Ten Years Experience of North Sea FPSO Moorings Repair, Renewal and Life Extension Work

2013 ◽  
Author(s):  
Martin Giles Brown
Keyword(s):  
North Sea ◽  
Life Extension ◽  
Extension Work

Ageing of Materials

2008 ◽  
Author(s):  
Erik Ho¨rnlund ◽  
O̸ystein Sævik ◽  
Rolf H. Hinderaker ◽  
Gerhard Ersdal
Keyword(s):  
North Sea ◽  
Life Extension ◽  
Research Projects ◽  
Considerable Part ◽  
The North ◽  
The North Sea ◽  
Degradation Of Materials

A considerable part of the structures in the Norwegian part of the North Sea have passed or are close to their design lifetime. Degradation of materials will play an important role in the ageing of these structures and the evaluation of their safety. Hence, Petroleum Safety Authority Norway has initiated several research projects to investigate into the ageing of materials, and how to ensure robust materials also for life extension. The present paper gives a summary of these research projects.

Development of a Micro-Habitat Hyperbaric Welding System

2021 ◽  
Author(s):  
Earl Lee Toups ◽  
Russell James Morrison ◽  
Russell John Harper
Keyword(s):  
North Sea ◽  
Design Thinking ◽  
Structural Integrity ◽  
Fatigue Cracks ◽  
Fatigue Cracking ◽  
Life Extension ◽  
Acceptance Testing ◽  
Offshore Structure ◽  
The North ◽  
Welding System

Abstract The maturation of North Sea platform jackets coupled with high fatigue stresses, fabrication defects, extensive usage, and low-redundancy design eventually result in fatigue cracking. The high sea states in the North Sea further exacerbate the problem. If not closely monitored, fatigue cracks can propagate into and around the circumference of a brace relatively quickly—ultimately leading to brace severance. When confronted with a loss of structural integrity, operators have two options: conduct expensive subsea repairs or decommission the asset. Realising a market gap, DCN Diving has explored alternate repair strategies, leading to the development of the DCN-patent pending µ-Habitat welding system. The µ-Habitat makes it possible to respond quicker, execute subsea repairs faster and guarantee quality at a fraction of the cost of bespoke or modular habitats. Through size reduction, it is possible to reduce the fabrication, production, and handling costs of µ-Habitat. Furthermore, the smaller footprint reduces installation time while simplifying sealing and de-watering offshore, saving time and money. Using a combination of product development facilitators and process improvement methodologies, such as AGILE, SCRUM, and design thinking, reduces the preparation time, making the system incredibly responsive yet flexible. Additionally, using an experienced and dedicated project team in combination with standardised products further minimises the response time to execute a repair. A dry environment, pre-heating, in-process cleaning/grinding, and unrestricted access are fundamental to ensuring high-quality welds. In addition, prototyping, extensive function testing, and mock-ups validate the habitat design before commissioning via factory acceptance testing and mobilisation to guarantee the failsafe performance of the µ-Habitat offshore. The µ-Habitat can play a crucial role in the overall life extension strategy for any offshore structure, ultimately minimising cost, risk and production downtime associated with future subsea repairs.

Environmental Assisted Cracking of High Strength Subsea Material due to CP

2019 ◽  
Author(s):  
Agnes Marie Horn ◽  
Erling Østby ◽  
Viggo Røneid ◽  
Finn Kirkemo
Keyword(s):  
Fatigue Life ◽  
North Sea ◽  
Fatigue Testing ◽  
Research Work ◽  
Design Guidelines ◽  
Life Extension ◽  
External Loading ◽  
Test Program ◽  
The North ◽  
The North Sea

Abstract Several of the offshore fields in the North Sea are approaching the end of their design life and a cost-effective solution to maximize production is to document that life extension is feasible for an asset. A trend the resent years [1] is that the BOP become larger, hence the required fatigue life increases. One way to meet the increased fatigue life and external loading is to use higher strength steel to meet the design requirements set by the operators. This has motivated research related to the fatigue performance of the base material connector material both for air and under sea water with cathodic protection (CP) [2,3,4] and possible degradation of ductility and toughness in seawater with CP. However, relevant test data for wellheads material that have been in service is not to the authors knowledge, available, nor recommendations in design guidelines related to possible material degradation to be safely applied for life extension of these assets. To better evaluate life extension of subsea wellheads, a test campaign was initiated by Equinor on a retrieved wellhead in 2015. The wellhead had been in operation since 2000 in the North Sea. The general purpose of the test program was to evaluate if the low alloy steel AISI 8630 modified material had been substantial degraded during 15 years in service compared to design material properties and the materials susceptibility to hydrogen embrittlement. The test program performed consisted of slow strain rate testing (SSRT) to document possible reduction of strength and ductility, CTOD testing to document possible reduction in toughness and S-N testing to establish the fatigue strength reduction due to seawater with CP. The outline of the paper is as follows: first a summary of the latest research and trends within wellhead fatigue and materials are discussed. Next, a detailed description of the test program is given: SSRT, toughness testing and fatigue testing are presented. Finally, recommendations and proposal for further research work are given.

