Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
INTRODUCTION Subsea Production Systems generally incorporate a template or satellite structure which has the following primary functionslocation and verticality of wells, support of subsea components and maintenance equipment, limitation of deflections between components of the system, protection of subsea equipment The first three of these requirements are normally driven by system parameters, such as number of wells, method of maintenance or method of flowline pull-in and connection. Protection of the system, however, depends largely on the local environment and can have far-reaching consequences on the layout, installation and maintenance of the subsea system In particular, if a subsea system is installed in a fishing zone, it must be decided at an early stage which of the follouring solutions is to be chosen:a structure which will protect equipment by snagging any trawl gear on an outer bumper frame, thus preventing snagging or snarling of equipment in the template the trawl gear is, of course, usually destroyed, a structure which will deflect trawl boards and nets without damage to either subsea equipment or fishing gear This chapter discusses options for alternative forms of protection, and describes and compares various structures already installed or taken to detail design as examples of the different philosophies PROTECTION REQUIREMENTS General It is general practice to protect equipment on a template or satellite to some degree, m order to limit damage from typically, the following sourcesfishing gear, dropped objects, anchor snags Because the wells on a subsea production system will be protected by subsea safety values, it is unlikely that damage from these causes could result m hydrocarbon spillage. Damage could, however, result in the followinginability to re-enter or kill the well, intervention required to replace damaged equipment, additional inspection requirements and removal of tangled nets It is interesting to note that the NPD Regulations now require that all subsea installations m the Norvegian Sector of the North Sea be designed so that fishing gear will not be harmed. This requirement may not apply to fishing exclusion zones, which could be requested on the grounds oflow fishing activity m the area, proximity to permanent platforms No such requirements yet exist in the UK sector Protection against fishing gear There are various trawling techniques commonly used in the North Sea, and among these arewhite-fish trawling, industrial trawling, beam trawling Since the white-fish trawl arrangement can apply the largest snag load to a subsea structure, only this form of trawl will be described Trawlers also deploy anchors which can cause similar loadings to trawl gear snag loads. White-fish trawling (Fig 1) A white-fish trawl consists of a net with a mouth up to 25 m wide and 9 m high. The net is connected to the two towing warps by a ground line with bobbins and a headline with floats.
So far there is no standard or code that clearly specifies the design Impact load caused by dropped objects from nearby platform or tankers method for subsea structure protection structure (ISO 13628-1 and is one of the latent dangers for subsea equipments which are very NORSOK U-001 only list the consideration items about protection vulnerable and difficult to repair. Therefore a protection structure is structure design and provide reference load about dropped object impact necessary for the subsea equipment to avoid impact load.
- Asia > China (0.29)
- North America > United States (0.28)
Abstract In certain offshore shallow water production areas in cold regions the sea conditions are characterized by first year and potentially multi-year ice features. Unlike some other arctic regions, which are characterized by icebergs, there are regions where no icebergs occur. However, gouges are formed by rafted ice, pressure ridges, and multi-year ice from the polar pack that forms deep keels. Ice gouging of the seabed in these areas is caused by winds, currents and waves driving the ice sheet containing these ice keels. As more reserves are being found in shallow water arctic and sub-arctic environments, there is a need to determine how best to develop these resources cost effectively. Recent interest has been raised for installing typical shallow water subsea drilling templates on the seabed to be drilled by jackup drilling rigs. However, these templates would be at risk of damage from sand intrusion and ice keel penetration. This paper discusses a novel design to best protect the subsea template and its mechanical equipment. Furthermore, this paper outlines the process undertaken for designing a subsea drilling and production template and protective structure by encasing the template within a protective structure that is placed in an armored excavation, or "Glory Hole", to prevent sand intrusion and ice keel penetration. To protect a drilling and production template in shallow water, an enclosed structure was required to be embedded in the soil at the bottom of a Glory Hole with a full-time domed protection cover to protect from ice and soil entrance. Slotted doors allow jackup access to the template during drilling. Operation of the Wellheads contained within the Subsea Template is remotely controlled by a subsea cable containing electrical, hydraulic and fiber optic cables and tubes. The operation of the facilities can be monitored and controlled at the Command and Control Center located onshore and connected to the offshore template by the control cable.
- North America > United States (1.00)
- Europe (0.68)
- North America > Canada > Newfoundland and Labrador > Newfoundland (0.28)
- Asia > Russia > Far Eastern Federal District > Sakhalin Island > Sea of Okhotsk (0.16)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.68)
- Europe > Norway > Barents Sea > Hammerfest Basin > License 100 > Block 7121/7 > Snøhvit Field > Stø Formation (0.99)
- Europe > Norway > Barents Sea > Hammerfest Basin > License 100 > Block 7121/7 > Snøhvit Field > Nordmela Formation (0.99)
- Europe > Norway > Barents Sea > Hammerfest Basin > License 100 > Block 7121/5 > Snøhvit Field > Stø Formation (0.99)
- (33 more...)
