“Offshore Installations: Guidance on Design, Construction and Certification,” HSE Books, 1995 (supersedes same title from UK Dept. Thrusters can be used to reduce the mooring system loads caused by mean environmental forces, provide damping of the low-frequency motions and assist in heading control. Ensuring that the mooring system has suitable reserve capacity when one mooring line or one thruster has failed – accidental limit state (ALS). Dry trees are possible on a TLP because the platform is heave-restrained by vertical tendons, or tethers. Further details are given in the standards. The following guidance is given on safety factors: γF = 3, for wire and chain line that can regularly be inspected on-shore. It is important that the model test or simulation is carried out over a suitable length of time to give appropriate statistical quantities. For water depth greater than 2000 m—Taut leg system with polyester rope is likely the most cost-effective choice, especially for harsh environments. The spread mooring is a natural extension of the traditional mooring of ships. The process plant on the vessel can handle about 19,000,000 cubic metres per day (670,000,000 cu ft/d) of gas and 13,500 cubic metres per day (480,000 cu ft/d) of oil. FPSOs are preferred in frontier offshore regions as they are easy to install, and do not require a local pipeline infrastructure to export oil. Floating production system (FPS) technology has come of age in the North Sea. Relatively speaking, a spread mooring system is simple and economical, and does not require complicated rotational mechanical systems. In an individual sea state the fatigue damage di is given by: where the number of stress cycles, ni, is calculated from the product of the mean up-crossing rate of the stress process (in Hz), the probability of occurrence of the sea state, together with the mooring system design lifetime in seconds. Thrust contributions to station-keeping can be evaluated using the methods of mean load reduction and system dynamic analysis as follows: The mean load reduction method involves subtracting the surge and sway components of allowable thrust from the mean environmental loads for spread-moored vessels. Floating production systems are flexible, cost and schedule effective solutions in particular for deep water applications. The selection of mooring line spread has to consider a number of factors such as design, installation, the directionality of environment, mooring material cost, etc. All materials supplied by TPK . Catenary systems tend to be costlier at larger water depths (say, more than 1000 m), as the mooring lines become very long. To overcome this problem, it is typical to have a CALM buoy next to the spread moored FPSO in the field setup for export operations of a shuttle tanker. This has caused many problems in the industry and has led to many offshore system repairs and replacements. FPSOs eliminate the need to lay expensive long-distance pipelines from the processing facility to an onshore terminal. Automatic control systems are more sophisticated than manual and can have features such as monitoring of vessel position and line tension alarms, consequence analysis and simulation capabilities, relevant data logging, self-diagnostics and allow system response to major failures. An example is Knock Nevis, ex Seawise Giant, which for many years was the world's largest ship. Values of aD and m are given in table 8.8. The FPSO conversion was carried out at MMHE Shipyard Pasir Gudang in Malaysia, while the topsides were fabricated in modules at various international vendor locations. In order to calculate the mooring line structural response it is necessary to apply appropriate environmental loads for the site under consideration. Ensuring that each mooring line has suitable reserve capacity when subject to cyclic loading – fatigue limit state (FLS). For ship-shaped floating vessels with spread moorings, the mooring lines are connected at the bow and stern and spread outward, which can restrain the lateral offset and heading of the hull. There is a significant difference in the current mooring criteria between European (mainly North Sea) and the U.S. Gulf of Mexico as reflected in API RP 2SK. Low-frequency motions for semi-submersibles and ships should be calculated in the horizontal directions only, that is, surge, sway and yaw. A production spar typically uses 9 or 12 mooring lines in three groups connected from the outer shell of the platform to the seabed. This might involve thousands of cases covering, for example, hindcast conditions every 6 h going back 10–20 yr at the specific site. So over the last 25 years we have seen significant technological advances in the FPS design. Oil Terminal "Belokamenka" L.L.C Rosnefteflot, Rubicon Offshore International with Langstein Slip. Presence of mean stress for non-welded components, Ovality and mis-match causing hi-lo conditions at the weld. [11] The unit is destined for the Kanowit gas field off Sarawak, Malaysia. 