Blowouts represent one of the most severe threats associated with exploration and exploitation of petroleum resources, involving the risk of losing human lives, environmental and economic values. In particular, today's focus on protection of the environment and the ambitions of the industry to operate safely in environmentally sensitive areas generates a need for improved cross disciplinary tools and work processes within blowout risk management. This paper will present a methodology aiming to form the foundation for a new standard for blowout risk assessment. Both details of the analysis method and its contributions to improving the risk management work process will be addressed. The new methodology combines knowledge from different technical disciplines by merging hydraulic flow modelling and different blowout duration models in a Monte Carlo simulation framework, and differs from traditional blowout evaluation methods both in terms of how to collect input data to the analysis and the way the final result is presented and communicated. This methodology introduces a common working platform for HSE engineers and the other disciplines involved in well planning, thus improving cross communication between different disciplines. The paper will present the building blocks of the methodology and illustrate its application on a case from the Norwegian Continental Shelf.


In the petroleum industry, a blowout is among the events that may potentially cause catastrophic consequences to human life and health, the environment and economic values. In this paper we will focus on management of environmental risk, and in particular on the analysis of blowout flow rate and duration for use in environmental risk analysis.

Several risk management activities are carried out in order to deal with blowout risk. Environmental risk management is important in general, particularly in environmentally sensitive areas, where the potential consequences are high and contingency planning for major accidents requires extra attention. This is an increasingly important theme, as the petroleum industry is moving to new and challenging areas and the public awareness around these issues is high.

The calculation of blowout rate and duration is a part of the contingency planning for all operators on the Norwegian Continental Shelf. Well prepared planning includes reflecting a blowout incident in the well design, in ensuring proper communication and understanding within the operating company and in being able to communicate the results from the blowout contingency planning to third parties.

The operating companies perform risk analyses addressing potential damages on environmental resources which can result from drilling, completion, operation and maintenance of wells. The evaluation of possible blowout scenarios resulting in discharges of oil or condensate is a central theme in the analyses. The calculated risk to exposed environmental resources is compared to criteria for acceptable risk and enters into the dimensioning for oil spill preparedness.

Today's practice in E&P companies varies with respect to level of detail, treatment of uncertainty, terminology, documentation and traceability of the blowout analysis. Due to lack of international and national standards relevant for environmental risk analysis, the Norwegian Oil Industry Association (OLF) has developed recommendations based on a reference methodology in order to standardize terminology, procedure and documentation of blowout calculations.

BlowFlow, a software tool and methodology developed by IRIS, meets the recommendations stated in the OLF report [1] by establishing a common methodology and workflow that can help standardizing terminology, methodology, documentation and communication related to the calculation of blowout discharges, thus improving communication within and between companies and to give decision makers stronger confidence with respect to blowout related issues.

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