Brazilian state-run energy giant Petroleo Brasileiro (PBR, PETR4.BR), or Petrobras, said late Friday that domestic crude oil output slipped for a third consecutive month in April because of maintenance work at several platforms and the shutdown of the Frade field.

Petrobras said domestic oil production slid 1.6% in April to an average 1.961 million barrels a day. Petrobras also produced an average of 149,900 barrels a day from international operations during the month.

Maintenance work on offshore platforms and submarine equipment in the
Campos Basin was behind the decrease in production, Petrobras said. Petrobras also continued to be affected by the shutdown of the Frade offshore field operated by U.S. oil major Chevron Corp. (CVX). Chevron halted output at the field to study the cause of oil seeps from the seabed after a drilling accident in November. Petrobras holds a 30% stake.

Natural gas output, meanwhile, was down 3.3% month-on-month in April at 71.2 million cubic meters a day, Petrobras said. Total crude oil and natural gas production was 2.5552 million barrels of oil equivalent, or BOE, in April.