HOUSTON, Feb 15 (Reuters) - Occidental Petroleum on Thursday said a U.S. regulator's second request for information on the acquisition of shale producer CrownRock has pushed back the deal's closing date to second half this year.

The delay in Federal Trade Commission (FTC) approval of the $12 billion acquisition will make the Houston-based oil company postpone planned sales of $4.5-6 billion in assets, Chief Executive Vicki Hollub said. It will also postpone any potential changes in the company's buyback program, she said.

"Some of our teams felt like they'd (FTC) asked for everything," Hollub told analysts during a call to discuss the company's 2023 financial results.

"We are progressing and hope to be able to close in the second half of this year," she said.

The FTC also asked U.S. oil company Exxon Mobil Corp for more information on its proposed acquisition of Pioneer Natural Resources, and Chevron Corp received requests for information on its deal to acquire Hess Corp. (Reporting by Sabrina Valle Editing by Chris Reese and David Gregorio)