Performance Of Offshore Platforms Research Articles

Offshore Platforms: Classification, Technologies, Architectures, and Applications

Offshore platforms deal with challenges brought by the marine environment, providing workplaces for oil production, wind energy, and marine research. Offshore platforms play important roles in the ocean development. Although there are still challenges such as stability, control, and sensing technology, offshore platforms hold the potential to further improve their performance and application value with the continuous progress in technology. This paper presents a summary of the present research status within the domain of offshore platform studies, introducing different types of offshore platforms from the perspectives of their applications and basic structures. In terms of technology, this paper presents the technical aspects and architectural framework of offshore platforms. Additionally, the applications of offshore platforms are discussed. Comprehensive analysis indicates that offshore platforms exhibit strong adaptability and stability in marine environments. With the advancement of technologies, the reliability and performance of offshore platform are expected to improve in practical scenarios. This paper may offer a reference for the research of offshore platforms.

Improved Structural Health Monitoring Using Mode Shapes: An Enhanced Framework for Damage Detection in 2D and 3D Structures

Structural health monitoring (SHM) is crucial for ensuring the safety and performance of offshore platforms. SHM uses advanced sensor systems to detect and respond to negative changes in structures, improving their reliability and extending their life cycle. Model updating methods are also useful for sensitivity analysis. It is feasible to discuss and introduce established techniques for detecting damage in structures by utilizing their mode shapes. In this research, by considering reducing the stiffness of elements in the damage scenarios, we conducted simulations of the models in MATLAB, including both two-dimensional and three-dimensional structures, to update the method suggested by Wang. Wang’s method was improved to produce a sensitivity equation for the damaged structures. The sensitivity equation solution using a subset of mode shapes data was found to evaluate structural parameter changes. Comparing the updated results for Wang’s method and the suggested method in the two- and three-dimensional frames showed a noticeable modification in damage recognition. Furthermore, the suggested method can update a model containing measurement errors. Since Wang’s damage detection formulation is suitable only for 2D structures, this modified framework provides a more accurate decision-making tool for damage detection of structures, regardless of whether a 2D or 3D formulation is used.

A Bufferable Tuned-Mass Damper of an Offshore Platform against Stroke and Response Delay Problems under Earthquake Loads

A tuned-mass damper (TMD) is applied to ensure the safety and stability of an offshore platform in practice; however, damper stroke and response delay problems always result in intractable performances of vibration control while exposed to large earthquake loads. Therefore, this paper proposes a bufferable TMD, a passive TMD with buffers on both sides, to improve the performance of offshore platforms subjected to large seismic waves. A comprehensive simulation and experimental study was executed to investigate the dynamic performances of the bufferable TMD, by application of a 1 : 200-scale offshore platform prototype. It is verified that the bufferable TMD can be effective in absorbing the stroke energy, while the damper exceeds limitations of motion. Meanwhile, the bufferable TMD can maintain high-response characteristics. In conclusion, the experimental results indicate that the displacement, acceleration, and frequency performances of an offshore platform can be significantly decreased, and the evaluation indices show that the method is effective in reducing overall vibration levels and maximum peak values, with the application of the bufferable damper system.

Research on Vibration Control of Offshore Platform Based on Self-Recentering Rocking Wall

Self-recentering rocking wall is used in JZ20-2 north high wellhead platform, making simulation analysis to the whole structure subjected to ice load and earthquake load by the finite element software ANSYS, then analyses the nodal displacement and acceleration responses under the condition of different platform rocking wall stiffness, different floating box’s location, different buoyancy case. The results show that stiffness is the main factor affecting the seismic performance of offshore platforms, floating box can effectively reduce the dynamic response of offshore platform.

