Xu Yin, Zhixun Yang, D. Shi, Jun Yan, Lifu Wang, Qingzhen Lu, Geng Tian
The umbilical which consists of hydraulic tubes, electrical cables and optical cables is a key equipment in the subsea production system. Each components perform different physical properties, so different cross-sections will present different geometrical characteristic, carrying capacities, the cost and the ease of manufacture. Therefore, the cross-sectional layout design of the umbilical is a typical multi-objective optimization problem. A mathematical model of the cross-sectional layout considering geometric and mechanical properties is proposed, and the genetic algorithm is introduced to copy with the optimization model in this paper. A steepest descent operator is embedded into the basic genetic algorithm, while the appropriate fitness function and the selection operator are advanced. The optimization strategy of the cross-sectional layout based on the hybrid genetic algorithm is proposed with the fast convergence and the great probability for global optimization. Finally, the cross-section of an umbilical case is performed to obtain the optimal the cross-sectional layout. The geometric and mechanical performance of results are compared with the initial design, which verify the feasibility of the proposed algorithm.
{"title":"The Optimization Design of the Cross-Sectional Layout of an Umbilical Based on the Hybrid Genetic Algorithm","authors":"Xu Yin, Zhixun Yang, D. Shi, Jun Yan, Lifu Wang, Qingzhen Lu, Geng Tian","doi":"10.1115/omae2021-63384","DOIUrl":"https://doi.org/10.1115/omae2021-63384","url":null,"abstract":"\u0000 The umbilical which consists of hydraulic tubes, electrical cables and optical cables is a key equipment in the subsea production system. Each components perform different physical properties, so different cross-sections will present different geometrical characteristic, carrying capacities, the cost and the ease of manufacture. Therefore, the cross-sectional layout design of the umbilical is a typical multi-objective optimization problem. A mathematical model of the cross-sectional layout considering geometric and mechanical properties is proposed, and the genetic algorithm is introduced to copy with the optimization model in this paper. A steepest descent operator is embedded into the basic genetic algorithm, while the appropriate fitness function and the selection operator are advanced. The optimization strategy of the cross-sectional layout based on the hybrid genetic algorithm is proposed with the fast convergence and the great probability for global optimization. Finally, the cross-section of an umbilical case is performed to obtain the optimal the cross-sectional layout. The geometric and mechanical performance of results are compared with the initial design, which verify the feasibility of the proposed algorithm.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133635372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Ang, Arriane Chiara Bernardo, R. Peek, Knut Vedeld, Mario Caruso, Jie Wu
This paper describes a multi-pronged continuous improvement effort to manage the spans of a deep-water pipeline, where even without wave action, the currents are strong enough to move sediments, leading to constantly changing spans. The effort includes: (1) using strakes rather than intermediate supports to suppress VIV, since the latter proved not to be a long-term solution, (2) using partial rather than full strake coverage of spans and developing tools to quantify the level of strake coverage that is required, (3) improving estimates of soil stiffness and damping, and tools to handle amplitude-dependent soil stiffness and damping, (4) performing pluck tests of the operating pipeline by pulling it laterally at midspan with the ROV until a weak link connecting the ROV to the pipe breaks, whereupon the resulting motion of the pipe is recorded with accelerometers, (5) developing tools that allow fatigue damage to be estimated and accumulated for every location along the pipeline (6) sponsoring a joint industry program by DNVGL to quantify the effect of seabed proximity and trench effects on VIV. This paper provides an overview of these activities, with emphasis on recent results and new assessment tools and methods developed and their validation covering items (2–4) above.
