Volume 4: Pipelines, Risers, and Subsea Systems最新文献

{"title":"A Novel Power Series Method for the Analysis of an Offshore Mooring Line","authors":"Kabutakapua Kakanda, Z. Han, B. Yan, N. Srinil, D. Zhou","doi":"10.1115/omae2021-63219","DOIUrl":"https://doi.org/10.1115/omae2021-63219","url":null,"abstract":"\u0000 The mechanics of offshore mooring lines are described by a set of nonlinear equations of motion which have typically been solved through a numerical finite element or finite difference method (FEM or FDM), and through the lumped mass method (LMM). The mooring line nonlinearities are associated with the distributed drag forces depending on the relative velocities of the environmental flow and the structure, as well as the axial dynamic strain-displacement relationship given by the geometric compatibility condition of the flexible mooring line. In this study, a semi analytical-numerical novel approach based on the power series method (PSM) is presented and applied to the analysis of offshore mooring lines for renewable energy and oil and gas applications. This PSM enables the construction of analytical solutions for ordinary and partial differential equations (ODEs and PDEs) by using series of polynomials whose coefficients are determined, depending on initial and boundary conditions. We introduce the mooring spatial response as a vector in the Lagrangian coordinate, whose components are infinite bivariate polynomials. For case studies, a two-dimensional mooring line with fixed-fixed ends and subject to nonlinear drag, buoyancy and gravity forces is considered. The introduced boundary and initial conditions enable the analysis of an equilibrium or steady-state of a catenary-like mooring line configuration with variable slenderness and flexibility. Polynomials’ coefficients computation is performed with the aid of a MATLAB package. Numerical results of mooring line configurations and resultant tensions are presented for deep-water applications, and compared with those obtained from a semi-analytical and finite element model. The PSM applied to the mooring line in the present study is efficient and more computationally robust than traditional numerical methods. The PSM can be directly applied to the dynamic analysis of mooring lines.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"18 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":"131950914","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}

{"title":"Fatigue Life Extension Procedure for Subsea Wells Based on Pressure Testing","authors":"Arne Fjeldstad, T. Hørte, G. Sigurdsson, A. Wormsen, E. Berg, K. Macdonald, L. Reinås","doi":"10.1115/omae2021-63003","DOIUrl":"https://doi.org/10.1115/omae2021-63003","url":null,"abstract":"\u0000 This article presents a fatigue life extension procedure for subsea wells based on fracture mechanics. It makes use of the outcome of an internal pressure test to determine a safe period for drilling and completion. The pressure test is used as a load test and can only reveal deep fatigue cracks. The safe operational period is estimated as the number of cycles required to grow a fatigue crack from the largest fatigue crack that remains stable after the pressure test until it becomes unstable due to an accidental load. The procedure takes into account the probability of the presence of the fatigue crack that can be revealed by the pressure test. This is used to determine design fatigue factors for the procedure. The design fatigue factor is formulated in terms of the (S-N based) accumulated fatigue damage for historical operations. The procedure is illustrated with two case examples (fatigue hot spots) for illustrating the procedure in more detail: wellhead extension girth weld and wellhead profile. Conditions for use are given at the end of the article.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"125 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":"123716621","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}

{"title":"Managing Pipeline Integrity and Dynamic Free Spans on Mobile Seabed in the Southern North Sea","authors":"Octavio E. Sequeiros, S. Ang, Craig Clavin, John G. Upton, Cliff Ho, Auke van der Werf","doi":"10.1115/omae2021-63455","DOIUrl":"https://doi.org/10.1115/omae2021-63455","url":null,"abstract":"\u0000 This paper describes the continuous improvement efforts to manage the integrity status of the Southern North Sea subsea pipeline system in the context of free spanning. The dynamic free-spanning threat is typically attributed to a mobile seabed. Current and wave action are constantly moving and eroding sediment by means of sand wave migration and scouring. It can lead to a fluctuation in span characteristics with respect to span length, span height and location over time. It makes pipeline integrity demonstration and spans remediation challenges. Focus areas include (1) identifying regions where operational pipelines are susceptible to critical span formation (2) understanding the broader context of seabed mobility, supported by several years of multibeam echo sound and met ocean data (3) risk-ranking & criticality of span formation (4) developing simplified calculation tool that allows fatigue damage to be estimated and accumulated for every location along the pipeline, conservatively (5) optimising and incorporating risk/event-based survey requirements (6) identification of suitable remediation solutions and developing a decision flow chart to facilitate selection of fit for purpose remediation solutions, with respect to span configuration and the surrounding seabed features. The outcome has improved the robustness of span management, reduced “reactive” span remediation activities, and allowed application of sound technical theory to allocate pipeline traffic light integrity status regarding the observed free spans.","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":"126881993","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}