2021 Floating Production Forecast More than 200 known projects in the planning stage are likely to require a floating production system for field development. Flexible risers, on the other hand, can be designed to tolerate larger offset and can be combined with any of the mooring systems. The jumper tension results are very preliminary since no dynamic is considered. Quasi-static analysis, allowing for submerged weight and elasticity of line, platform motion and seabed reaction/friction forces, is usually appropriate when dealing with platform mean- and low-frequency motions. The primary drivers are reservoir characteristics and infrastructure, which will dictate the facility size, number of wells, their location, and whether wet or dry trees are called for. The layout of the subsea architecture must also be considered within the context of mooring system analysis. The weather directions to be considered depend on the vessel mooring arrangement. It has wire rope and chain connections to an anchor, or it can be dynamically positioned using rotating thrusters. There is strong emphasis on catenary analysis using chain and wire and, more recently, guidance on taut moorings using fibre ropes. The HR and flexible jumper are in operation are filled with exported gas. 5.2 Cargo tank vent and inert gas systems. FPSOs are yet to operate in the Gulf of Mexico perhaps due to both regulatory requirements and the availability of infrastructure for production export, i.e. The EPcma contract covers detail engineering and procurement work for the FPSO topsides as well as construction management assistance to BP including hull and topside facilities. These include thruster tunnels, sea chests, and annular spaces inside turrets. Six-strand wire rope (fig. The FPSO has a disconnectable turret (APL). Chain wire fatigue curves based on stress (DNV OS-E301). The difference in cut-off pressure between a subsea well and a surface well can be as much as 1000 psi vs. 100 psi [OTRC, 2002]. A number of sea states should be selected along a “contour line” representing the joint probability of significant wave height and peak wave period combinations at the mooring location. the force associated with the pressure field of the incoming “undisturbed” wave. Therefore although the spread mooring system is cost-effective, its application to large ship-shaped floating structures is only suitable for areas of a benign environment or where the directionality of wind, wave, and current is persistent, such as in offshore West Africa. Unlike wells on fixed platforms and on land, subsea wells do not allow operators to have direct access to the wells for maintenance, or for re-completion (drilling into new reservoirs from an existing well). Floating, Production, Storage and Offloading (FPSO) is also a type of floating system which is used for production and storage of oil/gas at the sea. From a corrosion control standpoint, these structures offer a number of new challenges and a new set of design regulations and guidelines. Wellheads are on the ocean floor and connected to the surface deck with production risers designed to accommodate platform motion. Bittern, Guillemot West, Guillemot Northwest, This page was last edited on 12 January 2021, at 09:48. whether the facility needs to support a drilling rig or whether a leased Mobile Offshore Drilling Unit (MODU) will be used. Guide to FPSO (Floating Production Storage and Offloading) 2018-07-19 by Adam Muspratt Floating Production Storage and Offloading is a core element of the oil & gas extraction and refinement process. axial compression fatigue – on leeward lines during storms for example, prevented by maintaining a minimum tension on the rope. [6], On July 29, 2009, Shell and Samsung announced an agreement to build up to 10 LNG FPSOs,[7] at same Samsung Yard Flex LNG appeared to construct smaller units. The DNV curves are shown in fig. The report is titled “Floating Production System Market Size, Share & Industry Analysis, By Type (Floating Production, Storage, and Offloading (FPSO),Tension Leg Platforms (TLP), Spar … The term fSi represents the probability density of peak to trough nominal stress ranges for the individual state. [23] BP also selected Aker Solutions to perform the detail engineering, procurement and construction management assistance (EPcma) for the Skarv field development. [9] Royal Dutch Shell (2013), LNG FPSO (Liquefied Natural Gas Floating production Storage and Offloading), Samsung Heavy Industries at a cost of $12 Billion. Long-term floating production vessels use spiral strand steel wire ropes as this has improved fatigue and corrosion behaviour. All have reached a level of planning where the production solution has been narrowed to a few options -- including use of a floating production facility. Figure 1.6. [14], Floating production, storage and offloading vessels are particularly effective in remote or deep water locations, where seabed pipelines are not cost effective. Guidance is also given on stiffness values for polyester, aramid and HMPE for post-installation, drift and storm conditions for deepwater fibre moorings. The chokes and valves