The ultimate reference for selecting, operating and maintaining offshore structures, this book provides a road map for designing structures which will stand up even in the harshest environments. They vary considerably in size due to location, water depth, weather conditions and whether they are intended for gas or oil production, ii- May be constructed in sections and transported, iii- Large field, long term production , supports a large number of wells, i- Costs increase exponentially with depth, iv- Steel structural members subject to corrosion, Offshore structures are constructed on land. The generic Part 1 requirements are to be used together with the applicable supplemental Part 1 requirements for the specific type of unit or structure. Semi-sub may remain in close attendance to a fixed, Semi-subs have three characteristic drafts, i- Transport draft: when towed water level is at pontoon, ii- Operating draft: when drilling it is semisubmerged with water level through, iii- Survival draft (between above two drafts): in extreme wave conditions (small draft compared to operating draft). Subsea completions are also structures that are placed on the seafloor basically to support equipment. This is both quicker and safer, i-When elevated, the jack-up is a stable platform since it does not experience any, rigid body motions in the elevated position, ii- Economical due to low initial cost and operating costs, i- Limited to shallow waters , 140 meters, ii- Before transporting, raising and lowering; suitable weather conditions must be, ensured. It contains all equipment associated with a fixed installation and is used in conjunction with subsea wellheads to exploit moderate to deep water oil fields, They are selected for field development for one of three reasons, b) Field is isolated and there is no pipeline, c) Field is located in very deep water. High pressure jets of water or compressed air may be used to remove loose debris in the vicinity of the spud cans while the legs are manoeuvred into position, this process being referred to as spudding in. The legs are raised and lowered by means of a rack and pinion arrangement, the racks being attached to the chords of each leg, running from top to bottom while the pinions are driven by electric motors via reduction gearboxes, typically 12 motors for each leg, The hull of the jack-up must be raised and lowered on an even keel. It has no hydrocarbon processing facilities, but receives processed oil from a fixed platform or, Processes and offloads hydrocarbons without storage capacity. Heavy lift cranes mounted on semi-submersible barges are, used. This NORSOK standard is the principal standard for offshore structures, and together with the normative standards in this document, it constitutes a common basis covering those aspects addressing design requirements, integrity management and assessment of all types of offshore structures. Depths of approximately 2000m have now been reached. Detailed analysis methods, as applicable to both 2dimensional and 3-dimensional structures will be discussed. The drilling derrick is fitted to rails so that it can be cantilevered into a position which provides direct access to the wellhead area, In Figure 1, the following are shown: a- spud cans, b- elevating racks, c- legs, dgear units, e- drilling derrick and equipment, f- accommodation, g- helicopter pad, hcranes, i- nearby jacket platform, Such platforms are typically towed like a barge to the drilling site (over short distances) with the legs elevated vertically above the barge deck. The first type of offshore structure was a wooden type. Aside from simply setting up an offshore company, there are different tried and tested structures with which many knowledgeable individuals have successfully operated offshore accounts that often were in reality, big international businesses. It has a ship shape hull adapted to accommodate drilling equipment . Current industry practice is implemented in offshore codes, e.g. The main objective of the template is to provide a guide frame through which wells can be drilled before the arrival of the jacket. Offshore Structure Design, Construction and Maintenance covers all types of offshore structures and platforms employed worldwide. Deep-draft concrete floaters (DDCFs) 3. These types of platforms are as follows. Different Types Of Offshore Oil and Gas Production Structures Drillships have their own propulsion and move under their own power. Floating Structures † Floating Production System Editor. Many oil platforms will also contain facilities to accommodate their workforce. Current issue Browse list of issues Explore. Drillships and semisubmersibles are the two main types of drilling structures. Process Product Specification Absorbed energy / vEtemp. They are designed with good stability and seakeeping characteristics. The turret is a large diameter (16-32 meters) vertical cylinder mounted on heavy duty roller bearings. Floatable/bottom-founded concrete-hull structures 2. Compliant tower † Compliant Tower † Guyed Tower † Articulated Tower † Tension Leg Platform 3. Lexicon … Submit an article. Floating structures 