UPDATE 1-Conoco says L.A. refinery begins planned overhaul

(Adds detail)

HOUSTON, April 3 (Reuters) - ConocoPhillips' (COP.N: Quote, Profile, Research) 139,000-barrel-per-day (bpd) Los Angeles-area refinery in Wilmington, California, has begun a planned overhaul, a company spokeswoman said on Thursday.

Several units will be shut on a staggered basis during the work, said Conoco's Terry Hunt.

The overhaul is expected to last at least a month and include the refinery's crude distillation unit, coking unit and hydrocracker, according to sources familiar with refinery operations. (Reporting by Erwin Seba; Editing by David Gregorio)