Fatigue is a primary challenge in the design of steel catenary risers (SCRs) and different measures and methods are utilized to mitigate it. Traditional upset ends and steel lazy wave risers (SLWRs) are such methods to mitigate fatigue. SLWRs were first used in 2009 on the Espirito Santo floating, production, storage, and offloading (FPSO) vessel of Shell Company’s Parque das Conchas (BC-10) project offshore Brazil. SLWRs have been used increasingly since then and gained popularity especially in recent years. A novel patented tubular connection assembly is presented herein which improves the fatigue life of SCRs and welded connections in general. This novel tubular connection assembly has many advantages. It overcomes the thickness limitation of welding traditional upset ends and reduces offshore welding time, cost, and risk. When used in simple SCRs, this novel tubular connection assembly renders simple SCRs an alternative robustly viable at significantly lower cost, shorter schedule, and many additional advantages as compared to SLWRs. Of such many advantages, simple SCRs are simpler to configure, analyze, design, and install using wider installation methods and vessels. They also use less material and offer better short- and long-term integrity especially for insulated SCRs. In addition, they have smaller footprint and are less prone to clashing.
疲劳是钢悬链线立管(scr)设计的主要挑战，采用了不同的措施和方法来减轻疲劳。传统的加厚端部和钢制懒波立管(SLWRs)就是缓解疲劳的方法。SLWRs于2009年首次应用于壳牌公司位于巴西海上的Parque das Conchas (BC-10)项目的Espirito Santo浮式、生产、储存和卸载(FPSO)船。自那时以来，slwr的使用越来越多，特别是近年来越来越受欢迎。本文提出了一种新型的专利管状连接组件，可以提高scr和焊接连接的疲劳寿命。这种新型管状连接组件具有许多优点。它克服了传统镦粗端焊缝的厚度限制，降低了海上焊接的时间、成本和风险。当用于简单的scr时，与SLWRs相比，这种新型管状连接组件使简单scr成为一种可靠的替代方案，成本显著降低，工期更短，并且具有许多其他优点。由于这些优点，简单的scr更容易配置、分析、设计和安装，使用更广泛的安装方法和容器。它们还使用更少的材料，并提供更好的短期和长期的完整性，特别是绝缘scr。此外，它们占用空间更小，不容易发生冲突。
{"title":"Tubular Connection Assembly for Improved Fatigue Performance of Metallic Risers","authors":"G. Mansour","doi":"10.1115/omae2020-19303","DOIUrl":"https://doi.org/10.1115/omae2020-19303","url":null,"abstract":"\u0000 Fatigue is a primary challenge in the design of steel catenary risers (SCRs) and different measures and methods are utilized to mitigate it. Traditional upset ends and steel lazy wave risers (SLWRs) are such methods to mitigate fatigue.\u0000 SLWRs were first used in 2009 on the Espirito Santo floating, production, storage, and offloading (FPSO) vessel of Shell Company’s Parque das Conchas (BC-10) project offshore Brazil. SLWRs have been used increasingly since then and gained popularity especially in recent years.\u0000 A novel patented tubular connection assembly is presented herein which improves the fatigue life of SCRs and welded connections in general.\u0000 This novel tubular connection assembly has many advantages. It overcomes the thickness limitation of welding traditional upset ends and reduces offshore welding time, cost, and risk.\u0000 When used in simple SCRs, this novel tubular connection assembly renders simple SCRs an alternative robustly viable at significantly lower cost, shorter schedule, and many additional advantages as compared to SLWRs. Of such many advantages, simple SCRs are simpler to configure, analyze, design, and install using wider installation methods and vessels. They also use less material and offer better short- and long-term integrity especially for insulated SCRs. In addition, they have smaller footprint and are less prone to clashing.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124298510","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}
As many offshore production systems approach the end of their original Design Life, Operators are faced with the choice of either decommissioning or demonstrating that the original Design Life can be extended (Life Extension). Life extension requires the Operator to perform detailed engineering analyses to verify that the system can be operated safely over the period of Life Extension. In many cases this requires detailed fatigue analysis and inspection programs to demonstrate that original fabrication flaws or fatigue cracks that may have existed during the welding of the riser joints or initiated over the original Design Life will not grow to a critical size resulting in failure. Engineering Critical Assessment (ECA) is now routinely applied in the design and fabrication of new offshore riser systems to develop girth weld flaw acceptance criteria. The resulting flaw acceptance criteria ensure that fabrication flaws will not extend to a critical size over the Design Life and thus the riser still meet its calculated fatigue life. Although ECA procedures for new construction are well established and standard practices have been adopted throughout the industry, ECA procedures for Life Extension have not yet evolved to the same level of acceptance. This paper will review specific issues associated with applying ECA to support Life Extension of offshore Riser Systems. The paper will provide the overall ECA philosophy and methodology for life extension to be adopted for the historical (hindcast or Phase 1) and future (forecast or Phase 2) analysis of the risers. Some thoughts will also be given to the approach implemented to take advantage of the actual weld fabrication data with the focus on the fatigue critical sections of the risers. Finally, the paper will address the requirements for riser in-situ inspection and how the results could be analyzed and applied to the life extension analysis in conjunction with the ECA analysis.
