Royal Dutch Shell (RDS-A) already owns 30% of Arrow's international business. Arrow is a producer of coal-seam natural gas. Analysts based in Australia are saying the takeover offer may spur more offers for other Australian producers of coal-based gas. Asian countries, China in particular, are prime destinations for Australia's energy exports.

The offer made by Shell and PetroChina (PTR) is non-binding and at least one analyst speculated yesterday that the bid may need to go higher to finalize a deal. The price is lower than what has been paid by oil companies to acquire similar Australian firms over the past few years.

Coal-gas is considered a non-conventional natural gas source much the same way North American shale plays are. These deposits can break even with oil prices between $30 and $50 a barrel, making them more profitable than alternatives such as deepwater oil and gas or Canadian tar sands, according to Bloomberg News.