Geosyntec undertook a quantitative risk assessment (QRA) for the Cidade de Paraty Floating Production Storage and Offloading (FPSO) vessel, which will operate in the Lula oil field. The Lula oil field, which is the largest hydrocarbon find in the world since the Kazakh Kashagan discovery in 2000, is located in the Santos Basin, 250km south of Rio de Janeiro. It is estimated to hold five to eight billion barrels of oil equivalent. Due to the size of the field and the water depth, which in areas is in excess of 2000m, it will be developed using a number of FPSOs.
Geosyntec Scope of Services
The QRA, which was undertaken during the detailed design of the spread-moored FPSO, was one of a range of safety studies culminating in the preparation of a Design Safety Case. The safety studies were undertaken to comply with the requirements of Single Buoy Moorings Inc. (SBM) Offshore, the operator, Petrobras, and regulations in Brazil. In order to determine the robustness of the design, SBM Offshore required the preparation of a predictive hazard analysis. This analysis was carried out as a QRA, which used a standard approach applied in the offshore oil and gas industry. The assessment included a parts count, frequency assessment, consequence assessment, and risk determination. The aim of the study was to perform a quantitative review of all the identified hydrocarbon and non-hydrocarbon hazards on the FPSO to demonstrate the technical integrity and robustness of the design. The hazards assessed were taken from the Project Hazard Identification Study (HAZID) and reviewed against hazards identified in other QRAs undertaken by Geosyntec to ensure completeness. The QRA was undertaken using an Excel-based spreadsheet approach supported by Visual Basic for Applications (VBA) coding. This approach provided a significant level of transparency to the study, which facilitated the ready interrogation of inputs and results. The QRA calculated: The Individual Risk Per Annum (IRPA), The Potential Loss of Life (PLL), and The Temporary Refuge Impairment Frequency (TRIF), where applicable, for topsides releases (gas, two phase and liquid), riser releases (gas and two-phase), CO2 dispersion (asphyxiation), ship collision, helicopter transport, other fires (non-process), loss of mooring, structural failure, engine room flooding, and dropped objects.
The results of the assessment were mapped to SBM Offshore’s risk matrix for personnel and asset risk. Sensitivity analyses were carried out to assess the impact of varying the key input data and assumptions, and a risk control measures review meeting and assessment were undertaken to identify potential risk control measures. These measures could be implemented to reduce the calculated risks on the FPSO as part of the process of ensuring an “as low as reasonably practicable” (ALARP) design.