Zurwa Khan, R. Tafreshi, Md Ferdous Wahid, A. Retnanto
Mechanistic models are necessary for understanding and predicting the behavior of liquid-liquid flow for multiple pipe dimensions, mixture properties, and flow patterns. In this paper, a mechanistic model is proposed to calculate pressure drop across circular channels for liquid-liquid two-phase flow. The developed model considers several key aspects of liquid-liquid flow, such as mixed and wavy liquid-liquid interfaces and dispersion within each liquid’s layers. Unique identifiers, such as height, turbulence, and dispersion, are calculated for each phase, using an augmented separated flow model and nonlinear optimization. Comparison of the proposed model with experimental data, comprising of multiple inclination angles and flow patterns, shows accurate predictions for a variety of liquid-liquid flow patterns, including double- and triple-layered flow.
{"title":"Prediction of Pressure Drops in Liquid-Liquid Two-Phase Flow Across Circular Channels","authors":"Zurwa Khan, R. Tafreshi, Md Ferdous Wahid, A. Retnanto","doi":"10.1115/omae2021-62861","DOIUrl":"https://doi.org/10.1115/omae2021-62861","url":null,"abstract":"\u0000 Mechanistic models are necessary for understanding and predicting the behavior of liquid-liquid flow for multiple pipe dimensions, mixture properties, and flow patterns. In this paper, a mechanistic model is proposed to calculate pressure drop across circular channels for liquid-liquid two-phase flow. The developed model considers several key aspects of liquid-liquid flow, such as mixed and wavy liquid-liquid interfaces and dispersion within each liquid’s layers. Unique identifiers, such as height, turbulence, and dispersion, are calculated for each phase, using an augmented separated flow model and nonlinear optimization. Comparison of the proposed model with experimental data, comprising of multiple inclination angles and flow patterns, shows accurate predictions for a variety of liquid-liquid flow patterns, including double- and triple-layered flow.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"2008 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":"127318345","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}
Lifu Wang, Zhixun Yang, Jun Yan, D. Shi, Yandong Mao, Pengcheng Zhu
Umbilical is an indispensable link of offshore oil & gas resource development equipment for underwater production system, which are mainly composed of functional components such as steel tubes, electric cables and optical cables are in a helically wound structure. Filling bodies are required to support these functional components for improving anti-crushing capacity and fatigue life. Filling bodies have a significant impact on the mechanical and physical properties, which triggers the optimization design of filling bodies. However, the complexity of filling body space brings challenge to the optimization design. Moving Morphable Components (MMC) theory is introduced to topological optimization method in complicated filling body space with the objective of mechanical properties. The results show that the optimized filling bodies can effectively reduce structural weight with the same mechanical properties. Numerical models of cross-sections of umbilicals with the optimized filling bodies are constructed, the cross-sectional mechanical properties are compared with that under the initial filling body form, which can fully verify the feasibility and correctness of this optimization design strategy.
