As there are no specific guidelines on design of subsea pipelines crossing active seismic faults, methods for land buried pipelines have been applied to. Taking the large seismic fault movement into account, this pape...As there are no specific guidelines on design of subsea pipelines crossing active seismic faults, methods for land buried pipelines have been applied to. Taking the large seismic fault movement into account, this paper proposes improved methods for seismic designs of subsea pipelines by comprehensively investigating the real constraining of soil on the pipelines, the interaction processes of soil with the pipeline, the plastic slippage of the soil, and the elastic-plastic properties of the pipeline materials. New formulas are given to calculate the length of transition section and its total elongation. These formulas are more reasonable in mechanism, and more practical for seismic design of subsea pipelines crossing active faults.展开更多
The aim of this research is to develop an algorithm and application that can perform real-time monitoring of the safety operation of offshore platforms and subsea gas pipelines as well as determine the need for ship i...The aim of this research is to develop an algorithm and application that can perform real-time monitoring of the safety operation of offshore platforms and subsea gas pipelines as well as determine the need for ship inspection using data obtained from automatic identification system(AIS).The research also focuses on the integration of shipping database,AIS data,and others to develop a prototype for designing a real-time monitoring system of offshore platforms and pipelines.A simple concept is used in the development of this prototype,which is achieved by using an overlaying map that outlines the coordinates of the offshore platform and subsea gas pipeline with the ship’s coordinates(longitude/latitude)as detected by AIS.Using such information,we can then build an early warning system(EWS)relayed through short message service(SMS),email,or other means when the ship enters the restricted and exclusion zone of platforms and pipelines.The ship inspection system is developed by combining several attributes.Then,decision analysis software is employed to prioritize the vessel’s four attributes,including ship age,ship type,classification,and flag state.Results show that the EWS can increase the safety level of offshore platforms and pipelines,as well as the efficient use of patrol boats in monitoring the safety of the facilities.Meanwhile,ship inspection enables the port to prioritize the ship to be inspected in accordance with the priority ranking inspection score.展开更多
Conventional pipeline corrosion assessment methods result in failure pressure predictions that are conservative, especially for pipelines that are subjected to internal pressure and axial compressive stress. Alternati...Conventional pipeline corrosion assessment methods result in failure pressure predictions that are conservative, especially for pipelines that are subjected to internal pressure and axial compressive stress. Alternatively, numerical methods may be used. However, they are computationally expensive. This paper proposes an analytical equation based on finite element analysis (FEA) for failure pressure prediction of a high toughness corroded pipeline with a single corrosion defect subjected to internal pressure and axial compressive stress. The equations were developed based on the weights and biases of an Artificial Neural Network (ANN) model trained with failure pressure from finite element analysis (FEA) of a high toughness pipeline for various defect depths, defect lengths, and axial compressive stresses. The proposed model was validated against actual burst test results for high toughness materials and was found to be capable of making accurate predictions with a coefficient of determination (R<sup>2</sup>) of 0.99. An extensive parametric study using the proposed model was subsequently conducted to determine the effects of defect length, defect depth, and axial compressive stress on the failure pressure of a corroded pipe with a single defect. The application of ANN together with FEA has shown promising results in the development of an empirical solution for the failure pressure prediction of pipes with a single corrosion defect subjected to internal pressure and axial compressive stress.展开更多
To study the collapse of imperfect subsea pipelines, a 2D high-order nonlinear model is developed. In this model, the large deformation of the pipes is considered by retaining the high-order nonlinear terms of strain....To study the collapse of imperfect subsea pipelines, a 2D high-order nonlinear model is developed. In this model, the large deformation of the pipes is considered by retaining the high-order nonlinear terms of strain. In addition, the J2 plastic flow theory is adopted to describe the elastoplastic constitutive relations of material. The quasi-static process of collapse is analyzed by the increment method. For each load step, the equations based on the principle of virtual work are presented and solved by the discrete Newton's method. Furthermore, finite element simulations and full-scale experiments were preformed to validate the results of the model. Research on the major influencing factors of collapse pressure, including D/t, material type and initial ovality, is also presented.展开更多