{"title":"Deepwater Span Management on a Mobile Seabed","authors":"S. Ang, Arriane Chiara Bernardo, R. Peek, Knut Vedeld, Mario Caruso, Jie Wu","doi":"10.1115/omae2021-63458","DOIUrl":"https://doi.org/10.1115/omae2021-63458","url":null,"abstract":"\u0000 This paper describes a multi-pronged continuous improvement effort to manage the spans of a deep-water pipeline, where even without wave action, the currents are strong enough to move sediments, leading to constantly changing spans. The effort includes: (1) using strakes rather than intermediate supports to suppress VIV, since the latter proved not to be a long-term solution, (2) using partial rather than full strake coverage of spans and developing tools to quantify the level of strake coverage that is required, (3) improving estimates of soil stiffness and damping, and tools to handle amplitude-dependent soil stiffness and damping, (4) performing pluck tests of the operating pipeline by pulling it laterally at midspan with the ROV until a weak link connecting the ROV to the pipe breaks, whereupon the resulting motion of the pipe is recorded with accelerometers, (5) developing tools that allow fatigue damage to be estimated and accumulated for every location along the pipeline (6) sponsoring a joint industry program by DNVGL to quantify the effect of seabed proximity and trench effects on VIV. This paper provides an overview of these activities, with emphasis on recent results and new assessment tools and methods developed and their validation covering items (2–4) above.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132766556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fatigue analysis of flexible risers is a demanding task in terms of time and computational resources. The traditional time domain approach may take weeks of time in global simulation, local modelling and post-processing of riser responses to get fatigue results. Baker Hughes developed a fast hybrid approach, which is based on a frequency domain technique. The new approach was first implemented at the end fitting region and then to all other regions of the riser. Studies showed that the hybrid approach achieved convenient and conservative results in a significant shorter period of time. To improve the accuracy and reduce conservatism of the method, Baker Hughes has further optimized the analysis procedure to seek better results approaching true solutions. Several methods were proposed and studied. The duration of representative cases and noncritical cases have been extended. The steps to predict stress spectrum based on transfer functions have also been updated. From previous studies, only one transfer function was built for fatigue load cases with similar response spectra. This assumption linearizes the system response and produces certain level of discrepancy against true time domain solution. In this study, multiple ways of spectrum prediction are evaluated and compared. The paper summarizes several techniques to further optimize the hybrid frequency domain approach. The updated fatigue results are found to be more accurate. The optimized approach therefore gives more flexibility to engineers to approach the true solutions, which were originally acquired from full 3-hr time domain simulations. The approach requires less analysis time and reduces iterations in pipe structure and riser configuration design, which leads to faster project execution and potential cost reduction.
{"title":"Optimization of Frequency Domain Fatigue Analysis for Unbonded Flexible Risers","authors":"Jiabei Yuan, Yucheng Hou, Z. Tan","doi":"10.1115/omae2021-62886","DOIUrl":"https://doi.org/10.1115/omae2021-62886","url":null,"abstract":"\u0000 Fatigue analysis of flexible risers is a demanding task in terms of time and computational resources. The traditional time domain approach may take weeks of time in global simulation, local modelling and post-processing of riser responses to get fatigue results. Baker Hughes developed a fast hybrid approach, which is based on a frequency domain technique. The new approach was first implemented at the end fitting region and then to all other regions of the riser. Studies showed that the hybrid approach achieved convenient and conservative results in a significant shorter period of time.\u0000 To improve the accuracy and reduce conservatism of the method, Baker Hughes has further optimized the analysis procedure to seek better results approaching true solutions. Several methods were proposed and studied. The duration of representative cases and noncritical cases have been extended. The steps to predict stress spectrum based on transfer functions have also been updated. From previous studies, only one transfer function was built for fatigue load cases with similar response spectra. This assumption linearizes the system response and produces certain level of discrepancy against true time domain solution. In this study, multiple ways of spectrum prediction are evaluated and compared.\u0000 The paper summarizes several techniques to further optimize the hybrid frequency domain approach. The updated fatigue results are found to be more accurate. The optimized approach therefore gives more flexibility to engineers to approach the true solutions, which were originally acquired from full 3-hr time domain simulations. The approach requires less analysis time and reduces iterations in pipe structure and riser configuration design, which leads to faster project execution and potential cost reduction.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123067026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Minimizing the stress concentration factor (SCF) in pipe joint welding subjected to fatigue is a major concern. Machining the joint ends is one way to achieve this. However, this adds cost, time, risk of potential crack starters, and loss of wall thickness which is detrimental for fatigue, strength, and engineering criticality assessment (ECA) in particular. Pipe joint sorting (certain joints in sequence) and end matching (rotating the pipe joints for best fit) are other ways. However, this adds time, costly logistics, risk of errors, and does not guarantee the minimum possible SCF is achieved. In a typical project, more pipe joints are procured than required in order to mitigate contingencies. For pipelines, this overage is typically a percentage of the required number of joints or pipeline length. For risers, typically double the required number of joints is procured where half of the joints is sent offshore for installation and the remaining half is kept onshore for a spare riser. Then, it becomes very important to send for installation the best pipe joints that produce the best (lowest) SCFs out of the entire batch of pipe joints. This requires calculating the SCF for every potential match of any random joints to be welded together, and then choosing the best joints. Performing such calculations by spreadsheet is not feasible considering the tremendous number of required iterations and calculations. A pipe joint management software development is presented herein which accomplishes this task and examples provided to illustrate the benefits. Note: Selecting pipe joints with the best end measurements, whether ID, OD, OOR, or thickness does not guarantee that the minimum possible SCFs will be achieved since the SCF is a function of all those measurements.