{"title":"Topology Optimization Design of Filling Bodies in an Umbilical Based on Moving Morphable Components Theory","authors":"Lifu Wang, Zhixun Yang, Jun Yan, D. Shi, Yandong Mao, Pengcheng Zhu","doi":"10.1115/omae2021-63523","DOIUrl":"https://doi.org/10.1115/omae2021-63523","url":null,"abstract":"\u0000 Umbilical is an indispensable link of offshore oil & gas resource development equipment for underwater production system, which are mainly composed of functional components such as steel tubes, electric cables and optical cables are in a helically wound structure. Filling bodies are required to support these functional components for improving anti-crushing capacity and fatigue life. Filling bodies have a significant impact on the mechanical and physical properties, which triggers the optimization design of filling bodies. However, the complexity of filling body space brings challenge to the optimization design. Moving Morphable Components (MMC) theory is introduced to topological optimization method in complicated filling body space with the objective of mechanical properties. The results show that the optimized filling bodies can effectively reduce structural weight with the same mechanical properties. Numerical models of cross-sections of umbilicals with the optimized filling bodies are constructed, the cross-sectional mechanical properties are compared with that under the initial filling body form, which can fully verify the feasibility and correctness of this optimization design strategy.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"10 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":"131947975","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}
Lin Yuan, Jiasheng Zhou, Haowei Liu, Nian-Zhong Chen
Mechanically lined pipe, which was proven to be cost-effective in transporting corrosive hydrocarbons, has been used in many offshore applications. However, one weakness of this product is that the liner is extremely sensitive to geometric imperfections and can wrinkle and collapse under severe loading. As typical damage of the pipeline, the local dent of the lined pipe involves the deformation of both the carrier pipe and the liner, which poses a severe threat to the integrity of the composite structure. In this paper, we developed a numerical framework to study the responses of the lined pipe during indentation and, more importantly, the influence of local dents on the bending capacity of lined pipes. A slight separation between the liner and the carrier pipe was observed during the indentation, depending on the indenter’s geometric feature. Under bending, the liner typically collapsed earlier than the carrier pipe, causing a considerable reduction of the critical curvature and ultimate load-carrying capacity. The evolution of the deformation of the composite structure during the bending process is presented in this paper. Parametric investigations of some vital variables of the problem were also performed to study their influence on the behavior under indentation and the bending capacity of the composite structure.
{"title":"On the Plastic Bending Responses of Dented Lined Pipe","authors":"Lin Yuan, Jiasheng Zhou, Haowei Liu, Nian-Zhong Chen","doi":"10.1115/omae2021-64867","DOIUrl":"https://doi.org/10.1115/omae2021-64867","url":null,"abstract":"\u0000 Mechanically lined pipe, which was proven to be cost-effective in transporting corrosive hydrocarbons, has been used in many offshore applications. However, one weakness of this product is that the liner is extremely sensitive to geometric imperfections and can wrinkle and collapse under severe loading. As typical damage of the pipeline, the local dent of the lined pipe involves the deformation of both the carrier pipe and the liner, which poses a severe threat to the integrity of the composite structure.\u0000 In this paper, we developed a numerical framework to study the responses of the lined pipe during indentation and, more importantly, the influence of local dents on the bending capacity of lined pipes. A slight separation between the liner and the carrier pipe was observed during the indentation, depending on the indenter’s geometric feature. Under bending, the liner typically collapsed earlier than the carrier pipe, causing a considerable reduction of the critical curvature and ultimate load-carrying capacity. The evolution of the deformation of the composite structure during the bending process is presented in this paper. Parametric investigations of some vital variables of the problem were also performed to study their influence on the behavior under indentation and the bending capacity of the composite structure.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"11 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":"115280984","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}
Panagiotis Delizisis, I. Dolianitis, D. Chatzipetros, Vasileios Kanas, G. Georgallis, Konstantinos Tastavridis, Antonios Stamelos, Efstratios Angelis
Submarine, export cables behave, to some point, as long, flexible cylindrical bodies. Their mechanical performance is crucial during laying and operating processes, which depends to a large extent on their stiffness. Although theoretical methods, used to estimate cable stiffness, are currently available, it is difficult to account for the various physical mechanisms involved, such as internal friction, residual torsion and ‘relaxation’ effects. These mechanisms are expected to affect cable stiffness and should be included some way. To represent more realistically cable stiffness, full-scale tests are performed in this paper. The deviation between theoretical and experimental values appears to be significant in certain cases: hence, non-realistic values for cable stiffness would occur if the stiffness estimation relied only on the theoretical methods. Interesting results, affording an in more depth insight and allowing for a better understanding of the cable mechanical performance, are presented in this paper.
