The chief executive officers of Chevron Corp.’s and Transocean Ltd.’s Brazilian units are among 17 executives at the two companies banned from leaving the country, pending an investigation into an offshore oil spill. Chevron’s George Buck and Transocean’s Michael Legrand were on the list of managers federal prosecutors asked Judge Vlamir Costa Magalhaes to ban from leaving Brazil, according to a copy of the request sent today by Marcelo Del Negri, a spokesman for the prosecutor’s office. The judge issued the ban March 16. The November 7 leak of 3,000 barrels of oil at Chevron’s $3.6 billion Frade field off the coast of Rio de Janeiro occurred at a time when Brazil is increasing scrutiny of deepwater drilling, following the 2010 Macondo spill in the U.S.