The hard times continue for the energy sector as Houston-based oil and natural gas company Vanguard Natural Resources LLC became the latest casualty of falling commodities prices.

Vanguard filed for Chapter 11 protection in Houston on Thursday. Paul Hastings, a longtime legal adviser to the company, is advising the debtor in its bankruptcy case. In its filing, Vanguard lists assets and liabilities each of between $1 billion to $10 billion.