In this study,we propose a method for estimating the amount of expansion that occurs in subsea pipelines,which could be applied in the design of robust structures that transport oil and gas from offshore wells.We begi...In this study,we propose a method for estimating the amount of expansion that occurs in subsea pipelines,which could be applied in the design of robust structures that transport oil and gas from offshore wells.We begin with a literature review and general discussion of existing estimation methods and terminologies with respect to subsea pipelines.Due to the effects of high pressure and high temperature,the production of fluid from offshore wells is typically caused by physical deformation of subsea structures,e.g.,expansion and contraction during the transportation process.In severe cases,vertical and lateral buckling occurs,which causes a significant negative impact on structural safety,and which is related to on-bottom stability,free-span,structural collapse,and many other factors.In addition,these factors may affect the production rate with respect to flow assurance,wax,and hydration,to name a few.In this study,we developed a simple and efficient method for generating a reliable pipe expansion design in the early stage,which can lead to savings in both cost and computation time.As such,in this paper,we propose an applicable diagram,which we call the standard dimensionless ratio(SDR)versus virtual anchor length(LA)diagram,that utilizes an efficient procedure for estimating subsea pipeline expansion based on applied reliable scenarios.With this user guideline,offshore pipeline structural designers can reliably determine the amount of subsea pipeline expansion and the obtained results will also be useful for the installation,design,and maintenance of the subsea pipeline.展开更多
In order to theoretically study the buckle propagation of subsea pipelines with slip-on buckle arrestors, a two-dimensional ring model was set up to represent the pipeline and a nonlinear spring model was adopted to s...In order to theoretically study the buckle propagation of subsea pipelines with slip-on buckle arrestors, a two-dimensional ring model was set up to represent the pipeline and a nonlinear spring model was adopted to simulate the contact between pipeline's inner walls and between pipeline's outer wall and slip-on buckle arrestor's inner wall during buckle propagation. In addition, some reverse springs are added to prevent the wall of left and right sides separating from the inner wall of slip-on buckle arrestors. Considering large deformation kinematics relations and the elastic-plastic constitutive relation of material, balance equations were established with the principle of virtual work. The variation of external pressure with respect to the cross-sectional area of pipelines was analyzed, and the lower bound of the crossover pressure of slip-on buckle arrestors was calculated based on Maxwell's energy balance method. By comparing the theoretical results with experiment and finite element numerical simulation, the theoretical method is proved to be correct and reliable.展开更多
The deep‐sea ground contains a huge amount of energy and mineral resources,for example,oil,gas,and minerals.Various infrastructures such as floating structures,seabed structures,and foundations have been developed to...The deep‐sea ground contains a huge amount of energy and mineral resources,for example,oil,gas,and minerals.Various infrastructures such as floating structures,seabed structures,and foundations have been developed to exploit these resources.The seabed structures and foundations can be mainly classified into three types:subsea production structures,offshore pipelines,and anchors.This study reviewed the development,installation,and operation of these infrastructures,including their structures,design,installation,marine environment loads,and applications.On this basis,the research gaps and further research directions were explored through this literature review.First,different floating structures were briefly analyzed and reviewed to introduce the design requirements of the seabed structures and foundations.Second,the subsea production structures,including subsea manifolds and their foundations,were reviewed and discussed.Third,the basic characteristics and design methods of deep‐sea pipelines,including subsea pipelines and risers,were analyzed and reviewed.Finally,the installation and bearing capacity of deep‐sea subsea anchors and seabed trench influence on the anchor were reviewed.Through the review,it was found that marine environment conditions are the key inputs for any offshore structure design.The fabrication,installation,and operation of infrastructures should carefully consider the marine loads and geological conditions.Different structures have their own mechanical problems.The fatigue and stability of pipelines mainly depend on the soil‐structure interaction.Anchor selection should consider soil types and possible trench formation.These focuses and research gaps can provide a helpful guide on further research,installation,and operation of deep‐sea structures and foundations.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 50979113)the National High Technology Research and Development Program of China (863 Program, Grant No. 2006AA09A105)the China National Offshore Oil Corporation
文摘As there are no specific guidelines on design of subsea pipelines crossing active seismic faults, methods for land buried pipelines have been applied to. Taking the large seismic fault movement into account, this paper proposes improved methods for seismic designs of subsea pipelines by comprehensively investigating the real constraining of soil on the pipelines, the interaction processes of soil with the pipeline, the plastic slippage of the soil, and the elastic-plastic properties of the pipeline materials. New formulas are given to calculate the length of transition section and its total elongation. These formulas are more reasonable in mechanism, and more practical for seismic design of subsea pipelines crossing active faults.
