E&Y reported global oil and gas transactions reaching a "staggering" $402 billion in 2012, an average of more than four transactions announced every day (one of the most active sectors) and a 19% bump-up over 2011. The drivers? More capital becoming available to the "right class" of buyer along with increased pressure from asset and company owners to "crystallize returns," the firm said.

Meanwhile, PwC reports that 2012 had the highest U.S. oil and gas deal volume in 10 years -- reaching $146.2 billion. Deals stateside were fueled by private equity interest (the "most activity ever," the firm said, with 34 transactions representing $28.4 billion), foreign buyers (nine deals alone in the fourth quarter worth $3.2 billion), shale plays (particularly North Dakota's Bakken and South Texas' Eagle Ford) and companies looking to get deals done before the end of the year with the looming fiscal cliff and proposed tax changes.

So what do they expect for 2013? PwC principal Rick Roberge said that while there will be a "slight pause" in M&A during the first part of the year, he believes the fundamentals are in place for continued transactions, including the potential for some very large deals to get done and private equity to remain active in new investments. "The combination of independents who still control the majority of resources and the majors who have strong balance sheets and financial muscle may result in consolidation, as the capital requirements to develop shale plays continues to grow," he said.

Andy Brogan, Ernst & Young's global leader of oil and gas transaction advisory services, was a little more pessimistic. While he agreed that capital availability was improving, especially debt, he thinks funding will remain a challenge for smaller companies and cash constraints along with cost escalation will drive asset and corporate opportunities. "Those at the larger end of the scale with stronger balance sheets are likely to be beneficiaries of this," he said.