Study on Seismic Performance of Offshore Platform with Rocking Wall - TMD System

Offshore platform rocking wall system and tuned mass damper are briefly introduced, and the paper integrates the advantages of these two kinds of seismic method, and the TMD is attached to the jacket offshore platform - rocking wall system, using the ANSYS for finite element analysis, and the analysis results are optimized. The results show that compared with the offshore platform - rocking wall system, additional TMD can give full play to the performances of the two kinds of seismic methods, which is remarkable.

Finite Element Analysis for Structural Performance of Offshore Platforms under Environmental Loads

Offshore structures for oil and gas exploitation are subjected to various ocean environmental phenomena which can cause highly nonlinear action effects. Offshore structures should be designed for severe environmental loads and strict requirements should set for the optimum performance. The structural design requirements of an offshore platform subjected to wave induced forces and moments in the jacket can play a major role in the design of the offshore structures. For an economic and reliable design; good estimation of wave loadings are essential. The structure is discretized using the finite element method, wave force is determined according to linearized Morison equation. Hydrodynamic loading on horizontal and vertical tubular members and the dynamic response of fixed offshore structure together with the distribution of displacement, axial force and bending moment along the leg are investigated for regular and extreme conditions, where the structure should keep production capability in conditions of the one year return period wave and must be able to survive the 100 year return period storm conditions. The results show that the nonlinear response analysis is quite crucial for safe design and operation of offshore platform. Fixed Jacket type offshore platforms under extreme wave loading conditions may exhibit significant nonlinear behavior. The effect of current with different angles when hitting the offshore structure with the wave and wind forces, is very important for calculate the stress, the response displacement and deformation shapes. As the current increase or decrease the effect of wave force according to the hitting angle of current.

Analysis and performance of offshore platforms in hurricanes

Wind effects are critical considerations in the design of topside structures, overall structural systems, or both, depending on the water depth and type of offshore platform. The reliable design of these facilities for oil fields in regions of hostile environment can only be assured through better understanding of the environmental load effects and enhanced response prediction capabilities. This paper summarizes the analysis and performance of offshore platforms under extreme wind loads, including the quantification of wind load effects with focus on wind field characteristics, steady and unsteady loads, gust loading factors, application of wind tunnel tests, and the provisions of the American Petroleum Institute Recommended Practice 2A - Working Stress Design (API RP 2A-WSD) for the construction of offshore structures under the action of wind. A survey of the performance of platforms and satellite structures is provided, and failure mechanisms concerning different damage scenarios during Hurricane Andrew are examined. Guidelines and provisions for improving analysis and design of structures are addressed.

Nonlinear Performance of Offshore Platforms in Extreme Storm Waves

Dynamic-transient loading effects from extreme storm waves can have important influences on the nonlinear ultimate limit state performance of fixed offshore platforms. Recorded and synthetic storm wave time histories have been used to develop loading time histories acting on template-type platforms having natural periods in the range of 1-5 s. The interactions of these loading histories with the dynamic, nonlinear, hysteretic performance characteristics of idealized systems were analyzed. A modification to static pushover capacity analysis results is proposed to enable recognition of transient loading-structure performance characteristics. The results from the idealized systems were correlated with results from time domain nonlinear analyses of platform structure systems subjected to intense wave and earthquake loadings. For the global behavior of the platforms studied, the results based on the simplified systems are in good agreement with those from the complete analyses. ABSTRACT: Dynamic-transient loading effects from extreme storm waves can have important influences on the nonlinear ultimate limit state performance of fixed offshore platforms. Recorded and synthetic storm wave time histories have been used to develop loading time histories acting on template-type platforms having natural periods in the range of 1-5 s. The interactions of these loading histories with the dynamic, nonlinear, hysteretic performance characteristics of idealized systems were analyzed. A modification to static pushover capacity analysis results is proposed to enable recognition of transient loading-structure performance characteristics. The results from the idealized systems were correlated with results from time domain nonlinear analyses of platform structure systems subjected to intense wave and earthquake loadings. For the global behavior of the platforms studied, the results based on the simplified systems are in good agreement with those from the complete analyses.