文摘The aim of this research is to develop an algorithm and application that can perform real-time monitoring of the safety operation of offshore platforms and subsea gas pipelines as well as determine the need for ship inspection using data obtained from automatic identification system(AIS).The research also focuses on the integration of shipping database,AIS data,and others to develop a prototype for designing a real-time monitoring system of offshore platforms and pipelines.A simple concept is used in the development of this prototype,which is achieved by using an overlaying map that outlines the coordinates of the offshore platform and subsea gas pipeline with the ship’s coordinates(longitude/latitude)as detected by AIS.Using such information,we can then build an early warning system(EWS)relayed through short message service(SMS),email,or other means when the ship enters the restricted and exclusion zone of platforms and pipelines.The ship inspection system is developed by combining several attributes.Then,decision analysis software is employed to prioritize the vessel’s four attributes,including ship age,ship type,classification,and flag state.Results show that the EWS can increase the safety level of offshore platforms and pipelines,as well as the efficient use of patrol boats in monitoring the safety of the facilities.Meanwhile,ship inspection enables the port to prioritize the ship to be inspected in accordance with the priority ranking inspection score.
文摘Conventional pipeline corrosion assessment methods result in failure pressure predictions that are conservative, especially for pipelines that are subjected to internal pressure and axial compressive stress. Alternatively, numerical methods may be used. However, they are computationally expensive. This paper proposes an analytical equation based on finite element analysis (FEA) for failure pressure prediction of a high toughness corroded pipeline with a single corrosion defect subjected to internal pressure and axial compressive stress. The equations were developed based on the weights and biases of an Artificial Neural Network (ANN) model trained with failure pressure from finite element analysis (FEA) of a high toughness pipeline for various defect depths, defect lengths, and axial compressive stresses. The proposed model was validated against actual burst test results for high toughness materials and was found to be capable of making accurate predictions with a coefficient of determination (R<sup>2</sup>) of 0.99. An extensive parametric study using the proposed model was subsequently conducted to determine the effects of defect length, defect depth, and axial compressive stress on the failure pressure of a corroded pipe with a single defect. The application of ANN together with FEA has shown promising results in the development of an empirical solution for the failure pressure prediction of pipes with a single corrosion defect subjected to internal pressure and axial compressive stress.
基金Supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2011ZX05026-005)the National Natural Science Foundation of China(No.51239008)the National Basic Research Program of China("973"Program,No.2014CB046800)
文摘To study the collapse of imperfect subsea pipelines, a 2D high-order nonlinear model is developed. In this model, the large deformation of the pipes is considered by retaining the high-order nonlinear terms of strain. In addition, the J2 plastic flow theory is adopted to describe the elastoplastic constitutive relations of material. The quasi-static process of collapse is analyzed by the increment method. For each load step, the equations based on the principle of virtual work are presented and solved by the discrete Newton's method. Furthermore, finite element simulations and full-scale experiments were preformed to validate the results of the model. Research on the major influencing factors of collapse pressure, including D/t, material type and initial ovality, is also presented.
