It's the old supply and demand problem. If the price overseas for crude oil is $90/barrel, then the Aussie producers need local supply to be paying $90/barrel or else they'll sell it on the open (international) market.
Unless legislation intervenes, and the local natural gas supply right now is a good example of that.
Three LNG plants are being built in Gladstone to liquify coal seam gas (CSG) for export, but the production of CSG has turned out to be less than forecast so the LNG plants are prepared to pay more for natural gas to allow them to meet their contracted production requirements. This means that local natural gas users are being priced out of the market, and facilities such as the Swanbank gas fired power station are closing. People are now calling for legislation requiring fuel producers to meet local market needs first.