Jianbo Zhang, Zhiyuan Wang, Wenqiang Lou, Wenguang Duan, W. Fu, B. Yin, Baojiang Sun, Jian Liu
Hydrate plugging is an important factor affecting the safety and efficiency of flow assurance. Current prevention methods for hydrate plugging are costly or environmentally unfriendly or inefficient. In this work, an efficient method to prevent hydrate plugging during deep-water gas well testing was put forward, which is achieved by reasonably changing the testing orders of different gas production rates. The deposited hydrates in the tubing under low testing rates will be decomposed under high rates to reduce the risk of hydrate plugging without hydrate inhibitor injection. A case study is carried out to investigate the applicability of this method. The results show that the maximum dimensionless thickness of hydrate deposit reaches 68.14% under the conventional testing order, but decreases to 33.59% by using the proposed method. It is indicated that the proposed method can obviously decrease the risk of hydrate plugging without using hydrate inhibitor injection. Hence, the proposed method is a more economical and environmentally friendly method for hydrate plugging prevention, which can be applied as an alternative to the present prevention methods during deep-water gas well testing.
{"title":"An Efficient Method for Hydrate Plugging Prevention During Deep-Water Gas Well Testing","authors":"Jianbo Zhang, Zhiyuan Wang, Wenqiang Lou, Wenguang Duan, W. Fu, B. Yin, Baojiang Sun, Jian Liu","doi":"10.1115/omae2020-18188","DOIUrl":"https://doi.org/10.1115/omae2020-18188","url":null,"abstract":"\u0000 Hydrate plugging is an important factor affecting the safety and efficiency of flow assurance. Current prevention methods for hydrate plugging are costly or environmentally unfriendly or inefficient. In this work, an efficient method to prevent hydrate plugging during deep-water gas well testing was put forward, which is achieved by reasonably changing the testing orders of different gas production rates. The deposited hydrates in the tubing under low testing rates will be decomposed under high rates to reduce the risk of hydrate plugging without hydrate inhibitor injection. A case study is carried out to investigate the applicability of this method. The results show that the maximum dimensionless thickness of hydrate deposit reaches 68.14% under the conventional testing order, but decreases to 33.59% by using the proposed method. It is indicated that the proposed method can obviously decrease the risk of hydrate plugging without using hydrate inhibitor injection. Hence, the proposed method is a more economical and environmentally friendly method for hydrate plugging prevention, which can be applied as an alternative to the present prevention methods during deep-water gas well testing.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"38 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":"128658953","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. V. Wijhe, L. Buijs, L. Stachyra, Olivier Macchion
Vibrations in Subsea Production Systems are well recognized as a concern in the subsea industry. To identify the severity of the vibrations and potential accumulated fatigue damage, subsea vibrations need to be measured with great accuracy. Currently, accurate detection and subsea measurements are often performed by utilizing accelerometers, which have to be connected to the structure by ROV or a diver. ROV video analysis provides an alternative solution. Video analyses are widely utilized across different applications. With the increased quality of a HD camera on ROV, the accessibility of such measurements is an attractive substitute to other techniques. As a part of on-shore mechanical testing on a full assembled XT in St John’s Canada, a flowloop on a water injection XT was subjected to free vibrations. The vibrations were filmed using a commercial HD camera placed on a tripod. This test was done to validate data generated using video processing in which pipe vibration of an operating subsea XT was filmed using an ROV camera. A study that aimed to quantify the video processing accuracy, limitations and provide general guidance was conducted. For the onshore test filmed with a tripod the results of video analyses were compared with the measurements obtained by means of accelerometers. For the video of an operating subsea XT filmed by an ROV, the obtained vibration frequency and direction was compared with the free mechanical vibration obtained by a FEM model. The results obtained by means of the video analysis matched well with the accelerometer data. A high accuracy was reached, as vibration displacements as low as 20% of the pixel were accurately determined in the video analysis. With respect to detection frequencies, the upper cut-off frequency was around 15 Hz determined by the video framerate. The video analysis utilizing ROV videos was found to be applicable for low frequency vibration measurements, opening the opportunity for easier and more cost effective vibration detection and monitoring. The method is also reliable for subsea application in which the camera is placed on an ROV and is thus not affected by ROV movements, subsea lighting condition and moving ocean debris.
