Application of the Contour Line Method for Estimating Extreme Response in Mooring Lines of a Two-Body Floating Wave Energy Converter

2012 ◽  
Author(s):  
Made Jaya Muliawan ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Contour Line ◽  
Mooring Line ◽  
Sea State ◽  
Gas Industry ◽  
Line Method ◽  
Extreme Response ◽  
Two Bodies ◽  
Term Response

One of design criteria that have been used for the mooring system design for floating platforms in the oil and gas industry is the Ultimate Limit State (ULS). The 100-year level response in the mooring line should be applied for this ULS design check, which is ideally estimated by taking into account the dynamic mooring line tension in all sea state available in the operational site. This is called a full long-term response analysis using the all sea state approach. However, this approach is time consuming. Therefore, it is proposed to use the contour line method to estimate the 100-year response by primarily studying the short term response for the most unfavorable sea states along the 100-year environmental contour line. Experiences in the oil and gas industry confirmed that the method could give good prediction if the response at higher percentile than the median is used. In this paper, the mooring system of a two-body wave energy converter (WEC) is considered. Since this system involves interaction between two bodies, the estimation of the ULS level response by using the all sea state approach will be even more time consuming. Therefore, the application of the contour line method for this case will certainly be beneficial. However, its feasibility for a WEC case needs to be documented first. In the present paper, the ULS level response in the mooring tension that is predicted by the contour line method is compared with that estimated by taking into account all sea states. It is achieved by performing the coupled time domain mooring analyses using SIMO/Riflex for six cases with different mooring configurations and connections between two bodies. An axi-symmetric Wavebob-type WEC is chosen as the object of investigation and the Yeu site in France is assumed to be the operational site of the WEC. Hydrodynamic loads including 2nd order forces are determined using WAMIT. Finally, the applicability of the contour line method to predict the ULS level mooring tension for a two-body WEC is assessed and shown to yield accurate results with proper choice of percentile level for the extreme response.

Application of the Contour Line Method for Estimating Extreme Responses in the Mooring Lines of a Two-Body Floating Wave Energy Converter

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Made Jaya Muliawan ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Contour Line ◽  
Mooring Line ◽  
Energy Converter ◽  
Sea State ◽  
Gas Industry ◽  
Line Method ◽  
Two Bodies ◽  
Term Response

The ultimate limit state (ULS) is one of the design criteria used in the oil and gas industry in mooring system design for floating platforms. The 100 year level response in the mooring line should be applied for the ULS design check, which is ideally estimated by taking into account the dynamic mooring line tension in all sea states available at the operational site. This approach is known as a full long-term response analysis using the all-sea-state approach. However, this approach is time consuming, and therefore, the contour line method is proposed for estimation of the 100 year response by primarily studying the short-term response for the most unfavorable sea states along the 100 year environmental contour line. Experience in the oil and gas industry confirmed that this method could yield good predictions if the responses at higher percentiles than the median are used. In this paper, the mooring system of a two-body wave energy converter (WEC) is considered. Because this system involves the interaction between two bodies, the estimation of the ULS level response using the all-sea-state approach may be even more time consuming. Therefore, application of the contour line method for this case will certainly be beneficial. However, its feasibility for application to a WEC case must be documented first. In the present paper, the ULS level response in the mooring tension predicted by the contour line method is compared to that estimated by taking into account all sea states. This prediction is achieved by performing coupled time domain mooring analyses using Simo/Riflex for six cases with different mooring configurations and connections between two bodies. An axisymmetric Wavebob-type WEC is chosen for investigation, and the Yeu site in France is assumed as the operational site. Hydrodynamic loads including second-order forces are determined using Wamit. Finally, the applicability of the contour line method for prediction of the ULS level mooring tension for a two-body WEC is assessed and shown to yield accurate results with the proper choice of percentile level for the extreme response.

Machine Learning Models With Engineering Insight: Case Studies From the Oil and Gas Industry

2020 ◽  
Author(s):  
Ishita Chakraborty ◽  
Daniel Kluk ◽  
Scot McNeill
Keyword(s):  
Machine Learning ◽  
Case Studies ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Mooring Line ◽  
Learning Models ◽  
Gas Industry ◽  
Position Data ◽  
Machine Learning Models