{"title":"The Role of Engineering Critical Assessment in the Life Extension of Risers Connected to Floating Systems","authors":"B. Mekha, R. Gordon","doi":"10.1115/omae2020-19085","DOIUrl":"https://doi.org/10.1115/omae2020-19085","url":null,"abstract":"\u0000 As many offshore production systems approach the end of their original Design Life, Operators are faced with the choice of either decommissioning or demonstrating that the original Design Life can be extended (Life Extension). Life extension requires the Operator to perform detailed engineering analyses to verify that the system can be operated safely over the period of Life Extension. In many cases this requires detailed fatigue analysis and inspection programs to demonstrate that original fabrication flaws or fatigue cracks that may have existed during the welding of the riser joints or initiated over the original Design Life will not grow to a critical size resulting in failure.\u0000 Engineering Critical Assessment (ECA) is now routinely applied in the design and fabrication of new offshore riser systems to develop girth weld flaw acceptance criteria. The resulting flaw acceptance criteria ensure that fabrication flaws will not extend to a critical size over the Design Life and thus the riser still meet its calculated fatigue life. Although ECA procedures for new construction are well established and standard practices have been adopted throughout the industry, ECA procedures for Life Extension have not yet evolved to the same level of acceptance.\u0000 This paper will review specific issues associated with applying ECA to support Life Extension of offshore Riser Systems. The paper will provide the overall ECA philosophy and methodology for life extension to be adopted for the historical (hindcast or Phase 1) and future (forecast or Phase 2) analysis of the risers. Some thoughts will also be given to the approach implemented to take advantage of the actual weld fabrication data with the focus on the fatigue critical sections of the risers. Finally, the paper will address the requirements for riser in-situ inspection and how the results could be analyzed and applied to the life extension analysis in conjunction with the ECA analysis.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114357230","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}
Yang Zhixun, Yin Xu, D. Shi, Jun Yan, Lifu Wang, Qingzhen Lu, Q. Yue
Umbilical is a critical equipment in subsea production system for extracting offshore hydrocarbon resources, providing electrical and hydraulic power, control signal transmission and chemical injection. A diversity of components such as electrical cables, optical cables, steel tubes and filler bodies compose the cross-section of an umbilical. Different components perform different physical properties, so different cross-sections will present different geometrical characteristic, carrying capacities, thermal distribution, the cost and the ease of manufacture. Therefore, the cross-sectional design of the umbilical is a typical multi-objective optimization problem. The methodology of pseudo mechanical mechanism is introduced in this paper. Pseudo forces are assumed based on geometrical characteristics, carrying capacities and thermal productivities of different electrical cables, optical cables, steel tube and filler bodies. Each component is analogized to a sphere with different diameters on a funnel surface. Moreover, potential energy and interaction force between different components are defined to avoid the overlap and congestion. Then, the pseudo mechanical model is established and mathematics description is presented corresponding to the cross-section of an umbilical. Iteration algorithm procedure is given to solve this problem. Finally, a case of an umbilical is studied and the optimal cross-section is obtained, which is compared with the result used in practical engineering. It is shown that the methodology of the pseudo mechanical mechanism is effective to obtain the optimal design of cross-section of an umbilical.
