An observer-based adaptive backstepping boundary control is proposed for vibration control of flexible offshore riser systems with unknown nonlinear input dead zone and uncertain environmental disturbances.The control...An observer-based adaptive backstepping boundary control is proposed for vibration control of flexible offshore riser systems with unknown nonlinear input dead zone and uncertain environmental disturbances.The control algorithm can update the control law online through real-time data to make the controller adapt to the environment and improve the control precision.Specifically,based on the adaptive backstepping framework,virtual control laws and Lyapunov functions are designed for each subsystem.Three direction interference observers are designed to track the timevarying boundary disturbance.On this basis,the inverse of the dead zone and linear state transformation are used to compensate for the original system and eliminate the adverse effects of the dead zone.In addition,the stability of the closed-loop system is proven by Lyapunov stability theory.All the system states are bounded,and the vibration offset of the riser converges to a small area of the initial position.Finally,four examples of flexible marine risers are simulated in MATLAB to verify the effectiveness of the proposed controller.展开更多
The mooring and riser system is the most critical part of an ofshore oil terminal.Traditionally,these two parts are designed separately without considering the nonlinear interaction between them.Thus,the present paper...The mooring and riser system is the most critical part of an ofshore oil terminal.Traditionally,these two parts are designed separately without considering the nonlinear interaction between them.Thus,the present paper aims to develop an inte-grated design process for riser systems with a lazy-S confguration and mooring systems in the ofshore catenary anchor leg mooring(CALM)oil terminal.One of the important criteria considered in this integrated design is the ofset diagram and safe operation zone(SAFOP)related to the mooring system and the riser,respectively.These two diagrams are obtained separately by diferent analyses;therefore,codes or standards are available separately for two components.In this methodol-ogy,the diagrams of both risers and mooring lines are incorporated into a single spiral,thus identifying the safe and failure zones of risers and the mooring lines of the oil terminal.This,in turn,leads to substantial benefts in terms of overall system response,cost reduction,and safety to the ofshore oil terminal.To implement this process,three diferent riser lengths with the lazy-S confguration are considered at three diferent sea depths at the terminal installation site.For each condition,the integrated design of the mooring system and riser is executed according to the derived procedure.Then,coupled dynamic models,wherein both buoys and hoses are included,are developed using OrcaFlex.Results show that the criteria of the relevant regulations are not satisfed by reducing the length of the riser relative to the designed size.Further,as water depth increases,this type of riser confguration shows good coupled performance while interacting with the mooring system.In the cross ofset mode,the maximum margin is created between the ofset diagram and the SAFOP diagram,while the most critical dynamic response of the tanker and terminal system occurs in the near and far modes.Therefore,with this method,the best position for the riser direction with the tanker direction is 90°in the best case.展开更多
A multibody system including a drilling riser system,tensioners and a floating platform is key equipment for offshore oil and gas drilling.Most of the previous studies only focus on the drilling riser system rather th...A multibody system including a drilling riser system,tensioners and a floating platform is key equipment for offshore oil and gas drilling.Most of the previous studies only focus on the drilling riser system rather than the multibody system.Mechanical characteristics of the deepwater drilling riser system cannot be analyzed accurately in a simplified model.Therefore,a three-dimensional multibody analysis program is developed.The static and dynamic characteristics of the deepwater drilling riser system under different platform motions are analyzed based on the developed program.The results show that the static displacement of the riser system with tensioners is smaller than that without tensioners,which means the tensioners can suppress the deformation of the riser system.Under surge and sway motions of the platform,the dynamic displacement of the riser system with tensioners is also smaller than that without tensioners due to the tensioner suppression effect.Besides,the heave motion induces a uniform axial vibration of the riser system,while roll and pitch motions excite the riser system to vibrate laterally.Compared with the stress amplitude due to surge and sway motions,the stress amplitude of the riser system due to heave,roll and pitch motions is relatively small but cannot be neglected.展开更多
Stress Joint （SJ） plays a key role in the Top Tensioned Riser （TTR） system for deep water engineering. A preliminary design method of tapered SJ is proposed in the paper, which could help designers obtain accurate...Stress Joint （SJ） plays a key role in the Top Tensioned Riser （TTR） system for deep water engineering. A preliminary design method of tapered SJ is proposed in the paper, which could help designers obtain accurate design data. After a further sensitive analysis is carried out, the related parameters choice and control methods are recommended in the engineering practice. By taking the extreme environment conditions into consideration, the effects of bending stress reduction and curve control are analyzed, and the 3-D FE models are established by ABQOUS for numerical evaluation to verify the correctness of design results. At last, dynamic analysis and fatigue analysis, based on actual project, are carried out with designed stress joint. The analysis results prove the feasibility and guidance of this method in the practical engineering applications.展开更多