{"title":"Full Scale Axial, Bending and Torsion Stiffness Tests of a Three Core HVAC Submarine Cable","authors":"Panagiotis Delizisis, I. Dolianitis, D. Chatzipetros, Vasileios Kanas, G. Georgallis, Konstantinos Tastavridis, Antonios Stamelos, Efstratios Angelis","doi":"10.1115/omae2021-63238","DOIUrl":"https://doi.org/10.1115/omae2021-63238","url":null,"abstract":"\u0000 Submarine, export cables behave, to some point, as long, flexible cylindrical bodies. Their mechanical performance is crucial during laying and operating processes, which depends to a large extent on their stiffness. Although theoretical methods, used to estimate cable stiffness, are currently available, it is difficult to account for the various physical mechanisms involved, such as internal friction, residual torsion and ‘relaxation’ effects. These mechanisms are expected to affect cable stiffness and should be included some way. To represent more realistically cable stiffness, full-scale tests are performed in this paper. The deviation between theoretical and experimental values appears to be significant in certain cases: hence, non-realistic values for cable stiffness would occur if the stiffness estimation relied only on the theoretical methods. Interesting results, affording an in more depth insight and allowing for a better understanding of the cable mechanical performance, are presented in this paper.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"27 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":"125608294","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}
Slug flow, a flow pattern with alternating aerated liquid pockets (slugs) and large gas bubbles, is a commonly observed flow pattern in oil and gas pipelines. Due to its unsteady character, the force on a pipe bend is fluctuating which results in unacceptable motions when the piping is insufficiently supported. To investigate the risk of fatigue failure of the system, finite-element models are used to predict the dynamic stresses required to estimate the fatigue life of the system. The excitation force of the slug flow is the essential input required for accurate fatigue damage predictions. A new, simplified model of slug forces on a bend is proposed. The model is calculating the slug force by solving the momentum balance over the pipe bend using slug flow properties as liquid holdup and phase velocities. Average properties predicted by a unit slug model cannot predict the stochastic force variations caused by the slug flow. The new approach introduces the stochastic character of slug flow in the force calculations via a log-normal slug length distribution. A Lagrangian slug tracking method is used to solve the governing equations. The modelled liquid holdup, pressure and predicted forces are compared with available measurements and Computational Fluid Dynamics calculations. The measurements were done under atmospheric conditions and the fluids used were air and water. Whether these measurements are representative for high-pressure oil and gas slug flow is unknown. By using a mechanistic approach where the main equations are based on physical laws instead of fitted measured data, the model is applicable for different fluids and operational conditions. To validate the model for oil and gas flows, the results are compared with Computational Fluid Dynamics calculations done with high gas density and typical oil viscosity.
{"title":"Simplified Stochastic Modelling of the Force on a Pipe Bend Due to Two-Phase Slug Flow","authors":"Arnout M. Klinkenberg, A. Tijsseling","doi":"10.1115/omae2021-62951","DOIUrl":"https://doi.org/10.1115/omae2021-62951","url":null,"abstract":"\u0000 Slug flow, a flow pattern with alternating aerated liquid pockets (slugs) and large gas bubbles, is a commonly observed flow pattern in oil and gas pipelines. Due to its unsteady character, the force on a pipe bend is fluctuating which results in unacceptable motions when the piping is insufficiently supported. To investigate the risk of fatigue failure of the system, finite-element models are used to predict the dynamic stresses required to estimate the fatigue life of the system. The excitation force of the slug flow is the essential input required for accurate fatigue damage predictions.\u0000 A new, simplified model of slug forces on a bend is proposed. The model is calculating the slug force by solving the momentum balance over the pipe bend using slug flow properties as liquid holdup and phase velocities. Average properties predicted by a unit slug model cannot predict the stochastic force variations caused by the slug flow. The new approach introduces the stochastic character of slug flow in the force calculations via a log-normal slug length distribution. A Lagrangian slug tracking method is used to solve the governing equations.\u0000 The modelled liquid holdup, pressure and predicted forces are compared with available measurements and Computational Fluid Dynamics calculations. The measurements were done under atmospheric conditions and the fluids used were air and water. Whether these measurements are representative for high-pressure oil and gas slug flow is unknown. By using a mechanistic approach where the main equations are based on physical laws instead of fitted measured data, the model is applicable for different fluids and operational conditions. To validate the model for oil and gas flows, the results are compared with Computational Fluid Dynamics calculations done with high gas density and typical oil viscosity.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"152 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":"116526480","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}