{"title":"Optimization Design of the Cross-Section of the Umbilical Based on the Pseudo Mechanical Mechanism","authors":"Yang Zhixun, Yin Xu, D. Shi, Jun Yan, Lifu Wang, Qingzhen Lu, Q. Yue","doi":"10.1115/omae2020-19234","DOIUrl":"https://doi.org/10.1115/omae2020-19234","url":null,"abstract":"\u0000 Umbilical is a critical equipment in subsea production system for extracting offshore hydrocarbon resources, providing electrical and hydraulic power, control signal transmission and chemical injection. A diversity of components such as electrical cables, optical cables, steel tubes and filler bodies compose the cross-section of an umbilical. Different components perform different physical properties, so different cross-sections will present different geometrical characteristic, carrying capacities, thermal distribution, the cost and the ease of manufacture. Therefore, the cross-sectional design of the umbilical is a typical multi-objective optimization problem. The methodology of pseudo mechanical mechanism is introduced in this paper. Pseudo forces are assumed based on geometrical characteristics, carrying capacities and thermal productivities of different electrical cables, optical cables, steel tube and filler bodies. Each component is analogized to a sphere with different diameters on a funnel surface. Moreover, potential energy and interaction force between different components are defined to avoid the overlap and congestion. Then, the pseudo mechanical model is established and mathematics description is presented corresponding to the cross-section of an umbilical. Iteration algorithm procedure is given to solve this problem. Finally, a case of an umbilical is studied and the optimal cross-section is obtained, which is compared with the result used in practical engineering. It is shown that the methodology of the pseudo mechanical mechanism is effective to obtain the optimal design of cross-section of an umbilical.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116904043","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 criticality of girth weld flaws in subsea pipelines, installed by methods introducing plastic strains such as reel-lay, is usually evaluated through an engineering critical assessment (ECA). Most ECA methodologies require weld overmatch for pipes subjected to plastic deformation. This, however, is not always achievable for corrosion resistant or even carbon steel pipelines. In this case, a material and geometry-specific ECA is often applied. However, this ECA approach necessitates many 3D finite-element (FE) fracture analyses to be performed. Therefore, the authors propose a simpler screening assessment, which requires undertaking only a limited number of 3D FE fracture analyses. If the significance of a weld undermatch is shown to be negligible then a material and geometry-specific FE-based ECA is deemed unnecessary. Instead, flaw acceptance criteria can be determined under the assumption of weld evenmatch using a material-specific analytical ECA. The work was undertaken to define and validate the screening assessment process. Subsequently, DNV-GL endorsed the proposed approach which has since been successfully applied on several projects allowing optimization of the project cost and schedule. This paper describes the screening assessment methodology and discusses its application range and limitations. The conclusions and recommendations from a validation program are also provided.
{"title":"Fracture Assessment of Flaws in Undermatching Welds","authors":"Daniil Vasilikis, T. Tkaczyk, A. Pépin","doi":"10.1115/omae2020-18747","DOIUrl":"https://doi.org/10.1115/omae2020-18747","url":null,"abstract":"\u0000 The criticality of girth weld flaws in subsea pipelines, installed by methods introducing plastic strains such as reel-lay, is usually evaluated through an engineering critical assessment (ECA). Most ECA methodologies require weld overmatch for pipes subjected to plastic deformation. This, however, is not always achievable for corrosion resistant or even carbon steel pipelines. In this case, a material and geometry-specific ECA is often applied.\u0000 However, this ECA approach necessitates many 3D finite-element (FE) fracture analyses to be performed. Therefore, the authors propose a simpler screening assessment, which requires undertaking only a limited number of 3D FE fracture analyses. If the significance of a weld undermatch is shown to be negligible then a material and geometry-specific FE-based ECA is deemed unnecessary. Instead, flaw acceptance criteria can be determined under the assumption of weld evenmatch using a material-specific analytical ECA.\u0000 The work was undertaken to define and validate the screening assessment process. Subsequently, DNV-GL endorsed the proposed approach which has since been successfully applied on several projects allowing optimization of the project cost and schedule. This paper describes the screening assessment methodology and discusses its application range and limitations. The conclusions and recommendations from a validation program are also provided.