17. | Operating expenses, net |
| | 2017 | | 2016 | | 2015 | | |||
| | US$(000) | | US$(000) | | US$(000) | | |||
| | | | | | | | | | |
Exploration and advanced projects | | | 51,694 | | | 49,580 | | | 64,230 | |
Severance program | | | 9,419 | | | 9,659 | | | 14,904 | |
Write-off of fixed assets | | | 1,368 | | | 14,036 | | | 2,411 | |
Cost of fixed assets sold | | | 1,632 | | | 160 | | | 1,624 | |
Income from fixed asset sales | | | (2,235) | | | (471) | | | (1,116) | |
Others, net | | | 1,636 | | | (1,468) | | | 793 | |
| | | 63,514 | | | 71,496 | | | 82,846 | |