Origin Energy’s $25 billion liquefied natural gas (LNG) project in Queensland is now more than half finished.

Australia’s largest energy retailer says drilling of coal seam gas wells in central and south west Queensland was 50 per cent complete at the end of September.

Construction of the Origin-operated Australia Pacific LNG plant, and dredging around Curtis Island off the coast at Gladstone, was 54 per cent complete, it said.

The project is due to start exporting in mid-2015, and will ramp up to 9 million tonnes of LNG per annum.

Origin says the project will double its cashflow and revenue, that current comes mostly from its gas and electricity generation and retailing operations.

Gas users, especially businesses in the NSW manufacturing sector, are worried that the suite of LNG export projects will leave a supply shortfall as export prices jump.

But Origin insisted on Thursday that its reserves were enough to cover its domestic and export requirements.

Meanwhile, the company increased natural gas production and sales revenue during the three months to the end of September.

A 12 per cent production rise from a year earlier to 38 petajoules reflected a better contribution from its Bass Strait, Otway and Kupe New Zealand ventures, Origin said.

Sales revenue was 38 per cent higher at $307 million, due to stronger production, prices and third party sales.

Origin shares gained 11 cents to $14.63.