Integrity Management for Steel Catenary Risers With Design Life of 30 Years

Author(s):  
Hao Song ◽  
Chenteh Alan Yu ◽  
Yongming Cheng ◽  
Jing Hou

Abstract The riser is a critical element in a subsea production system for transporting hydrocarbons from the seafloor to the surface. The track record of existing riser systems worldwide has shown that risers tend to be designed conservatively to accommodate dynamic loads, strength and fatigue requirements, and corrosion/erosion provision needs. Among all the riser types, the steel catenary riser (SCR) is the most installed riser configuration for deepwater oil and gas production worldwide in the last two decades. This is mainly because of their simple configuration and relatively low manufacturing and installation cost. As riser technology advances, SCRs are designed to tackle more challenging environments and longer service lives. For the riser life extension applications, regulatory bodies prefer riser operations to be managed through an integrity management program, demonstrating that a robust framework with detailed records on the conditions of the risers is in place. This paper studies an integrity management program for SCRs with a 30-year design life in a harsh environment. The planned riser integrity management program is based on successful industry practice and the newly published riser integrity management standard API RP 2RIM [4]. It starts with a review of the riser design basis and as-built data, continuing with key field data measurement and production fluid sampling. A digital model, continuously calibrated with the measured data, is established to assess the integrity of the riser system. Key physical quantities are selected to monitor the structural health of the SCRs, including vessel motion measurement, measurement of SCR top hang-off angles and tensions, and full water column current measurement. The relationship between the measurement data and the riser strength and fatigue performance is established. Details of the riser integrity assessment in a digital model utilizing the measurement data are presented. The implemented proposed riser integrity management program is expected to provide a more focused and efficient method with a higher level of confidence in operating the SCRs during the design life and potentially beyond.

Author(s):  
Robert B. Gordon ◽  
Juan Carlos Ruiz-Rico ◽  
Michiel Peter Hein Brongers ◽  
Julian Gomez

This paper applies state-of-the-art integrity management and life extension methodologies to address degradation and failure modes specific to CALM buoy export terminals. The main objectives are to (1) classify the components of the export terminal according to their criticality, (2) establish risk-based inspection and maintenance plans to reduce or mitigate risk to acceptable levels and (3) assess remaining life. The method is applied to a CALM buoy operating off the coast of Colombia. This buoy serves as the oil export terminal for all crude oil transmitted by the Ocensa pipeline, which has a capacity of 560 kBPD or around 60% of total Colombia oil production. The buoy is nearing the end of its design life, and options for life extension have been investigated based on an integrity assessment of the current condition of the equipment. As part of the assessment, detailed plans for future Risk Based Inspections (RBI) and Mitigation, Intervention, and Repair (MIR) have been developed.


Author(s):  
Abe Nezamian ◽  
Joshua Altmann

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.


Author(s):  
S. Ruik Beyhaut

To control the threats from external forces, pipeline owners and operators require detailed information about their pipeline infrastructure and the environment surrounding that infrastructure. The contribution from geographic data is recognized as an increasingly important part of a complete integrity management program, particularly for the identification of geohazards. This is because geohazards are generally characterized by high spatial variability, are complex and difficult to quantify but may result in catastrophic failure of pipelines. In recent years we have seen widespread technological development surrounding the processes to capture information in order to deliver quantitative inputs for pipeline engineers, risk & geotechnical experts. International codes & best practices (e.g. AS 2885.1-2012) state that “Environmental impact assessment is not simply a vehicle to obtain regulatory approval, it is a critical element of the planning for design, construction and operation of the pipeline.” Furthermore, geohazards frequently develop during the service life of pipelines. Consequently, regulators recommend that assessments are conducted on an ongoing basis to identify all potential threats and implement mitigation measures. A process has been developed to create efficient and economical solutions for monitoring and assessing the significance of pipeline bending strain and whether actual movement has taken place. This process can make use of a variety of inputs including slope gradient, climate, groundwater conditions, slope instability, seismic intensity, and environmental impacts, and can provide important information in the determination of potential mitigations. This paper will review the benefits which can be gained from the implementation of integrated approaches to inform geohazard management.


Author(s):  
Honglong Zheng ◽  
Muyang Ai ◽  
Lijian Zhou ◽  
Mingfei Li ◽  
Ting Wang ◽  
...  

