AAP

Origin Energy Ltd has reported an improvement in September quarter revenue compared to the previous period due to better prices for all of its products.

Revenue for the oil and gas producer and retailer for the three months to September 30 was $146.2 million, up eight per cent from $135.3 million for the June quarter because of improved product prices.

The company produced 25.4 petajoules equivalent (PJe) of gas, up slightly from 25.2 PJe in the June quarter.

Over the year, however, output and revenue slumped by 25 per cent and 26 per cent, respectively.

This was mostly due to the effect of the sale of half of its coal seam gas (CSG) interests in October 2008 into an equal joint venture with US energy giant ConocoPhillips.

The equal joint venture, named Australia Pacific LNG Pty Ltd (APLNG), converts CSG to liquefied natural gas (LNG).

Origin also said in its third quarter production report on Wednesday that the budget had blown out for its 50 per cent held Kupe gas project under development south of New Zealand's Taranaki Peninsula.

"The estimated cost of the project on completion has increased approximately 10 per cent," it said.

The project was previously expected to cost $NZ1.2 billion ($A974.4 million).

Origin said the project was on target to bring raw gas ashore in the December quarter.

Chief executive of the Kupe joint venture partner New Zealand Oil and Gas (NZOG), David Salisbury, said the project had been a long time coming but would provide a solid income stream for the next 15 years.

"The Kupe field was discovered by NZOG way back in 1986 but for a long period was uneconomic to develop," Mr Salisbury told the company's annual general meeting in Wellington on Wednesday.

"Twenty three years on, and NZOG and its shareholders are about to be rewarded for their perseverance."

NZOG has a 15 per cent stake in the project.

Origin shares closed down 10 cents at $15.82, while NZOG inched 1.5 cents higher to $1.395.