The disruption was caused by an electrical fault on the power generation system, which has now been repaired, according to the field's operator China's CNOOC.
Buzzard produces medium sour crude and is normally the largest single contributor to the Forties stream. The field's contribution to unstabilised Forties production dropped to 5pc in the week to 26 April, compared with 23pc the week before, according to Forties Pipeline System (FPS) operator Ineos.
This means the Forties blend was lighter and sweeter last week, with a gravity of 43.2°API and 34pc sulphur content.
Prior to last week's shutdown, Ineos had forecast that Buzzard's contribution to Forties would average 26.9pc this month, yielding a gravity of 39.6-40.3°API and sulphur content of 0.62-0.69pc.
By Riyan Zerrouki