Shale consumption in the US last year accounted for 25 percent of the world's biggest economy's total energy use, from 1 percent in 2006, according to Chen Weidong, chief researcher at China National Offshore Oil Corp's research institute,

The revolutionary breakthrough in the US shale gas sector may soon turn the world's biggest oil importer into a net exporter of natural gas, Chen said.

The shale boom in the US attracted $22.8 billion in foreign investment to the sector from 2009 to January 2012, according to figures from US Energy Information Administration. In the same period, only $1.1 billion was invested in China's shale gas.

Compared with conventional gas, the exploration of shale gas requires more wells and larger-scale investment. In this regard, foreign companies' participation will help accelerate the development pace of the industry, Chen said.

In March, China National Petroleum Corp and Shell China Exploration and Production Co signed the country's first production-sharing contract for shale gas exploration in the Fushun-Yongchuan block in Sichuan province.

The two companies inked a joint assessment agreement to evaluate and assess the reserves of the block in 2010.

So far, most of the world's biggest oil companies, including Exxon Mobil Corp, Chevron Corp, BP Plc, and Norway's biggest energy conglomerate, Statoil ASA, are participating in China's shale gas development.

It is estimated that $6 billion in investment is required in 2015 alone to meet China's targets of 6.5 billion cu m shale production by then, Chen said. "There will be no gas coming out without capital flowing into the industry," Chen said.

The initial investment in exploration is huge. Drilling a well in Sichuan Basin, for instance, requires 60 million to 70 million yuan in capital. In some areas with poor infrastructure and more complex geological conditions, the investment can climb to as high as more than 100 million yuan.

"We're seeking to optimize technologies through innovation to downsize the investment to about 40 million yuan a well, but it takes time," said Ye Dengsheng, managing director of CNPC Chuanqing Drilling Engineering Co's downhole operation unit.

Drilling costs may rise to a very high level if the block is not adjacent to pipelines or LNG terminals, Ye said.

Since 2011, CNPC has drilled 18 wells in South Sichuan Basin located in southwestern China, which is one of the areas estimated to have the country's biggest shale gas reserves and is the major exploration focus at present. Other regions include the Ordos Basin in western China and Tarim Basin in northwestern China.

"We're considering simultaneous fracturing in several wells to cut costs and improve efficiency," Ye said.

On top of sky-high exploration costs, CNOOC's Chen pointed out that the shale gas industry is a "systemic" project, requiring more construction of gas pipes and LNG terminals to facilitate the transportation of the energy source.