The default rate for oil and gas companies with lower credit ratings could more than double in the coming year, Moody's Investors Service said.

Moody's estimates the default for oil and gas companies with lower credit ratings – B2 or lower – will increase from 2.7 percent to 7.4 percent by March.

Quicksilver Resources, a Texas company focused on North American shale, is among the smaller companies filing for Chapter 11 bankruptcy this year. British energy company BG Group, meanwhile, was acquired by Royal Dutch Shell as low oil prices forced companies to find ways to streamline capital.

Oil prices started the year around the $50 per barrel range, but have since recovered to near $65 per barrel for the global benchmark Brent.

"With a gradual recovery in energy prices, the weaker oil and gas issuers are at a much greater risk of default," Moody's Senior Vice President David Keisman said in a statement. "The companies on the lower end of spec-grade ratings are the ones that should be most worried."

Moody's said that, as of May 1, 15 percent of the companies with credit ratings of B3 or lower were from the oil and gas sector, the largest share for any U.S. corporate sector. That's about twice the number with lower credit ratings than one year ago.

As a silver lining, the analytics firm said more than 70 percent of the exploration and production companies in the United States with ratings in the B1 range maintained or improved since June 2014, when oil prices started their steady plummet below the $100 per barrel range.

"The oil and gas industry is characterized by boom and bust cycles, and many U.S. exploration and production companies with experienced management teams have seen this game before," Senior Vice President Pete Speer said. "While these companies have successfully navigated the waters thus far, low oil prices will continue to pressure the industry-at-large and these companies' credit metrics."