{"title":"Effect of the Installation Process on the Pullout Capacity of Helical Anchors","authors":"Abdul‐Kader El Haj, A. Soubra","doi":"10.1115/omae2021-62211","DOIUrl":"https://doi.org/10.1115/omae2021-62211","url":null,"abstract":"\u0000 In this paper, an advanced numerical method called Coupled Eulerian-Lagrangian (CEL) method is used for the prediction of the behavior of helical anchors in sandy soil under ultimate limit state ULS including the effect of anchor installation process. The CEL analysis allows one to overcome the drawback of the classical finite element FE method in the case of large deformation problems as it takes the advantages of both Lagrangian and Eulerian methodologies. Results have shown that the CEL analysis is relevant for the computation of the helical anchor pullout capacity. Indeed, the CEL analysis was able to rigorously determine the ultimate capacity of the anchor contrary to the classical FE method; the calculation via the CEL approach has been carried out for relatively large displacement values without encountering any problem of convergence. Furthermore, CEL analysis was able to simulate the installation process of the anchor and thus enables one to consider the effect of the soil disturbance induced by the installation process on the computed pullout capacity. The numerical simulations have shown that the pullout capacity of the helical anchor may be significantly decreased when considering the anchor installation effect.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"19 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":"127776309","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}

{"title":"Independent Design Verification of Deepwater SCRs for the Application in South China Sea","authors":"H. Yang, Yongming Cheng, Fanli Xu, Ning He","doi":"10.1115/omae2021-63906","DOIUrl":"https://doi.org/10.1115/omae2021-63906","url":null,"abstract":"\u0000 Through nearly 30 years of design and implementation, Steel Catenary Risers (SCRs) have been found to have the advantages of relatively low cost and good adaptability to floating platform’s motion. SCRs have been selected as the production and export riser solution for Lingshui 17-2 (termed LS17-2) field in South China Sea, which consists of a subsea production system, a deep-draft semi-submersible, and an export riser/pipeline. This paper investigates independent design verification of deepwater SCRs for the application in South China Sea.\u0000 This paper first introduces a SCR system for LS17-2 project. The field for this project is located in northern South China Sea, with water depth of 1220m to 1560m. This paper describes the design verification methodology, procedure, riser computer modelling, extreme challenges, findings, and technical discussions. The independent design verification includes riser sizing, adjacent riser interference, cathodic protection, dynamic strength analysis, Vortex-Induced Vibration (VIV) analysis, wave motion fatigue analysis, semi-submersible Vortex-Induced Motion (VIM) fatigue analysis, and riser installation. Sensitivity study was carried out to demonstrate the accuracy of the results and the robustness of the riser design.\u0000 SCR designs are extremely sensitive to environmental loading and the motion characteristics of a host platform. The independent design verification shows that the riser governing location of global performance is at the riser Touch Down Point (TDP) region. Compression forces in an SCR touchdown area can be caused by extreme or survival load cases. Among the fatigue damage sources, fatigue damage contributions are dominated by wave motion, VIM and VIV.\u0000 This paper finally summarizes the findings from the independent verification work. It concludes that the SCR system design for LS17-2 development meets the requirements of API 2RD design code.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"15 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":"127389992","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}