In this study,the dynamics of the tendon/top tension riser(TTR)system of a tension-leg platform(TLP)are investigated through an experiment and by using absolute nodal coordinate formulation(ANCF).First,the model test ...In this study,the dynamics of the tendon/top tension riser(TTR)system of a tension-leg platform(TLP)are investigated through an experiment and by using absolute nodal coordinate formulation(ANCF).First,the model test of the TLP system is conducted in the water tank of Harbin Engineering University to examine the motion response of the TLP and the dynamic response characteristics of the tendon and TTR.The test scale ratio is set to 1:66.3.Then,on the basis of the ANCF,the stiffness,external load,and mass matrices of the element are deduced to establish the motion equation of the tendon/riser.Finally,the static and dynamic characteristics of the tendon/TTR system of TLP are analyzed systematically by using the ANCF method.The results are compared with commercial software and test results.The motion response of tendon/TTR is affected by the TLP movement and environmental load simultaneously.The analysis proves the effectiveness and accuracy of the ANCF method despite the low number of riser units,suggesting the superiority of the ANCF method for calculating the dynamics of tendon/riser in the field of ocean engineering.展开更多
When using topside choking to eliminate severe slugging in offshore pipeline-riser systems,the resulting stability and effectiveness depend critically on the choice of variables in the associated control model.In this...When using topside choking to eliminate severe slugging in offshore pipeline-riser systems,the resulting stability and effectiveness depend critically on the choice of variables in the associated control model.In this study,both potential process variables and manipulated variables are investigated via manual choking experiments.Monotonicity and linearity are adopted as principles for selecting the optimal variables,and the availability of signals in an offshore field is also considered.Both amplitude-domain and time-domain variables are studied,of which five are recommended as the process variable,while the resistance factor of the choking valve is the optimal manipulated variable;other variables may act as auxiliary variables in the control model.How to determine the set value of the process variable is also discussed.Validation experiments with automatic control show that the optimized variables enable faster stabilization.This study offers a reference for the design of slugging control for offshore fields.展开更多
The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich i...The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich in deep-sea polymetallic nodules.These nodules,which are nodular and unevenly distributed in seafloor sediments,have significant industrial exploitation value.Over the decades,the deep-sea mining industry has increasingly adopted systems that combine rigid and flexible risers supported by large surface mining vessels.However,current systems face economic and structural stability challenges,hindering the development of deep-sea mining technology.This paper proposes a new structural design for a deep-sea mining system based on flexible risers,validated through numerical simulations and experimental research.The system composition,function and operational characteristics are comprehensively introduced.Detailed calculations determine the production capacity of the deep-sea mining system and the dimensions of the seabed mining subsystem.Finite element numerical simulations analyze the morphological changes of flexible risers and the stress conditions at key connection points under different ocean current incident angles.Experimental research verifies the feasibility of collaborative movement between two tethered underwater devices.The proposed deep-sea mining system,utilizing flexible risers,significantly advances the establishment of a commercial deep-sea mining system.The production calculations and parameter determinations provide essential references for the system’s future detailed design.Furthermore,the finite element simulation model established in this paper provides a research basis,and the method established in this paper offers a foundation for subsequent research under more complex ocean conditions.The control strategy for the collaborative movement between two tethered underwater devices provides an effective solution for deep-sea mining control systems.展开更多
A new hang-off system has been proposed to improve the security of risers in hang-off modes during typhoons.However,efficient anti-typhoon evacuation strategies have not been investigated.Optimiza-tion model and metho...A new hang-off system has been proposed to improve the security of risers in hang-off modes during typhoons.However,efficient anti-typhoon evacuation strategies have not been investigated.Optimiza-tion model and method for the anti-typhoon evacuation strategies should be researched.Therefore,multi-objective functions are proposed based on operation time,evacuation speed stability,and steering stability.An evacuation path model and a dynamic model of risers with the new hang-off system are developed for design variables and constraints.A multi-objective optimization model with high-dimensional variables and complex constraints is established.Finally,a three-stage optimization method based on genetic algorithm,least square method,and the penalty function method is proposed to solve the multi-objective optimization model.Optimization results show that the operation time can be reduced through operation parameter optimization,especially evacuation heading optimization.The optimal anti-typhoon strategy is evacuation with all risers suspended along a variable path when the direction angle is large,while evacuation with all risers suspended along a straight path at another di-rection angle.Besides,the influencing factors on anti-typhoon evacuation strategies indicate that the proposed optimization model and method have strong applicability to working conditions and remarkable optimization effects.展开更多
