Both Saudi Aramco and ADNOC have been conducting preliminary evaluations of Santos as a possible acquisition target, the report said, citing sources who declined to be named as the information was private.
The sources said Santos could attract interest from other potential buyers, according to the report. Deliberations are on, and the suitors have not decided whether to proceed with any proposals, it added.
"Santos does not comment on media speculation," a company spokesperson said.
Saudi Aramco did not immediately respond to Reuters' request for comment, while ADNOC declined to comment.
Santos shares rose to a high of A$8.18 and last traded up 5% at A$8.09, outpacing a 1% rise in the benchmark S&P/ASX200 (.AXJO), opens new tab.
Adelaide-based Santos had a market capitalisation of $16.63 billion as of Wednesday's close, up 1% since the start of the year.
Santos, with assets stretching across Australia to Alaska and Papua New Guinea (PNG), has been eyed by suitors over the past several years for its liquefied natural gas (LNG) business, especially its stake in PNG LNG.
The company produced 91.7 million barrels of oil equivalent (mmboe) last year and had proven plus probable reserves of 1,661 mmboe as of the end of last year.
Its biggest development project is the Barossa gas project in waters off northwestern Australia, which has faced delays and cost increases following court fights with an Indigenous group over the planned route for a gas pipeline from the field.
DOUBTS ON A DEAL
A Santos shareholder and an analyst both played down the likelihood of an offer from Aramco or ADNOC.
"I think Santos is an attractively priced company with a handful of great assets, but despite this, I find it hard to imagine a would-be buyer flagging its interest prior to making an offer," said Simon Mawhinney, managing director of fund manager Allan Gray.
"So I’m inclined not to put too much, if any, weight on these reports and happily be proven wrong on this point."
MST Financial senior analyst Saul Kavonic said Aramco and ADNOC have been looking at a number of LNG opportunities but Santos would be "a big step out of their comfort zone", politically, operationally and by size.
Australia's Woodside Energy (WDS.AX), opens new tab held preliminary talks with Santos earlier this year to form a $52 billion energy giant, however discussions collapsed, and Santos said it would continue to review options to unlock value for its shareholders.
"Santos has been shopping itself for a while, so there could be quite a few players out there who have pursued preliminary assessments," Kavonic said, adding that Santos' domestic assets might be an obstacle to any buyout.
"We remain of the view that a bid for Santos at a material premium is unlikely to emerge, despite Santos shopping itself for some time," he said.