Effect of Deployment of Jack-Up on Piles and Structure of Existing Offshore platform—A Case Study

2021 ◽  
pp. 641-652
Author(s):  
Rupam Mahanta ◽  
Praveen Bhat
Keyword(s):  
Offshore Platform ◽  
Jack Up

Local Buckling in end Expansion of Subsea Pipelines

2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Jaswar Koto ◽  
Abd. Khair Junaidi ◽  
M. H. Hashim
Keyword(s):  
Crude Oil ◽  
Axial Force ◽  
Oil And Gas ◽  
Local Buckling ◽  
Offshore Platform ◽  
Offshore Pipeline ◽  
Specific Rule ◽  
Subsea Pipelines ◽  
Study Development

Offshore pipeline is mainly to transport crude oil and gas from offshore to onshore. It is also used to transport crude oil and gas from well to offshore platform and from platform to another platform. The crude oil and gas horizontally flows on the seabed, and then vertically flows inside the riser to the offshore platform. One of current issues of the oil and gas transportation system is an end expansion caused by the axial force. If the end expansion occurs over it limit can cause overstress to riser. This paper explores the effect of axial force toward local buckling in end expansion. In the study, development of programming in visual basic 2010 firstly was constructed using empirical equation. The programming code, then, was validated by comparing simulation result with actual data from company. As case study, the end expansion for various thicknesses of pipes was simulated. In this programming, DNV regulation is included for checking either design complied or not with regulation. However, DNV regulation doesn’t have specific rule regarding the end expansion but it is evaluated under load displacement control under strain condition.

Installation of Long Span Boat Landing on Float Over Platforms - A Case Study

2021 ◽  
Author(s):  
Charles John George ◽  
Cibu Varghese ◽  
Faris Ragheb Kamal
Keyword(s):  
Production Process ◽  
Energy Absorption ◽  
Arabian Gulf ◽  
Offshore Platform ◽  
Offshore Platforms ◽  
Long Span ◽  
Heavy Lift

Abstract Fixed offshore platforms are normally provided with landing platforms that enable berthing of supply vessels, crew boats etc. These landing platforms or ‘Boat landings’ are energy absorption structures provided on substructures (jackets) of offshore platforms. Their purpose is to facilitate personnel access from vessel to platforms for performing various tasks including manning the platform, its maintenance etc. Vessel also approach the platforms for providing supplies in case of a manned platform and for providing bunkers, spares etc. As such, boat landing is an integral part of offshore platform and its design and installation becomes equally important. They are preferably located at leeward direction as far as practical, to avoid accidental vessel drift into the platform. For smaller standalone offshore platforms installed with Heavy Lift Crane Vessels, boat landing is installed after the jacket is piled to seabed. Since sequence of installation of boat landing is prior to that of Topside, such installations are straightforward and without obstructions from the Topside. For the bigger accommodation, production, process platforms located in super-complex (or standalone) with topsides installed by float over method, boat landings sometimes are in the wide float over barge slots. In such cases, installation of boat landing becomes very critical due to the post installation after the Topside and associated obstructions from the Topside. This is similar or more critical than a boat landing removal / refurbishment activity carried for a brownfield project. This paper explores the challenges and associated steps adopted to execute the safe installation of these critical structures underneath a newly installed Topside. This case study details the installation of ∼300mt boat landings onto recently installed Greenfield platforms in Arabian Gulf using efficient rigging, suiting the EPC Contractors’ crane assets.

A Generator Differential Relay Trip on an Offshore Platform: A Case Study

2020 ◽  
Vol 26 (5) ◽  
pp. 14-25
Author(s):  
Alok Gupta ◽  
Dibyendu Bhattacharya
Keyword(s):  
Offshore Platform

Semi-Submersible Gravity Based Hybrid Structure: An Alternative to Jacket and Topside Platforms

2014 ◽  
Author(s):  
Peter Sjögren ◽  
Björn Fagerström ◽  
Monica Bellgran ◽  
Peter Sandeberg
Keyword(s):  
Wind Farm ◽  
Hybrid Structure ◽  
Offshore Platform ◽  
Offshore Wind ◽  
Cost Overruns ◽  
Direct Observations ◽  
Specialized Equipment ◽  
Pros And Cons ◽  
Safety And Environment