This paper investigates the recoil control of the deepwater drilling riser system with nonlinear tension force and energy-bounded friction force under the circumstances of limited network resources and unreliable comm...This paper investigates the recoil control of the deepwater drilling riser system with nonlinear tension force and energy-bounded friction force under the circumstances of limited network resources and unreliable communication.Different from the existing linearization modeling method,a triangle-based polytope modeling method is applied to the nonlinear riser system.Based on the polytope model,to improve resource utilization and accommodate random data loss and communication delay,an asynchronous gain-scheduled control strategy under a hybrid event-triggered scheme is proposed.An asynchronous linear parameter-varying system that blends input delay and impulsive update equation is presented to model the nonlinear networked recoil control system,where the asynchronous deviation bounds of scheduling parameters are calculated.Resorting to the Lyapunov-Krasovskii functional method,some solvable conditions of disturbance attenuation analysis and recoil control design are derived such that the resulting networked system is exponentially mean-square stable with prescribed H∞performance.The obtained numerical results verified that the proposed nonlinear networked control method can achieve a better recoil response of the riser system with less transmission data compared with the linear control method.展开更多
The safety of risers in hang-off states is a vital challenge in offshore oil and gas engineering.A new hang-off system installed on top of risers is proposed for improving the security of risers.This approach leads to...The safety of risers in hang-off states is a vital challenge in offshore oil and gas engineering.A new hang-off system installed on top of risers is proposed for improving the security of risers.This approach leads to a challenging problem:coupling the dynamics of risers with a new hang-off system combined with multiple structures and complex constraints.To accurately analyze the dynamic responses of the coupled system,a coupled dynamic model is established based on the Euler-Bernoulli beam-column theory and penalty function method.A comprehensive analysis method is proposed for coupled dynamic analysis by combining the finite element method and the Newmarkβmethod.An analysis program is also developed in MATLAB for dynamic simulation.The simulation results show that the dynamic performances of the risers at the top part are significantly improved by the new hang-off system,especially the novel design,which includes the centralizer and articulation joint.The bending moment and lateral deformation of the risers at the top part decrease,while the hang-off joint experiences a great bending moment at the bottom of the lateral restraint area which requires particular attention in design and application.The platform navigation speed range under the safety limits of risers expands with the new hang-off system in use.展开更多
With the increasing exploration of oil and gas into deep waters,the necessity for material development increases for lighter conduits such as composite marine risers,in the oil and gas industry.To understand the resea...With the increasing exploration of oil and gas into deep waters,the necessity for material development increases for lighter conduits such as composite marine risers,in the oil and gas industry.To understand the research knowledge on this novel area,there is a need to have a bibliometric analysis on composite marine risers.A research methodology was developed whereby the data retrieval was from SCOPUS database from 1977–2023.Then,VOSviewer was used to visualize the knowledge maps.This study focuses on the progress made by conducting knowledge mapping and scientometric review on composite marine risers.This scientometric analysis on the subject shows current advances,geographical activities by countries,authorship records,collaborations,funders,affiiliations,co‑occurrences,and future research areas.It was observed that the research trends recorded the highest publication volume in the U.S.A.,but less cluster affiiliated,as it was followed by countries like the U.K.,China,Nigeria,Australia and Singapore.Also,thisfiield has more conference papers than journal papers due to the challenge of adaptability,acceptance,qualifiication,and application of composite marine risers in the marine industry.Hence,there is a need for more collaborations on composite marine risers and more funding to enhance the research trend.展开更多