基金Supported by the Technology Innovation Program(Grant No.:10053121 and 10051279) funded by the Ministry of Trade,Industry&Energy(MI,Korea)
文摘In this study,we propose a method for estimating the amount of expansion that occurs in subsea pipelines,which could be applied in the design of robust structures that transport oil and gas from offshore wells.We begin with a literature review and general discussion of existing estimation methods and terminologies with respect to subsea pipelines.Due to the effects of high pressure and high temperature,the production of fluid from offshore wells is typically caused by physical deformation of subsea structures,e.g.,expansion and contraction during the transportation process.In severe cases,vertical and lateral buckling occurs,which causes a significant negative impact on structural safety,and which is related to on-bottom stability,free-span,structural collapse,and many other factors.In addition,these factors may affect the production rate with respect to flow assurance,wax,and hydration,to name a few.In this study,we developed a simple and efficient method for generating a reliable pipe expansion design in the early stage,which can lead to savings in both cost and computation time.As such,in this paper,we propose an applicable diagram,which we call the standard dimensionless ratio(SDR)versus virtual anchor length(LA)diagram,that utilizes an efficient procedure for estimating subsea pipeline expansion based on applied reliable scenarios.With this user guideline,offshore pipeline structural designers can reliably determine the amount of subsea pipeline expansion and the obtained results will also be useful for the installation,design,and maintenance of the subsea pipeline.
基金supported by the National Natural Science Foundation of China (Grant No. 51609222)the Natural Science Foundation of Shandong Province (Grant No. ZR2016EEB03)+2 种基金the Opening Fund of State Key Laboratory of Coastal and Offshore Engineering (Dalian University of Technology) (Grant No. LP1505)the Opening Fund of State Key Laboratory of Hydraulic Engineering Simulation and Safety (Tianjin University) (Grant No. HESS-1602)the Fundamental Research Funds for the Central Universities (Grant No. 201513039)
文摘In order to theoretically study the buckle propagation of subsea pipelines with slip-on buckle arrestors, a two-dimensional ring model was set up to represent the pipeline and a nonlinear spring model was adopted to simulate the contact between pipeline's inner walls and between pipeline's outer wall and slip-on buckle arrestor's inner wall during buckle propagation. In addition, some reverse springs are added to prevent the wall of left and right sides separating from the inner wall of slip-on buckle arrestors. Considering large deformation kinematics relations and the elastic-plastic constitutive relation of material, balance equations were established with the principle of virtual work. The variation of external pressure with respect to the cross-sectional area of pipelines was analyzed, and the lower bound of the crossover pressure of slip-on buckle arrestors was calculated based on Maxwell's energy balance method. By comparing the theoretical results with experiment and finite element numerical simulation, the theoretical method is proved to be correct and reliable.
基金Key Research and Development program of Zhejiang ProvinceGrant/Award Number:2018C03031+3 种基金The Open Foundation of Key Laboratory of Offshore Geotechnical and Material Engineering of Zhejiang Province,Grant/Award Number:OGME21003Natural Science Foundation of Zhejiang Province,Grant/Award Numbers:LHZ19E090003,LY15E090002Norges Forskningsr?d,Grant/Award Number:OGME21003National Natural Science Foundation of China,Grant/Award Numbers:51209183,51779220,52101334。
文摘The deep‐sea ground contains a huge amount of energy and mineral resources,for example,oil,gas,and minerals.Various infrastructures such as floating structures,seabed structures,and foundations have been developed to exploit these resources.The seabed structures and foundations can be mainly classified into three types:subsea production structures,offshore pipelines,and anchors.This study reviewed the development,installation,and operation of these infrastructures,including their structures,design,installation,marine environment loads,and applications.On this basis,the research gaps and further research directions were explored through this literature review.First,different floating structures were briefly analyzed and reviewed to introduce the design requirements of the seabed structures and foundations.Second,the subsea production structures,including subsea manifolds and their foundations,were reviewed and discussed.Third,the basic characteristics and design methods of deep‐sea pipelines,including subsea pipelines and risers,were analyzed and reviewed.Finally,the installation and bearing capacity of deep‐sea subsea anchors and seabed trench influence on the anchor were reviewed.Through the review,it was found that marine environment conditions are the key inputs for any offshore structure design.The fabrication,installation,and operation of infrastructures should carefully consider the marine loads and geological conditions.Different structures have their own mechanical problems.The fatigue and stability of pipelines mainly depend on the soil‐structure interaction.Anchor selection should consider soil types and possible trench formation.These focuses and research gaps can provide a helpful guide on further research,installation,and operation of deep‐sea structures and foundations.