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124033292","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 recent years the residual curvature (RC) method has been used to provide buckle initiators to control and mitigate the lateral buckling of pipelines for some shallow water projects. With the appropriate planning of the controlled buckles using RC sections, an acceptable design of the pipeline in-place behavior is achieved. However, the RC method has not yet been applied to deep-water pipelines. The twist of RC sections in the sagbend during installation has been observed, and the orientation of as-laid RC section on the seabed is difficult to control in deep-water pipelines. The effects of as-laid RC-section orientation on in-place lateral buckling in deep water are unknown. The FRIC user subroutine in the Abaqus finite-element software suite has been developed for modelling pipe-soil interactions based on uncoupled axial and lateral soil resistances that are assumed to be independent of vertical pipe penetration after initial embedment into the soil surface. However, the penetration of a twisted RC section can vary dramatically from a normal pipeline on the seabed. The UINTER user subroutine in Abaqus was selected for presenting 3D pipe-soil interactions that incorporate the variations of independent axial and lateral soil resistances as a function of pipe penetration more accurately. UINTER is used in the present study to account for the effects of soil penetration on the lateral buckling performance of a pipeline with RC sections in soft clay. The analysis results show that the RC section twists in the sagbend area during installation, and the twist angle reaches its maximum value just prior to the RC section touching the seabed. The in-place lateral buckling analysis is carried out after the installation analysis is finished. The analysis results demonstrate the feasibility of applying the RC method as the primary buckle triggering mechanism for deep water pipelines, and it shows how the RC orientation affects the pipeline in-place performance in terms of strength and fatigue damage (only the stress ranges for use in fatigue calculations are shown in the paper).
{"title":"Feasibility Study of Lateral Buckling Using Residual Curvature Method for Deep Water Pipelines","authors":"Q. Bai, Fengbin Xu, M. Brunner","doi":"10.1115/omae2020-18111","DOIUrl":"https://doi.org/10.1115/omae2020-18111","url":null,"abstract":"\u0000 In recent years the residual curvature (RC) method has been used to provide buckle initiators to control and mitigate the lateral buckling of pipelines for some shallow water projects. With the appropriate planning of the controlled buckles using RC sections, an acceptable design of the pipeline in-place behavior is achieved. However, the RC method has not yet been applied to deep-water pipelines. The twist of RC sections in the sagbend during installation has been observed, and the orientation of as-laid RC section on the seabed is difficult to control in deep-water pipelines. The effects of as-laid RC-section orientation on in-place lateral buckling in deep water are unknown.\u0000 The FRIC user subroutine in the Abaqus finite-element software suite has been developed for modelling pipe-soil interactions based on uncoupled axial and lateral soil resistances that are assumed to be independent of vertical pipe penetration after initial embedment into the soil surface. However, the penetration of a twisted RC section can vary dramatically from a normal pipeline on the seabed. The UINTER user subroutine in Abaqus was selected for presenting 3D pipe-soil interactions that incorporate the variations of independent axial and lateral soil resistances as a function of pipe penetration more accurately. UINTER is used in the present study to account for the effects of soil penetration on the lateral buckling performance of a pipeline with RC sections in soft clay.\u0000 The analysis results show that the RC section twists in the sagbend area during installation, and the twist angle reaches its maximum value just prior to the RC section touching the seabed. The in-place lateral buckling analysis is carried out after the installation analysis is finished. The analysis results demonstrate the feasibility of applying the RC method as the primary buckle triggering mechanism for deep water pipelines, and it shows how the RC orientation affects the pipeline in-place performance in terms of strength and fatigue damage (only the stress ranges for use in fatigue calculations are shown in the paper).","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122676114","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}
Eric Giry, V. Cocault-Duverger, M. Pauthenet, L. Chec
Installation of subsea pipelines using reeling process is an attractive method. The pipeline is welded in long segments, typically several kilometers in length, and reeled onto a large diameter drum. The pipeline is then transported onto such reel to the offshore site where it is unreeled and lowered on the seabed. The deformation imposed on the pipeline while spooled onto the drum needs to be controlled so that local buckling is avoided. Mitigation of such failure is generally provided by proper pipeline design & reeling operation parameters. Buckling stems from excessive strain concentration near the circumferential weld area resulting from strength discontinuity at pipeline joints, mainly depending on steel wall thickness and yield strength. This requires the characterization of critical mismatches obtained by trial and error. Such method is a long process since each “trial” requires a complete Finite Element Analysis run. Such simulations are complex and lengthy. Occasionally, this can drive the selection of the pipeline minimum wall thickness, which is a key parameter for progressing the project. The timeframe of such method is therefore not compatible with such a key decision. The paper discusses the use of approximation models to capitalize on the data and alleviate the design cost. To do so, design of experiments and automation of the computational tool chain are implemented. It is demonstrated that initial complex chain of FEA computational process can be replaced using design space description and exploration techniques such as design of experiments combined with advanced statistical regression techniques in order to provide an approximation model. This paper presents the implementation of such methodology and the results are discussed.
