Incorporating the Higher Harmonics in VIV Fatigue Predictions

2007 ◽  
Author(s):  
Vikas Jhingran ◽  
J. Kim Vandiver
Keyword(s):  
Fatigue Damage ◽  
Strain Energy ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Dynamic Strain ◽  
Higher Harmonics ◽  
Gas Industry ◽  
Ongoing Research ◽  
Fatigue Design ◽  
Vortex Induced Vibrations

Vortex-Induced Vibrations (VIV) are an important source of fatigue damage for risers in the Oil and Gas industry. Results from resent VIV experiments by Vandiver et al. [1] indicate significant dynamic strain energy at not only the Strouhal frequency, but also its harmonics. In certain regions of the pipe, these higher harmonics accounted for more that half of the measured RMS strain and increased fatigue damage by a factor exceeding twenty. However, the state-of-the-art in VIV prediction only accounts for the vibrations at the Strouhal frequency. Preliminary results from a second set of experiments, described in this paper, confirm the importance of the higher harmonics in fatigue life estimates of pipes. Further, the authors formulate an approach to incorporate the higher harmonics in VIV related fatigue design. Finally, the authors identify the estimation of the higher harmonics, in both location and magnitude, as an important area of ongoing research, the results of which will be required to implement this proposed method.

Prediction of Riser VIV With Staggered Buoyancy Elements

2016 ◽  
Author(s):  
Jie Wu ◽  
Malakonda Reddy Lekkala ◽  
Muk Chen Ong
Keyword(s):  
Fatigue Damage ◽  
Oil And Gas ◽  
Systems Design ◽  
Oil And Gas Industry ◽  
Flexible Cylinder ◽  
Natural Period ◽  
Gas Industry ◽  
Vibration Period ◽  
Offshore Industry ◽  
Different Diameters

Steel lazy-wave riser (SLWR) are attractive deepwater applications for offshore oil and gas industry. When subjected to current, both the buoyancy elements and the riser may experience Vortex Induced Vibrations (VIV). Such vibrations are the result of the periodic hydrodynamic forces that are induced by the interaction of slender bodies and external fluid flow. If the vibration period is close to the natural period of the system, it can lead to fast accumulation of fatigue damage to the risers and amplified drag loads. There is a competition between the vortex induced forces acting on the buoyancy element and the riser segment due to its different diameters. The interaction of the vortex shedding from the riser and the buoyancy element depends on many parameters, such as the arrangement of the buoyancy element, aspect ratio of the buoyancy element, etc. Shell Oil Company conducted VIV model tests with a straight flexible cylinder and staggered buoyancy elements corresponding to a buoyant section of a SLWR in MARINTEK in 2011. Five different buoyancy element configurations were tested. The test data has been extensively studied (Rao, et al 2015 and Jhingran, et al 2012). The interaction of the buoyancy elements and bare riser and its influence on the riser response (frequency, displacement and fatigue damage) have been investigated. Semi-empirical VIV prediction software, such as VIVANA [4], SHEAR7 [13] and VIVA [11] are most commonly used by the offshore industry in the riser systems design against VIV loads. However, these software are not purposely designed to account for the interaction of the bare riser section and the buoyancy elements. It is of great interest to evaluate the prediction accuracy. The purpose of this study is to benchmark the VIV prediction of riser with buoyancy elements using VIVANA. The prediction is compared with Shell model test results with focus on CF responses. Uncertainty and improvement of the prediction are also discussed.

Wellhead Fatigue Damage Based on Indirect Measurements

2015 ◽  
Author(s):  
Guttorm Grytøyr ◽  
Fredy Coral ◽  
Halvor Borgen Lindstad ◽  
Massimilliano Russo
Keyword(s):  
Fatigue Damage ◽  
Oil And Gas ◽  
Time History ◽  
Bending Moment ◽  
Oil And Gas Industry ◽  
Fatigue Properties ◽  
Marine Riser ◽  
Gas Industry ◽  
Blowout Preventer ◽  
The Moment

Enabling safe and reliable operations of subsea wellheads has a high priority in the global oil and gas industry. The objective of the current paper is to provide a novel method for bending moment estimates at the wellhead based on indirect moment measurements; this moment, together with fatigue properties are then used for fatigue damage estimation. Indirect bending moments are based on inclinations and accelerations measured by motion reference units (MRU) attached to blowout preventer (BOP), lower marine riser package (LMRP) and lower riser joint (LRJ) immediately above the lower flexible joint (LFJ). Also, required is the tension time history in the same period at the LRJ. The proposed methodology here can be implemented and integrated into a portal for data acquisition and visualisation. In order to validate the proposed method for indirect bending moment estimation, strain gages have been attached to a BOP and marine riser during drilling operations offshore Norway. Strain gage readings are transformed to bending moment which is used as reference (the so-called direct moment). The proposed method is used to calculate the moment indirectly, the so-called indirect moment. The resulting indirect moments agree very well with the direct moments.

Vortex Induced Vibrations of Deep Water Risers: Sensitivity to Current Profile, Shear and Directionality

2014 ◽  
Author(s):  
Rafael Vergara Schiller ◽  
Marcelo Caire ◽  
Pedro Henrique Affonso Nóbrega ◽  
Elizabeth Passano ◽  
Halvor Lie
Keyword(s):  
Deep Water ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Offshore Structures ◽  
Sensitivity Analyses ◽  
Current Profile ◽  
Boundary Current ◽  
Gas Industry ◽  
Vortex Induced Vibrations ◽  
Se Brazil

Slender offshore structures such as risers experience vortex induced vibrations (VIV) when they are exposed to currents and accumulate significant fatigue damage through that process. VIV will depend on several structural properties of the riser and on the current profile that the structure is exposed to. In deep water regions, risers will be subject to intricate circulation systems that impose currents profiles which may vary in intensity, shear and direction throughout the water column. The increased complexity of currents will make the prediction of VIV more difficult and represents a clear challenge to the Oil and Gas Industry. The objective of this study is to investigate how selected properties of a current profile affect the development and excitation of VIV for a deep water tensioned riser. We employ a semi-empirical frequency-domain program to perform a series of numerical sensitivity analyses where the riser model is subject to current profiles that vary in complexity and include uniform profiles, linearly-sheared profiles and more realistic profiles that represent offshore boundary current regimes from SE Brazil. We address the sensitivity of the VIV response to current intensity, shear and directionality. Our results demonstrate that those properties of the current profile have significant influence on the range of VIV modes that are excited and on the VIV response. Overall, uniform profiles produced the largest responses and the linearly-sheared profiles demonstrated the large range of VIV modes that can be excited. The realistic profiles also excited a broad range of VIV modes and variations between the profiles produced changes in the VIV response. This study highlights the need to further understand how complex current profiles in the offshore region affect VIV development in comparison to simpler profiles that are recurrent in model test conditions.

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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