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In the event of a collision between a vessel and an offshore installation (whether passing or in-field), given the likely volumes of oil that could be released, the possibility for large scale loss of life, asset and environmental catastrophe exists. This paper provides an overview of the ship/platform collision risks and presents the methodologies that can be applied to quantify the frequency and consequences of these events. Particular focus is placed on application of risk assessment methodologies to offshore platforms located in the Gulf of Mexico. This is being demonstrated through a JIP on "Risk and Reliability of a FPSO in Deepwater Gulf of Mexico." Following an introduction, the paper focuses on three main collision scenarios, which from North Sea experience tend to present greatest threat to an installation. A historical review of each of these collision scenarios is presented and an overview of risk assessment methodologies is provided for the two scenarios most likely to result in pollution, loss of life and asset, and production loss/delay. Measures that have potential to reduce the risk of ship collision are highlighted. Finally recommendations are made for future developments in this area, which could reduce the risk of pollution, fatality and loss of asset. This paper draws on a large amount of experience developed from research and analysis work performed in the North Sea. Introduction and Background Designated shipping fairways for vessels approaching ports and navigating between various ports are provided in the U.S. Gulf of Mexico (GOM). These fairways are located in water depths up to 200m (660 ft). Beyond this, the routes followed are based on the shortest distance from entry to the GOM to the most appropriate shipping fairway. The fixed platforms in the GOM are designed for protection against collisions from in-field supply vessels by provision of rubber fenders on boat landings and barge bumpers at the platform legs. The assessment of risk from passing vessel collisions and offloading tankers is not normally performed for the fixed platforms in the GOM. Several deep water jackets and floating platforms (TLP, SPAR), have reduced the risk of vessel collision by designing/installing protection systems such as platform based radar systems and by the provision of a 500 m radius designated safety zone around the platform with restrictions on entry by unauthorized vessels. Collisions can occur with in-field vessels (e.g. shuttle tankers, supply vessels, drill rigs/ships, accommodation barges etc.) or with passing traffic such as merchant craft (e.g. ferries, VLCCs etc.). These vessels could be under power or drifting (i.e. environmental forces acting on the vessel) when they collide with the structure. The main causes of powered passing vessel collision tend to be related to watchkeeping failure (e.g. no navigator on the bridge, watchkeeper asleep or radar malfunction). For drifting vessels, the main cause tends to be engine/propulsion unit failure. Such collision incidents have the potential to inflict significant damage to an offshore installation and, for an Floating Production Storage and Offloading (FPSO), puncture of cargo tanks could lead to significant hydrocarbon spillage as well as loss of life, impairment of safety functions, and production loss/delay. In some cases, the damage could lead to fire and explosions, or major structural failure leading to complete loss of the FPSO. Technologies for collision risk assessment and risk management have advanced within the North Sea, where installations are located away from the shore in proximity to high volumes of passing traffic and where there are also a large number of FPSO facilities whic

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Controlling the trapping of CO2 in the subsurface, i.e. storage containment, is of fundamental importance for a safe geological storage of carbon dioxide. During CO2 injection, increasing fluid pressure, temperature variations, and chemical reactions between fluids and rocks inherently affect the state of stress inside the reservoir and in its surroundings. Besides, the mechanical properties of the rocks exposed to CO2 may be altered. The impact of the resulting deformations on seal integrity must therefore be assessed in order to properly manage containment performance and leakage-incurred risks. The analysis starts with the construction and the calibration of a Mechanical Earth Model of the site, through joint analysis of geologic, seismic, logging, drilling, and laboratory test data. Such a model consistently describes ambient stresses, fluid pressures, and poro-mechanical and strength properties of the formations. It is linked to a reservoir model to achieve initial equilibrium and also to further simulate the coupled transport, chemical and mechanical processes occurring during CO2 injection operations and the subsequent re-equilibration. The predicted stress path allows the evaluation of the mechanical stability of both cap-rock and faults (which may bound the reservoir, penetrate the cap-rock or intercept wells). The stability of wells in formations experiencing strain is also investigated. In addition, an accurate Mechanical Earth Model contributes to optimizing well construction and stimulation operations. Profiles of stresses and mechanical properties along a planned-well trajectory allow designing a drilling operation that will maximize subsequent hydraulic isolation of the well by optimizing the wellbore condition. Similar information along existing wells helps to control hydro-fracture propagation when injectivity enhancement is required. The Mechanical Earth Model can be used to develop operating envelopes for well placement, hydraulic fracturing, and CO2 injection that best ensure containment while achieving injectivity and capacity requirements. Introduction The climate of the Earth is warming, with widespread changes in ocean salinity, wind patterns, precipitation and aspects of extreme weather. This is very likely forced by the increase in anthropogenic greenhouse gas concentration in the atmosphere. It is estimated that over 60% of this increase is due to carbon dioxide (CO2) emissions alone[i]. Carbon Capture and Storage (CCS), that is the capture of CO2 from industrial and energy-related sources, transport, and injection into the subsurface for long term sequestration purposes, is a viable means to keep a significant fraction of emitted CO2 out of the atmosphere. CCS is thus recognized as a promising solution to mitigate climate change.[ii] Along with capacity and injectivity, containment is agreed to be a primary function in geological storage performance. As evidenced by oil, gas, and even CO2 natural accumulations, rock formations can be impervious enough to act as flow barriers over geological periods of time. Delineating such a seal, safeguarding its integrity under operational conditions, and verifying whether isolation is effective or not are key objectives in achieving a successful storage project. In particular, seal integrity must not be impaired by the mechanical effects of storage operations. Indeed, rocks and faults permeability may drastically increase as they undergo stress changes and deformation[iii]. The mechanical response of the sealing components to the loads induced by well drilling and completion, CO2 injection, and the corresponding effects on the risk of leakage must therefore be assessed when evaluating the suitability of candidate sites, designing operations, and planning monitoring schemes. This paper presents a methodology where characterization, modeling, monitoring, and construction technologies are integrated for containment performance and risk management. The first section frames the performance and risk management methodology under whose umbrella the geomechanical analysis takes place. The following sections describe the building of a Mechanical Earth Model (MEM) and how mechanical modeling is coupled with fluid flow simulation so as to forecast the dynamic response of the rock mass to fluid pressure increase, temperature variations, and fluid/rocks chemical interactions caused by massive CO2 injection and subsequent re-equilibration. Implications in terms of risk evaluation and strategy for risk control are discussed in the last sections.Working Group I contribution to the Intergovernmental Panel on Climate Change Fourth Assessment Report "The Physical Science Basis", 2007.Working Group III contribution to the Intergovernmental Panel on Climate Change Fourth Assessment Report "Mitigation of Climate Change - Summary for Policymakers", 2007.Sibson, R.H.:"Brittle-failure controls on maximum sustainable overpressure in different tectonic regimes", AAPG Bull, v. 87(6), p. 901–908, 2003.

The paper describes a process for constructing a risk register to be used to track the evolving perception of risk during a CO 2 storage project. A project-specific risk register is developed through a structured elicitation process to determine initial perception of risk and through discussion with experts. Regular updating of the register by experts is used to track changes in the assessment of risk as the project progresses and inform decision and actions during the project with the aim of reducing risk to an acceptable level.