Fatigue Tests on Corroded Mooring Chains Retrieved From Various Fields in Offshore West Africa and the North Sea

2019 ◽  
Author(s):  
Kai-tung Ma ◽  
Øystein Gabrielsen ◽  
Zhen Li ◽  
David Baker ◽  
Aifeng Yao ◽  
...  
Keyword(s):  
Fatigue Life ◽  
West Africa ◽  
North Sea ◽  
Test Procedure ◽  
Fatigue Tests ◽  
Surface Feature ◽  
Life Extension ◽  
Mooring System ◽  
Remaining Fatigue Life ◽  
Mooring Chain

Abstract When an aged mooring system seeks a life extension, it is necessary to assess the remaining fatigue life of the corroded mooring chain. This paper summarizes the results of fatigue tests performed on mooring chain samples retrieved from six different fields in West Africa and North Sea. The impacts of corrosion on fatigue life on the samples were researched. The tests were managed under a Joint Development Project, “Fatigue of Corroded Chains (FoCCs JDP)”. The objectives of the JDP are (1) to derive a methodology for assessing the remaining fatigue life of corroded chain, (2) to develop guidance for performing reliable FEA of chain links to assess remaining fatigue life, and (3) to provide more rational basis to improve industry guidance on mooring line replacement criteria for life extension. Fatigue test procedure was defined by the fifteen (15) participating members. The procedure specified the testing parameters, including mean tension, tension range, and test frequency. Six sets of fatigue tests have been completed in seawater with the number of cycles to failure recorded. These chain samples were retrieved from floating production and storage units, e.g. FPSOs and FSUs, that were still in service. Fatigue data obtained from the tests were plotted against the design SN curves and results from fatigue testing of new chain. It was found that most of these samples have limited amount of fatigue capacity remained. Most interesting finding is that the sharpness of the surface feature on the corroded chain link has a significant impact on the remaining fatigue life. Another interesting finding is that the surface feature created by corrosion can be quite distinct and unique depending on the geophysical locations where the sample came from. These findings and test results may serve as references for life extension assessment of an aged mooring system.

Material Issues in Ageing and Life Extension

2011 ◽  
Author(s):  
Erik Ho¨rnlund ◽  
Gerhard Ersdal ◽  
Rolf H. Hinderaker ◽  
Roy Johnsen ◽  
John Sharp
Keyword(s):  
North Sea ◽  
Research Work ◽  
Life Extension ◽  
Material Degradation ◽  
The North ◽  
Design Life ◽  
The North Sea ◽  
Extension Process

A considerable number of the structures in the Norwegian part of the North Sea have passed or are close to their design life. Material degradation will play an important role in the ageing of these structures and the evaluation of their safety. An overview of research work initiated by the Petroleum Safety Authority (PSA) is presented. The paper focuses on various material aspects of ageing related to offshore facilities, the risks they represent to the integrity of a facility and how to deal with them in a life extension process. The paper presents and discusses expectations towards the industry with respect to evaluation of ageing materials in life extension.

The Rubie Field, Block 15/28b, UK North Sea

2020 ◽  
Vol 52 (1) ◽  
pp. 790-803 ◽  
Author(s):  
Graham Tegerdine
Keyword(s):  
North Sea ◽  
Oil Recovery ◽  
Initial Rate ◽  
Development Plan ◽  
Recovery Factor ◽  
Life Extension ◽  
Field Development ◽  
Phillips Petroleum ◽  
Moray Firth

AbstractThe Rubie Field is located within the Outer Moray Firth in Block 15/28b, towards the eastern end of the Renee Ridge and 6 km east of the Renee Field. The block was awarded to a BNOC-operated group following the 7th Licensing Round in 1980. The 15/28b-4 discovery was drilled by Britoil in 1985, encountering hydrocarbons at two stratigraphic levels within the Paleocene Andrew Sandstone unit and Eocene Cromarty Sandstone Member reservoirs. No further appraisal was undertaken prior to a late 1997 Annex B submission for a joint Renee and Rubie Field development by new operator, Phillips Petroleum. The Rubie development plan comprised a single 6000 ft Andrew Sandstone horizontal producer which was completed in March 1999 and tested at an initial rate of 9700 bopd and 1.65 MMscfgd. Export of fluids was via a 6 km-long pipeline to the Renee Field manifold and then onwards to the host facility in the Ivanhoe–Rob Roy fields. Rubie was brought on stream on 29 May 1999. Abandonment was originally scheduled for end 2006, but field-life extension initiatives deferred cessation of production (COP) to March 2009. Cumulative Andrew Sandstone production at COP was 11.5 MMbbl and the oil recovery factor 50%, based on a final mapped oil-in-place of 23 MMbbl.

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