{"title":"Measurements of Low Frequency Vibration in Subsea Piping Using ROV Video Analysis","authors":"A. V. Wijhe, L. Buijs, L. Stachyra, Olivier Macchion","doi":"10.1115/omae2020-18579","DOIUrl":"https://doi.org/10.1115/omae2020-18579","url":null,"abstract":"\u0000 Vibrations in Subsea Production Systems are well recognized as a concern in the subsea industry. To identify the severity of the vibrations and potential accumulated fatigue damage, subsea vibrations need to be measured with great accuracy. Currently, accurate detection and subsea measurements are often performed by utilizing accelerometers, which have to be connected to the structure by ROV or a diver.\u0000 ROV video analysis provides an alternative solution. Video analyses are widely utilized across different applications. With the increased quality of a HD camera on ROV, the accessibility of such measurements is an attractive substitute to other techniques.\u0000 As a part of on-shore mechanical testing on a full assembled XT in St John’s Canada, a flowloop on a water injection XT was subjected to free vibrations. The vibrations were filmed using a commercial HD camera placed on a tripod.\u0000 This test was done to validate data generated using video processing in which pipe vibration of an operating subsea XT was filmed using an ROV camera.\u0000 A study that aimed to quantify the video processing accuracy, limitations and provide general guidance was conducted. For the onshore test filmed with a tripod the results of video analyses were compared with the measurements obtained by means of accelerometers. For the video of an operating subsea XT filmed by an ROV, the obtained vibration frequency and direction was compared with the free mechanical vibration obtained by a FEM model.\u0000 The results obtained by means of the video analysis matched well with the accelerometer data. A high accuracy was reached, as vibration displacements as low as 20% of the pixel were accurately determined in the video analysis. With respect to detection frequencies, the upper cut-off frequency was around 15 Hz determined by the video framerate. The video analysis utilizing ROV videos was found to be applicable for low frequency vibration measurements, opening the opportunity for easier and more cost effective vibration detection and monitoring. The method is also reliable for subsea application in which the camera is placed on an ROV and is thus not affected by ROV movements, subsea lighting condition and moving ocean debris.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"1 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":"122411030","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 riser is a critical element in a subsea production system for transporting hydrocarbons from the seafloor to the surface. The track record of existing riser systems worldwide has shown that risers tend to be designed conservatively to accommodate dynamic loads, strength and fatigue requirements, and corrosion/erosion provision needs. Among all the riser types, the steel catenary riser (SCR) is the most installed riser configuration for deepwater oil and gas production worldwide in the last two decades. This is mainly because of their simple configuration and relatively low manufacturing and installation cost. As riser technology advances, SCRs are designed to tackle more challenging environments and longer service lives. For the riser life extension applications, regulatory bodies prefer riser operations to be managed through an integrity management program, demonstrating that a robust framework with detailed records on the conditions of the risers is in place. This paper studies an integrity management program for SCRs with a 30-year design life in a harsh environment. The planned riser integrity management program is based on successful industry practice and the newly published riser integrity management standard API RP 2RIM [4]. It starts with a review of the riser design basis and as-built data, continuing with key field data measurement and production fluid sampling. A digital model, continuously calibrated with the measured data, is established to assess the integrity of the riser system. Key physical quantities are selected to monitor the structural health of the SCRs, including vessel motion measurement, measurement of SCR top hang-off angles and tensions, and full water column current measurement. The relationship between the measurement data and the riser strength and fatigue performance is established. Details of the riser integrity assessment in a digital model utilizing the measurement data are presented. The implemented proposed riser integrity management program is expected to provide a more focused and efficient method with a higher level of confidence in operating the SCRs during the design life and potentially beyond.