{"title":"Machine Learning for Subsea Pipeline Reeling Mechanics","authors":"Eric Giry, V. Cocault-Duverger, M. Pauthenet, L. Chec","doi":"10.1115/omae2020-18685","DOIUrl":"https://doi.org/10.1115/omae2020-18685","url":null,"abstract":"\u0000 Installation of subsea pipelines using reeling process is an attractive method. The pipeline is welded in long segments, typically several kilometers in length, and reeled onto a large diameter drum. The pipeline is then transported onto such reel to the offshore site where it is unreeled and lowered on the seabed. The deformation imposed on the pipeline while spooled onto the drum needs to be controlled so that local buckling is avoided.\u0000 Mitigation of such failure is generally provided by proper pipeline design & reeling operation parameters. Buckling stems from excessive strain concentration near the circumferential weld area resulting from strength discontinuity at pipeline joints, mainly depending on steel wall thickness and yield strength. This requires the characterization of critical mismatches obtained by trial and error. Such method is a long process since each “trial” requires a complete Finite Element Analysis run. Such simulations are complex and lengthy. Occasionally, this can drive the selection of the pipeline minimum wall thickness, which is a key parameter for progressing the project. The timeframe of such method is therefore not compatible with such a key decision.\u0000 The paper discusses the use of approximation models to capitalize on the data and alleviate the design cost. To do so, design of experiments and automation of the computational tool chain are implemented.\u0000 It is demonstrated that initial complex chain of FEA computational process can be replaced using design space description and exploration techniques such as design of experiments combined with advanced statistical regression techniques in order to provide an approximation model. This paper presents the implementation of such methodology and the results are discussed.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131453177","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 rotating buoyancy modules (RBM) system was developed as an improvement to the non-rotating buoyancy from the collaboration between a major oil company and Trelleborg Offshore. In this system, a finned external shell rotates around an inner core strapped to pipeline. The rotating buoyancy reduces berm build-up, decreases friction for pipe-soil interaction, and ensures the robustness of buckling mitigation for HPHT thermal design. In the contrast, for a non-rotating buoyancy module, seabed soil berms can build up after the initial flowline lateral movement which can limit further lateral movement. As result of berm build-up, the effectiveness of non-rotating buoyancy modules to control pipeline buckling reduces. RBM was applied for the first time in a tie-back flowline for a Gulf of Mexico (GOM) deepwater development project. In this paper, flowline thermal design using RBM for the project is presented. The project field conditions that impacted the tie-back flowline design included existing crossings and limited space for subsea structures and flowlines. The pipe-seabed interaction and RBM-seabed model is presented along with the axial and lateral friction parameters used for peak and large displacement on normal pipe sections and RBM sections. The main loads for the flowline were from the operational conditions in term of temperature and pressure profiles. Lateral buckling mitigation results include the RBM location configurations, buckling locations, effective axial forces and von Mises stresses. Recommendations for situations when RBM should be used for high temperature high pressure thermal design are presented.