Babafemi Olugunwa, J. Race, A. Yurtseven, T. Tezdogan
Buried pipelines transporting dense phase Carbon dioxide CO2 are crucial to carbon reduction and climate change mitigating technologies such as Carbon Capture and Storage (CCS) and Carbon Capture Utilization and Storage (CCUS). One of the major challenges for optimum pipeline operating conditions is to avoid phase change of the compressed CO2 and maintain temperature and pressure above the critical point throughout the pipeline route. A suitable pipe-soil heat transfer model during design can mitigate this challenge. However, variations in annual ambient temperatures, ground temperature at pipeline burial depth and soil temperature profile behaviors with seasonal climatic conditions especially during winter and summer periods also affect the heat transfer process between the soil burial medium and the CO2 pipeline. Assuming steady state, this paper investigates the nearfield temperature distribution up to 3m lateral distance away from a buried dense phase CO2 pipeline by numerical simulation with a two-dimensional pipe-soil heat transfer model at a burial depth of 2.3m to pipe center using a finite volume computational code. Results show that thermal parameters such as thermal conductivity and the soil temperature profile influence the heat exchange between pipe walls and porous soil medium. Consequently, this study shows that the near-field temperature distribution and effect of heat around a buried CO2 pipeline diminishes with distance and burial depth further away within the immediate vicinity of the pipeline.
{"title":"Investigation of Near-Field Temperature Distribution in Buried Dense Phase CO2 Pipelines","authors":"Babafemi Olugunwa, J. Race, A. Yurtseven, T. Tezdogan","doi":"10.1115/omae2021-65310","DOIUrl":"https://doi.org/10.1115/omae2021-65310","url":null,"abstract":"\u0000 Buried pipelines transporting dense phase Carbon dioxide CO2 are crucial to carbon reduction and climate change mitigating technologies such as Carbon Capture and Storage (CCS) and Carbon Capture Utilization and Storage (CCUS). One of the major challenges for optimum pipeline operating conditions is to avoid phase change of the compressed CO2 and maintain temperature and pressure above the critical point throughout the pipeline route. A suitable pipe-soil heat transfer model during design can mitigate this challenge. However, variations in annual ambient temperatures, ground temperature at pipeline burial depth and soil temperature profile behaviors with seasonal climatic conditions especially during winter and summer periods also affect the heat transfer process between the soil burial medium and the CO2 pipeline. Assuming steady state, this paper investigates the nearfield temperature distribution up to 3m lateral distance away from a buried dense phase CO2 pipeline by numerical simulation with a two-dimensional pipe-soil heat transfer model at a burial depth of 2.3m to pipe center using a finite volume computational code. Results show that thermal parameters such as thermal conductivity and the soil temperature profile influence the heat exchange between pipe walls and porous soil medium. Consequently, this study shows that the near-field temperature distribution and effect of heat around a buried CO2 pipeline diminishes with distance and burial depth further away within the immediate vicinity of the pipeline.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"75 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":"115124838","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}
For safe and cost-efficient operations of new and existing offshore Arctic pipelines, monitoring of pipeline structural integrity is imperative. A well-founded pipeline integrity management program can optimize production output, extend the life of the pipeline, and serve as a tool for providing preventative maintenance information. Without the implementation of a routine integrity monitoring campaign, pipeline integrity degradation may go undetected until the point of failure. Arctic-specific offshore pipeline design and operational challenges, such as strudel scour, seabed ice gouge, pipeline upheaval buckling, permafrost thaw settlement, and remote location increase the risk and severity of a loss of pipeline integrity. These design cases can create abnormal conditions and ground deformations along sections of the pipeline which can be difficult to immediately detect through standard integrity monitoring systems and schedules. Many of the existing offshore pipelines in the Arctic are buried in remote locations under seasonal ice cover and the failure to detect pipeline damage in a timely manner could have severe safety, environmental, and economic consequences. An Arctic pipeline integrity monitoring philosophy can be implemented to provide further mitigation against loss of pipeline structural integrity by means of regular bathymetry surveys, In-Line Inspection (ILI) campaigns and Fiber Optic Cable (FOC) monitoring. This paper provides a guideline for buried offshore Arctic pipeline integrity monitoring. The guideline covers pipeline integrity assurance incorporated into the pipeline design, the surveys to be completed during installation, as-built assessment of the pipeline profile, the warm-up assessment/implementation needed before start-up, and the integrity inspections to be completed during operations.
