Oil and gas producer Santos Ltd announced it expects to book a net impairment charge of about US$690 million after tax in its half-year results because of weaker oil prices.

Santos said it would write down the value of the Gladstone LNG project in Queensland - which it co-owns with PetroNas, Total, and Kogas - to the tune of about US$870 million after taxes.  This is in addition to the $1.1 Billion writedown last year on the $18.5 Billion project.  Supply from GLNG's coal seam gas fields has been weaker than expected.

The copany says this writedown will be slightly offset by a $330 Million gain in the value of its Cooper Basin gas assets.  This was due to cost cuts, increased drilling activity, and output.