By Gary McWilliams

Chesapeake Energy Corp's bankruptcy will pile more pain onto leading energy service and pipeline companies whose revenues were already being slammed during the latest collapse in oil prices, according to energy analysts and corporate filings.

Chesapeake, the sixth-largest U.S. natural gas producer, sought protection from creditors on Sunday in U.S. Bankruptcy Court for Southern District of Texas in the biggest oil and gas bankruptcy in five years. Its Chapter 11 filing, citing $10 billion in debts, would affect drilling firms and gas transporters from Texas to Wyoming to Pennsylvania.

Williams Cos, Energy Transfer and Crestwood Equity Partners have contracts with Chesapeake that face rate cuts or rejections in bankruptcy court, said Ryan Smith, a senior director at energy information provider East Daley Capital.

Consolidated Edison Inc earlier this month asked U.S. gas regulators to declare Chesapeake must seek approval before canceling regulated natural gas contracts in bankruptcy court.

Crestwood declined to comment. Energy Transfer did not respond to requests for comment.

Crestwood last month lowered its 2020 pre-tax earnings forecast by $60 million, but said it expected to generate "significant free cash flow" this year and next.

Williams, one of the largest natural gas pipeline operators, reduced its exposure to Chesapeake, to 6% of revenue from 18% five years ago, and expects to continue providing services amid any restructuring, said Vice President Laura Creekmur.

"We are confident in our ability to defend the integrity of our contracts," she said in response to questions about the filing's impact. Williams' pipelines remain integral to "maximize the value" of Chesapeake's assets.

Patterson-UTI Energy, the driller that acquired a former Chesapeake unit, said in a February regulatory filing that under a tax-sharing agreement it could face a "material adverse effect" were Chesapeake to fail to pay taxes potentially due on the split. Ahead of the bankruptcy filing, Patterson-UTI said it did not believe it has "material exposure to any Chesapeake liability" based on its earlier filings.

(Reporting by Gary McWilliams; editing by Dave Gregorio and Diane Craft)