OREANDA-NEWS. UK-Australian resources firm BHP Billiton has taken a $7.2bn write-down on the value of its US onshore assets and is reviewing its investment plans for the next six months.

The company will book the impairment, which is about $4.9bn after tax, in its financial results for July-December. The charge cuts the value of its US onshore assets to about $16bn.

BHP Billiton acquired the onshore assets through its 2011 takeovers of US upstream independent Petrohawk for $15.1bn and US independent Chesapeake Energy's Fayetteville shale gas assets for $4.75bn. It has previously written down the value of the assets three times, most recently in July when it cut $2bn from the carrying value of the US shale fields to about $24bn.

The charge "reflects changes to price assumptions, discount rates and development plans which have more than offset substantial productivity improvements," BHP Billiton said. It will reduce the number of operated rigs in its onshore US business from seven to five in January-March, comprising three rigs at its Black Hawk operations and two in the Permian. This is down from 26 a year earlier.

Investment and development plans for the rest of the 2015-16 financial year to June are under review, with a focus on preserving cash flow. BHP Billiton last revised its capital expenditure guidance in October, cutting spending plans for its US onshore upstream business to about $1.4bn in 2015-16 from its previous guidance of $1.5bn. It spent $463mn during July-September.

The industry has experienced "significant volatility and much weaker prices," the company said. It has reduced its medium- and long-term gas price assumptions to reflect productivity improvements that have resulted in higher-than-expected US supply at lower cost. And it has cut its oil price assumptions for the short-to-medium term, although it said its long-term price assumptions "continue to reflect the market's attractive supply and demand fundamentals." It did not give details of its new price assumptions.

"Oil and gas markets have been significantly weaker than the industry expected," chief executive Andrew Mackenzie said. But the company remains confident in the long-term outlook and quality of its acreage.

A broader assessment of the value of the company's assets will be finalised when its interim financial results are released on 23 February.