A private-equity firm that focuses on the energy industry is preparing to launch a fund to provide credit for debt-laden takeovers as regulators seek to curtail such lending by big banks.

Riverstone Holdings is hiring a pair of senior takeover-finance bankers- Chris Abbate from Citigroup and Jamie Brodsky from Japan's Nomura -as part of the effort, people familiar with the matter said. The firm is expected to raise as much as $1 billion to provide loans to buyers of energy companies and other assets, the people said.