Los Angeles ? Shareholders of oil and gas company Unocal Corp. formally voted Wednesday to accept a takeover bid by Chevron Corp., even as some at the company’s meeting continued to lament a failed rival bid by a Chinese oil company.

The approval of the approximately $18 billion purchase of the world’s ninth-largest oil company followed months of negotiations and a high-profile courtship from CNOOC Ltd., a Chinese oil company that hoped to secure energy resources needed to accompany its country’s rapid economic growth.

Unocal announced that holders of 77.2 percent of its eligible shares favored the Chevron buyout and 2.6 percent were opposed. Of the shares actually voted, 96.6 percent approved the deal.

The combined companies will produce the equivalent of 2.8 million barrels of oil per day and the acquisition will increase Chevron’s reserves by about 15 percent, Chevron said in a press release.