立管是海底生产系统中将碳氢化合物从海底输送到地面的关键部件。全球现有立管系统的历史记录表明，为了适应动态载荷、强度和疲劳要求以及腐蚀/侵蚀供应需求，立管的设计往往比较保守。在所有立管类型中，钢制悬链线立管(SCR)是过去20年来全球深水油气生产中安装最多的立管配置。这主要是因为它们配置简单，制造和安装成本相对较低。随着立管技术的进步，scr被设计用于应对更具挑战性的环境和更长的使用寿命。对于隔水管使用寿命延长的应用，监管机构更倾向于通过完整性管理程序来管理隔水管的操作，这表明有一个关于隔水管状况的详细记录的强大框架。本文研究了在恶劣环境下设计寿命为30年的scr的完整性管理方案。计划中的立管完整性管理方案基于成功的行业实践和新发布的立管完整性管理标准API RP 2RIM[4]。首先回顾立管的设计基础和建成数据，接着是关键的现场数据测量和生产流体采样。通过不断校准测量数据，建立一个数字模型来评估立管系统的完整性。选择关键物理量来监测SCR的结构健康状况，包括船舶运动测量、SCR顶部悬垂角和张力测量以及全水柱电流测量。建立了测量数据与隔水管强度和疲劳性能之间的关系。提出了利用测量数据在数字模型中进行立管完整性评估的细节。立管完整性管理方案的实施有望提供一种更专注、更有效的方法，在设计寿命期间甚至更长时间内对scr的操作有更高的信心。
{"title":"Integrity Management for Steel Catenary Risers With Design Life of 30 Years","authors":"Hao Song, Chen Yu, Yongming Cheng, Jing Hou","doi":"10.1115/omae2020-18065","DOIUrl":"https://doi.org/10.1115/omae2020-18065","url":null,"abstract":"\u0000 The riser is a critical element in a subsea production system for transporting hydrocarbons from the seafloor to the surface. The track record of existing riser systems worldwide has shown that risers tend to be designed conservatively to accommodate dynamic loads, strength and fatigue requirements, and corrosion/erosion provision needs. Among all the riser types, the steel catenary riser (SCR) is the most installed riser configuration for deepwater oil and gas production worldwide in the last two decades. This is mainly because of their simple configuration and relatively low manufacturing and installation cost.\u0000 As riser technology advances, SCRs are designed to tackle more challenging environments and longer service lives. For the riser life extension applications, regulatory bodies prefer riser operations to be managed through an integrity management program, demonstrating that a robust framework with detailed records on the conditions of the risers is in place. This paper studies an integrity management program for SCRs with a 30-year design life in a harsh environment.\u0000 The planned riser integrity management program is based on successful industry practice and the newly published riser integrity management standard API RP 2RIM [4]. It starts with a review of the riser design basis and as-built data, continuing with key field data measurement and production fluid sampling. A digital model, continuously calibrated with the measured data, is established to assess the integrity of the riser system.\u0000 Key physical quantities are selected to monitor the structural health of the SCRs, including vessel motion measurement, measurement of SCR top hang-off angles and tensions, and full water column current measurement. The relationship between the measurement data and the riser strength and fatigue performance is established. Details of the riser integrity assessment in a digital model utilizing the measurement data are presented. The implemented proposed riser integrity management program is expected to provide a more focused and efficient method with a higher level of confidence in operating the SCRs during the design life and potentially beyond.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"6 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":"125308011","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 fluid conduit connecting from a subsea well to a surface floating production vessel such as a spar, TLP, or a semi-submersible. It 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 manufacturing cost and good adaptability to floating platform’s motion. Thus, SCRs are widely used in GoM and Brazilian water. This paper investigates design challenges of SCRs used for a semi-submersible in deepwater and ultra deepwater. As the application moves to deepwater and ultra deepwater, challenges of a conventional SCRs increase significantly in terms of global performance, fabrication, and installation. This paper first introduces an SCR system used for a semi-submersible platform. One of the challenges is the harsh environmental condition such as hurricanes or tropical cyclones. Severe motions of a semi-submersible platform may cause significant compression loads on SCRs at the Touch Down Zone (TDZ). It is challenging to design the SCRs to meet API RP 2RD requirement for the riser dynamic strength. Multiple seeds of random motion simulations for irregular wave are necessary for the evaluation. The new riser design code of API STD 2RD can also be used to assess riser strength, especially under 1000-yr survival environmental conditions. It is challenging to design SCRs to meet a design life of 30 years and beyond. The fatigue assessment of the SCRs considers the damage contributions from the semi wave motions, riser Vortex-Induced Vibration (VIV) due to ambient current, and Vortex-Induced Motion (VIM) of a semi-submersible platform. Fatigue contribution from installation is also considered and included in the combined fatigue damage calculation. The long term combined factored fatigue life is computed to ensure that the SCRs meet the requirement of design life. This paper further investigates intermittent Vortex-Induced Vibration (VIV) caused by heave motions of a semi-submersible platform. This VIV phenomenon has an impact on SCR strength due to the drag amplification as well as fatigue damage. The installation concerns come from riser pipe size, installation method and capacity of an installation vessel. Examples are provided for illustrations of the design challenges. In addition, this paper explores likely solutions to meet SCR design challenges for the applications in deepwater and ultra deepwater.