{"title":"Pipe Joint Management for Risers and Pipelines","authors":"G. Mansour","doi":"10.1115/omae2021-63173","DOIUrl":"https://doi.org/10.1115/omae2021-63173","url":null,"abstract":"\u0000 Minimizing the stress concentration factor (SCF) in pipe joint welding subjected to fatigue is a major concern. Machining the joint ends is one way to achieve this. However, this adds cost, time, risk of potential crack starters, and loss of wall thickness which is detrimental for fatigue, strength, and engineering criticality assessment (ECA) in particular. Pipe joint sorting (certain joints in sequence) and end matching (rotating the pipe joints for best fit) are other ways. However, this adds time, costly logistics, risk of errors, and does not guarantee the minimum possible SCF is achieved. In a typical project, more pipe joints are procured than required in order to mitigate contingencies. For pipelines, this overage is typically a percentage of the required number of joints or pipeline length. For risers, typically double the required number of joints is procured where half of the joints is sent offshore for installation and the remaining half is kept onshore for a spare riser. Then, it becomes very important to send for installation the best pipe joints that produce the best (lowest) SCFs out of the entire batch of pipe joints. This requires calculating the SCF for every potential match of any random joints to be welded together, and then choosing the best joints. Performing such calculations by spreadsheet is not feasible considering the tremendous number of required iterations and calculations. A pipe joint management software development is presented herein which accomplishes this task and examples provided to illustrate the benefits.\u0000 Note: Selecting pipe joints with the best end measurements, whether ID, OD, OOR, or thickness does not guarantee that the minimum possible SCFs will be achieved since the SCF is a function of all those measurements.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125296826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Internally pressurised pipe behaves differently than externally pressurised pipe. DNVGL-ST-F101 [4], a prevailing standard for the design of submarine pipelines, provides limit-state equations for combined loading that are valid only if the diameter-to-wall-thickness ratio (D/t) is between 15 and 45. A recent study has shown that the results are increasingly conservative for lower values of this ratio if the nett pressure is acting on the pipe’s outside [8], especially if it is below 20. In this paper, the applicability of the limit-state equations for thick-walled pipe with D/t less than 15 and loaded by a nett internal pressure has been investigated. The first step was a fundamental review of the formulations. Next, the predicted capacities were compared with those estimated using a finite-element (FE) model. The results greatly coincided, which indicates that the conservatism underlying the formulations does not depend on D/t. Hence they can be used for design against local buckling under internal overpressure, too, when the ratio is below 15.
