TOKYO, Dec 16 (Reuters) - A unit of Tokyo Gas has bought Texas-based natural gas producer Rockcliff Energy from private equity firm Quantum Energy Partners for $2.7 billion, it said on Saturday.

The deal is part of Tokyo Gas' efforts to expand its North American shale gas operations to meet growing demand for natural gas, it said.

The deal is expected to close on December 29, Tokyo Gas said.

(Reporting by Anton Bridge; Editing by Michael Perry)