A company spokesman was not available for comment.
The 40,000-bpd reformer was shut in early February as partof a planned multi-unit overhaul, the sources said.
Also on Thursday, Shell was boosting production on the40,000-bpd hydrocracker, which restarted on Tuesday.
The hydrocracker uses hydrogen and a catalyst under highheat and pressure to convert gas oil to motor fuels, especiallydiesel.
The reformer converts refining by-products intooctane-boosting components that are blended into gasoline.(Reporting by Erwin Seba; Editing by Cynthia Osterman and PeterCooney)