US oil explorer Apache is expanding its already substantial exploration position in Western Australia, farming into two permits in the petroleum-rich Carnarvon Basin.

The Houston-based firm will take a 40 per cent stake in the adjacent WA-409-P and WA-359-P permits in return for carrying out a three-dimensional seismic survey over the licenses, scheduled to start later this year. It also has the option to fund the first well in either permit in return for up to a 30 per cent additional stake.