The aim of this research is to present the result from a case study comparing a semi-submersible gravity based hybrid structure and a jacket topside structure for two offshore wind farm converter station projects. The cases are analyzed from a transportation and installation perspective. Converter stations enable the conversion from alternating to direct current, more efficiently bringing generated wind energy to shore. Out of the project process phases e.g. planning, engineering, fabrication, transport, installation and commissioning; transportation and installation are two of the most demanding during offshore platform projects. The weight and size of an offshore platform require specialized equipment, vessels and marine contractors’ expertise to be transported and installed. The risks associated with transportation and installation (T&I) operations are related to health, safety and environment, and T&I operations are also sensitive to any disturbance e.g. accidents and delays. Many interdependencies between disciplines in the project execution process may result in consequential and immediate impact, should an activity not follow the plan and thus the risk of cost overruns increases. In an attempt to circumvent risks related to heavy lifts offshore and consequently mitigate the corresponding risks, a new platform concept has been developed a Norwegian EPC–company and a Swiss converter station manufacturer, a semi-submersible gravity based hybrid, SSGBH. The subjects presented in this paper include the general principles of the SSGBH concept and in what way risk associated with T&I operations are reduced. This paper present the platform concepts, data gathered from interviews, archival data and direct observations. Their pros and cons are presented in an objective way, while concluding that platform concepts of this kind are and should be highly customized, as should the concept selection.

Case study of a synchronous hydraulic jack-up system for constructing high-rise residential buildings

2010 ◽  
Vol 37 (6) ◽  
pp. 922-926 ◽  
Author(s):  
Jangwoo Seo ◽  
Wi Sung Yoo ◽  
Ung-Kyun Lee ◽  
Chunhak Kim ◽  
Kyung-In Kang ◽  
...  
Keyword(s):  
Residential Buildings ◽  
High Accuracy ◽  
Hydraulic Jack ◽  
High Rise ◽  
Construction Procedure ◽  
Jack Up ◽  
Heavy Structure ◽  
Financial Losses ◽  
Housing Facility

In recent years, contractors have frequently needed to apply innovative technologies to fulfil architects’ creative and intricate designs. They have often encountered abnormal construction conditions. One of the challenging and difficult process is the lifting of a heavy structure called the sky transfer truss (STT), especially if undertaking such a lift is not prevalently experienced. This can result in hazards, accidents, schedule delays, and financial losses to contractors. Traditionally, this structure is fabricated at elevation using scaffolds; however, this approach is costly, time-consuming, and labour-intensive. We introduce a procedure for lifting a 600 metric ton structure that has been fabricated on the ground with a synchronous hydraulic jack-up system. We also discuss the technical difficulties of integrating such a structure into a housing facility. This note addresses several challenging issues: high-accuracy fabrication, design of preventing interference and deformation, and the development of a construction procedure. The case study may be helpful for the flexible construction of extended designs and for the use of a jack-up system in lifting heavy structures of massive sizes and weights.

Bending Stiffeners for Extreme and Fatigue Loading of Unbonded Flexible Risers

2008 ◽  
Author(s):  
Russell Smith
Keyword(s):  
Corrosion Fatigue ◽  
Fatigue Loading ◽  
Rapid Onset ◽  
Offshore Platform ◽  
Fatigue Performance ◽  
Flexible Riser ◽  
Short Notice ◽  
Bending Radius ◽  
Flexible Risers

Bending stiffeners constrain the dynamic radius of flexible risers at offshore platform and subsea interfaces. The extreme bending and fatigue hotspots of a flexible riser occur near these interfaces. Conventional design of bending stiffeners first account for the extreme metocoean environment to ensure the riser does not bend below the minimum allowable bending radius (MBR). The stiffener design for extreme loading normally proves acceptable for less onerous fatigue loading provided the steel armour in riser annulus stays dry. Flexible riser operations have shown that there are several mechanisms for the annulus to loose its dry-state. A flexible riser that is not fatigue tolerant to a non-dry annulus often needs to be replaced at short notice or shut-down due to the rapid onset of corrosion fatigue of the steel armour wires. This paper demonstrates recent advances in designing bending stiffeners so that a flexible riser can sustain life of field operation with a non-dry annulus. These advances are accomplished by optimising the tapered profile of the bending stiffener and accounting for additional stiffening due to bending hysteresis in a flexible riser. A case study is presented to demonstrate the improvement in fatigue performance of a flexible riser.

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