{"title":"Integrity Monitoring of Offshore Arctic Pipelines","authors":"Todd G. Cowin, G. Lanan, M. Paulin, D. Degeer","doi":"10.1115/omae2021-64174","DOIUrl":"https://doi.org/10.1115/omae2021-64174","url":null,"abstract":"\u0000 For safe and cost-efficient operations of new and existing offshore Arctic pipelines, monitoring of pipeline structural integrity is imperative. A well-founded pipeline integrity management program can optimize production output, extend the life of the pipeline, and serve as a tool for providing preventative maintenance information. Without the implementation of a routine integrity monitoring campaign, pipeline integrity degradation may go undetected until the point of failure.\u0000 Arctic-specific offshore pipeline design and operational challenges, such as strudel scour, seabed ice gouge, pipeline upheaval buckling, permafrost thaw settlement, and remote location increase the risk and severity of a loss of pipeline integrity. These design cases can create abnormal conditions and ground deformations along sections of the pipeline which can be difficult to immediately detect through standard integrity monitoring systems and schedules. Many of the existing offshore pipelines in the Arctic are buried in remote locations under seasonal ice cover and the failure to detect pipeline damage in a timely manner could have severe safety, environmental, and economic consequences. An Arctic pipeline integrity monitoring philosophy can be implemented to provide further mitigation against loss of pipeline structural integrity by means of regular bathymetry surveys, In-Line Inspection (ILI) campaigns and Fiber Optic Cable (FOC) monitoring.\u0000 This paper provides a guideline for buried offshore Arctic pipeline integrity monitoring. The guideline covers pipeline integrity assurance incorporated into the pipeline design, the surveys to be completed during installation, as-built assessment of the pipeline profile, the warm-up assessment/implementation needed before start-up, and the integrity inspections to be completed during operations.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"12 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113967828","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 proper understanding of cooling temperature and cooldown time for the operation of a subsea system producing hydrocarbons from the reservoir to the host facility is one of the important flow assurance issues for managing heat retention in the production system due to solids formation and their deposition. In this paper, an analytical transient thermal model is developed for determining the cooling temperature and cooldown time for shut-in operations of a subsea pipe-in-pipe production system, transporting waxy crude oil from the reservoir to the host facility. Here, the cooldown time is defined as the time when the fluid temperature approaches the wax appearance temperature before reaching the hydrate formation temperature during any shut-in operations. The analytical model builds upon an inhomogeneous transient method incorporating an internal temperature gradient. The model results are benchmarked against the commercial OLGA simulation results for a few selected deepwater pipe-in-pipe flowline configuration. The model predictions resemble well with OLGA results over a range of conditions. The analytical model could optimize dry insulation and cooldown time requirements efficiently for the assumed PIP flowline configurations and fluid properties under any subsea environments.
