Stephen C. Lipman, president of Unocal Corp.’s...

Stephen C. Lipman, president of Unocal Corp.’s Geothermal division since 1989, has been named president of the company’s Science and Technology and Energy Mining divisions and a corporate vice president, replacing Cloyd P. Reeg, who is retiring. Darcel L. Hulse, director of corporate engineering and construction, will replace Lipman, and John R. Dietzman, manager of Unocal’s San Francisco refinery, will take Hulse’s old job.