{"title":"High Temperature Flowline Thermal Design Using Rotating Buoyancy Modules","authors":"Shen Yu, T. Chapman, S. Rich, Austin B Harbison","doi":"10.1115/omae2020-18893","DOIUrl":"https://doi.org/10.1115/omae2020-18893","url":null,"abstract":"\u0000 A rotating buoyancy modules (RBM) system was developed as an improvement to the non-rotating buoyancy from the collaboration between a major oil company and Trelleborg Offshore. In this system, a finned external shell rotates around an inner core strapped to pipeline. The rotating buoyancy reduces berm build-up, decreases friction for pipe-soil interaction, and ensures the robustness of buckling mitigation for HPHT thermal design. In the contrast, for a non-rotating buoyancy module, seabed soil berms can build up after the initial flowline lateral movement which can limit further lateral movement. As result of berm build-up, the effectiveness of non-rotating buoyancy modules to control pipeline buckling reduces.\u0000 RBM was applied for the first time in a tie-back flowline for a Gulf of Mexico (GOM) deepwater development project. In this paper, flowline thermal design using RBM for the project is presented.\u0000 The project field conditions that impacted the tie-back flowline design included existing crossings and limited space for subsea structures and flowlines. The pipe-seabed interaction and RBM-seabed model is presented along with the axial and lateral friction parameters used for peak and large displacement on normal pipe sections and RBM sections. The main loads for the flowline were from the operational conditions in term of temperature and pressure profiles. Lateral buckling mitigation results include the RBM location configurations, buckling locations, effective axial forces and von Mises stresses. Recommendations for situations when RBM should be used for high temperature high pressure thermal design are presented.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127702098","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}
One type of submarine composite pipeline structure, with carbon steel-concrete-stainless steel (CCS) double-skin tube (DST), was introduced in this paper. This composite pipeline was expected to make optimal use of the three types of the materials, and provide significant structural and internal corrosion resistance. During installation and service stage, submarine pipelines may experience significant torsion effects. Global response of the system depends on both the behavior of each constituent part and interactions between them. In this paper, an interaction model considering the friction and the cohesive force between the steel tube and the concrete is introduced, and a finite element model of the submarine pipeline under torsion is established by using this interaction model. The developed finite element model was verified through the comparisons between the numerical and experimental determined results, in terms of torque rotation angle histories, stiffness and ultimate torque. The results show that the ultimate strength and stiffness of the model considering cohesive force are increased by 4.6% and 11.9% respectively compared with the model only considering friction force.
{"title":"Numerical Study on Torsional Behavior of Carbon Steel-Concrete-Stainless Steel Double-Skin Tube (DST)","authors":"Facheng Wang, Wenzhen Xie, Lin-Hai Han","doi":"10.1115/omae2020-18195","DOIUrl":"https://doi.org/10.1115/omae2020-18195","url":null,"abstract":"\u0000 One type of submarine composite pipeline structure, with carbon steel-concrete-stainless steel (CCS) double-skin tube (DST), was introduced in this paper. This composite pipeline was expected to make optimal use of the three types of the materials, and provide significant structural and internal corrosion resistance. During installation and service stage, submarine pipelines may experience significant torsion effects. Global response of the system depends on both the behavior of each constituent part and interactions between them. In this paper, an interaction model considering the friction and the cohesive force between the steel tube and the concrete is introduced, and a finite element model of the submarine pipeline under torsion is established by using this interaction model. The developed finite element model was verified through the comparisons between the numerical and experimental determined results, in terms of torque rotation angle histories, stiffness and ultimate torque. The results show that the ultimate strength and stiffness of the model considering cohesive force are increased by 4.6% and 11.9% respectively compared with the model only considering friction force.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114871502","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}
Rodrigo Provasi, Fernando Geremias Toni, C. Martins
Flexible pipes are structures composed by many layers varying in composition and shapes, in which the structural behavior is defined by the role it must play. Flexible pipes construction is such that layers are unbounded, allowing relative movement between them and modifying its behavior. Many approaches are used to model such cables, both analytical and numerical, such as the macroelements model. This sort of model consists in finite elements where geometrical characteristics are taken into account by the formulation and is under development by the authors. Previous works have shown in detail the modeled cylindrical and helical elements, as well node-to-node connection elements (bounded, frictionless and frictional), which have allowed simplified flexible pipe with bonded elements simulations. This article will focus on modeling a simplified cable consisting in an external sheath, two armor layers and a polymeric core, since recent advances in the contact formulation opens the possibility to incorporate friction between the layers. Taking into consideration accuracy, computational time and memory usage, results from macroelements are compared to commercial finite element software.