{"title":"A New Transient Thermal Model for Predicting Cooling Temperature and Cooldown Time of a Subsea Pipe-in-Pipe Flowline System Transporting Waxy Hydrocarbons","authors":"K. Shukla","doi":"10.1115/omae2021-64866","DOIUrl":"https://doi.org/10.1115/omae2021-64866","url":null,"abstract":"\u0000 The proper understanding of cooling temperature and cooldown time for the operation of a subsea system producing hydrocarbons from the reservoir to the host facility is one of the important flow assurance issues for managing heat retention in the production system due to solids formation and their deposition. In this paper, an analytical transient thermal model is developed for determining the cooling temperature and cooldown time for shut-in operations of a subsea pipe-in-pipe production system, transporting waxy crude oil from the reservoir to the host facility. Here, the cooldown time is defined as the time when the fluid temperature approaches the wax appearance temperature before reaching the hydrate formation temperature during any shut-in operations. The analytical model builds upon an inhomogeneous transient method incorporating an internal temperature gradient. The model results are benchmarked against the commercial OLGA simulation results for a few selected deepwater pipe-in-pipe flowline configuration. The model predictions resemble well with OLGA results over a range of conditions. The analytical model could optimize dry insulation and cooldown time requirements efficiently for the assumed PIP flowline configurations and fluid properties under any subsea environments.","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":"133372848","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 objective of a free span fatigue assessment is to provide a rational criterion to evaluate the long-term integrity of a free spanning pipeline, to which DNVGL-RP-F105 was developed. The Recommended Practice has a long history. Guideline 14, the foundation document to it, was released in 1998. The guidelines of the DNVGL-RP-F105 were gradually adopted by the industry for free spans analysis, and even API 1111 makes direct reference to it. Today, DNVGL-RP-F105 is the de facto Vortex Induced Vibration analysis guide for all applications where small number of bending driven modes are expected to be excited, overstepping its original purpose of free spanning pipelines and providing guidance when no other source exists. With such a long history, it is easy to forget the basis for the Recommended Practice fatigue model and obtain results that do not match expectations. A prime example is when assessing a free span based on survey and the fatigue life capacity calculated following the Recommended Practice is much smaller than the actual exposure time. In this situation one may ask “why my free span has not failed?” and conclude that the Recommended Practice is either too over conservative or plainly wrong. This paper reviews some key aspects of the DNVGL-RP-F105 fatigue model and explore their implication to fatigue design and assessment. And it hopes to clarify why your free span has not failed even when you expected it to.
{"title":"A Review of DNVGL-RP-F105 Fatigue Assessment Model or Why My Free Span Has Not Failed","authors":"Mario Caruso","doi":"10.1115/omae2021-63747","DOIUrl":"https://doi.org/10.1115/omae2021-63747","url":null,"abstract":"\u0000 The objective of a free span fatigue assessment is to provide a rational criterion to evaluate the long-term integrity of a free spanning pipeline, to which DNVGL-RP-F105 was developed. The Recommended Practice has a long history. Guideline 14, the foundation document to it, was released in 1998. The guidelines of the DNVGL-RP-F105 were gradually adopted by the industry for free spans analysis, and even API 1111 makes direct reference to it. Today, DNVGL-RP-F105 is the de facto Vortex Induced Vibration analysis guide for all applications where small number of bending driven modes are expected to be excited, overstepping its original purpose of free spanning pipelines and providing guidance when no other source exists.\u0000 With such a long history, it is easy to forget the basis for the Recommended Practice fatigue model and obtain results that do not match expectations. A prime example is when assessing a free span based on survey and the fatigue life capacity calculated following the Recommended Practice is much smaller than the actual exposure time. In this situation one may ask “why my free span has not failed?” and conclude that the Recommended Practice is either too over conservative or plainly wrong.\u0000 This paper reviews some key aspects of the DNVGL-RP-F105 fatigue model and explore their implication to fatigue design and assessment. And it hopes to clarify why your free span has not failed even when you expected it to.","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":"125214681","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. Bughi, Luigi Foschi, Lorenzo Marchionni, R. Vichi, Yansa Zulkarnain