立管是一种流体管道，将海底油井连接到水面浮式生产船(如桅杆、张力腿平台或半潜式作业船)。它是将产出的石油和天然气从海底井输送到地面生产船的关键部件。通过近30年的设计与实施，发现钢链链立管具有制造成本相对较低、对浮式平台运动适应性较好的优点。因此，scr在墨西哥湾和巴西水域得到了广泛的应用。本文研究了用于深水和超深水半潜式平台的scr的设计挑战。随着应用向深水和超深水领域发展，传统scr在全球性能、制造和安装方面面临的挑战显著增加。本文首先介绍了一种用于半潜式平台的可控硅系统。其中一个挑战是恶劣的环境条件，如飓风或热带气旋。半潜式平台的剧烈运动可能会对触地区(TDZ)的scr造成巨大的压缩载荷。设计scr以满足API RP 2RD对立管动态强度的要求是一项挑战。对不规则波进行多种子随机运动模拟是评估的必要条件。新的立管设计规范API STD 2RD也可用于评估立管强度，特别是在1000年的生存环境条件下。设计scr以满足30年及以上的设计寿命是一项挑战。scr的疲劳评估考虑了半波运动、环境电流引起的隔水管涡激振动(VIV)和半潜式平台涡激运动(VIM)的损伤贡献。在组合疲劳损伤计算中也考虑了安装对疲劳的贡献。计算了scr的长期组合疲劳寿命，保证了scr满足设计寿命要求。本文进一步研究了半潜式平台升沉运动引起的间歇涡激振动。由于阻力放大和疲劳损伤，这种涡激振动现象对可燃硅的强度产生影响。安装问题来自立管尺寸、安装方法和安装船的容量。举例说明了设计挑战。此外，本文还探讨了在深水和超深水应用中应对SCR设计挑战的可能解决方案。
{"title":"Design Challenges of SCRs in Deepwater and Ultra Deepwater","authors":"Yongming Cheng, Chen Yu, Hao Song","doi":"10.1115/omae2020-18382","DOIUrl":"https://doi.org/10.1115/omae2020-18382","url":null,"abstract":"\u0000 A riser is a fluid conduit connecting from a subsea well to a surface floating production vessel such as a spar, TLP, or a semi-submersible. It 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 manufacturing cost and good adaptability to floating platform’s motion. Thus, SCRs are widely used in GoM and Brazilian water. This paper investigates design challenges of SCRs used for a semi-submersible in deepwater and ultra deepwater.\u0000 As the application moves to deepwater and ultra deepwater, challenges of a conventional SCRs increase significantly in terms of global performance, fabrication, and installation. This paper first introduces an SCR system used for a semi-submersible platform. One of the challenges is the harsh environmental condition such as hurricanes or tropical cyclones. Severe motions of a semi-submersible platform may cause significant compression loads on SCRs at the Touch Down Zone (TDZ). It is challenging to design the SCRs to meet API RP 2RD requirement for the riser dynamic strength. Multiple seeds of random motion simulations for irregular wave are necessary for the evaluation. The new riser design code of API STD 2RD can also be used to assess riser strength, especially under 1000-yr survival environmental conditions.\u0000 It is challenging to design SCRs to meet a design life of 30 years and beyond. The fatigue assessment of the SCRs considers the damage contributions from the semi wave motions, riser Vortex-Induced Vibration (VIV) due to ambient current, and Vortex-Induced Motion (VIM) of a semi-submersible platform. Fatigue contribution from installation is also considered and included in the combined fatigue damage calculation. The long term combined factored fatigue life is computed to ensure that the SCRs meet the requirement of design life.\u0000 This paper further investigates intermittent Vortex-Induced Vibration (VIV) caused by heave motions of a semi-submersible platform. This VIV phenomenon has an impact on SCR strength due to the drag amplification as well as fatigue damage. The installation concerns come from riser pipe size, installation method and capacity of an installation vessel. Examples are provided for illustrations of the design challenges. In addition, this paper explores likely solutions to meet SCR design challenges for the applications in deepwater and ultra deepwater.