KBR Inc., the U.S. engineering firm that split from Halliburton Co. last year, and Sonangol, Angola’s state oil company, signed an agreement to build a refinery in the port of Lobito, KBR said. The Houston-based company got involved in the project after Sonangol in March last year said it ended talks with China Petroleum & Chemical Corp. over the $3.7 billion, 200,000- barrel-a-day refinery project, known as Sonaref.