Offshore Helicopter Routing in a Hub and Spoke Fashion: Minimizing Expected Number of Fatalities

AbstractHelicopters are often used for transportation of workers to and from offshore installations. Flying helicopter is a risky business and is often considered as one of the main risk factors in this industry. The present paper is dealing with different routing policies for minimizing the expected number of fatalities where the transportation is performed in a hub and spoke fashion from a land based heliport to a set of offshore installations either using the heliport as a hub or using one or more offshore installations as hubs. Some theoretical results are offered as well as an exact model when one operates with more than one offshore hub

Disposal of Petroleum Installations - Major Policy Issues

Following the Brent Spar controversy, the OSPAR countries reached a unanimous agreement in 1998 for the future rules for disposal of petroleum installations. The vast majority of existing offshore installations will be re-used or returned to shore for recycling or disposal. For installations where there is no generic solution, one should take a case-by-case approach. We provide a survey of international economic and regulatory issues pertaining to disposal of petroleum installations, and provide specific examples by analysing the Norwegian decommissioning and disposal policy. Optimal disposal policy can be analysed by cost-benefit analyses with distributional effects, subject to environmental and goodwill constraints.Petroleum installations, decommissioning, disposal, externalities

EU-Norsewind : Investigation of flow distortion effects on offshore instrumentation

In 2008 the EC programme NORSEWInD kicked off with a mission to deliver high quality offshore wind speed data for the wind industry. The aim of the project is to deliver offshore wind speed data to the wind industry by measuring offshore wind speed data from remote sensing instruments (LiDAR) on off shore platforms. This work reports on the techniques used to assesses the interference effects of the various mounting platforms on the measured wind speed data

Namibia.

This chapter highlights the legal framework concerning the decommissioning of offshore oil and gas installations in Namibia. It starts with a brief summary of the exploration and production activities in the country, before discussing the legal and institutional setup for the decommissioning of offshore installations

LCA for Offshore Installations Decommissioning: Environmental Impact Assessment

In the upcoming years, many offshore oil and gas installations around the world will be decommissioned as they approach the end of their economic production lives. Offshore installations decommissioning brings along environmental impacts. However, there is minimal published information on environmental impact assessment of offshore decommissioning. Life-cycle assessment (LCA) is preferable to be used as it provides quantitative and structured comparisons between decommissioning options, while addressing environmental impacts simultaneously. The main objective of this study is to determine and to quantify the environmental impacts associated with decommissioning of an offshore platform in North Sea using LCA tools, process LCA and Economic Input Output(EIO-LCA). Two offshore decommissioning options are studied; complete removal and partial removal. The environmental impacts of offshore decommissioning concerned in this study are total energy consumption and gaseous emissions (CO2, SO2 and NOx). For this research, data from an estimation of the energy consumption and gaseous emission for decommissioning of an offshore platform in North Sea is used as input data for LCA analysis. Cost data for decommissioning is obtained from a published report on decommissioning insights and EIO model is constructed using online model. Results from both process LCA and EIO-LCA prove that partial removal is a better decommissioning option over complete removal in terms of energy consumption and gaseous emissions. The findings from this research provide a relative comparison between complete and partial removal that shall help the owners of platform to decide suitable decommissioning option. For future LCA analysis, it is recommended to have a complete set of detailed and up-to-date data to produce a more comprehensive results. Keywords: Offshore decommissioning; environmental impacts; life-cycle assessment; process LCA; EIO-LC

Adaptive Signal Processing Strategy for a Wind Farm System Fault Accommodation

In order to improve the availability of offshore wind farms, thus avoiding unplanned operation and maintenance costs, which can be high for offshore installations, the accommodation of faults in their earlier occurrence is fundamental. This paper addresses the design of an active fault tolerant control scheme that is applied to a wind park benchmark of nine wind turbines, based on their nonlinear models, as well as the wind and interactions between the wind turbines in the wind farm. Note that, due to the structure of the system and its control strategy, it can be considered as a fault tolerant cooperative control problem of an autonomous plant. The controller accommodation scheme provides the on-line estimate of the fault signals generated by nonlinear filters exploiting the nonlinear geometric approach to obtain estimates decoupled from both model uncertainty and the interactions among the turbines. This paper proposes also a data-driven approach to provide these disturbance terms in analytical forms, which are subsequently used for designing the nonlinear filters for fault estimation. This feature of the work, followed by the simpler solution relying on a data-driven approach, can represent the key point when on-line implementations are considered for a viable application of the proposed scheme

Corrosion fatigue crack growth mechanisms in offshore monopile steel weldments

Offshore structures are generally fabricated of welded joints, which are considered as potential spots for crack initiation owing to the degree of stress concentrations imposed by the weld geometry and the effects of residual stresses introduced by welding processes. There are significant numbers of the current and anticipated offshore installations coupled with the use of newer materials and fabrication techniques. It is therefore important to understand the crack growth mechanisms in these structures accompanied with the effects of mean or residual stresses for a safe estimation of their service lives. In this paper, crack growth results of HAZ and weld materials similar to those used for offshore installations are presented. Tests were conducted in air and in simulated free-corrosion conditions at loading frequencies of 0.3 Hz in seawater, 5 Hz in air and at loading ratios of 0.1, 0.5 and 0.7. Results showed that crack growth rates were influenced by mean stresses, materials microstructure accompanied by welding procedure and environment. Crack growth results showed good agreement when compared with those obtained from other steels used for offshore structures

Evaluation of the Wadden Sea Particularly sensitive Sea Area. On behalf of the Common Wadden Sea Secretariat.

The purpose of this document is to present the high level outcomes for the evaluation of the effectiveness of the Wadden Sea PSSA, seven years after its designation by the IMO. Key changes with regard to IMO and EU shipping policy are identified and described, followed by a review of ‘expert’ opinion focused on the issues relating to PSSAs. The development of an evaluative framework and the resulting findings are introduced and discussed in context. Using existing data against this evaluative framework we conclude that six key elements require action in order to fully describe the efficacy of the designation, and our recommendations to address these concerns are presented.<br/