Story updated from Dec. 12 to correct the following: Exco Resources net debt to EBITDA is 3.7, not 7.81 as a previous version of this article incorrectly stated.

NEW YORK (TheStreet) -- The selloff in oil prices is expected to spur more energy mergers next year, as giants such as Exxon Mobil (XOM - Get Report) , Chevron (CVX - Get Report) , Royal Dutch Shell (RDS.A - Get Report) and Total (TOT - Get Report) snap up weaker players.

"There are a number of companies out there that are more leveraged that are going to find it difficult to service their debt at current oil prices," says Scott Bok, CEO of investment bank Greenhill (GHL) . "So I think there will be a lot of restructuring, but also a lot of M&A."

In the short term, however, the oil price slide may actually delay any combinations. That's because the boards of target companies, whose stocks have plunged along with oil prices, don't want to sell those companies at bargain-basement prices.

Still, once energy stocks rebound or industry executives become resigned to the new price environment, weaker companies are likely to look to sell themselves.

Big oil companies were already looking at acquisitions before oil prices fell off a cliff, one investment banker says. He expects major M&A activity to pick up in about six months.

Investors, meanwhile, should be on the lookout for possible candidates. Click through to see three companies that are likely targets. 

Halcon Resources (HK - Get Report)

Houston-based Halcon is an oil and gas explorer and producer operating principally in the Bakken/Three Forks formations in North Dakota and the El Halcon area in East Texas. 

Its shares are down some 60% over the past three months. Its debt is at nearly five times EBITDA, a metric that looks at earnings while stripping away tax and accounting decisions that can distort the picture.

Quicksilver Resources

Quicksilver Resources is a Fort Worth, Texas-based oil and natural gas explorer and producer. The company's actively producing oil and natural gas facilities in the U.S. are located primarily in Texas, while its Canadian properties are in Alberta and British Columbia.

Shares are down nearly 70% over the past three months, while total debt to EBITDA is a whopping 13.42.

Exco Resources

Dallas-based EXCO has seen shares fall some 50% over the past three months. Total debt to EBITDA is 3.7.

Exco owns 70,000 acres in the Haynesville/Bossier shales in East Texas and North Louisiana, 47,800 acres in the Eagle Ford shale in South Texas and 145,000 acres in the Marcellus shale in Appalachia, according to its 2013 annual regulatory filing.

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