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"136 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":"127414373","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 this paper is to answer the questions posed and in doing so create an awareness of the necessity to use reliability based design when looking at vessel operating windows rather than working stress design which has been used for marine drilling riser analysis and design for many decades. In answering, this paper presents several case studies of drilling riser stresses and operating windows when drilling to access reservoirs with pressure greater than 15,000 psi and up to 20,000 psi. This paper examines the need for full and proper use of a more probabilistic design over working stress design for a set of water depth, subsea equipment, environments and loading conditions.
{"title":"How Reliability Based Design Can Increase Operating Window for 20k Drilling Risers","authors":"N. Pilisi, D. Lewis","doi":"10.1115/omae2020-19006","DOIUrl":"https://doi.org/10.1115/omae2020-19006","url":null,"abstract":"\u0000 The objective of this paper is to answer the questions posed and in doing so create an awareness of the necessity to use reliability based design when looking at vessel operating windows rather than working stress design which has been used for marine drilling riser analysis and design for many decades. In answering, this paper presents several case studies of drilling riser stresses and operating windows when drilling to access reservoirs with pressure greater than 15,000 psi and up to 20,000 psi. This paper examines the need for full and proper use of a more probabilistic design over working stress design for a set of water depth, subsea equipment, environments and loading conditions.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"2011 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":"125631025","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 single wave or uni-modal wave analysis approach to define the installation seastates, based on a single wave with varying directions, wave heights and periods, is a standard approach among the installation contractors. However, in many of the offshore projects, e.g. offshore Trinidad, and Senegal and Mauritania, bi-modal seatates or waves are a common occurrence, but they are not considered in the installation analysis due to the complexity of the analysis and the computation time required to capture two waves, i.e. wind-sea and swell concurrently from different directions. A novel bi-modal wave analysis approach is developed to assess the risk to pipelay installation operations due to the impact of bi-modal waves on the installation vessel, characterised by two peak frequencies of varying directions, wave heights and periods. The approach requires the use of clustered data, based on hindcast wave data over a period of time which can be provided by the Metocean Specialist. A combination of statistical evaluation of the clustered data and vessel response screening is used to identify critical clustered pairs for further installation analysis, and to complement the established single wave analysis and the associated installation seastates. An example is provided in this paper to illustrate the benefits of bi-modal waves consideration, and to demonstrate the use of this novel approach in order to ensure any potential risk is captured so that the pipelay installation operations can be carried out in a safe offshore environment.
