PRICES for liquefied natural gas have "peaked for now", analysts say as Australia races to complete seven giant LNG export projects worth almost $200 billion and ponders further greenfield and expansion projects.

Citi oil and gas analyst Mark Greenwood has called the top of the LNG market, with competitors in the US and Africa posing a threat to the "traditional Asian pricing" that underpinned Australian developments such as the North-West Shelf in Western Australia.

While big falls were unlikely, Mr Greenwood downgraded earnings forecasts and valuations of Woodside Petroleum, Oil Search and Santos based on the lower long-term LNG price assumptions.

LNG has traditionally been sold from Australia to Asian markets such as Japan or Korea on long-term contracts struck at a proportion of the oil price - known as the "slope" - typically about 14.85 per cent. Citi said these prices would be difficult to achieve in a more competitive global LNG market and lowered its long-term slope projections from 14.5 per cent to 14 per cent.

This was higher than some forecasters who predicted slopes as low as 11-12 per cent, but recent deals, including Woodside's May sale of LNG from its Browse project to Japan's MIMI - struck in line with traditional Asian pricing - showed Asian customers continue to support Australian suppliers. North American LNG from unconventional fields had a lower calorific value than Australian LNG, Mr Greenwood noted.

But Asian customers also were increasingly vocal about the gap between the price of Australian LNG - typically north of $US14 per million British thermal units (mmbtu) - and lower US gas prices at the Henry Hub, recently above $US3/mmbtu. As a result, Henry Hub linkages were creeping into Asian LNG contracts, Mr Greenwood said.

Citi estimated BG Group's recent LNG sale to China's CNOOC, including of gas sourced from its Queensland Curtis project in Gladstone, was 25 per cent Henry Hub-linked and 75 per cent oil-linked.

Chevron's LNG sales from its Wheatstone project in Western Australia to Chubu Electric and Tohoku Electric were largely oil-linked but included a small Henry Hub linkage.