premise that the global demand for gas, particularly in the United States, would continue to grow.

"Something that was not factored into the equation was a sharp increase in U.S. gas output," observed the Middle East Economic Digest.

The EIA recently more than doubled its estimate of proven U.S. gas reserves to 827 trillion cubic feet in 2010.

Qatar's reserves are estimated at 899 tcf, most of it in the offshore North Field in the Persian Gulf, which extends northward to Iran's South Pars field.

That contains 900 tcf, making it the world's largest gas field.

The tiny emirate, lying between Saudi Arabia and the United Arab Emirates, currently has a production capacity of 77 million tons of LNG a year.

"Since taking the decision to develop its giant offshore North Field in the early 1990s, Qatar has banked on the global gas market to provide it with its hydrocarbon wealth," MEED reported.

"To deliver its gas to markets around the world it has built infrastructure, including a total of seven LNG trains, among them the world's four largest megatrains with a capacity of 7.8 million tons a year."

"Qatar was forced to change its whole LNG strategy" because of the growth of U.S. gas production, said Giles Farrar of Edinburgh-based energy consultants Wood Mackenzie.

"Its megatrains were sanctioned on the basis that it was going to ship large quantities to the North American and Northern European markets, at prices that are not that dissimilar to today's.

"The shale gas revolution changed that picture. The U.S. did not require any imports, so Qatar diverted its LNG to either Europe or to high-grade Asian markets."

In recent years, global demand for gas has grown steadily, from 84.72 tcf in 2000 to 112.9 tcf in 2010, according to the BP Statistical Review.

This is particularly true of Asia, and has been complicated by the absence of new sources of natural gas.

The Fukushima nuclear plant disaster in March, when Japan was hit by an earthquake and tsunami, has pushed Tokyo to switch to gas-fired power plants, boosting Asian demand for gas.

"We expect the market to tighten between 2013 and 2015, as there will be little new LNG supply coming to market," Farrar told MEED.

"As a result we believe some buyers will be forced to turn to Qatar in this time period as there will be no alternative supplier."

Meanwhile, Qatar's main rival, Iran, across the gulf, is having problems because of international sanctions imposed in June 2010 over its contentious nuclear program.

On Monday, the state-owned Iranian Offshore Oil Co. announced it has abandoned plans to build an LNG plant on Lavan Island in the south of the gulf because Western companies have pulled out of the project.

However, the EIA recently forecast the Islamic Republic's gas production would hit 9.4 trillion cubic feet a year by 2035, which could challenge Qatar.

Iran has reserves of 1,045.7 tcf, 15.8 percent of the world total and second only to Russia's.