{"title":"A Novel Bi-Modal Wave Analysis Approach to Pipelay Installation Analysis","authors":"D. Lee, Piotr Niesluchowski","doi":"10.1115/omae2020-19269","DOIUrl":"https://doi.org/10.1115/omae2020-19269","url":null,"abstract":"\u0000 The single wave or uni-modal wave analysis approach to define the installation seastates, based on a single wave with varying directions, wave heights and periods, is a standard approach among the installation contractors. However, in many of the offshore projects, e.g. offshore Trinidad, and Senegal and Mauritania, bi-modal seatates or waves are a common occurrence, but they are not considered in the installation analysis due to the complexity of the analysis and the computation time required to capture two waves, i.e. wind-sea and swell concurrently from different directions.\u0000 A novel bi-modal wave analysis approach is developed to assess the risk to pipelay installation operations due to the impact of bi-modal waves on the installation vessel, characterised by two peak frequencies of varying directions, wave heights and periods. The approach requires the use of clustered data, based on hindcast wave data over a period of time which can be provided by the Metocean Specialist. A combination of statistical evaluation of the clustered data and vessel response screening is used to identify critical clustered pairs for further installation analysis, and to complement the established single wave analysis and the associated installation seastates.\u0000 An example is provided in this paper to illustrate the benefits of bi-modal waves consideration, and to demonstrate the use of this novel approach in order to ensure any potential risk is captured so that the pipelay installation operations can be carried out in a safe offshore environment.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"4 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":"117048035","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}
Shaosong Zhang, Yongming Cheng, Yuanlang Cai, Ning He, Xiaolong Yang, Z. Cao
Steel Catenary Risers (SCRs) are widely used in deepwater and ultra-deepwater field developments. The dynamic strength of SCRs is a concern in terms of the global performance. The analysis results are quite scattered in many cases due to the nature of the irregular wave stochastic properties. The widely accepted approach to predict the riser dynamic response in the irregular seas is to run the multiple time domain simulations based on different random seeds. This paper will address the impacts on the predicted riser dynamic response due to the random seeds selection. The discussion is based on the independent engineering verification work for a production Semi project in South China Sea. The site specific irregular waves are usually defined by not only the wave spectrum, but also the properties of individual waves, such as maximum wave height and minimum wave trough, which have big impacts on the riser extreme response. The code recommended approach for irregular wave simulation is based on the linear wave theory, which can ensure the match of the target wave spectrum, for example, Hs, Tp (or Tz), wave peakness for JONSWAP spectrum. But the variation of simulated individual wave properties to the specified value can be significant or there is no specified value to match. The simulated irregular waves based on linear theory is also a distortion to the real wave elevation time trace, such as the asymmetry of the wave crest and trough, especially for the tropical cyclone sea states. Some riser response, such as the compression load at riser touch down zone, can be significantly impacted by the nonlinear nature of the waves and the variation to the target individual wave properties. This paper will discuss the random wave simulation and its impacts on riser dynamic response. A SCR strength design case is presented for illustration in this paper. Key parameters are identified to show the correlation with the SCR dynamic response. The conclusion is finally drawn from the work presented in this paper.
{"title":"Irregular Wave Simulation and its Impact on Riser Extreme Response for a Production Semi","authors":"Shaosong Zhang, Yongming Cheng, Yuanlang Cai, Ning He, Xiaolong Yang, Z. Cao","doi":"10.1115/omae2020-19032","DOIUrl":"https://doi.org/10.1115/omae2020-19032","url":null,"abstract":"\u0000 Steel Catenary Risers (SCRs) are widely used in deepwater and ultra-deepwater field developments. The dynamic strength of SCRs is a concern in terms of the global performance. The analysis results are quite scattered in many cases due to the nature of the irregular wave stochastic properties. The widely accepted approach to predict the riser dynamic response in the irregular seas is to run the multiple time domain simulations based on different random seeds. This paper will address the impacts on the predicted riser dynamic response due to the random seeds selection. The discussion is based on the independent engineering verification work for a production Semi project in South China Sea.\u0000 The site specific irregular waves are usually defined by not only the wave spectrum, but also the properties of individual waves, such as maximum wave height and minimum wave trough, which have big impacts on the riser extreme response. The code recommended approach for irregular wave simulation is based on the linear wave theory, which can ensure the match of the target wave spectrum, for example, Hs, Tp (or Tz), wave peakness for JONSWAP spectrum. But the variation of simulated individual wave properties to the specified value can be significant or there is no specified value to match. The simulated irregular waves based on linear theory is also a distortion to the real wave elevation time trace, such as the asymmetry of the wave crest and trough, especially for the tropical cyclone sea states. Some riser response, such as the compression load at riser touch down zone, can be significantly impacted by the nonlinear nature of the waves and the variation to the target individual wave properties.\u0000 This paper will discuss the random wave simulation and its impacts on riser dynamic response. A SCR strength design case is presented for illustration in this paper. Key parameters are identified to show the correlation with the SCR dynamic response. The conclusion is finally drawn from the work presented in this paper.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"86 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":"116173493","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}
Estimating wellhead loads from lower stack motion measurements is a practical and cost-effective approach. In this paper, a new method is proposed, which is based on system identification techniques rather than Newtonian mechanics, thus omitting reliance on uncertain and variable quantities such as lowerflex joint stiffness/damping, riser and drill pipe tension etc. The proposed method is simple and easy to apply, while maintaining accuracy. Both simulation and real-world measurement data are utilized to demonstrate and evaluate the method.