This paper is based on the experience made during the design and installation of an offshore pipeline recently completed in Indonesia, where a 24” subsea production pipeline (16km long in 70m water depth) was found susceptible during design to lateral buckling. Buckling is a well understood phenomenon. However, this project was characterized by major uncertainties mainly driven by soil characterization, soil zonation, soil-pipe interaction, seabed mobility and seabed liquefaction. These uncertainties have played a key role in the in-service buckling design. In particular, extreme pipeline embedment scenarios ranging from fully exposed to fully covered (due to natural sand transportation) were accounted with a significant impact on soil-pipe interaction. To limit the development of excessive strain within the acceptance criteria, a mitigation strategy based on interacting planned buckles has been adopted installing three Buckle Initiators (BI) along the pipeline route. During design great efforts have been spent with the aim to demonstrate the robustness of the proposed solution. 3-D FEM simulations with ABAQUS have been performed taking into account the pipeline route including route curves and the sea bottom profile and the buckle initiators with their main geometries. All uncertainties have been considered following a deterministic approach. The impact of environmental and accidental loads due to a potential trawl-gear interaction were assessed as well. The pipeline susceptibility to lateral and/or upheaval buckling along the sandwave areas has been analyzed as well in order to evaluate the need of mitigation measures suitable to freeze the pipeline configuration during the operating life. Finally, once the lateral buckling design philosophy was established, the cyclic expansion and walking behavior of the pipeline were assessed to verify the pipeline structural integrity at buckles, route curve pull-out and the accumulative pipeline expansion at spools. This paper presents all main engineering aspects faced during design and first feedbacks from field after the pipeline installation.
{"title":"Tangguh Project: In-Service Buckling Design of Offshore Pipelines With Major Uncertainties on Soil Characterization and Seabed Mobility","authors":"S. Bughi, Luigi Foschi, Lorenzo Marchionni, R. Vichi, Yansa Zulkarnain","doi":"10.1115/omae2021-62361","DOIUrl":"https://doi.org/10.1115/omae2021-62361","url":null,"abstract":"\u0000 This paper is based on the experience made during the design and installation of an offshore pipeline recently completed in Indonesia, where a 24” subsea production pipeline (16km long in 70m water depth) was found susceptible during design to lateral buckling.\u0000 Buckling is a well understood phenomenon. However, this project was characterized by major uncertainties mainly driven by soil characterization, soil zonation, soil-pipe interaction, seabed mobility and seabed liquefaction. These uncertainties have played a key role in the in-service buckling design. In particular, extreme pipeline embedment scenarios ranging from fully exposed to fully covered (due to natural sand transportation) were accounted with a significant impact on soil-pipe interaction.\u0000 To limit the development of excessive strain within the acceptance criteria, a mitigation strategy based on interacting planned buckles has been adopted installing three Buckle Initiators (BI) along the pipeline route. During design great efforts have been spent with the aim to demonstrate the robustness of the proposed solution.\u0000 3-D FEM simulations with ABAQUS have been performed taking into account the pipeline route including route curves and the sea bottom profile and the buckle initiators with their main geometries. All uncertainties have been considered following a deterministic approach. The impact of environmental and accidental loads due to a potential trawl-gear interaction were assessed as well.\u0000 The pipeline susceptibility to lateral and/or upheaval buckling along the sandwave areas has been analyzed as well in order to evaluate the need of mitigation measures suitable to freeze the pipeline configuration during the operating life.\u0000 Finally, once the lateral buckling design philosophy was established, the cyclic expansion and walking behavior of the pipeline were assessed to verify the pipeline structural integrity at buckles, route curve pull-out and the accumulative pipeline expansion at spools.\u0000 This paper presents all main engineering aspects faced during design and first feedbacks from field after the pipeline installation.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"25 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":"122560375","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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