Aug 15 (Reuters) - Santos Ltd STO.AX
* Expects to recognise a non-cash net impairment charge of approximately US$690 million after tax in its 2017 half-year results
* Expects to recognise an impairment of glng of approximately US$870 million after tax, predominantly due to lower oil prices
* Expected net impairment charge is an after-tax, non-cash item with no impact on EBITDAX or cash flow
* Expects to take an impairment charge against non-core AAL asset in Indonesia of approximately us$150 million after tax
* Lowered its brent oil price forecasts to US$50/bbl in 2017, US$55/bbl in 2018, US$60/bbl in 2019, US$65/bbl in 2020, US$70/bbl in 2021 and US$70/bbl from 2022
* "Expected positive net write-back to cooper basin carrying value of approximately US$330 million after tax"