{"title":"Robust Method for Wellhead Loads Estimation Based on Lower Stack Motion Measurements","authors":"A. Çetin, H. Holden, Vegard R. Solum","doi":"10.1115/omae2020-18890","DOIUrl":"https://doi.org/10.1115/omae2020-18890","url":null,"abstract":"\u0000 Estimating wellhead loads from lower stack motion measurements is a practical and cost-effective approach. In this paper, a new method is proposed, which is based on system identification techniques rather than Newtonian mechanics, thus omitting reliance on uncertain and variable quantities such as lowerflex joint stiffness/damping, riser and drill pipe tension etc. The proposed method is simple and easy to apply, while maintaining accuracy. Both simulation and real-world measurement data are utilized to demonstrate and evaluate the method.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"16 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":"134477107","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 industry standard approach for the design of flexible pipes makes use of non-linear finite element analysis (FEA) in time domain to simulate the physical responses of the structure in different environmental conditions. Wave dynamics can be represented either by an irregular wave (IW) or an equivalent regular wave (RW) approach, which simplifies the analysis. Irregular wave modeling approximates better the structural responses, due to the stochastic nature of the environmental loading, having the drawback of being more computationally expensive. The computer processing time of IW-FEA often becomes intractable due to the large number of scenarios that need to be simulated, for different values of Hs (significant height), Tp (peak period) and different wave directions. Reducing the time needed to simulate each scenario would reduce significantly the total processing time. In order to achieve this, alternative hybrid methods have been proposed in the literature, combining FEA with machine learning models. This paper proposes the use of nonlinear autoregressive exogeneous convolutional neural networks (NARX-CNN) to predict tension and curvature responses along the length of a flexible riser. Experimental results show that the proposed model can generate more accurate responses than previous models. This work also extends the region analyzed by forecasting responses beyond the bending stiffener level, going down to the end-fitting and touch down zone locations. It is the first time that such regions, prone to fatigue issues, are evaluated with these types of algorithms for flexible pipes, as per authors’ knowledge.
