News: OSH UPDATE 1-Australia's Oil Search quarterly revenue misses estimate on planned upkeep

• Lowers FY investment expenditure guidance
• Revenue $378.9 mln vs Citi $421 mln estimate

(Adds estimates, details on PNG LNG project, guidance and share movement)

July 16 (Reuters) - Australia's Oil Search Ltd (OSH) on Tuesday posted second-quarter revenue that missed estimates by a wide margin due to a planned maintenance at its main asset, the Papua New Guinea LNG plant.

It also lowered full-year investment expenditure guidance to $500 million-$610 million from $545 million-$655 million due to a delayed start to front-end engineering and design work for the expansion of the PNG LNG plant.

Oil Search was poised for a $13 billion expansion plan of the PNG LNG project in which it is a partner, but political turmoil in the country has threatened to delay the venture.

Commodity and energy firms with projects in the resource-rich archipelago are closely watching new leader James Marape's agenda for the state to hold a bigger stake in extractive projects and raise more revenue from the resources sector.

Oil Search said talks with the government on the P'nyang gas agreement have been put on hold until the new government completes a review of the Papua LNG agreement.

Both agreements are key to plans to add three new liquefied natural gas production units, called trains, at the PNG LNG plant, run by Exxon Mobil Corp XOM.N , which will double Papua New Guinea's LNG exports.

Revenue for the quarter ended June 30 rose to $378.9 million from $262.8 million a year earlier, when a deadly earthquake had ravaged the Papua New Guinea-focused energy explorer's production facilities. Citi had estimated a quarterly revenue of $421 million.

Production rates were impacted by a 13-day period of rate reduction in late May to early June due to the planned maintenance, the firm said.

Shares of Oil Search fell as much as 1.6% in early trade, their sharpest intraday decline in nearly two weeks, while the broader market (xjo) was little changed.