Abstract In iceberg prone regions, subsea substructures placed on the seabed are atrisk of impacts from free-floating and scouring iceberg keels. Here themethodology for assessing iceberg loads and two mitigation strategies aredescribed. The iceberg load model was an extension of previous work forestimating iceberg impact loads on offshore surface-piercing structures. Components of the algorithms were modified such that global design loads fromkeel contacts account for the change in contact location (i.e., longer leverarm in the vertical direction resulting in greater rotation effects). Theiceberg eccentricity model and the relationship between contact area andpenetration distance were also modified to account for iceberg keel contactswith a generic low profile structure on the seabed. One concept considered wasa single wellhead structure fitted with a special weak shear link incorporatedinto the design at the expected scour level. The shear link, or failure joint, would act as a mechanical fuse designed to fail in a combination of shear, tension and buckling during keel loading. The failure joint minimizes downholestructural response during iceberg keel loading on the production tree. Thedesigned failure mechanism would allow the well to be re-entered by protectingthe well casing from damage. Another concept considered was a steel truncatedcone structure installed over the well installation and fixed to the seabed byone of several identified foundation concepts. The protection structure absorbsenergy through crushing of the ice keel and encourages the iceberg to deflectaround and over the structure. The steel structure would be designed accordingto ultimate limit states accounting for energy absorption through elastic andplastic deformation of the structure. Design loads would correspond to anAbnormal Level Ice Event (ALIE) with an annual exceedance probability of 10–4. The size of the frame is governed by the size of the wellhead and tree system, Remotely Operated Vehicle (ROV) access requirements, and slope to encourageiceberg keel deflection. Piles may be the best option for securing a protectionstructure to the seabed, especially if a local vessel can be sourced to performthe installation. As an alternative to piles, using a drill rig to install wellcasings may be an option; however, market conditions for drilling rigs maydictate economic feasibility.
- North America > United States (1.00)
- North America > Canada > Newfoundland and Labrador > Newfoundland (0.29)
- North America > Canada > Newfoundland and Labrador > Newfoundland > North Atlantic Ocean > Atlantic Margin Basin > Grand Banks Basin > Jeanne d'Arc Basin (0.99)
- North America > United States > Oklahoma > Anadarko Basin > Carter Field (0.93)
- North America > Canada > Newfoundland and Labrador > Newfoundland > North Atlantic Ocean > Labrador Shelf Basin (0.89)
- North America > Canada > Newfoundland and Labrador > Newfoundland > North Atlantic Ocean > Grand Banks Basin (0.89)
This article, written by Technology Editor Dennis Denney, contains highlights of paper OTC 18965, "Ormen Lange Subsea Production System," by Thomas Bernt, Hydro, and Endre Smedsrud, FMC Technologies, prepared for the 2007 Offshore Technology Conference, Houston, 30 April-3 May. The Ormen Lange field, in the Norwegian Sea, approximately 100 km off Norway, is within the prehistoric Storegga slide area with water depths reaching 850 m in the main production area. The gas will be produced from up to 24 subsea wells. The well fluid will be transported to the Nyhamna plant through two 30-in. multiphase lines. After processing, the dry export gas will be transported from the onshore plant through a new 42-in. pipeline by way of the Sleipner riser platform and further through a new 44-in. pipeline to the gas-receiving terminal in Easington, England. Introduction Fig. 1 shows the development concept selected for Ormen Lange, which comprises a subsea tieback to an onshore processing plant at Nyhamna. Conceptual engineering of the subsea production system was initiated in 2002. The main contracts for subsea-equipment supply, umbilical fabrication, and template installation were awarded between the autumn of 2003 and the summer of 2004. The main part of fabrication and testing took place during 2004–05, with the subsea templates installed offshore in late summer 2005. Umbilical A and the remaining subsea equipment were installed during the summer of 2006, and the first subsea tree was installed on Template A in December 2006. Completion of the first subsea well on Template A was scheduled for spring 2007, and subsea production startup was scheduled for autumn of 2007. Subsea-System Configuration With the large geographical extent of the Ormen Lange reservoir and the risk of reservoir segmentation, the subsea-system design has a high degree of flexibility, with four planned template locations. Therefore, a phased-development scheme was chosen. The phasing and location of the subsea wells will be timed to maintain plateau production as the field depletes. Initial Development. The initial sub-sea development consists of two eight-slot production templates (Templates A and B), approximately 4 km apart in the main production area. Each tem-plate is tied back into the two 30-in. multiphase pipelines to shore. As Fig. 2 shows, these lines are interconnected through a pipeline-end-termination (PLET) system. Two main control umbilicals link the onshore plant to the subsea production system; one is connected to Template A and the other to Template B. A cross-over-control umbilical interconnects the two production templates, providing redundant hydraulic supply to all the subsea wells. To prevent hydrate formation, all wells are injected continuously with monoethylene glycol (MEG) through two 6-in. pipelines from the onshore plant. One line is connected to Template A and the other to Template B. A 6-in. crossover-MEG line interconnects the two production templates for added flexibility.
- Europe > United Kingdom > England (0.25)
- Europe > Norway > Norwegian Sea (0.25)
- Europe > Norway > Norwegian Sea > Møre Basin > PL 442 > Block 6305/8 > Ormen Lange Field > Springar Formation (0.99)
- Europe > Norway > Norwegian Sea > Møre Basin > PL 442 > Block 6305/8 > Ormen Lange Field > Egga Formation (0.99)
- Europe > Norway > Norwegian Sea > Møre Basin > PL 442 > Block 6305/6 > Ormen Lange Field > Springar Formation (0.99)
- (21 more...)