An audit of development plans for the Johan Sverdrup oil field off the Norwegian coast found only relatively minor issues, a regulator said.

The Petroleum Safety Authority of Norway published its findings from a March audit of plans by Norwegian energy company Statoil to develop the offshore oil field. The PSA found no major violations and only one "improvement point" tied to an electrical plant associated with development.

An improvement point is defined as an area of weakness not severe enough to warrant a breach of regulatory requirements.

"Statoil has been given a deadline of April 22 to report on how the improvement point will be dealt with," the regulator said.

Johan Sverdrup is one of the five biggest oil fields ever discovered on the Norwegian continental shelf, with a reserve basin of as much as 3 billion barrels of oil equivalent. Operators with Statoil started spinning the tap on the first of the 35 wells slated for the preliminary phase of the field's development in March.

Fabrication of parts for a 22,000-ton platform for Johan Sverdrup started in mid-February at a shipyard in Haugesund, a port city in northern Norway. Statoil started construction on the utility and living-quarters platform designated for field operations last month.

Contracts worth more than $5.7 billion have been awarded for the project, with more than 70 percent of them going to Norwegian companies.

The Norwegian regulator said production is expected to start at the end of 2019 and last through 2050.