New Practical Approach to Assess the Robustness and Redundancy of Offshore Structures: Application in Life Extension of Fixed Steel Offshore Platforms

2022 ◽  
pp. 325-332
Author(s):  
Binh Nguyen Thanh ◽  
Hung Nguyen Manh
Keyword(s):  
Offshore Structures ◽  
Practical Approach ◽  
Life Extension ◽  
Offshore Platforms

Structural Safety Assessment of Existing Ice-Resistant Jacket Platforms in Ice Zone

2009 ◽  
Author(s):  
Dayong Zhang ◽  
Qianjin Yue ◽  
Yuan Liu ◽  
Xiaofei Che
Keyword(s):  
Safety Assessment ◽  
Failure Modes ◽  
Evaluation Criteria ◽  
Offshore Structures ◽  
Life Extension ◽  
Structural Safety ◽  
Bohai Bay ◽  
Offshore Platforms ◽  
Oil And Natural Gas ◽  
Ice Loads

Until now dozens of offshore structures have been deployed in Bohai bay since the first drilling platform was erected in 1965. The oil and natural gas resources of Bohai Bay are mainly marginal oil fields. It is necessary to build both ice-resistant and economical offshore platforms. Full-scale measurement for many years shows the design of some ice-resistant platforms is not so sophisticated, the most significant is that ice induced vibration is the main which has caused harmful accidents in Liaodong bay of Bohai. In order to ensure security operation, structural safety assessment and life extension become key problems. In this paper, failure modes of ice resist jacket platforms, the related failure evaluation criteria, and risk grade are treated. Combined with monitoring data of ice loads, assessment strategy is presented. Lastly, as an application example, safety assessments of a practical platform in Bohai Bay are carried on.

A method of technical diagnostics for offshore structures

1994 ◽  
Vol 16 (2) ◽  
pp. 43-48
Author(s):  
Do Son
Keyword(s):  
Diagnostic Method ◽  
Joint Venture ◽  
Oil And Gas ◽  
Residual Life ◽  
Life Time ◽  
Offshore Structures ◽  
Technical Diagnostics ◽  
Offshore Platforms ◽  
South Vietnam ◽  
Local Destruction

This paper describes the results of measurements and analysis of the parameters, characterizing technical state of offshore platforms in Vietnam Sea. Based on decreasing in time material characteristics because of corrosion and local destruction assessment on residual life time of platforms is given and variants for its repair are recommended. The results allowed to confirm advantage of proposed technical diagnostic method in comparison with others and have been used for oil and gas platform of Joint Venture "Vietsovpetro" in South Vietnam.

Evaluation of Residual Life of Existing Offshore Platforms in Western Offshore, India

2021 ◽  
Author(s):  
A. Renugadevi ◽  
S. Nallayarasu ◽  
S. Karunanithi
Keyword(s):  
Residual Life ◽  
Probability Of Failure ◽  
Oil Field ◽  
Life Extension ◽  
Offshore Platforms ◽  
Strength Assessment ◽  
Encounter Probability ◽  
Reliability Method ◽  
Reserve Strength ◽  
Extension Period

Abstract Western offshore oil field in India has nearly 300 offshore platforms for oil and gas exploration, of which almost 50% of platforms have outlived their life. Life extension of these platforms has become essential for further production activities. In many cases, design level analyses combined with ultimate strength assessment, life extension has been granted. However, risk-based assessment based on the probability of failure based on available reserve strength linked to additional life extension could be a logical method. The Reserve Strength Ratio (RSR) is defined as a ratio of reserve capacity of the jacket structure and the design level environmental loads (1 year or 5year or 10 year or 100-year return period). The encounter probability of these design storms for the life extension period has been established probability for the extension period has been used as a threshold to determining the required RSR using the probability of collapse. For the present study, four typical aged wellhead platforms with different water depths are selected, and RSR is evaluated by carrying out push over analysis. The Monte Carlo Simulation method is used to generate the statistical values of RSR. The probability of failure is then calculated by First Order Reliability Method (FORM) using MATLAB for different RSR values. Reassessment criteria for the existing offshore platforms have been described from the reliability analysis results based on probability failure and encounter probability.

