Will Shell-BG deal open an Australia M&A floodgate?

Shell's $70 billion takeover bid for BG may be a harbinger of more deals to come for Australia's resources sector, which has taken a body blow from low prices for oil and other commodities.

"Some companies have quite weakened balance sheets and are looking to sell assets," said Rob Brierley, head of research at Patersons, adding that there's plenty of "bottom of the cycle maneuvering" going on.

Santos in particular may come under pressure to sell assets, he said, noting that the Shell-BG deal could "change the landscape" for Queensland-based liquefied natural gas (LNG) projects. Hit by lower oil prices, Santos wrote off around 1.6 billion Australian dollars (around $1.23 billion) worth of assets in February; S&P cut the company's credit rating late last year.

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"The tie-up between Shell and BG could effectively enhance [the BG] projects' economics to the detriment of all other projects," as there's a shortage of long-term gas supply, Brierley said. Many projects, including Santos' Gladstone LNG plant, may have been penciling in supply from Shell's 50 percent-owned Arrow Energy, which may prioritize supply to BG's LNG operations if the acquisition deal is completed.

Royal Dutch Shell announced on Wednesday it had struck a cash-and-stock deal to buy BG Group for 47 billion pounds ($70.2 billion), the third-largest oil-and-gas deal of all time, according to Thomson Reuters data. Globally, oil and gas M&A is at the highest year-to-date level ever, Thomson Reuters data show.

"I'd expect a lot more of this activity to come," Jonathan Barratt, chief investment officer at Ayers Alliance Securities, told CNBC. If oil prices remain around these levels for some time, "you'll start to see those balance sheets tip over."

Case by case

But Barratt expects potential deals will get reviewed on a case-by-case basis.

"When you look at those reserves the companies have, then you can start to get a sense of how long they can actually survive," Barratt said. "Down here [in Australia], their assets are a bit depressed so it makes sense for the big guys to do a little bit of cleanup."

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Deals are already getting pushed through. Earlier this year, Australia's Woodside Petroleum has completed an around $2.75 billion deal to buy Apache Corp.'s stakes in LNG projects in Australia; another deal for Woodside to buy Apache's interest in a Canadian LNG project for $854 million is expected to close soon.

Apache has also sold Western Australian oil and gas assets to Macquarie Capital and Brookfield Asset Management for around $2.1 billion as the Texas-based company fully exited Australia's market.

Declines in stock market valuations of listed energy players have also made that an attractive potential acquisition route, Roger Dartnell, EY Oceania oil and gas transactions leader, said in a note in December, noting that "shopping on the ASX" could offer better value than the cost of exploration.

Paul Kane | Getty Images

Australia's S&P/ASX 200 Energy index is down around 28 percent from its early-September peak.

But the "hunters" aren't being indiscriminate, Patersons' Brierley said.

"The acquirers can afford to be discerning and dig for the ones that derive the right sort of benefits for shareholders rather than just putting one oil and gas company with another," he said. "I don't see a huge panic on behalf of the hunters to acquire right now."

--Tom DiChristopher contributed to this article.

—By CNBC.Com's Leslie Shaffer; Follow her on Twitter @LeslieShaffer1