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The Oil and gas industry is a risky business: e&p activities have the potential to give rise to major accidents such as Blow Out events, as well as hydrocarbon leaks and also catastrophic pipeline/ riser release leading to fire and or explosion. These dramatic events can result in loss of human lives, severe pollution to the environment, damage to the asset and production disruption, and in additional to the emotional and ethical impact can seriously compromise company reputation.On top of that, in recent years another critical challenge is posed by e&p activities in sensitive and hostile environment that represent the new frontier of development: in fact the increasing hydrocarbon demand pushes operators towards unconventional deposits and higher-risk and remote areas characterized by social and environmental sensitivities where the emergency response and the oil spill preparedness become particularly difficult.This paper describes the successful synergy of some consolidated methodologies and new initiatives undertaken within our Company to foresee consequences of major accidents and enhance emergency response and oil spill preparedness in e&p operations: -a new procedure for the evaluation and prevention of the exposure to pollution of e&p wells that foresees the identification of exposure to pollution classes (High, Medium, Low EtP), for different typologies of wells; -the development of SMART GIS project, a web application to acquire data source information to support emergency management and oil spill preparedness; -the combination of in house Short Cut Model (SCM) i ii iii in BART tool for an expeditive estimation of Blow Out consequences; -the development of an expeditive semi-quantitative methodology to assess risk of release from pipeline combined with a Bow tie approach for the identification of preventive and recovery barriers to reduce frequency of hazardous event or mitigate their consequences.

Increasingly stringent HS&E requirements inevitably leads to an improvement in the predictive risk analysis tools used to estimate the HS&E consequences of a major accident. One potentially major accident, associated with the exploration and exploitation of hydrocarbon fields, is a blow-out e.g. an uncontrolled release of formation fluid from the reservoir. In the event of a blow-out it is essential to implement the blow-out contingency plan as quickly as possible to minimise the potential damage, particularly for onshore wells where the oil and gas is dispersed into the atmosphere and over the land. To improve the evaluation of the safety and environmental consequences of a blow-out the Agip Division commissioned a multi-disciplinary R&D project. This project utilises technical and scientific support from EniTecnologie, TEA Sistemi and TEMARS companies. The main objective of this project is the development, assessment and validation of an integrated methodology for the evaluation of the safety and environmental consequences of a blow-out. The extension of the contaminated area, the gas and oil droplets concentration distribution and the oil and gas discharge flow-rates from the well are the main deliverables from the methodology. As the primary use of this methodology would be in the management of the emergency response to a blow-out it is essential to optimise the response time. Subsequently, the following predictive approaches were developed and validated against actual blow-outs:A "One Minute" estimation tool;A "Ten Minute" estimation software;A "Best Estimation" approach. To better characterise the oil droplet field from the wellhead to the environment "ad hoc" experimental work is undertaken to reproduce the real conditions associated with a blow-out. Introduction The availability of validated predictive tools for application during an accident scenario is essential. Their use should not be restricted to design activities. They generate vital information on the evolution of an accident and can be readily applied to optimise the emergency response. One potentially major accident event that is associated with the exploration and exploitation of hydrocarbon fields is an uncontrolled release of formation fluid from the reservoir e.g. a blow-out1,2. In the event of a blow-out it is essential to implement the blow-out contingency plan as quickly as possible to minimise the potential damage, particularly for onshore wells where the oil and gas is dispersed into the atmosphere and over the land and can have an impact also on people. To improve the evaluation of the safety and environmental consequences of a blow-out the Agip Division commissioned a multi-disciplinary R&D project. This project utilises technical and scientific support from Eni Technologie, TEA Sistemi and TEMARS companies. Due to the wide range of knowledge and expertise required by this project (e.g. safety, reservoir, drilling, completion and well fluid dynamic, discharge phenomena and atmospheric dispersion) it proved necessary to "integrate" the various disciplines to ensure good quality project deliverables. The key features of the project are described in the following sections.

The uncontrolled blow-out of a well is one of the most critical accidents that can occur during both exploration and exploitation of hydrocarbon fields. Significant HSE issues are associated to this event that introduces safety risks for field operators, potential health injury for the population and impacts on the environment. Blowouts need to be evaluated through specific models: commercial packages may lead to a non-exhaustive analysis and underestimate the effects. Some phenomena that occur during a blow-out event are not sufficiently treated in literature, so that experimental or CFD investigations are sometime necessary to allow an exhaustive analysis and the expansion of a specific database, useful to develop and validate simplified models. ENI E&P has been carrying out a specific R&D project since 1998. This paper describes some blow-out jet simulations, and the associated methodology, carried out applying the CFD approach. The jet development into atmosphere affects strongly the cloud evolution, in terms of shape and concentration, and then the flammable/toxic gas dispersion as well as heat radiation. Different release conditions have been analyzed:horizontal and vertical jet, both ignited and un-ignited;free and restrained jet;heavy and neutral gas dispersion. Jet direction has a strong effect on cloud formation and dispersion: for example if a horizontal jet take place near the ground, it can remain glued on it (KOANDA effect), resulting in high concentration. This phenomena take place also in case of ignited jet: the flame remains glued to the ground, resulting in high temperature and radiation level. Moreover, totally restrained jet could generate a heavy-gas cloud, resulting in high concentration in the near-field. In this case, the cloud formation happens in different consequent stages, and a transition analysis is necessary to reproduce the event correctly, in terms of risk area evaluation. "Blow-out Project" Objectives e Work Phases Eni E&P is developing the methodology, for the simulation of a blow-out event, in the framework of three subsequent specific R&D project phases, in order to allow the complete analysis of the phenomenology associated to the blow-out event:Phase 1: 1998 - 2000: "Blow-out 1";Phase 2: 2001 - 2004: "Blow-out 2";Phase 3: 2005 - 2007: "Blow-out 3". The main objectives of the project have been:Provide tools to evaluate the consequences of a blow-out during the various drilling stages and exploitation activities.Supply information on the evolution of the event that can be used as a basis to:Support authorization phases, providing important and reliable information direct to the authorities;Optimize the location of the well area taking into account the possible consequences of a blow-out just from the first step in the drilling activities;Plan and manage the emergency actions to mitigate real blow-out situations, providing decision making tools to key people;Produce the data required to prepare a Contingency Plan. The Methodology includes all the kind of impact associated with a blow-out event and with pipeline releases accidents also including underwater discharges, oil spill analysis and transient releases (typical of a pipeline leakage). "Blow-out 1" and "Blow-out 2" phases allowed to obtain two PC softwares (for the "Short-Cut" and "Standard" Approaches) for an exhaustive simulation of the consequences of a blow-out. The software has just been presented in other Conferences,5,6,7. Presently, Eni E&P and TEA Group are carrying out a 3rd phase of the project (2005–2007) "Blow-out 3". This activity will allow to improve the model and the methodology, taking into account problems, results and the know-how resulting from a great number of applications performed and scenarios analyzed. CFD investigation is one of the most important activities of the "Blow-out 3" phase.