The oil and gas industry uses an array of marine vessels and structures, such as FPSO, FSU, FSO and LNG FSRU. • Marine hazards include extremes of weather, accelerated corrosion, the proximity of other vessels, hazardous substances, cargo and personnel transfer operations, and piracy. • Loading and unloading of vessels at marine terminals needs to be strictly controlled; the vessel must be securely moored; cargo transfer must be planned; and precautions against fire and explosion must be observed.
• Vessels and crew are subject to regulatory controls, commonly known as ‘flagging’.
• The crew of a vessel has a strict command structure – the Master (or captain) has ultimate authority and responsibility for the safety of the vessel and crew.
• Personnel transfers can be achieved using methods such as bridges, baskets and rope ladders.
• Required PPE is task-dependent but typically includes hard hats, hi-viz jackets, boiler suits and gloves. • Diving operations must be carefully planned and executed; they make use of the permit-to-work system.
Hazards of Vessels and Working
Floating storage and offloading unit – a floating hull fitted with oil storage tanks and a facility to transfer oil to tankers. Many FSOs are old, converted supertankers. The off-shore oil industry uses a vast array of marine vessels and structures, ranging from the large (floating oil rigs and oil tankers) to the small (survival craft).
The floating production, storage and offloading (FPSO) vessel performs the key functions of:
• Receiving hydrocarbons which are produced from nearby platforms.
• Processing them.
• Storing them.
• Off-loading them via a tanker or a pipeline.
FPSOs are often converted oil tankers or may be vessels built specially for the application.
Other vessels may perform a more limited range of functions such as:
Floating storage unit – can either be the same as an FSO or, more commonly, transfer the oil by pipeline to a land-based facility.
Floating production, storage and offloading unit – for receiving crude oil from wells, processing it (separation of oil, gas and water), storing and offloading.
Liquefied natural gas floating storage and regasification unit – receives LNG from other vessels, ‘regasifies’ it (i.e. converts the liquid back into gas) and distributes it via pipelines to onshore facilities.
• Floating storage and offloading unit (FSO) – used only to store oil and off-load to oil tankers.
• Floating storage unit (FSU) – used to transfer oil by pipeline to a land-based facility.
Similar vessels (FSRUs – floating storage and regasification units) are used to store and handle liquefied natural gas (LNG). They receive LNG from other vessels, convert the liquid back into gas and distribute it via pipelines to onshore facilities.
A marine oil and gas terminal is a dock where ships/tankers moor to transfer crude oil (and derived products) and gas (LNG, LPG) to, or from, storage facilities. Some terminals are on-shore and some are off-shore. You will notice that F(P)SO/FSU can be regarded as off-shore terminals in this respect, though transfer will only be from the storage unit to the ship/tanker. Activities at terminals would include escorting (by use of tug boat) to safely berth/moor the ship and offloading/loading (using
hoses, pipelines or loading arms). Some tankers (‘supertankers’) may be too large to moor at the terminal itself. In these cases, ship-to-ship transfers are the usual solution, whereby liquid from the larger ship is transferred by hose to a smaller, lighter vessel, which can then moor at the terminal. This process is called
• Extreme environmental conditions (weather, waves, sea currents/temperature, ice, etc.).
• Accelerated wear and corrosion – the stress of constant movement/buffeting and aggressive salt spray means that structures and equipment can quickly fail if maintenance is neglected. We looked at this in an earlier element.
• Collisions with other vessels and structures (including running aground and damage from icebergs) – these may also result in environmental damage (oil spills). An inadequate/defective mooring, combined with extreme weather may contribute to this. We will look at control of vessel design and marine operations later.
• The intrinsic hazards of the substances – we looked at the hazards of the main substances in Element 1, e.g. LNG, hydrogen sulphide and drilling
fluids (‘mud’). We also looked at the potential for fire and the different methods of fire and explosion protection in earlier elements.
• Oil/LNG transfer operations – which, again, could result in environmental damage (oil spills). We will look at loading/ unloading operations later.
• Personnel transfer operations – see later in this element. • Drilling rig hazards (other than those already mentioned, such as fire and substances in use) – working at height, manual handling.
• Lone working (we will look at diving operations later). • Personnel falling overboard (through tripping, slipping), with the risk of cold shock (from icy water), extreme fatigue (the effort to stay afloat with water-logged clothing), hypothermia (if not rescued immediately) and drowning. We looked at recovery and rescue in the last element.
• Piracy (a specific problem around East Africa/Somalia). We will look at some aspects of vessel safety/security later.