(Adds company comment, details)
HOUSTON Jan 15 (Reuters) - ConocoPhillips (COP.N) began a plantwide overhaul during the past weekend of its 247,000 barrel per day (bpd) Alliance, Louisiana, refinery according to sources familiar with refinery operations on Thursday.
The refinery 23 miles (37 km) south of New Orleans, began the overhaul with the shutdown a catalytic reformer and a delayed coking unit, according to the sources. Other units will be shut on a staggered basis.
The Alliance refinery is scheduled to return to full production by mid-March, according to the sources.
A Conoco spokesman said maintenance was underway at the refinery.
"The ConocoPhillips Alliance refinery has begun a period of planned maintenance, which is expected to take several weeks to complete," said spokesman Bill Tanner in a statement.
Tanner declined to discuss the maintenance work in detail.
Conoco has made preparations to ship out oil delivered to the refinery once its storage tanks become full while units are shut for the overhaul, according to the sources. (Reporting by Erwin Seba; Editing by Marguerita Choy)