{"title":"Limit Load Capacity of Thick-Walled Pipe Loaded by Internal Pressure and Bending","authors":"R. Selker, J. Brugmans, Ping Liu, C. Sicilia","doi":"10.1115/omae2021-62890","DOIUrl":"https://doi.org/10.1115/omae2021-62890","url":null,"abstract":"\u0000 Internally pressurised pipe behaves differently than externally pressurised pipe. DNVGL-ST-F101 [4], a prevailing standard for the design of submarine pipelines, provides limit-state equations for combined loading that are valid only if the diameter-to-wall-thickness ratio (D/t) is between 15 and 45. A recent study has shown that the results are increasingly conservative for lower values of this ratio if the nett pressure is acting on the pipe’s outside [8], especially if it is below 20.\u0000 In this paper, the applicability of the limit-state equations for thick-walled pipe with D/t less than 15 and loaded by a nett internal pressure has been investigated. The first step was a fundamental review of the formulations. Next, the predicted capacities were compared with those estimated using a finite-element (FE) model. The results greatly coincided, which indicates that the conservatism underlying the formulations does not depend on D/t. Hence they can be used for design against local buckling under internal overpressure, too, when the ratio is below 15.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129287356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A riser is a key component for transporting produced oil and gas from the subsea wells to the surface production vessel. Through nearly 30 years of design and implementation, Steel Catenary Risers (SCRs) have been found to have the advantages of relatively low cost and good adaptability to floating platform’s motion. This paper investigates deepwater SCR system design for the Lingshui 17-2 (termed LS17-2) project. This paper first introduces a SCR system for the LS17-2 project. The field for this project is located in the northern South China Sea, with water depth of 1220m to 1560m. LS17-2 consists of a subsea production system, a deep-draft semi-submersible (SEMI), and an export riser/pipeline. The platform was designed to have a large storage capacity with a variable draft during its operation. Based on deepwater SCR engineering experience, the key SCR design challenges are summarized from the engineering executive perspective. The challenges to the SCR system design for the LS17-2 project include harsh environment condition in South China Sea and the impact on fatigue design for the requirement of 30-years’ service life. They call for design optimization and innovative ideas. The engineering design and analysis are discussed together solutions. To demonstrate the deepwater SCR system design for LS17-2 project, examples are provided to illustrate the challenges and solutions. The experience learned from this paper should have significant relevance to future SCR design.
{"title":"Deepwater Steel Catenary Riser System Design for Lingshui 17-2 Project","authors":"Ning He, H. Yang, Fanli Xu, Yongming Cheng","doi":"10.1115/omae2021-63881","DOIUrl":"https://doi.org/10.1115/omae2021-63881","url":null,"abstract":"\u0000 A riser is a key component for transporting produced oil and gas from the subsea wells to the surface production vessel. Through nearly 30 years of design and implementation, Steel Catenary Risers (SCRs) have been found to have the advantages of relatively low cost and good adaptability to floating platform’s motion. This paper investigates deepwater SCR system design for the Lingshui 17-2 (termed LS17-2) project.\u0000 This paper first introduces a SCR system for the LS17-2 project. The field for this project is located in the northern South China Sea, with water depth of 1220m to 1560m. LS17-2 consists of a subsea production system, a deep-draft semi-submersible (SEMI), and an export riser/pipeline. The platform was designed to have a large storage capacity with a variable draft during its operation.\u0000 Based on deepwater SCR engineering experience, the key SCR design challenges are summarized from the engineering executive perspective. The challenges to the SCR system design for the LS17-2 project include harsh environment condition in South China Sea and the impact on fatigue design for the requirement of 30-years’ service life. They call for design optimization and innovative ideas. The engineering design and analysis are discussed together solutions.\u0000 To demonstrate the deepwater SCR system design for LS17-2 project, examples are provided to illustrate the challenges and solutions. The experience learned from this paper should have significant relevance to future SCR design.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129591193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deepwater steel lazy wave risers (SLWR) subject to vessel motion will be exposed to time-varying oscillatory flow, vortices could be generated and the cyclic vortex shedding force causes the structure vibrate, such fluid-structure interaction is called vortex-induced vibrations (VIV). To investigate VIV on a riser with non-linear structures under vessel motion and oscillatory flows, time domain approaches are needed. In this study, a time-domain approach is used to simulate a full-scale SLWR. Two cases with simplified riser top motions are simulated numerically. By using default input parameters to the time domain approach, the key oscillatory flow induced VIV response characteristics such as response frequency, curvature and displacements are examined and discussed. More accurate VIV prediction could be achieved by using realistic hydrodynamic inputs into the time domain model.