By large-scale cold mold experiments,pressure pulsation signals within the jet influence zone of riser reactor are processed by using Hilbert-Huang analysis(HHT)in this study.Effects of different jet forms and operati...By large-scale cold mold experiments,pressure pulsation signals within the jet influence zone of riser reactor are processed by using Hilbert-Huang analysis(HHT)in this study.Effects of different jet forms and operating conditions on the intrinsic mode function(IMF)energy and Hilbert-Huang spectrum are compared.Results show that the IMF energy and Hilbert-Huang spectrum of pressure pulsation signals show significant differences under the influence of upward and downward jets.Moreover,the change of jet velocity will also lead to significant changes in IMF energy and Hilbert-Huang spectrum.Among them,energy values and energy proportions corresponding to high-frequency pressure pulsations show a good correlation with the jet velocity.On this basis,energy value and energy proportion data in the high frequency range of the original pressure signal are clustered and analyzed by using the K-means clustering algorithm.Based on clustering results,the jet influence zone of riser can be defined into three regions.From partitioning results,it is found that the introduction of downward inclined jets could effectively improve the gas-solid mixing in the feed injection zone of riser.展开更多
Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce f...Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce fatigue failure and even cause unpredictable drilling accidents.Therefore,it is important to study the ViV characteristics of deepwater drilling riser and reveal the main controlling factors for ensuring the safe and efficient operation of deepwater drilling engineering.In this paper,the ViV of deepwater drilling riser is numerically simulated in time domain based on the discrete vortex method(DvM).A hydrodynamic analysis model and governing equation of VIV is proposed with considering the effect of riser motion using DVM and slice method,where the governing equation is solved by Runge-Kutta method.Model validation is performed,which verified the correctness and accuracy of the mechanical model and the solution method.On this basis,the influence of the number of control points,current velocity,riser outer diameter,shear flow and top tension on the ViV characteristics of deepwater drilling risers are discussed in detail.The results show that with the increase of current velocity,the vibration amplitude of deepwater drilling riser decreases obviously,while the vibration frequency increases gradually.However,if the outer diameter of riser increases,the vibration amplitude increases,while the vibration frequency decreases gradually.The top tension also has great influence on the VIV of riser.When the top tension is 1.25 G,the VIV is suppressed to a certain extent.This study has guiding significance for optimal design and engineering control of deepwater drilling riser.展开更多
This study proposed a novel experimental platform to conduct dynamic loading tests of a truncated model steel catenary riser(SCR)within the touchdown zone(TDZ).The facilities of the platform,including a soil tank,a lo...This study proposed a novel experimental platform to conduct dynamic loading tests of a truncated model steel catenary riser(SCR)within the touchdown zone(TDZ).The facilities of the platform,including a soil tank,a loading system,and a soil stirring system,are introduced in detail.A steel pipe with the same diameter as the in situ SCR has been used in the laboratory tests to investigate the vertical motion of the pipe and the effect of the trench on the lateral motion.As the amplitude of the vertical motion increases,the depth of the trench deepens,the bending moment range increases,and the excess pore water pressure at the bottom of the pipeline first accumulates and then dissipates during loading.The development trend of the trench depth and the influence of the soil strength on the SCR bending moment are also studied.During the test,a seabed trench develops,and its shape is similar to that of the in situ trench.展开更多
Steel lazy-wave riser(SLWR)is one of the key technical components of offshore oil-gas production systems and is widely utilized in deepwater areas.On the basis of the vector form intrinsic finite element(VFIFE)method,...Steel lazy-wave riser(SLWR)is one of the key technical components of offshore oil-gas production systems and is widely utilized in deepwater areas.On the basis of the vector form intrinsic finite element(VFIFE)method,this study develops a reasonable numerical model for the SLWR to investigate the effects of the buoyancy section on its mechanical characteristics.In the SLWR model,the buoyancy section is simulated using an equivalent riser segment with the same outer diameter and unit weight.The riser is considered to be composed of a series of space vector particles connected by elements,and virtual reverse motions are applied to establish the fundamental equations of forces and displacements.The explicit central difference technique is used to solve the governing equations for particle motion within the riser through programming implementation.To provide a detailed explanation of the process by which the SLWR achieves a stable lazy-wave configuration,a numerical model of a 2800-m-long riser is established at a water depth of 1600 m,and the feasibility of this model for riser behavior analysis is validated.The remarkable influences of the position,length,number and spacing of the buoyancy section on the mechanical behavior of the SLWR are observed,which provides a theoretical foundation for the optimal design of the SLWR in deepwaters.展开更多
In this study,we develop an adaptive neural network based boundary control method for a flexible marine riser system with unknown nonlinear disturbances and output constraints to suppress vibrations.We begin with desc...In this study,we develop an adaptive neural network based boundary control method for a flexible marine riser system with unknown nonlinear disturbances and output constraints to suppress vibrations.We begin with describing the dynamic behavior of the riser system using a distributed parameter system with partial differential equations.To compensate for the effect of nonlinear disturbances,we construct a neural network based boundary controller using a radial basis neural network to reduce vibrations.Under the proposed boundary controller,the state of the riser is guaranteed to be uniformly bounded based on the Lyapunov method.The proposed methodology provides a way to integrate neural networks into boundary control for other flexible robotic manipulator systems.Finally,numerical simulations are given to demonstrate the effectiveness of the proposed control method.展开更多
