Rumors are swirling that Australian resources giant BHP Billiton Ltd. (NYSE:BHP) may make a run at Houston oil and gas explorer Anadarko Petroleum Corp. (NYSE:APC). On Dec. 29, London's Daily Mail ran a story saying BHP is lining up a $90 per share, $44.6 billion offer for Anadarko, which also has interests in coal and other industrial minerals. Anadarko's stock shot up on the news to $78.98 on Dec. 30 -- a two-year high -- but settled back down to close at $75.59. It closed at $76.63 on Monday.

The newspaper said BHP chief executive Marius Kloppers must be "desperate" to complete a successful acquisition after abandoning deals with Rio Tinto Group (NYSE:RIO) and Potash Corp. of Saskatchewan Inc. (NYSE:POT).

Bond research firm Gimme Credit LLC wrote in a report Tuesday that it suspects these rumors are started by opportunists "unlucky enough to be chained to their desks" when much of the world has settled down for a long winter's nap. "But sometimes, where there's smoke, fire may also be found, depending on the kindling."

Indeed, there has been plenty of fuel for this particular blaze. In September, after BP plc's (NYSE:BP) disastrous spill at the Macondo oil well -- in which Anadarko owns a 25% interest -- the Australian newspaper reported that BHP was interested in picking up the company. At that point, the shares had slipped to a low of $34.54 and Anadarko was facing a $272 million bill from BP for cleanup costs. The rationale for the deal would be to provide BHP access to valuable oil and gas properties in the U.S. and around the world. Over the next few months, Credit Suisse Group (NYSE:CS) and UBS (NYSE:UBS) also raised the possibility.

The two would obviously make a good fit. There's not much crossover: They're both big players in the deepwater Gulf of Mexico, but Algeria is the only international market in which they both operate. Adding oil and gas assets would diversify mining-focused BHP, whose petroleum assets only contribute 23% of its Ebitda.

According to Gimme Credit's figures, Anadarko actually has more proved oil and gas reserves -- 2.3 billion cubic feet equivalent, versus BHP's 1.4 billion; with its financial strength (equity valuation of $243 billion and $12.5 billion in cash) and access to capital, BHP would have little trouble swinging the purchase price.

The price, however, may be the sticky wicket. Bank of America Merrill Lynch (NYSE:BAC) analysts think the company should fetch at least $110 per share, but that doesn't take into consideration recent increases in oil prices and new discoveries, including big finds in Sierra Leone, Brazil and Mozambique.

Gimme Credit was also skeptical of the price -- and the timing. BHP's bid for Potash died in early November but was in trouble long before then, so if a bid is coming, what's taking so long?

"If the answer to that question has anything to do with judging potential Macondo liability, we'd say there can't be any deal in the near future, because that number may not be known for a very long time," it wrote. If BHP is really desperate, maybe it won't wait for that day.