{"title":"Convolutional Neural Networks Applied to Flexible Pipes for Fatigue Calculations","authors":"V. Silva, Breno Serrano de Araujo","doi":"10.1115/omae2020-18212","DOIUrl":"https://doi.org/10.1115/omae2020-18212","url":null,"abstract":"\u0000 The industry standard approach for the design of flexible pipes makes use of non-linear finite element analysis (FEA) in time domain to simulate the physical responses of the structure in different environmental conditions. Wave dynamics can be represented either by an irregular wave (IW) or an equivalent regular wave (RW) approach, which simplifies the analysis. Irregular wave modeling approximates better the structural responses, due to the stochastic nature of the environmental loading, having the drawback of being more computationally expensive. The computer processing time of IW-FEA often becomes intractable due to the large number of scenarios that need to be simulated, for different values of Hs (significant height), Tp (peak period) and different wave directions. Reducing the time needed to simulate each scenario would reduce significantly the total processing time. In order to achieve this, alternative hybrid methods have been proposed in the literature, combining FEA with machine learning models. This paper proposes the use of nonlinear autoregressive exogeneous convolutional neural networks (NARX-CNN) to predict tension and curvature responses along the length of a flexible riser. Experimental results show that the proposed model can generate more accurate responses than previous models. This work also extends the region analyzed by forecasting responses beyond the bending stiffener level, going down to the end-fitting and touch down zone locations. It is the first time that such regions, prone to fatigue issues, are evaluated with these types of algorithms for flexible pipes, as per authors’ knowledge.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"17 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":"133798903","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}
H. Xia, C. Shi, Jian Wang, Xingxian Bao, H. Li, G. Fu
Thermoplastic composite pipes (TCPs) are increasingly used to transport hydrocarbons and water in the oil and gas industry due to their superior properties including corrosion resistance, thermal insulation, light weight, etc. The cross-section of TCPs generally consists of three layers: inner liner, composite laminate, and outer jacket. Three layers are bonded together and form a solid-wall construction. Inner liner and outer jacket made of thermoplastic polymer provide protective barriers for the laminate to against the inner fluid and outer environment. The laminate is constructed by an even number of helically wounded continuous fiber reinforced thermoplastic composite tapes. In this study, mechanical behaviors of a TCP under an internal pressure were investigated by using analytical and finite element analysis (FEA) methods. The analytical method which is based on the three-dimensional (3D) anisotropy elastic theory can take account of non-uniformly distributed stress and strain through the thickness of the pipe wall. FEA models were setup by using the software ABAQUS to predict the stress distribution of the pipe. 3D Tsai-Wu failure criterion was used to predict the maximum internal pressure of the pipe. Effects of some critical parameters, such as the winding angle of composite tapes and the number of reinforced plies, on the internal pressure capacity of TCPs were studied. Results obtained from the analytical and FEA methods were fairly agreed with each other, which showed that with the increasing of the number of reinforced plies the internal pressure capacity of a TCP gradually increases and approaches to an extreme value. In addition, the optimal winding angle which results the maximum internal pressure is not a constant value, instead, it varies with the increasing thickness of the laminate layer. This study provides useful tools and guidance for the design and analysis of TCPs, and is currently under validation through experiments.
{"title":"Effects of Thickness and Winding Angle of the Laminate on Internal Pressure Capacity of Thermoplastic Composite Pipes","authors":"H. Xia, C. Shi, Jian Wang, Xingxian Bao, H. Li, G. Fu","doi":"10.1115/omae2020-18046","DOIUrl":"https://doi.org/10.1115/omae2020-18046","url":null,"abstract":"\u0000 Thermoplastic composite pipes (TCPs) are increasingly used to transport hydrocarbons and water in the oil and gas industry due to their superior properties including corrosion resistance, thermal insulation, light weight, etc. The cross-section of TCPs generally consists of three layers: inner liner, composite laminate, and outer jacket. Three layers are bonded together and form a solid-wall construction. Inner liner and outer jacket made of thermoplastic polymer provide protective barriers for the laminate to against the inner fluid and outer environment. The laminate is constructed by an even number of helically wounded continuous fiber reinforced thermoplastic composite tapes. In this study, mechanical behaviors of a TCP under an internal pressure were investigated by using analytical and finite element analysis (FEA) methods. The analytical method which is based on the three-dimensional (3D) anisotropy elastic theory can take account of non-uniformly distributed stress and strain through the thickness of the pipe wall. FEA models were setup by using the software ABAQUS to predict the stress distribution of the pipe. 3D Tsai-Wu failure criterion was used to predict the maximum internal pressure of the pipe. Effects of some critical parameters, such as the winding angle of composite tapes and the number of reinforced plies, on the internal pressure capacity of TCPs were studied. Results obtained from the analytical and FEA methods were fairly agreed with each other, which showed that with the increasing of the number of reinforced plies the internal pressure capacity of a TCP gradually increases and approaches to an extreme value. In addition, the optimal winding angle which results the maximum internal pressure is not a constant value, instead, it varies with the increasing thickness of the laminate layer. This study provides useful tools and guidance for the design and analysis of TCPs, and is currently under validation through experiments.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"1 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":"125993607","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：