CNOOC Ltd.’s chairman said Friday the company was ready to start immediate talks with Unocal Corp. on its uncolicited $18.5 billion cash offer. The offer from the Chinese state-owned oil company is nearly $2 billion higher than the $16.6 billion Chevron has agreed to pay for El Segundo-based Unocal.

“We are extremely pleased that Unocal has indicated they will begin engaging in talks concerning our all cash offer,” Fu Chengyu, chief executive of Beijing-based CNOOC, said in a statement Friday.

CNOOC’s offer will “bring superior value to Unocal shareholders,” Chengyu said.

Fu said that that CNOOC mainly seeks the 70 percent of Unocal’s reserves that are located in Asia. He also promised that all of the oil and gas produced by Unocal in the U.S. will continue to be sold in the country itself, if CNOOC wins the bid. And he reiterated previous statements that all current Unocal employees would be retained if the offer is accepted. Chevron plans to lay off Unocal employees to save costs.

Fu also said that CNOOC is open to discussing with the committee the possibility of placing certain assets under American management to satisfy energy security concerns.

He said CNOOC had expected a review by the U.S. Committee on Foreign Investment, and assured there would be no threat to the ownership of Unocal assets in the country, and is willing to sell Unocal’s minority pipeline interests and storage assets “so long as such a sale does not cause substantial economic harm to Unocal,” Fu said.

CNOOC’s all-cash bid puts pressure on Chevron to up its stock-and-cash offer. It also sets up a potential showdown between U.S. politicians over whether Chinese-owned CNOOC ought to be able to purchase the El Segundo-based oil-and-gas production company.

China’s state-run energy firm offered $67 a share, versus a value of $61 or so that Chevron’s bid represented. Chevron is expected to counterbid as early as next week, although Chevron hasn’t said it will do so.