placed in a subsea tree result in a pressure drop in the flow of oil or gas. Manual and automatic remote thruster systems. Additionally, vortex-induced vibration needs to be addressed for platforms of deep draft. A floating production storage and offloading (FPSO) unit is a floating vessel used by the offshore oil and gas industry for the production and processing of hydrocarbons, and for the storage of oil. In order to convert from tension to stress the nominal steel areas given in a table in the API RP2SK may be used. Updated daily – 24/7/365 – courtesy of World Energy Reports’ global network of correspondents and analysts – the database is a powerful tool that enables you to research, discover and produce the information you need, when you need it, in the form you want to see it. Hydrodynamic loading is covered in Chapter 3 and physical modeling in Chapter 13. As of this writing, production Spars have only been installed in the Gulf of Mexico. Taut (or semitaut) leg system with a chain–wire–chain setup. Floating Production systems (FPSs) emerged in the 1970s as an option to produce hydrocarbons that were discovered further offshore in water depths that exceeded viability of fixed platform installation. “Recommended Practice RP B401: Cathodic Protection Design: 1993,” DNV. Furthermore, once the field is depleted, the FPSO can be moved to a new location. The FPS is moored in place by various mooring systems—a central mooring system allows the vessel to rotate freely to best respond to weather conditions, or weathervane, whereas spread-mooring systems anchor the vessel from various locations on the seafloor. The production started in field in August 2011. A minimum of 3 h full-scale equivalent time is specified, though usually significantly longer time is beneficial. Note however that when addressing the FLS, only 50% of the corrosion allowance need be applied. We will not repeat the discussions there, but will summarise the practical implementation for Global Strength analysis. In high current environments, such as, the Gulf of Mexico deepwater, North Atlantic and certain areas of West Africa and Southeast Asia, the current may be the controlling event and a 100-yr current plus associated wind and waves is also specified. Guidance notes and standards give examples of contour lines. Waves provide three loading mechanisms acting on the floating vessel. Subsea wells may also result in lower reservoir recovery simply because of the physics of their operation. The first commercial application of this technology, and the first dry tree completion from a floating platform, was the Conoco Hutton TLP installed in the UK sector of the North Sea in 1984 [Mercier, et al 1980]. Large capacities of steam, hot-water or thermal oil are required for the processes onboard Floating Production Systems. These are often referred to as clustered-spread mooring systems. The FPS can be used in water depths from 600 to 6,000 ft. In addition to the historical records already mentioned, a few more are added in this section. As an example, the DNV Offshore Standard for Position Mooring specifies different safety factors for design depending on the criticality of the production. The equal spread design in which all mooring lines are spread symmetrically with a uniform spread angle is for ease of design and possibly installation. [24] BP awarded the contract for fabrication of the Skarv FPSO hull to Samsung Heavy Industries in South Korea and the Turret contract to SBM. Crude oil is then transferred to the vessel’s double-hull for storage. An FPSO is a floating production system that receives fluids (crude oil, water and a host of other things) from a subsea reservoir through risers, which then separate fluids into crude oil, natural gas, water and impurities within the topsides production facilities onboard. This allows the maximum wave and low-frequency platform excursions to be found, based on the relevant motion standard deviation and the number of oscillations during a specified period, usually taken as 3 h. The above excursions are combined, after including the mean offset, by taking the larger of the sum of the significant and maximum excursions. The contour represents wave height and period pairs for a specified return period, for example, 100-yr. Section 8.4.5 describes these stiffness criteria in more detail. Offset constraints imposed by riser type or vicinity to other structures may govern selection. In evaluating the vessel excursions and line tensions, care must be taken not to exceed the permissible vessel offset and line length. The types of production concepts available for deepwater production are illustrated in fig. Industry Guidance Notes or Recommended Practices are non-binding recommendations, which are sometimes incorporated into design criteria either in whole or in part. It is important to establish a stable equilibrium position for the vessel, where the steady forces of current, wind and wave drift balance the restoring forces from the station-keeping system. 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