As a preventative management mode, integrity management which is significantly effective is now applicable in modern industry. Based on the successful application of integrity management for the pipeline, managers expect an extension of the integrity management program for the oil and gas stations such as pumping stations, so as to make the best arrangement of resources and guarantee the safety of station facilities. The differences between station integrity management system in China and abroad are analyzed. It is claimed that the oil and gas station integrity management is more difficult and complicated in China. An integrity management program is developed for the oil and gas stations in China. The authors summarily introduce the station integrity management framework, and determine the processes and elements of management. For the main parts of the stations are plenty of facilities, the authors attempt to carry out the management on each category of facilities in particular. According to the characteristics and working status, field facilities can be classified into three categories: static facilities, dynamic facilities, and electrical instruments. For all these facilities, integrity management approach consists of five steps: data collection, risk assessment, integrity assessment, repair & maintenance, and performance evaluation. Station integrity management system comprises five aspects: system documents, standards & specifications, supporting technologies, management platforms and applications. This paper should be considered as a reference for the oil and gas station integrity managers in the future.


Author(s):  
M. Robb Isaac ◽  
Saleh Al-Sulaiman ◽  
Monty R. Martin ◽  
Sandeep Sharma

In early 2005, Kuwait Oil Company (KOC) initiated a Total Pipeline Integrity Management System (TPIMS) implementation in order to carry out a major integrity assessment of its operating facilities, equipment, buried plant piping and pipeline network and to establish a continuing integrity management program. KOC Transit System is a complex infrastructure consisting of over three hundred pipelines, thousands of wellhead flow lines, and consumer and offshore lines for which there was a significant loss of data when the facilities were destroyed during a military invasion in 1990. An initial pipeline system assessment identified issues and actions regarding condition of the pipelines, corridors, requirements on in-line inspection (ILI), documentation, RISK assessment, status of international code compliance, and overall state of the system. Following recommendations from that initial assessment led to the development of a long term strategy; the execution of which required the implementation of a comprehensive integrity management program. This case study discusses the results obtained after five years of implementation of TPIMS at KOC. It will demonstrate some of the complex components involved in managing the integrity of the Transit System that have been made possible through the implementation of the system. The general concept and structure of TPIMS will be described, and how it deals with the complexity of the KOC pipeline system. The system made it possible to integrate and manage data from various sources, by conducting integrity assessment using ILI, Direct Assessment and hydrostatic testing, as well as structure a comprehensive RISK & Decision Support mechanism. This is one of the world’s first implementations of this magnitude which encompasses such a wide range of services and variables; all being managed in a single environment and utilized by a multitude of users in different areas at KOC. The biggest challenge in a project of this scope is data management. Examples will be shown of the integration structure to illustrate the benefits of using a single comprehensive and versatile platform to manage system requirements; ultimately providing system reliability and improving overall operational efficiency.


Author(s):  
Keith Adams ◽  
Joe Zhou

Pipeline dents are common occurrences that have a potential integrity threat to the system. Dents are typically found through in-line inspections, and historically, low-resolution in-line inspection geometry tools were used to find the locations of dents. These tools gave little information about shape, orientation or other dent features. Newer ‘high-resolution’ tools give a much clearer picture of the dent shape, location, orientation and location of welds. This information has been previously unavailable and has enabled dent integrity assessment with much greater accuracy and confidence. However this still leaves the question of how to best address the information from older, low-resolution inspection tools. In the past, CSA Z662 required that all dents with a deflection greater than 6% or that contained stress concentrators, including welds, had to be repaired. In the newly published 2003 edition of CSA Z662, dents can be assessed by an engineering assessment to determine their acceptability. Historical evidence has shown that dents less than 6% can also be subject to failure under certain conditions, and is indicated in the notes of CSA Z662-03 10.8.2.4.2. Dents that contain stress concentrators, including corrosion, welds and cracks must be given special consideration, however often little information is available for the dent from solely a geometry tool. TransCanada PipeLines Limited has been involved in the development of a dent assessment methodology for several years. Based on the 2003 revisions to CSA Z662, TransCanada has started to implement a dent integrity management program. This paper discusses the approach taken by TransCanada: to create a database of dent features, classification of dents, finite element analysis (FEA) to determine cyclic stress spectra, fatigue analysis, validation through dig programs, and the management of these features from a system integrity standpoint.


