Oil prices were slightly lower Monday after Crimea's vote to split from Ukraine and join Russia, AP reported. Benchmark U.S. crude for April delivery was down 9 cents to $98.80 a barrel at 0715 GMT in electronic trading on the New York Mercantile Exchange. The contract rose 69 cents to close at $98.89 on Friday. Brent crude, used to set prices for international varieties of crude, was down 21 cents to $108 on the ICE exchange in London.