SAO PAULO (Reuters) – an error of calculation of the pressure of the Sea project Frade Chevron inside caused a spill of oil off the coast of Brazil last week, he published Saturday a local newspaper, quoting the President of Chevron Brazil.

The spill occurred because there was an error in the injection of mud heavy in the tank to prevent the return of oil through the pipeline, said the newspaper O State of S.Paulo.

“Underestimate the pressure of the tank.” “The weight of the mud was planned for another pressure,” he told State George Buck, President of the subsidiary Chevron’s Brazil.

The field Frade is located in the Campos Basin, which produces most of the oil of Brazil, in places where the sea reaches depths of 1.2 kilometers.

Chevron had previously said that the spill came from a natural filtration of the seafloor and had no relationship with the production from Frade. The company is now investigating why was badly calculated pressure and why was the spill, said Buck.

The newspaper also said that the federal police of Brazil is investigating if Chevron was trying to achieve in an irregular manner an area deep below the sea bed known as the subsal, a region the size of the State of New York is believed to contain about 50 billion barrels of oil reserves.

The ability of the team of drilling that is using the company in the project reaches up to 7,360 m, while oil reserves of the area lie about half of that distance, according to experts of the national agency of petroleum, Natural Gas and biofuels (ANP), said State.

“One of the hypotheses with which we work is that the accident could have occurred because the company drilled deeper than the limits,” said Fabio Scliar, head of the Division of environment and historical heritage of the police federal, according to the newspaper.

The company has permission to drill distances, provided that communicate their plans to reserve in advance, said the newspaper.

Scliar had told Reuters this week that the earliest evidence showed that the drilling of Chevron was 500 metres beyond what is permitted.

The police are also investigating if Chevron has expatriate working illegally in the country.

Brazil Chevron officials were not available immediately for comment.

Brazil is located on huge reserves of oil in deep waters, which were discovered during the past decade. The Government is eager to exploit these deposits as a new source of income for Governments federal, State and municipal.

(Inae Riveras report.) (Edited in Spanish by Patrick Abusleme)