Author(s):  
Abe Nezamian ◽  
Robert J. Nicolson

Floating facilities for production, storage and offtake (FPSO) and other offshore production facilities have been used safely and reliably throughout the oil industry for many years. Asset Integrity is increasingly important to optimising safety and operational life and asset performance efficiency. Operators need to comply with Corporate, Regulatory and Certification requirements but recognise that developing and managing an effective and compliant Asset Integrity Management System is both time consuming and costly. Review of operational history of existing large FPSOs around the world indicated low confidence in operational life expectancy and to achieve the design life without possible dry docking or major repair. FPSOs have certain loading characteristics and damage consequences that make them different to other offshore installations and conventional ships, and often more challenging to maintain and operate. Maintenance and inspection campaigns are important inputs in the Asset Integrity Management (AIM) system of FPSOs and other floating offshore facilities. Considering that the unit shall stay on site during the whole life of the field, where disconnection or the removal of the mooring system is not planned, a comprehensive methodology for the asset integrity management, survey, inspection, testing, maintenance and repair of the unit during this period needs to be developed and subject to review based on the results of the scheduled inspections and audits. So as well as class and statutory requirements, inspection and survey, maintenance and repair plans should reflect the required availability, functionality, survivability and durability of the unit, giving due regard to its field life, as part of the safety management of the facility. Risk Based Integrity management methodology has been adopted in several projects and is an important tool to establish a rational inspection campaign for structural components, mainly for those located in areas where access is critical and operational constraints are an important parameter. This paper gives an overview of the challenges and discusses various aspects of ageing related to FPSO facilities, represented risk to the integrity of a facility and the required procedures and reassessment criteria for maintaining the structural integrity. This paper also provides an overall view on the regulatory requirements, documentation and calibrations/validations of the original design values to maintain the safety level by means of a maintenance and inspection programs balancing the ageing mechanisms and improving the reliability of assessment results. A brief summary of an example project of an asset integrity assessment and management program for life preservation of a purpose built FPSO and associated subsea system facilities is presented.


Author(s):  
A. Stacey ◽  
M. Birkinshaw ◽  
J. V. Sharp

With many offshore installations in the UK sector of the North Sea now reaching or being in excess of their original anticipated design life, there is a particular need to evaluate approaches to structural integrity management by offshore operators. Ageing processes can affect the structural integrity of the installation and demonstration of adequate performance beyond its original design life is thus a necessary requirement. This paper addresses the issues relevant to the life extension of ageing installations.


Author(s):  
Mingjiang Xie ◽  
Zhigang Tian ◽  
Jeff Sutherland ◽  
Bingyan Fang ◽  
Bill Gu

A pipeline integrity management program is greatly affected by integrity planning methods and inline inspection (ILI) tool performance. In integrity management program planning, inspection and maintenance activities are in common practice, determined from risk and integrity assessment practices with the objective to reduce risk and effectively exceed a reliability target for the safe operation of the pipeline. An efficient and effective integrity planning method can address the most significant risk and optimize the operational and maintenance costs. In this paper, a method is presented for analyzing the impact of ILI tool accuracy on integrity planning for pipelines for fatigue cracks. Crack inspection and threat of fatigue cracking was used as the working case for the analysis although the approach could potentially be used for any pipeline threat type. The proposed method is based on the use of a Monte Carlo simulation framework, where initial crack defect size and ILI measurement errors are considered as key random variables. The integrity (severity) assessment of the crack population scenarios used the CorLAS™ burst pressure model, and the Paris’ law crack growth model based on API 579. The subsequent pipeline reliability assessments also considered single and multiple cracks scenarios. Using a reliability / probability of failure (PoF) approach, the impact of ILI tool accuracy and initial crack size on when to set reinspection and reassessment intervals was investigated. Furthermore, integrity program cost scenarios for pipeline integrity programs with multiple cracks was also evaluated with respect to different (crack) populations, pipe conditions and ILI accuracies. A sensitivity analysis was performed considering different inspection costs, maintenance costs and relative crack severity for pipelines with financial metrics. Various scenarios were discussed regarding maintenance and inspection planning and a “total cost rate” for different situations. The proposed method can support integrity management program planning by linking risks with integrity plan costs associated with ILI accuracies, and optimal re-assessment intervals.


Author(s):  
Tara Podnar ◽  
Thomas A. Bubenik ◽  
Jim Andrew ◽  
Dyke Hicks

Det Norske Veritas (U.S.A.), Inc. (DNV) has had the opportunity to observe and contribute to a significant number of longitudinal seam weld integrity management programs. DNV has used these opportunities to identify activities with a positive impact on the integrity management of the longitudinal seam welds for which they are implemented. The Integrity Assessment activities identified by DNV include those pertaining to hydrostatic pressure testing, in-line inspection data, and in-line inspection technology. The Anomaly Review and Prioritization activities include excavation prioritization, control excavations, and investigative excavations. The Excavation and Repair Program activities include non-destructive examination techniques, technologies and validation, repair methods, and safety measures. The Tool Validation activities include in-line inspection specification and vendor feedback. The Reassessment activities include those pertaining to in-line inspection validation, operations, and reassessment interval calculation methodologies. Not all longitudinal seam weld integrity management activities are appropriate for all pipelines. In these cases, the correct combination of integrity management activities will result in an effective longitudinal seam weld integrity management program.


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