{"title":"On Vessel Motion Induced Vortex-Induced Vibrations of a Steel Lazy Wave Riser","authors":"Decao Yin","doi":"10.1115/omae2021-60371","DOIUrl":"https://doi.org/10.1115/omae2021-60371","url":null,"abstract":"\u0000 Deepwater steel lazy wave risers (SLWR) subject to vessel motion will be exposed to time-varying oscillatory flow, vortices could be generated and the cyclic vortex shedding force causes the structure vibrate, such fluid-structure interaction is called vortex-induced vibrations (VIV). To investigate VIV on a riser with non-linear structures under vessel motion and oscillatory flows, time domain approaches are needed. In this study, a time-domain approach is used to simulate a full-scale SLWR. Two cases with simplified riser top motions are simulated numerically. By using default input parameters to the time domain approach, the key oscillatory flow induced VIV response characteristics such as response frequency, curvature and displacements are examined and discussed. More accurate VIV prediction could be achieved by using realistic hydrodynamic inputs into the time domain model.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126206476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Over the past few years, a number of deepwater projects that use steel lazy wave risers have been commissioned or are under development. Steel lazy wave risers have an advantage over steel catenary risers as they offer flexibility of use with a floater having severe motion such as FPSO. They also impart lower loads at the interface with the floater compared to a traditional steel catenary riser, and hence can be used in deeper waters. Therefore, design of steel lazy wave risers has gained importance over the years as exploration of oil happens in ever deeper waters. In this paper, artificial neural networks and genetic algorithm are used to automatically generate a steel lazy wave riser design. A dataset of optimized designs of steel lazy wave risers for various inputs such as water depth, pipe OD, wall thickness etc. are generated using genetic algorithm. This dataset is used to train a neural network to automatically output a steel lazy wave riser design. The SLWR configuration that is automatically generated can be used as a starting point for conceptual and pre-FEED studies and help engineers come up with an initial SLWR design capturing the basic requirements without going through rigorous analyses. It has potential for cost savings and meeting schedule demands of fast paced projects as it will speed up the steel lazy wave risers’ design.
{"title":"Steel Lazy Wave Riser Optimization Using Artificial Neural Networks and Genetic Algorithm","authors":"M. Lal, A. Sebastian, Yashpal Rana","doi":"10.1115/omae2021-61600","DOIUrl":"https://doi.org/10.1115/omae2021-61600","url":null,"abstract":"\u0000 Over the past few years, a number of deepwater projects that use steel lazy wave risers have been commissioned or are under development. Steel lazy wave risers have an advantage over steel catenary risers as they offer flexibility of use with a floater having severe motion such as FPSO. They also impart lower loads at the interface with the floater compared to a traditional steel catenary riser, and hence can be used in deeper waters. Therefore, design of steel lazy wave risers has gained importance over the years as exploration of oil happens in ever deeper waters.\u0000 In this paper, artificial neural networks and genetic algorithm are used to automatically generate a steel lazy wave riser design. A dataset of optimized designs of steel lazy wave risers for various inputs such as water depth, pipe OD, wall thickness etc. are generated using genetic algorithm. This dataset is used to train a neural network to automatically output a steel lazy wave riser design. The SLWR configuration that is automatically generated can be used as a starting point for conceptual and pre-FEED studies and help engineers come up with an initial SLWR design capturing the basic requirements without going through rigorous analyses. It has potential for cost savings and meeting schedule demands of fast paced projects as it will speed up the steel lazy wave risers’ design.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129136649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The design process of lateral buckling has gained in maturity over the last ten years. However the design of any required engineered trigger to control the formation of lateral buckles remains open to a wide range of design concepts (like sleeper, buoyancy modules, snake lay or residual curvature method) with sometimes increasing complexity in either engineering, fabrication or installation. This paper will describe how a lateral deflection initiated by a temporary subsea winch after pipelay can be used as a reliable mitigation with limited impact on the project execution. The interaction between the winch pull and the pipe soil interaction and the consequences on both the post buckle behaviour and reliability design of the mitigation architecture will be presented. The advantages of this technique (decoupling of construction activities between pipelay and lateral buckling mitigation, standard engineering process, no offset from seabed, no additional permanent equipment) and its limitations (stiff pipeline, detailed pipe soil interaction) will be discussed. The operational feedback from several flowlines designed, installed and operated with this winch pull mitigation will be reviewed and the main lessons learnt will be highlighted. It can be concluded that this temporary subsea winch pull is an interesting and cost effective option for lateral buckling initiation of subsea pipelines.