{"title":"An Alternative Carcass Design to Prevent Flow-Induced Pulsations in Flexibles","authors":"N. González Díez, S. Belfroid, T. Iversen Solfeldt, C. Kristiansen","doi":"10.1115/omae2021-62391","DOIUrl":"https://doi.org/10.1115/omae2021-62391","url":null,"abstract":"\u0000 Flow-induced pulsations (FLIP) are pressure oscillations generated inside of flexibles used in dry gas applications that can cause unacceptable vibration levels and eventually failure of equipment. Because of the design of inner layer of the flexibles, the carcass, the frequency of the pulsations is high, potentially leading to fatigue failures of adjacent structures in a relatively short time.\u0000 The traditional carcass is made of a steel strip formed into an interlocked s-shape in a series of preforming and winding steps. To enable bending of the pipe, gaps are present between each winding with a shape that can cause FLIP. The gaps can be reduced, and the profiles optimized, but they will always be able to generate FLIP at a certain gas velocity. To remove the risk of FLIP in dry gas projects and ensure that operator does not get operational constraints, an alternative carcass design has been developed. This is essentially a conventional agraff carcass but with an additional cover strip to close the gap, making the resulting carcass nearly smooth bore in nature. With a smooth bore this carcass can be used for flexibles which have a risk of FLIP or to produce pipes with a lower internal roughness. This alternative design can be manufactured and can therefore build on the large manufacturing and design experience of the traditional strip carcass.\u0000 This alternative carcass technology is to undergo a full qualification process, in which the risk of flow induced pulsations is an essential component. With the investigated alternative carcass design, the cavities present in the traditional agraff designs are covered. It is expected that the risk due to the appearance of FLIP is therefore eliminated. Theoretical analysis, numerical simulations and scaled experiments are used to explore the risk for the alternative technology to create FLIP. The theoretical analysis is based on existing knowledge and literature. The numerical simulations and scaled tests are done to generate direct evidence for the end statements resulting from the qualification process. Numerical simulations follow the power balance method presented by the same authors in earlier papers. The same applies to the techniques used for the scaled tests.\u0000 The main outcome of the qualification presented here are the pressure drop performance and the anti-FLIP capabilities of the design. The new design performs significantly better than the nominal design carcass for the same purpose. The pressure drop coefficients found are close to those expected for a normal, non-corrugated pipe, and thus the recommendation given by the API 17J standard does not apply to this design. The pressure drop coefficient is dependent on the installation direction of the flexible with respect to the flow. No signs of FLIP are found for the nominal design of the investigated carcass technology. This is the case for either installation direction. This is explained from a theoretical point of view, but also numerical a","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"33 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133171075","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}

{"title":"A KNN Based Collapse Methodology and Recent Qualification of Flexible Pipes in Deepwater Application","authors":"Linfa Zhu, V. Nogueira, Z. Tan","doi":"10.1115/omae2020-18304","DOIUrl":"https://doi.org/10.1115/omae2020-18304","url":null,"abstract":"\u0000 As the flexible pipe industry targets more on deepwater applications, collapse performance of flexible pipes becomes a key challenge due to the huge hydrostatic pressure during installation and service. The collapse strength of flexible pipes largely depends on the structural characteristics of carcass, pressure sheath and pressure armor layers. Therefore, the collapse prediction methodology involving a sound modeling of these layers is essential. Over the years, Baker Hughes have collected a large amount of collapse testing data. The prediction tool needs to be validated and calibrated against all the collapse tests for best accuracy. In this paper, the latest progress of the collapse prediction methodology and qualification tests are presented. A generalized collapse model was developed to predict the collapse pressure of flexible pipes. This model incorporates the advantages of both the weighted kNN regression technique and an analytical collapse model. It is able to reproduce the exact collapse pressure on the pipes tested and can predict the collapse pressure of other pipe designs not tested. As part of the qualification process, the capacity to prevent collapse must be demonstrated. Several flexible pipes were designed based on this generalized prediction methodology for deep water application, and pipe samples were manufactured using industrial production facilities for collapse tests. The results show that flexible pipes following current design guidelines are suitable for deepwater applications.","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":"117146001","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}

{"title":"Feasible Numerical Technique for Analysis of Offshore Pipelines and Risers","authors":"P. Trapper","doi":"10.1115/omae2020-18564","DOIUrl":"https://doi.org/10.1115/omae2020-18564","url":null,"abstract":"\u0000 A simple 2D numerical model for pipeline and riser configuration analyses is presented. The model considers large deformations of the pipe, pipe-seabed contact detection, pipe’s interaction with uneven inelastic seabed, environmental loading such as drag forces applied by the ocean currents, water surface level variations and incorporation of buoyancy modules.\u0000 The solution technique is based on a consistent minimization of the total potential energy of the deformed pipe discretized as a Riemann sum, which results in a system of nonlinear algebraic finite difference equations that is solved in an incremental/iterative manner. At each increment, the total potential energy is being updated, thus accounting for energy dissipation due to irrecoverable plastic deformation of the seabed and according to hydrodynamic drag forces. The whole pipe is treated as a single continuous segment.\u0000 To demonstrate the method, examples with several riser configurations and pipe-lay scenarios are presented. It is shown how on-bottom unevenness, including pits and hills, incorporation of buoyancy modules and tidal effects can affect pipeline or riser configurations and their internal forces. Results are compared to those obtained with Abaqus and appear to be in an excellent agreement.\u0000 The model presents simple and time-efficient way to analyze the pipe-lay or riser configurations with various boundary and loading conditions. The proposed model, contrary to commercial packages, which impose using time-consuming Graphical User Interface (GUI), allows for performing the series of analyses for varying geometric and/or material properties, and processing the results in reasonable time by single click.","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":"127693280","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}

