According to a report in the Financial Times, Sasol is also investigating opportunities in countries including Uzbekistan, Australia and South Africa.
The company has recently invested $US2.1 billion ($A1.97 billion) in two Canadian shale gas projects
Sasol chief executive officer Pat Davies said he expected gas prices to go up in the future.
"Gas prices are particularly low in North America at the moment, but obviously we believe that they'll go up, in which case it's better to be integrated along the value chain," he said.
"I think the fears around nuclear [following the crisis at Japan's Fukushima plant] are going to cause more of a demand for gas,
"It will also be driven by robust demand in China as they need a huge amount of gas there. And it will be driven by climate change issues - gas has a smaller CO2 footprint [than other fossil fuels]."
Sasol currently has an interest in PNG, with the company conducting seismic in its four onshore licenses in the Western Province in late-2010 and identifying the Awapa prospect as the likely target for first drilling.