A Model to Estimate the Failure Rates of Offshore Pipelines

Author(s):  
Vania De Stefani ◽  
Peter Carr

Pipelines are subjected to several threats which can cause failure of the line, such as external impact, mechanical defects, corrosion and natural hazards. In particular, offshore operations present a unique set of environmental conditions and adverse exposure not observed in a land environment. For example, offshore pipelines located near harbor areas and in major shipping lanes are likely to be exposed to the risk of damage from anchor and dropped object impact. Such damage may result in potential risk to people and the environment, and significant repair costs. Quantitative Risk Assessment (QRA) is a method which is often used in the oil and gas industry to predict the level of risk. In QRA calculations the frequency of an incident is often assessed by a generic failure frequency approach. Generic failure frequencies derived from local incident databases are largely used in pipeline risk assessments. As a result, risk assessments for offshore pipelines may not reflect accurately operational experience for a specific pipeline or region of operation. In addition, a better understanding of the causes and characteristics of pipeline failure should provide important information to improve inspection and maintenance activity for existing pipelines and to aid in selection of design criteria for new pipelines. This paper presents an analysis of the failure data from various pipelines databases to see if there is a common trend regarding failure rates, and failure-rate dependence on pipeline parameters. A breakdown of the causes of failure has been carried out. The effect on failure frequency of factors such as pipeline age, location, diameter, wall thickness, steel grade, burial depth, and fluid transported have been investigated and are discussed. The objective of this paper is to provide a guideline for the determination of failure frequency for offshore pipelines and to describe a new model developed for use within BP for this purpose. This model uses historical databases and predictive methods to develop failure frequencies as a function of a range of influencing parameters.

Author(s):  
Robert W. Brewerton ◽  
Paul Geddes ◽  
Sava Medonos ◽  
Raghu Raman ◽  
Christopher C. E. Wilkins

The research and development activities following the Piper Alpha disaster have resulted in significantly improved technical safety of oil & gas facilities offshore and onshore. This improved technical safety resulted from the development of goal-setting, risk-based approach, the objective of which was to open the routes for design optimization and remove previous constraints that addressed the worst case and was prescriptive. Despite this initiative, a Quantitative Risk Assessment (QRA), while still being carried out, often remains “disconnected” from the practical design and prescriptive methods still take precedence. Resorting solely to a prescriptive approach can result in adequate protection missing in places where it should be, and applied in areas where there is a low likelihood of the hazard. This Paper addresses the application in the facility design, risk based methods and known behavior of structures and equipment in accidents. It stresses the importance of practical experience in the application of fire and explosion protection, and adequate design and operational experience. The Paper focuses on fire and explosion hazards and is based on more than 30 years of the authors’ experience in supporting facility design and assessment. Such approach has resulted in solutions with improved technical safety and significant cost-savings. It addresses both new installations and modifications of existing facilities.


Author(s):  
Maria V Clavijo ◽  
Adriana M Schleder ◽  
Enrique Lopez Droguett ◽  
Marcelo R Martins

Currently, a Dynamic Position (DP) System is commonly used for offshore operations. However, DP failures may generate environmental and economic losses; thus, this paper presents the Reliability, Availability and Maintainability (RAM) analysis for two different generations of DP system (DP2 and DP3) used in drilling operations. In addition to the RAM analysis, the approach proposed herein considers the uncertainties present in the equipment failure data and provides more information about criticality equipment ratings and probability density functions (pdf) of the repair times. The reliability analysis shows that, for 3 months of operation, the total failure probability of the DP2 system is 1.52% whereas this probability for the DP3 system is only 0.16%. The results reveal that the bus-bar is the most critical equipment of the DP2 system, whereas the wind sensor represents the priority equipment in the DP3 system. Using 90% confidence level, each DP configuration was evaluated for a 1-year operation, finding a reliability mean equal to 70.39% and 86.77% for the DP2 system and the DP3 system, respectively. The DP2 system asymptotic availability tends to present a constant value of 99.98% whereas for the DP3 system, it tends to be 99.99%. Finally, the maintainability analysis allows concluding that the mean time for system repair is expected to be 3.6 h. This paper presents a logical pathway for analysts, operators, and reliability engineers of the oil and gas industry.


Author(s):  
Madhumitha Ramachandran ◽  
Jon Keegan ◽  
Zahed Siddique

Abstract Reciprocating seal located directly on the rod/piston of a reciprocating equipment is used for preventing leakage and reducing wear between two parts that are in relative motion. Degradation assessment of reciprocating seal is extremely important in the manufacturing industry to avoid fatal breakdown of reciprocating equipment and machines. In this paper, we have proposed a data-driven prognostics approach using friction force to predict the degradation of reciprocating seal using Support Vector Regression. Statistical time domain features are extracted from friction force signal to reduce the complexity of raw data. Principal Component Analysis is used to fuse the relevant features and remove the redundant features from the process. Based on the selected features, a Support Vector Regression model is then built and trained for the prediction of seal degradation. A Grid search method is used to tune the hyperparameters in the SVR model. Run-to-failure data collected from an experimental test set-up is used to validate the proposed methodology. The study findings indicate that a small set of relevant features which can represent the pattern related to degradation is sufficient to have a high prediction accuracy. The seal tested for this study comes from oil and gas industry, but the proposed method can be implemented in any industry with reciprocating equipment and machines.