1. and behaviour, the ofishore structures for oil and gas development has been divided into following categories. Offshore oil and gas vessels are used for a multitude of purposes such as the transportation of drilling units, maintenance and drilling. An oil platform, offshore platform, or offshore drilling rig is a large structure with facilities for well drilling to explore, extract, store, and process petroleum and natural gas that lies in rock formations beneath the seabed. Generally, offshore concrete structures are classified into fixed and floating structures. Structures supported on the seafloor can experience failure of the structure, foundation or soil, while buoyant structures can experience capsizing or sinking , hull or mooring system failure. Helicopters and supply boats ferry workers and equipment to the platform. The ultimate reference for selecting, operating and maintaining offshore structures, this book provides a road map for designing structures which will stand up even in the harshest environments. petroleum reserves has been conducted in most continental shelf areas of the world. Over the past 40 years, two major types of fixed platforms have been developed: the steel template, which was pioneered in the Gulf of Mexico, and the concrete gravity type, first developed in the North Sea. Corrosion Control for Offshore Structures ++ + Unwanted gas may be burned. The line is a combination of wires and chains with buoys or sinkers (clump weights) along the line, b- Wellhead area: containing the Christmas trees, c- Process area: contains pressure vessels and equipment for production, d- Power generation: alternators are provided, driven by diesel engines or gas turbines, e- Heli-deck: to transport personnel and for evacuation in emergencies, g- Radio mast: for communication components such as satellite and telemetry dishes, h- Vent stack: for gas producing installations. The cost of corrosion in the United States is estimated to be about 4.3% ... also need to know how to understand various types of corrosion and how they can be identified, measured, and mitigated. Fixed Offshore Structures (hereafter referred to as "structure" in these Rules) as used herein means structure supported by and fixed to the sea floor of specific site of the installation. Ah, layman terms. One reason is the uncertainty associated with the performance of these materials and the concern that such … For large sized jackets, piling through the legs becomes impractical so a pile cluster is fitted to the base of each leg. Main propulsion system may be omitted with reliance on electrically powered thruster units to assist in station keeping. Your email address will not be published. The piles can then be driven through the cluster guides to the required depth of 60-90 meters before being grouted into position, Topsides are constructed in liftable packages that are installed and welded one at a, time, see Figure 6. The maximum water depth is 500m. ASD. Offshore Structure. One end of the leg is secured in a foundation template piled into the sea bed while the other end is connected to a tensioning winch within the floating superstructure. According to John (2014), generally, there are four types of fixed structures and four types of floating structures. The design of the base includes caissons (void spaces), suitably dimensioned to provide the structure with a natural buoyancy to enable it to, be floated clear of the drydock for finishing off before towing to its final destination, Once on location the void spaces are flooded to position the base on the sea bed. Introduction to offshore structures 1. 1.3.1 Steel template Structures The steel template type structure consists of a tall vertical section made of tubular steel members supported by piles driven into the sea be with a deck placed on top, providing space This typically takes place in lakes, swamps, rivers and canals. ♦ Production Structures: A production unit can have several functions, e.g. Offshore Structures: Design, Construction and Maintenance, Second Edition covers all types of offshore structures and platforms employed worldwide. There are various types and arrangements or configuration of coastal protection structures includes bulkhead (Figure-20), seawalls (Figure-21), groins (Figure-22), jetties (Figure-23), and … DIFFERENT TYPES OF OFFSHORE STRUCTURES . In the last few years, we have seen pure sea bottom installations with multiphase piping to shore and no offshore topside structure at all. It is mainly used for exploratory drilling operations to drill wells for permanent platforms but a number have been constructed as accommodation support vessels to provide assistance to, fixed installations during construction,modification or repair, The majority of jack-ups are used for exploration (wildcat drilling) purposes and work-over. Ok last time I already explained about the introduction of the offshore structures and now we move to the main contents, types of offshore structures. Jacket size dictates the method of pile installation as can be seen from Figure 5. 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