The semi submersible platform P-36 was operating in Roncador Field, in Campos Basin, producing 84.000 bopd, with capacity to reach the peak production of 180.000 bopd. On the 15th of March of 2001 an accident took place on board of the unit causing the death of 11 crewmembers and the sinking of the platform five days later.

An inquiry commission was formed just after the accident in order to investigate the causes and set up recommendations in order to prevent similar events.

This paper describes the methodology applied by the commission during the investigation phase, the work developed by them, what happened on board on that day, the conclusions about the main causes which led to the sinking of the unit and the recommendations addressing design, operation and safety of floating offshore units.

The results, conclusions and recommendations relative to this accident were used by Petrobras as bases to create a program inside the company called Operational Excellence Program whose main goal is to implement several actions toward increasing of the safety of offshore operations.

As for Petrobras, the information disclosed in this article can help other oil companies improve their HSE programs.

The detailed description of the events which took place the moment of the accident until the sinking, the main causes, conclusions, observations and recommendations of the inquiry commission and a general picture of the content of the Operational Excellence Program of Petrobras are addressed by this article.

Description of the P-36 platform

The P-36, formerly called "Spirit of Columbus", was a floating production unit (FPU) based on a conversion of a Friede & Goldman L-1020 Trendsetter type semi submersible platform. It was initially designed and built, in Italy, as a FPU to operate at 500m water depth, with a capacity to process 100,000 bopd and 2 million cubic meters per day of gas. The design and construction began in 1984 and ended in 1994.

The field, which it was intended to produce, did not prove to be commercial during the development phase. As a consequence it was offered to Petrobras that analyzed the possibility of converting the unit to produce in Campos Basin. After the evaluation for use in Marlin South and Roncador fields, Petrobras decided to select the unit to be the first FPU of the giant Roncador field.

The main modifications done during the conversion phase were: complete substitution of the process plant, installation of a new power generation plant, removal of the drilling equipment and propulsion system, changing the mooring system and increasing the payload by the addition of stability boxes in the pontoons and blisters in the columns.

After the conversion, which lasted from September 1997 to October 1999, the platform had the capacity to produce 180,000 bopd, to handle 7.2 million cubic meters per day of gas and could be installed at water depths around 1500m.

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