{"title":"Frictional Flexible Pipe Model Using Macroelements","authors":"Rodrigo Provasi, Fernando Geremias Toni, C. Martins","doi":"10.1115/omae2020-18005","DOIUrl":"https://doi.org/10.1115/omae2020-18005","url":null,"abstract":"\u0000 Flexible pipes are structures composed by many layers varying in composition and shapes, in which the structural behavior is defined by the role it must play. Flexible pipes construction is such that layers are unbounded, allowing relative movement between them and modifying its behavior.\u0000 Many approaches are used to model such cables, both analytical and numerical, such as the macroelements model. This sort of model consists in finite elements where geometrical characteristics are taken into account by the formulation and is under development by the authors.\u0000 Previous works have shown in detail the modeled cylindrical and helical elements, as well node-to-node connection elements (bounded, frictionless and frictional), which have allowed simplified flexible pipe with bonded elements simulations.\u0000 This article will focus on modeling a simplified cable consisting in an external sheath, two armor layers and a polymeric core, since recent advances in the contact formulation opens the possibility to incorporate friction between the layers.\u0000 Taking into consideration accuracy, computational time and memory usage, results from macroelements are compared to commercial finite element software.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123938574","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}
Duanfeng Han, Kuo Huang, Yingfei Zan, Lihao Yuan, Zhaohui Wu
In order to figure out the dynamic characteristics of the pipeline and cable during pipeline end termination (PLET) installation based on S-laying, numerical simulation is carried out based on a practical operation project performed at Liwan oil and gas fields in the South China Sea. Four scenarios are selected from the PLET installation process in sequence for simulation. Critical responses of the pipeline and the cable in different scenarios of the operation are analyzed in this paper with a coupled model using RIFLEX module of SIMA software. Both the pipeline and the cable are modeled by the finite element method, and the pipelaying vessel is controlled by a dynamic positioning system. The simulation results are validated by the commonly used OrcaFlex software. The critical responses analyzed include static configuration, time-domain variation of axial tension at the top of the cable and bending moment variation near the touchdown point (TDP) of the pipeline. Furthermore, the time-domain variation of the tension at the top of the cable under different wave and current directions are also compared and analyzed, in order to study the effect of sea environment on the pipeline and cable during PLET installation operation. The results show that the responses of pipeline and cable vary in different operation scenarios, and the sea environment has remarkable effect on the pipeline and cable. The study in this paper is of value to the design of PLET installation based on pipelaying and can help predict the response of pipeline and cable during the operation.
{"title":"Dynamic Analysis on Critical Responses of Pipeline and Cable During Pipeline End Termination Installation","authors":"Duanfeng Han, Kuo Huang, Yingfei Zan, Lihao Yuan, Zhaohui Wu","doi":"10.1115/omae2020-18723","DOIUrl":"https://doi.org/10.1115/omae2020-18723","url":null,"abstract":"\u0000 In order to figure out the dynamic characteristics of the pipeline and cable during pipeline end termination (PLET) installation based on S-laying, numerical simulation is carried out based on a practical operation project performed at Liwan oil and gas fields in the South China Sea. Four scenarios are selected from the PLET installation process in sequence for simulation. Critical responses of the pipeline and the cable in different scenarios of the operation are analyzed in this paper with a coupled model using RIFLEX module of SIMA software. Both the pipeline and the cable are modeled by the finite element method, and the pipelaying vessel is controlled by a dynamic positioning system. The simulation results are validated by the commonly used OrcaFlex software. The critical responses analyzed include static configuration, time-domain variation of axial tension at the top of the cable and bending moment variation near the touchdown point (TDP) of the pipeline. Furthermore, the time-domain variation of the tension at the top of the cable under different wave and current directions are also compared and analyzed, in order to study the effect of sea environment on the pipeline and cable during PLET installation operation. The results show that the responses of pipeline and cable vary in different operation scenarios, and the sea environment has remarkable effect on the pipeline and cable. The study in this paper is of value to the design of PLET installation based on pipelaying and can help predict the response of pipeline and cable during the operation.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130846483","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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