July 31 (Reuters) - Shares of Origin Energy marked their biggest intraday loss in eight months on Wednesday after the firm posted a drop in quarterly revenue from its stake in the Australia Pacific LNG (APLNG) project, reflecting a fall in gas sales and prices.

The decline was partly due to a weaker average realised price for liquefied natural gas (LNG), which dropped to $11.70 per metric million British thermal units (mmBtu) in the quarter, compared with $12.17/mmBtu in the prior quarter.

The energy retailer said its share of revenue from APLNG, a joint venture with U.S.-based oil and gas giant ConocoPhillips and China state-owned Sinopec, fell to A$590 million ($385.74 million) for the quarter, compared with A$633 million in the previous quarter.

LNG sales at the APLNG project fell 3% to 35.1 petajoules quarter-on-quarter.

Shares of the utility company fell as much as 4.1% to A$10.17, losing most since December 2023. The stock hit its lowest levels since June 18.

The result comes after oil prices remained volatile in the second quarter, as a price increase following OPEC+ supply cut was countered by weak Chinese demand.

Origin's output from an Eraring coal-fired power plant, the country's largest, rose by 14.3 Terawatt hours (TWh) in fiscal 2024, up 2.1 TWh from prior year.

"Gas volumes to generation were higher to cover an Eraring outage," analysts at Citi said, adding that it would weigh on electricity procurement costs.

Recently, the company and the state of New South Wales (NSW) agreed to delay the closure of Eraring plant by two years.

The company's policy centres around aiming to increase generation to help put downward pressure on electricity prices.

($1 = 1.5295 Australian dollars)

(Reporting by Roshan Thomas and Archishma Iyer in Bengaluru; Editing by Tasim Zahid and Sherry Jacob-Phillips)