Offshore evacuation

The methods of evacuation offshore are dependent on the ambient environmental conditions that may develop in the area and relative distance to the mainland. Regions that experience colder ambient conditions inhibit immersion opportunities and remote offshore locations retard onshore assistance capabilities. The preferred and most expedient evacuation means from an offshore installation is by helicopter. Because of the nature of fire and explosions to affect the vertical atmosphere surrounding an offshore installation, helicopter evacuation means cannot always be accommodated and should be considered of low probability where the accommodation quarters are located on the same structure as a hydrocarbon process. 

North/South Atlantic and North/South Pacific Environments 

Areas of the North and South Atlantic, and North and South Pacific present continual extreme and hostile ambient conditions that make survival exposed to such conditions a very limited probability with adequate protection measures. In these locations the probability of survival is increased with the provision of a fixed safe refuge rather than the provision of an immediate means of escape. For offshore facilities historical evidence indicates that both helicopter and lifeboat mechanism may be unavailable in some catastrophic incidents. Remote onshore facilities may also experience severe winter conditions that also render this philosophy applicable. 

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Immediate facility evacuation should be considered as a prime safeguard for all personnel from a major incident. All onsite personnel should be fully trained and where required certified for such an eventuality (i.e., offshore evacuation mechanisms). 

Having defined and gathered data adequate for an initial reserves estimation, the next step is to look at the various options to develop the field. The objective of the feasibility study is to document various technical options, of which at least one should be economically viable. The study will contain the subsurface development options, the process design, equipment sizes, the proposed locations (e.g. offshore platforms), and the crude evacuation and export system. The cases considered will be accompanied by a cost estimate and planning schedule. Such a document gives a complete overview of all the requirements, opportunities, risks and constraints. 

Where space and weight are considerations (such as on an offshore facility) plate separators may be used to dehydrate crude to evacuation specification. Packs of plates are used to accelerate extraction of the water phase by intercepting water droplets with... 

The function of offshore production facilities are very much the same as those described for land operations. An offshore production platform is rather like a gathering station hydrocarbons have to be collected, processed and evacuated for further treatment or storage. However, the design and layout of the offshore facilities are very different from those on land for the following reasons ... 

This section describes the main types of offshore production platform and satellite development facilities, as well as associated evacuation systems. 

Crude oil and gas from offshore platforms are evacuated by pipeline or alternatively, in the case of oil, by tanker. Pipeline transport is the most common means of evacuating hydrocarbons, particularly where large volumes are concerned. Although a pipeline may seem a fairly basic piece of equipment, failure to design a line for the appropriate capacity, or to withstand operating conditions over the field life time, can prove very costly in terms of deferred oil production. 

The OREDA Offshore Reliability Data Handbooks covers a variety of components used in offshore oil drilling and platforms, including gas/fire detection systems, process alarm systems, firefighting systems, pressure relieving systems, general alarm and communication systems, evacuation systems, process systems (vessels, valves, pumps, heat exchangers, and compressors), electrical and utility systems, and drilling equipment. 

It is common in many offshore areas to encounter a shallow gas hazard. Quite often, these hazards can be spotted on seismic, and a surface location is chosen to avoid the hazard. However, there is always a risk of encountering a shallow gas flow with insufficient casing in the well to allow a shut-in. In this instance a diverter system is called on as a safety measure. The ideal function of the diverter system is to allow the well to flow and subside by natural means. In many cases the diverter system simply provides enough time to evacuate the rig. 

Smoke is a by-product of most fires caused by the incomplete oxidation of the fuel supply during the chemical process of combustion. It accounts for a large majority of fatalities of from fire incidents at both onshore and offshore petroleum facilities. In the Piper Alpha incident of 1988, probably the worst petroleum industry offshore life loss incident, the majority of deaths were not from bums, drowning or explosion impacts but from smoke and gas inhalation. The report on the incident concluded that, of the bodies recovered from the incident, 83% were as a result of inhalation of smoke and gas. Most of these victims were assembled in the accommodation awaiting evacuation directions or as they may have thought - a possible rescue. 

The primary safety feature for any installation should be its evacuation mechanisms for its personnel. If personnel cannot escape from an incident they may be affected from it. Personnel must first be aware that an incident has occurred, and then have an available means to escape or evacuate from it. An adequate means of escape should be provided from all buildings, process areas, elevated structures, and offshore installations. Provision of an adequate means of escape is listed in most national safety regulations for the industry as a whole as well as local building code ordinances. 

Two evacuation routes, situated as far apart as practical, should be provided from all hydrocarbon processes or normally occupied work areas. Areas that are considered low hazard (no hydrocarbons, chemicals or other flammables are in the immediate area) may be allowed one escape route. The exception to this is rooms located on an offshore installation in proximity to hydrocarbon processes. 

