Underreamed Footings Support Offshore Platforms In The North Sea

1973 ◽  
Author(s):  
Clarence J. Ehlers ◽  
William R. Bowles
Author(s):  
P. Whomersley ◽  
G.B. Picken

Inspection videos of four offshore platforms in the central and northern North Sea were used to study the development of fouling communities on clamps and guides of oil export risers over an 11-y period (1989–2000). Results from multivariate analyses (multi-dimensional scaling and analysis of similarities) indicated that distinct assemblages developed in different geographical locations. These differences were mainly due to the protracted development of theMetridium senile(Cnidaria: Actinaria) zone on the northern sector platforms. The vertical zonation of fouling organisms was similar on all installations, although the water depth at platform locations varied from 80 to 169 m, indicating that fouling organisms display a wide bathymetric tolerance. This study has highlighted the value of long-term data present in operational inspection videos for the study of fouling communities.


2021 ◽  
Vol 9 (3) ◽  
Author(s):  
Marcio Soares Pinheiro ◽  
Paulo Roberto Duailibe Monteiro

Brazil began to explore its seas in the 60’s of the XX Century looking for petroleum. This journey began in the Northeast and the first oil field produced offshore was the Guaricema Field, in the State of Sergipe. During the 70’s, Petrobrás found oil in the Campos Basin, between the States of Espírito Santo and Rio de Janeiro, that became the most important oil province in Brazil until the discovery of the Pre-Salt province, in the Santos Basin. As these fields are producing for a long time, many of them are already completely depleted or their production is in way of to be not commercial anymore, and their facilities need to be decommissioned. This review of decommissioning practices of fixed offshore platforms carried out worldwide has focus on the removal of topside with special vessels designed for this purpose or with conventional methods (crane vessels + barge). It will show the benefits of using specialised heavy lift vessels to remove the topsides and move it to shore for dismantling / recycling / reuse / disposal. The cases for study were the successful decommissioning projects in the North Sea: Brent B/D, Valhall QP, Viking, Curlew, Eider A, Golden Eye and Leman, Iwaki-Oki, Halfweg Q1, Yme and Ninian North.


2020 ◽  
Author(s):  
Florian Mauffrey ◽  
Tristan Cordier ◽  
Laure Apothéloz‐Perret‐Gentil ◽  
Kristina Cermakova ◽  
Thomas Merzi ◽  
...  

2020 ◽  
Author(s):  
Yosra Afrasteh ◽  
Cornelis Slobbe ◽  
Martin Verlaan ◽  
Martina Sacher ◽  
Roland Klees

<p>Model-based hydrodynamic leveling is an efficient and flexible alternative method to connect islands and offshore tide gauges with the height system on land. The method uses a regional, high-resolution hydrodynamic model that provides total water levels. From the model, we obtain the differences in mean water level (MWL) between tide gauges at the mainland and at the islands or offshore platforms, respectively. Adding them to the MWL relative to the national height system at the mainland’s tide gauges realizes a connection of the island and offshore platforms with the height system on the mainland. Usually, the geodetic leveling networks are based on spirit leveling. So, as we can not make the direct connections between coastal countries, due to the inability of the spirit leveling method to cross the water bodies, they are weak in these regions. In this study, we assessed the impact of using model-based hydrodynamic leveling connections among the North Sea countries on the quality at which the European Vertical Reference System can be realized. In doing so, we combined the model-based hydrodynamic leveling data with synthetic geopotential differences among the height markers of the Unified European Leveling Network (UELN) used to realize the European Vertical Reference Frame 2019. The uncertainties of the latter data set were provided by the BKG. The impact is assessed in terms of both precision and reliability. We will show that adding model-based hydrodynamic leveling connections lowers the standard deviations of the estimated heights in the North Sea countries significantly. In terms of reliability, no significant improvements are observed.</p>


Author(s):  
Diogo do Amaral M. Amante ◽  
Segen F. Estefen

A review of accidents involving collisions between ships and offshore platforms was carried out. There are reports and publications that present numbers, statistics and even details of the most important collisions between ships and offshore platforms, especially considering the North Sea region, but publications about accidents in Brazilian waters are rare. Thus, this paper reports the few existing publications that consider this problem in Brazilian waters and shows the results of eleven years of collecting data of collisions on Petrobras’ platforms.


Author(s):  
R. B. Spector ◽  
L. S. Cimino

Approximately 50 years of offshore oil exploration drilling and production have led to refined techniques and equipment selection criteria. Gas turbines have established themselves as the prime source of energy transfer in that sector of the industrial marketplace where space and weight are of major importance. The increased worldwide demand for petroleum has pushed offshore platforms into deeper waters requiring further sophistication in the allocation of space, weight and maintenance resources. The aeroderivative gas turbine meets the above criteria and in addition offers the platform designer high thermal efficiency and system flexibility coupled with ease of maintenance. This paper presents a summary of experience gained in over 10 years of operation of the General Electric LM2500 gas turbine on platforms in the North Sea. Although all of the circumstances that may be encountered cannot be adequately covered, highlighting the events which occurred in over one million hours of operation presents the potential user with a better understanding of the uniqueness of this type application. The advantages and the reliability of the aeroderivative gas turbine are also discussed. The LM2500 gas turbine was first introduced into off-shore operation in the Norwegian sector of the North Sea in November 1979, after successful application in gas compression and transmission duty on pipelines and other on shore facilities.


2008 ◽  
Author(s):  
Jamie Cochran ◽  
Daniele Petrone ◽  
Alexander Clubb ◽  
Scott Greig

This Royal Society Discussion Meeting has examined the total environmental impact of a whole industry in a single geographical area. Land-based developments related to the exploitation of the North Sea oilfields and their social consequences have been substantial, although neither the worst fears nor the best hopes have been realized. An accommodation has been reached with the fishing industry in the affected area. Offshore platforms are a source of chronic pollution from production water, but in recent years there has been a marked increase in the use of oil-based drilling muds and it is estimated that 20 Mt per year of petroleum hydrocarbons are added to the sea in oil-contaminated drill cuttings. The effect of these additions has been studied in the laboratory, in mesocosms and in field surveys which, together, yield a consistent picture. Within a radius of a few hundred metres of a platform there is impoverishment of the benthic fauna. Close to the platform the production of anoxic conditions through smothering and the activity of sulphide-producing bacteria is probably more significant than the toxic effect of the oil-based muds. Outside this immediate zone of impact, the oil results in organic enrichment and enhanced populations of some of the fauna. The total area affected is, in the context of the North Sea, minuscule. There is no evidence that plankton is materially affected and the success of commercial fisheries dependent upon the plankton crop is more influenced by fishery practices than by any other factor. Seabird populations, about which there was formerly much concern, have not so far been affected by oil pollution in the North Sea. There is wide fluctuation in recruitment success, but populations of species thought most vulnerable to oil pollution are generally increasing. Although marine pollution research has yielded valuable insights into the responses of individuals, populations and communities to perturbation, natural as well as man-made, it is not likely that future problems associated with oil extraction from the sea will be as stimulating to fundamental research. Different problems relating to environmental pollution should now be addressed by marine scientists.


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