Integrity Management System for Fixed Offshore Structures Inspection Strategy

2004 ◽  
Author(s):  
Mohamed A. El-Reedy
Keyword(s):  
Management System ◽  
Offshore Structures ◽  
Assessment Method ◽  
Offshore Platforms ◽  
Offshore Structure ◽  
Structure Comparison ◽  
Actual Structure ◽  
Existing Structures ◽  
Integrity Management

The GUPCO offshore structure management system was developed as a part of an integrated infrastructure management system. This paper presents a case study of providing an integrity management system for inspection, evaluation and repair of the fixed offshore platforms in Gulf of Suez. The management system procedure is presented focusing on the first step for defining the highly risky weight to the lower risky weight structure based on API criteria for assessment of the existing structures. The risk analysis methodology for developing design and assessment criteria for fixed offshore structure based on consequence of failure is illustrated. In our case study the assessment method is applied for a number of fixed offshore structures. The above methodology is performed after theoretical assessment and then verifying by using ROV subsea inspection for the fixed offshore structure. Comparison between the actual structure performance and the predicting risk assessment for the structure from the model will be studied. The overall management system will be illustrated in scope of predictive maintenance philosophy and reliability for all offshore structures.

Ageing and Life Extension of Offshore Structures

2019 ◽  
Author(s):  
Gerhard Ersdal ◽  
John V. Sharp ◽  
Alexander Stacey
Keyword(s):  
Offshore Structures ◽  
Life Extension

A Holistic Approach to Life Extension of Fixed Offshore Platforms in Malaysian Waters

2019 ◽  
Author(s):  
Sok Mooi Ng ◽  
Riaz Khan ◽  
Biramarta Isnadi ◽  
Luong Ann Lee ◽  
Siti Nurshamshinazzatulbalqis Saminal
Keyword(s):  
Holistic Approach ◽  
Life Extension ◽  
Offshore Platforms

scholarly journals Condition Assessment Techniques for Aged Fixed-Type Offshore Platforms Considering Decommissioning: a Historical Review

2020 ◽  
Author(s):  
Mohamed Mubarak Abdul Wahab ◽  
V. John Kurian ◽  
Mohd Shahir Liew ◽  
Do Kyun Kim
Keyword(s):  
Pushover Analysis ◽  
Historical Review ◽  
Structural Condition ◽  
Condition Assessment ◽  
Life Extension ◽  
Nonlinear Behaviour ◽  
Offshore Platforms ◽  
Structural Behaviour ◽  
Strength Capacity ◽  
Fixed Type

AbstractIn this study, the technical papers on structural condition assessment of aged fixed-type offshore platforms reported over the past few decades are presented. Other ancillary related works are also discussed. Large numbers of researches are available in the area of requalification for life extension of offshore jacket platforms. Many of these studies involve reassessment of existing platforms by means of conducting pushover analysis, a static nonlinear collapse analysis method to evaluate the structure nonlinear behaviour and capacity beyond the elastic limit. From here, the failure mechanism and inherent reserve strength/capacity of the overall truss structure are determined. This method of doing reassessment is described clearly in the industry-adopted codes and standards such the API, ISO, PTS and NORSOK codes. This may help understand the structural behaviour of aged fixed offshore jacket structures for maintenance or decommissioning.

An Oil Field Structural Integrity Assessment for Re-Qualification and Life Extension

2013 ◽  
Author(s):  
Abe Nezamian ◽  
Joshua Altmann
Keyword(s):  
Weight Control ◽  
Structural Integrity ◽  
Offshore Structures ◽  
Oil Field ◽  
Assessment Process ◽  
Performance Criteria ◽  
Life Extension ◽  
Original Design ◽  
Integrity Assessment ◽  
Design Life

