Woodside Petroleum has flagged first-half write downs of $US4.37 billion ($A6.27 billion), as it joined global energy majors that have slashed the value of their assets after a coronavirus-induced slump in oil prices.

The bulk of the impairment – $US3.92 billion ($A5.63 billion) – is related to writing down the value of its oil and gas properties and exploration assets, the company said in a statement late on Tuesday.

Nearly 80 per cent of the impairment losses on its oil and gas properties were because of the drop in crude prices but it also factored in longer term demand uncertainty and an increased risk of higher carbon pricing.

Woodside joins BP, Royal Dutch Shell and Eni in announcing write-downs and impairments on their assets as the slump in fuel demand has led to a dire outlook for energy prices.

The company made a $US447 million provision for an onerous liquefied natural gas supply deal in Corpus Christi, Texas, at a time when several Asian and European buyers have cancelled cargoes.

Woodside will report its second-quarter production figures on Wednesday and first-half fiscal 2020 earnings on August 13.