{"title":"Lateral Buckling Mitigation of Subsea Pipeline by Temporary Winch Pull","authors":"Yann Le Maout, Michele Ceruli","doi":"10.1115/omae2021-62362","DOIUrl":"https://doi.org/10.1115/omae2021-62362","url":null,"abstract":"\u0000 The design process of lateral buckling has gained in maturity over the last ten years. However the design of any required engineered trigger to control the formation of lateral buckles remains open to a wide range of design concepts (like sleeper, buoyancy modules, snake lay or residual curvature method) with sometimes increasing complexity in either engineering, fabrication or installation.\u0000 This paper will describe how a lateral deflection initiated by a temporary subsea winch after pipelay can be used as a reliable mitigation with limited impact on the project execution.\u0000 The interaction between the winch pull and the pipe soil interaction and the consequences on both the post buckle behaviour and reliability design of the mitigation architecture will be presented. The advantages of this technique (decoupling of construction activities between pipelay and lateral buckling mitigation, standard engineering process, no offset from seabed, no additional permanent equipment) and its limitations (stiff pipeline, detailed pipe soil interaction) will be discussed.\u0000 The operational feedback from several flowlines designed, installed and operated with this winch pull mitigation will be reviewed and the main lessons learnt will be highlighted.\u0000 It can be concluded that this temporary subsea winch pull is an interesting and cost effective option for lateral buckling initiation of subsea pipelines.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131139690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In subsea pipelines projects, the design of rigid spool and jumper can be a challenging and time-consuming task. The selected spool layout for connecting the pipelines to the subsea structures, including the number of bends and leg lengths, must offer the flexibility to accommodate the pipeline thermal expansion, the pipe-lay target box and misalignments associated with the post-lay survey metrology and spool fabrication. The analysis results are considerably affected by many uncertainties involved. Consequently, a very large amount of calculations is required to assess the full combination of uncertainties and to capture the worst-case scenario. Rather than applying the deterministic solution, this paper uses machine learning prediction to significantly improve the efficiency of the design process. In addition, thanks to the fast predictive model using machine learning algorithms, the uncertainty quantification and propagation analysis using probabilistic statistical method becomes feasible in terms of CPU time and can be incorporated into the design process to evaluate the reliability of the outputs. The latter allows us to perform a systematic probabilistic design by considering a certain level of acceptance on the probability of failure, for example as per DNVGL design code. The machine learning predictive modelling and the reliability analysis based upon the probability distribution of the uncertainties are introduced and explained in this paper. Some project examples are shown to highlight the method’s comprehensive nature and efficient characteristics.
{"title":"Machine Learning Prediction and Reliability Analysis Applied to Subsea Spool and Jumper Design","authors":"Mengdi Song, Massyl Gheroufella, Paul Chartier","doi":"10.1115/omae2021-62033","DOIUrl":"https://doi.org/10.1115/omae2021-62033","url":null,"abstract":"\u0000 In subsea pipelines projects, the design of rigid spool and jumper can be a challenging and time-consuming task. The selected spool layout for connecting the pipelines to the subsea structures, including the number of bends and leg lengths, must offer the flexibility to accommodate the pipeline thermal expansion, the pipe-lay target box and misalignments associated with the post-lay survey metrology and spool fabrication. The analysis results are considerably affected by many uncertainties involved. Consequently, a very large amount of calculations is required to assess the full combination of uncertainties and to capture the worst-case scenario.\u0000 Rather than applying the deterministic solution, this paper uses machine learning prediction to significantly improve the efficiency of the design process. In addition, thanks to the fast predictive model using machine learning algorithms, the uncertainty quantification and propagation analysis using probabilistic statistical method becomes feasible in terms of CPU time and can be incorporated into the design process to evaluate the reliability of the outputs. The latter allows us to perform a systematic probabilistic design by considering a certain level of acceptance on the probability of failure, for example as per DNVGL design code.\u0000 The machine learning predictive modelling and the reliability analysis based upon the probability distribution of the uncertainties are introduced and explained in this paper. Some project examples are shown to highlight the method’s comprehensive nature and efficient characteristics.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127066163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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