A prime consideration in the provision of lifeboats for offshore installations is that they can be readily maneuvered away from the structure of the installation. Recent trends have been for the orientation of lifeboats to point outwards so that egress away from the structure is improved and the fear of being swept into the platform by the waves and current is lessened. Positioning in an outward orientation also improves the evacuation time for the boat to "get away" from the incident. 

Offshore facilities are dramatically different from onshore facilities because instead of being spread out the equipment is segregated essentially into compartments or separated into a complex of platforms. Offshore facilities pose critical questions of personnel evacuation and the possibility of total asset destruction if prudent risk assessments are not performed. A through analysis of both life safety and asset protection measures must be undertaken. These analyses should be commensurate with the level of risk a particular facility represents, either in personnel exposed or financial loss. An unmanned wellhead platform might only require the review of wellhead shut-in, flowline protection and platform ship collisions to be effective, while manned drilling and production platforms may require the most extensive analysis. 

The helidecks of offshore facilities are usually provided at the highest portion of the offshore installation for avoidance of obstructions during aircraft maneuvering and available space. As a result the roof of the accommodation is typically selected. The location also facilitates evacuation of personnel from installation by helicopter due to its proximity to the highest concentration of personnel. This enhances one of the avenues of escape from the installation but also exposes the accommodation to several hazards. The accommodation becomes subject to the hazards of helicopter crashes, fuel spillages, and incidental helicopter fuel storage and transfer facilities. 

Orange a. Offshore survival or evacuation craft and personnel floatation devices. b. Identification of the hazardous parts of machines. c. Marking of the guards for the hazardous parts of machine operations. d. Danger signs. e. Relief valve identification or specialized isolation equipment, e. Directional wind socks. 

Additional models and software are identified in A Guide to Quantitative Risk Assessment for Offshore Installations (Spouge, 1999) which address offshore risk analysis, explosion modeling, evacuation and rescue analysis, reliability analysis, accident databases, event tree analysis, and safety management. 

Helicopters are used to transport personnel and light freight to and from offshore platforms. They are also used for the emergency evacuation of injured personnel (but cannot be used, of course, if the platform itself is sinking or on fire). The crash of a helicopter is almost always a very serious event—often leading to fatalities and serious economic loss. 

Offshore platforms can be hit by ships— usually the service boats that provide equipment and supplies. Sometimes these impacts can be very serious. In the case of the Mumbai High incident, for example, a large support vessel approached the platform to evacuate an injured man. The boat had problems with its computer-assisted azimuth thrusters so she was brought in stem-first under manual control. The helideck on the support vessel hit a riser, which started leaking. The leak resulted in a fire that leads to approximately 22 fatalities and total loss of the platform and of the vessel. 

Some facilities—particularly those offshore—require personnel to evacuate during an emergency shutdown. The emergency systems continue to operate, but the personnel abandon the facility by lifeboat or helicopter. 

Fire Prevention and Portable Fire Extinguishers Walking Working Surfaces Job Safety and Environmental Analysis Offshore Orientation and Emergency Evacuation Personal Protective Equipment, Respiratory Prevention of Workplace Violence Marine Debris Fall Protection Introduction Permitting... 

BOEMRE inspectors and investigators are based in 7 district offices (5 in the COM, r in California, r in Alaska) and fly offshore regularly. OCS Eands Act mandates annual inspections. Inspectors have authority to issue Incidents of non-compliance which may be a warning or a facility shut-in. Civil penalties may be issued when violations pose actual harm or threat of harm to personnel or the environment. Industry self-inspections and records are required by regulation. Drills (spill response, BOPE, H2S, evacuation, etc.) are required and may be initiated by BOEMRE without notice. Third-party reviews (design, fabrication and installation) are required for deepwater or novel structures. 

Lack of communication and information transfer offshore-onshore, e.g. cable rupture. However, there are satellite and radio systems that function as backup systems. Control systems can fail independent of 10, but one will have emergency backup systems for such failures as well. However, one can have a situation where everyone is evacuated from the installation - can one then control the installation from onshore ... 

Collapse scenarios similar to that illustrated in Figure 1 developed as a result of a few offshore platforms fires. It is important to predict the time to collapse as accurately as possible in order to design the offshore installation such that platform persotmel will have adequate time escape and evacuate from the installation before the onset of the collapse. 

Risk influence factors related to evacuation from offshore installations... 

Fire, explosions, terrorist acts and extreme weather are examples of situations that may force the crew on an offshore installation to evacuate. There have been several tragic accidents were a large number of the crew have been injured or lost in the mustering and evacuation phase. It is therefore important to better rmderstand the risk and performance of barriers (both technical and not-technical) in an evacuation situation. 

Leafloor, EC. (2006). Survey of Offshore Escape, Evacuation Rescue Safety Systems (Post Ocean Ranger Recommendations) 243. 

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