Author(s):  
Frank Gareau ◽  
Alex Tatarov

Fibreglass reinforced plastic pipe (FRP) is the second most common type of pipe in the Canadian oil and gas industry, based on installed length. Industry methods to define risks and prevent failures are difficult because industry is still learning how these types of materials fail. Current industry failure records indicate that the failure rates for some of these materials are higher than steel failure rates. Unique details related to a specific FRP failure will be discussed in this paper. This failure occurred on an 8-inch OD FRP pipeline at the bottom of a riser. The failure resulted in a spill and a fire. The reasons for failure and fire initiation were analysed separately. The failure was a result of a combination of several types of stresses and material degradation. Both static and dynamic stresses contributed to the failure. • Ground settling resulted in high static bending stress of the last section of the pipeline connected to the riser elbow supported by the anchor. • The failure was in the last connection of the pipeline. Static tie-in stresses could have contributed to the failure. • Static stresses were evaluated using Finite Element Analysis (FEA) approach and found to be insufficient for the failure. • Dynamic stresses contributed to the failure. The failure happened soon after a power outage, when numerous wells were restarted, and several fluid surges may have occurred. • Material degradation associated with a specific orientation of glass fibres at the connection pup contributed to the failure. The failure sequence was established and different modes of fire initiation were analysed.


Author(s):  
Guy Desjardins ◽  
Kar Mun Cheng ◽  
Shahani Kariyawasam ◽  
Boon Ong ◽  
Pauline Kwong

As part of its ongoing continuous improvement efforts, TransCanada has analyzed the system-wide historical failure data to understand trends and benchmark risk algorithms. The analysis of historical in-service and hydrostatic-test failures is a good diagnostic tool to assess threats to the pipeline system. This knowledge and understanding can be used to build risk algorithms. Quantification of failure rates also enables risk values among different threats and along the pipeline to be benchmarked appropriately. This paper focuses on the assessment of the expected failure frequency of the pipeline to SCC and corrosion.


2017 ◽  
Vol 57 (1) ◽  
pp. 79 ◽  
Author(s):  
Eric Jas ◽  
Allison Selman ◽  
Valerie Linton

Existing legislation, regulation and documentation dealing with decommissioning of offshore oil and gas infrastructure has traditionally been derived from experience gained in the North Sea and the Gulf of Mexico. The Australian operating environments are very different and, consequently, there is no Australian industry-wide engineering standard dedicated to the decommissioning of offshore pipelines. Decommissioning of Australian offshore pipelines is currently handled on a case-by-case basis. The efficiency and effectiveness of any given decommissioning project is variable, and highly dependent upon the experience of the pipeline operator. Given the maturity stage of the Australian offshore oil and gas industry, it is foreseen that in the coming years many operators will approach the task of decommissioning offshore pipelines for the first time. In 2014 the Energy Pipelines Cooperative Research Centre (EPCRC) formed an offshore users group, comprising pipeline experts from several offshore oil and gas operators and engineering consultancies that are members of the Australian Pipelines and Gas Association’s Research and Standards Committee (APGA RSC). This group is developing an engineering guideline for the decommissioning of offshore pipelines. It is being developed in close communication with the Australian Petroleum Production and Exploration Association (APPEA), which has formed a decommissioning committee in relation to offshore facilities. This ensures the guideline is being developed by and with input from a broad spectrum of the Australian offshore oil and gas industry, with the aim of capturing best practice in the Australian context.


2017 ◽  
Vol Vol 159 (A2) ◽  
Author(s):  
S J Kim ◽  
J M Sohn ◽  
J K Paik

Hydrocarbon explosion and fire are typical accidents in the offshore oil and gas industry, sometimes with catastrophic consequences such as casualties, property damage and pollution. Successful engineering and design should meet both functional requirements associated with operability in normal conditions and health, safety, environmental and ergonomics (HSE&E) requirements associated with accidental and extreme conditions. A risk-based approach is best for successful design and engineering to meet HSE&E requirements. This study aimed to develop an advanced procedure for assessing the quantitative risk of offshore installations in explosions. Unlike existing industry practices based on prescriptive rules or qualitative approaches, the proposed procedure uses an entirely probabilistic approach. The procedure starts with probabilistic selection of accident scenarios. As the defining components of risk, both the frequency and consequences associated with selected accident scenarios are computed using the most refined technologies. Probabilistic technology is then applied to establish the relationship between the probability of exceedance and the physical values of the accident. Acceptance risk criteria can be applied to define the nominal values of design and/or level of risk. To validate and demonstrate the applicability of the proposed procedure, an example of its application to topside structures of an FPSO unit subjected to hydrocarbon explosions is detailed. The conclusions and insights obtained are documented.


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