The ageing of offshore infrastructure presents a constant and growing challenge for operators. Ageing is characterised by deterioration, change in operational conditions or accidental damages which, in the severe operational environment offshore, can be significant with serious consequences for installation integrity if not managed adequately and efficiently. An oil field consisting of twelve well head platforms, a living quarter platform (XQ), a flare platform (XFP) and a processing platform (XPA) are the focus of this paper, providing an overview of the integrity assessment process. In order to ensure technical and operational integrity of these ageing facilities, the fitness for service of these offshore structures needs to be maintained. Assessments of the structural integrity of thirteen identified platforms under existing conditions were undertaken as these platforms are either nearing the end of their design life or have exceeded more than 50% of their design life. Information on history, characteristic data, condition data and inspection results were collected to assess the current state and to predict the future state of the facility for possible life extension. The information included but was not limited to as built data, brown fields modifications, additional risers and clamp-on conductors and incorporation of subsea and topside inspection findings. In-service integrity assessments, pushover analyses, corrosion control and cathodic protection assessments and weight control reports were completed to evaluate the integrity of these facilities for requalification to 2019 and life extension to 2030. The analytical models and calculations were updated based on the most recent inspection results and weight control reports. A requalification and life extension report was prepared for each platform to outline the performance criteria acceptance to achieve requalification until 2019 and life extension until 2030. This paper documents the methodology to assess the platform structural integrity in order to evaluate platform integrity for the remaining and extended design life. An overview of various aspects of ageing related to these offshore facilities, representing risk to the integrity, the required procedures and re assessment criteria for deciding on life extension of these facilities is presented. This paper also provides an overall view of the structural requirements, justifications and calibrations of the original design for the life extension to maintain the safety level by means of maintenance and inspection programs balancing the ageing mechanisms and improving the reliability of assessment results.

Water Deluge System Design for Fire Fighting

2016 ◽  
Author(s):  
Jin Lee ◽  
Sang Hwan Kim ◽  
Jung Kwan Seo ◽  
Jeom Kee Paik
Keyword(s):  
Fluid Dynamic ◽  
Design Procedure ◽  
Offshore Structures ◽  
Offshore Platforms ◽  
Probabilistic Sampling ◽  
Spray System ◽  
Safety Design ◽  
Fire Scenarios ◽  
Fire And Explosion ◽  
The Cost

The ships and offshore structures are exposed to inherently the risk of fire and explosion. These fire and explosion, accident caused by grave consequences not only to the ships and offshore platforms on the sea but the environment all mankind. The aim of this paper is to focus on an optimization of water deluge and mist spray system locations subjected to jet on the ships and offshore platforms. A trustworthy set of fire scenarios is identified and classified using probabilistic sampling methods calling for Latin Hyper Sampling. These events of fire are numerically calculated for selected scenarios by the computational Fluid Dynamic (CFD) code using a KFX. The Water Deluge Location Index (WLI) is then calculated by using the frequency and consequence of fire scenarios. And then, WLI are utilized to prioritize the optimal locations of water deluge and mist spray systems. The recommended methodology believes that can increase to certainties in the design procedure of unreliability and can regard the cost-effectiveness of safety design.

The Interaction Between Strength and Fatigue Reliability for a Minimum Structure in Shallow Water

2003 ◽  
Vol 125 (4) ◽  
pp. 281-287 ◽  
Author(s):  
G. K. Cole ◽  
B. F. Ronalds ◽  
E. Fakas
Keyword(s):  
Shallow Water ◽  
Wave Climate ◽  
Offshore Structures ◽  
Life Extension ◽  
Fatigue Reliability ◽  
North West ◽  
The North ◽  
Local Wave ◽  
Structural Inspection ◽  
The Relationship

The relationship between strength and fatigue reliability of an offshore platform is an important aspect in the setting of appropriate structural inspection programs, as well as providing valuable information when considering the life extension of ageing offshore structures. This paper uses the example of a braced monopod to examine the interaction between strength and fatigue reliability for shallow-water platforms subjected to wave climates typical of the North West Shelf of Australia. The central role played by the local wave climate in both the strength and fatigue response of the structure is investigated. The probability of fatigue failure at the critical location was found to be approximately three orders of magnitude less than the overall probability of storm overload failure. This inequity between strength and fatigue reliability raises the possibility of redirecting inspection effort toward higher-risk threats such as accidental damage and corrosion. The potential for further optimizing the total life-cycle costs of new offshore structures is also briefly discussed.

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