Chesapeake Energy Corp, the U.S. oil and gas company facing a funding shortfall this year and next, must sell at least $7 billion in assets to avoid breaching a loan covenant, analysts at Moody's Investors Service said on Thursday.

Decade-low natural gas prices and hefty spending have left Chesapeake to fill a shortfall that Moody's estimates at nearly $6 billion in 2013. The company is also facing corporate governance issues and some of its largest investors are calling for major changes.

"Even $7 billion in asset sales could place Chesapeake's covenant compliance for its revolving credit facility in some doubt and the company would still face a significant funding gap in 2013," Moody's said in a note.

The company would "gain far more covenant headroom" with the sale of an additional $10 billion in asset sales this year, the analysts said.

Any sales total below $7 billion will likely lead to a credit rating downgrade from its current Ba2 rating, Moody's said.

Earlier this month, Chesapeake secured a high-interest $4 billion term loan from its investment bankers, an amount that is expected to be repaid with the proceeds from planned asset sales of up to $11.5 billion.

So far, Chesapeake has put its 1.5 million acres in the Permian Basin up for sale along with a half a million acres in Colorado and Wyoming. The company is also searching for a joint venture partner in the Mississippi Lime basin.

This year, Chesapeake's cash flow shortfall is expected to be more than $10 billion, according to Moody's.