{"title":"Feasibility Study of S-Lay Installation for Deepwater SCRs and Pipelines","authors":"Jing Hou, Chen Yu, Yongming Cheng, G. Bangalore, Hao Song","doi":"10.1115/omae2020-18377","DOIUrl":"https://doi.org/10.1115/omae2020-18377","url":null,"abstract":"\u0000 The J-lay and S-lay are two common methods for SCR and pipeline installations. When using the S-lay installation method, onboard welded pipe joints leave the vessel horizontally and are guided to the seabed over a stinger structure. The pipe is lowered using tensioners. With the advantage of high production rate, Slay can be a cost-effective solution for deepwater riser and pipeline installation. Based on HYSY201 installation vessel, this paper investigates the feasibility of S-lay installation for deepwater SCRs and pipelines to be used in South China Sea.\u0000 It first introduces the SCRs and pipelines to be used for a deep draft semi-submersible for the Lingshui 17-2 project. It then presents the S-lay installation vessel HYSY201 and S-lay configuration. The hydrodynamic motion analysis for a Response Amplitude Operator (RAO) was computered for HYSY201 in different environmental headings. With the site-specific metocean design basis, this paper presents an installation procedure, analysis methodology, and acceptance criteria.\u0000 The study covers different sizes of SCRs and pipelines to investigate the feasibility of S-lay installation. The study starts from the static installation analysis of SCRs and pipelines and includes different installation steps. The acceptance criteria are examined for the pipes at over bend and sag bend regions. The support reactions load on the stinger structure are reported at each step. The dynamic analysis is selectively performed to evaluate Dynamic Amplification Factors (DAFs) of support reaction loads especially for roller box supports on the stinger structure. The sensitivity of DAFs to wave parameters such as wave height and peak period is analyzed as well.\u0000 The extreme support reaction loads are computed for evaluating the strength performance of the stinger structure. The feasibility of S-lay installation for deepwater SCRs and pipelines is determined by the global performance of SCRs and pipelines, installation vessel hold back tension and A&R winch load capacity, and performance of the stinger structure.\u0000 Based on the study work, this paper finds the feasibility of S-lay installation of deepwater SCRs and pipelines for Lingshui 17-2 project using the installation vessel of HYSY201.","PeriodicalId":240325,"journal":{"name":"Volume 4: Pipelines, Risers, and Subsea Systems","volume":"30 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":"126564628","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}

{"title":"Finite Element Analysis of Trawl Pull-Over Behaviour of Pipe-in-Pipe With Residual Curvatures","authors":"Yi Yu, Kristian Norland","doi":"10.1115/omae2020-18206","DOIUrl":"https://doi.org/10.1115/omae2020-18206","url":null,"abstract":"\u0000 Subsea 7 is currently planning for the installation of PiP flowlines in the Norwegian Sea. A case study has been performed for a 8 × 12in PiP to be installed in a water depth between 320 m to 420 m. Fishing activities are frequent in this area. Therefore, the integrity of the pipeline in case of trawl pull-over must be checked. It is found that pipelines with residual curvatures could behave very differently from pipelines without residual curvatures when they are pulled over by trawl gear. However, the effect of residual curvature on pull-over resistance capacity of rigid pipelines has not been mentioned in DNVGL-RP-F111 [1]. Therefore, an optimised methodology involving FE analyses and Monte Carlo simulation has been used in this project to check the integrity of the pipe-in-pipe flowline for the trawl pull-over load case.\u0000 This paper focuses on the FE analyses of the pipe-in-pipe flowline pulled over by trawl gear. The related Monte Carlo simulation has been discussed elsewhere [2]. To understand in detail the behaviour of the pipeline with trawl pull-over loading, the pipeline was modelled using a combination of beam, shell and brick (solid) elements. The advantage of the model was demonstrated by comparing output from the model with corresponding output using beam elements. The effects of some result-sensitive parameters were studied, which include centralizer location, pressure, trawl contact area and wall thickness. Special attention was paid to these parameters because their effects are not able to be captured with the normal beam element. Finally, the impact of residual curvatures on the trawl pull-over behaviour was studied. It was found that the pipeline pull-over resistance capacity is sensitive to residual curvature direction and contact location, but not sensitive to RC spacing and RC shape. Based on the advantage of this analysis methodology, it is believed to be a good option for pipeline trawl pull-over analysis, especially with complex pipeline configuration.","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":"115200678","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}