ENERGY

Unocal Completes Refinery Purchase: Unocal Corp. completed the purchase of a substantial portion of Shell’s refinery in Carson and said it would shut down operations at part of its own refinery in Wilmington. Terms of the transaction were not disclosed. Unocal will operate the Shell site and its existing Los Angeles refinery as a single unit. The acquisition will allow Unocal to lower refining costs, make a higher percentage of gasoline--including lower-emissions products required under new state and federal rules--and refine cheaper California crude oil instead of Alaskan crude.