Abstract Machine learning is gaining rapid popularity as a tool of choice for applications in almost every field. In the oil and gas industry, machine learning is used as a tool for solving problems which could not be solved by traditional methods or for providing a cost-effective and faster data driven solution. Engineering expertise and knowledge of fundamentals remain relevant and necessary to draw meaningful conclusions from the data-based models. Two case studies are presented in different applications that will illustrate the importance of using engineering domain knowledge for feature extraction and feature manipulation in creating insightful machine learning models. The first case study involves condition-based monitoring (CBM) of pumps. A variety of pumps are employed in all aspects of the oilfield life cycle, such as drilling, completion (including hydraulic fracturing), production, and intervention. There is no well-established method to monitor the pump fault states as they are operating based on sensor feedback. As a result, maintenance is performed either prematurely or reactively, both of which result in wasteful downtime and unnecessary expense. A machine learning based neural network model is used for identifying different fault states in a triplex pump from measured pressure sensor data. In the second case study, failures of mooring lines of an offshore floating production unit are predicted from the vessel position data. Identifying a damaged mooring line can be critical for the structural health of the floating production system. In offshore floating platforms, mooring line tension is highly correlated to a vessel’s motions. The vessel position data is created from running coupled analysis models. A K-Nearest-Neighbor (KNN) classifier model is trained to predict mooring line failures. In all the case studies, the importance of combining a deep understanding of the physics of the problem with machine learning tools is emphasized.

Deployment of Digital NDT Solutions in the Oil and Gas Industry

2020 ◽  
Vol 78 (7) ◽  
pp. 861-868
Author(s):  
Casper Wassink ◽  
Marc Grenier ◽  
Oliver Roy ◽  
Neil Pearson
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Gas Industry

What Does Rent Give to Federal Budget (on the Russia's Budget Dependence upon "Oil Dollars")

2004 ◽  
pp. 51-69 ◽  
Author(s):  
E. Sharipova ◽  
I. Tcherkashin
Keyword(s):  
Oil And Gas ◽  
Strong Dependence ◽  
Oil Prices ◽  
Federal Budget ◽  
Oil And Gas Industry ◽  
Gas Industry ◽  
Resource Rent ◽  
Tax Legislation ◽  
Russian Economy ◽  
The Government

Federal tax revenues from the main sectors of the Russian economy after the 1998 crisis are examined in the article. Authors present the structure of revenues from these sectors by main taxes for 1999-2003 and prospects for 2004. Emphasis is given to an increasing dependence of budget on revenues from oil and gas industries. The share of proceeds from these sectors has reached 1/3 of total federal revenues. To explain this fact world oil prices dynamics and changes in tax legislation in Russia are considered. Empirical results show strong dependence of budget revenues on oil prices. The analysis of changes in tax legislation in oil and gas industry shows that the government has managed to redistribute resource rent in favor of the state.

The Political Economy of Power: Approaches to the Analysis of Relationships between the State and Business in Russia

2011 ◽  
pp. 19-33
Author(s):  
A. Oleinik
Keyword(s):  
Oil And Gas ◽  
Road Construction ◽  
Oil And Gas Industry ◽  
Retail Trade ◽  
Business Community ◽  
The Political ◽  
Economic Power ◽  
Gas Industry ◽  
The Road ◽  
Ruling Elites

The article deals with the issues of political and economic power as well as their constellation on the market. The theory of public choice and the theory of public contract are confronted with an approach centered on the power triad. If structured in the power triad, interactions among states representatives, businesses with structural advantages and businesses without structural advantages allow capturing administrative rents. The political power of the ruling elites coexists with economic power of certain members of the business community. The situation in the oil and gas industry, the retail trade and the road construction and operation industry in Russia illustrates key moments in the proposed analysis.

Consideration of Geopolitical Challenges within the Analysis of Geoenvironmental Risks for Oil and Gas Development of the Russian Arctic

2019 ◽  
Vol 16 (6) ◽  
pp. 50-59
Author(s):  
O. P. Trubitsina ◽  
V. N. Bashkin
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Optimal Operation ◽  
The Arctic ◽  
Stage Model ◽  
Oil And Gas Development ◽  
Gas Industry ◽  
The Impact ◽  
Further Development ◽  
Geopolitical Risks

The article is devoted to the consideration of geopolitical challenges for the analysis of geoenvironmental risks (GERs) in the hydrocarbon development of the Arctic territory. Geopolitical risks (GPRs), like GERs, can be transformed into opposite external environment factors of oil and gas industry facilities in the form of additional opportunities or threats, which the authors identify in detail for each type of risk. This is necessary for further development of methodological base of expert methods for GER management in the context of the implementational proposed two-stage model of the GER analysis taking to account GPR for the improvement of effectiveness making decisions to ensure optimal operation of the facility oil and gas industry and minimize the impact on the environment in the geopolitical conditions of the Arctic.The authors declare no conflict of interest

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