The effect of the surfactant additive on the upward intermittent flows in a pipeline-riser system is studied experimentally, in a 3 m long horizontal pipe connected to a Perspex pipe of 2.0 m long and 25 mm in diamete...The effect of the surfactant additive on the upward intermittent flows in a pipeline-riser system is studied experimentally, in a 3 m long horizontal pipe connected to a Perspex pipe of 2.0 m long and 25 mm in diameter, inclined to the horizontal plane by 7？, followed by the vertical PVC riser of 3.5 m high and 25 mm in diameter, operating at the atmospheric end pressure. Based on the analysis of the pressure signal and the visual observation of the riser, it is shown that the additive of surfactant to the carrying liquid makes bubbles smaller in size but much larger in number in the upward intermittent flows. In addition, the additive of surfactant to a two-phase flow does not have a significant impact on the in-situ gas fraction, the pressure drop and the frequency of the liquid slug, but it reduces significantly the velocity of the liquid slug. When the superficial liquid velocity is set, an exponential relationship between the dimensionless velocity of the liquid slug and the Webber number can be obtained. These results might be used for estimating the characteristic parameters of the upward intermittent flow based upon the input operating conditions.展开更多
An S-lay crane barge,named CNOOC 201,has been built for pipe laying in deepwater oil/gas fields in the South China Sea.It is due to be commissioned by the end of the year 2010.A special lifting system is developed to ...An S-lay crane barge,named CNOOC 201,has been built for pipe laying in deepwater oil/gas fields in the South China Sea.It is due to be commissioned by the end of the year 2010.A special lifting system is developed to meet the challenge that installing deepwater risers from an S-lay barge is difficult and has not been achieved.The purpose of this paper was to investigate the model test on such an innovative system,which has to be done before field application.By applying the similarity theory,the movement of the S-lay barge is simulated through a six degrees-of-freedom motion platform,and a truncated model riser is utilized for the model testing.The displacement and force boundary conditions at the truncated position of the riser are obtained from the catenary governing equation and become realized by a slideway cart and a loading system designed to control the configuration of the model riser,which presents a similar configuration to a real riser in deepwater.The test results are in very good agreement with theoretical calculations,showing that the active truncated test is applicable for controlling the configuration of the deepwater riser in model testing investigation.展开更多
Along with the consumption increase of the petroleum products, more countries have transferred their attentions to the offshore fields, especially the deepwater oil and gas reserves. For deepwater exploitation, the ri...Along with the consumption increase of the petroleum products, more countries have transferred their attentions to the offshore fields, especially the deepwater oil and gas reserves. For deepwater exploitation, the risers must be installed to act as the conduits connecting surface platforms to subsea facilities. In this paper, the typical risers sorted by different classes are introduced, and the correspondent installation methods are presented. By investigating the recent projects performed in the deepwater hot spots, and combining the challenges of HYSY20 l for riser installation, a lifting device developed for assisting riser installation is proposed and detailed to satisfy the installation of deepwater risers in the LW3-1 Gas Field of 1500 m in the South China Sea. Tests on both the functions and performances of such a new system exhibit the satisfaction of meeting all challenging requirements of HYSY201 for application to riser installation in waters up to a depth of 3000 m in the South China Sea.展开更多
Marine risers play a key role in the deep and ultra-deep water oil and gas production. The vortex-induced vibration （VIV） of marine risers constitutes an important problem in deep water oil exploration and productio...Marine risers play a key role in the deep and ultra-deep water oil and gas production. The vortex-induced vibration （VIV） of marine risers constitutes an important problem in deep water oil exploration and production. VIV will result in high rates of structural failure of marine riser due to fatigue damage accumulation and diminishes the riser fatigue life. In-service monitoring or full scale testing is essential to improve our understanding of V1V response and enhance our ability to predict fatigue damage. One ma- rine riser fatigue acoustic telemetry scheme is proposed and an engineering prototype machine has been developed to monitor deep and ultra-deep water risers＇ fatigue and failure that can diminish the riser fatigue life and lead to economic losses and eco-catastrophe. Many breakthroughs and innovation have been achieved in the process of developing an engineering prototype machine. Sea trials were done on the 6th generation deep-water drilling platform HYSY-981 in the South China Sea. The inclination monitoring results show that the marine riser fatigue acoustic telemetry scheme is feasible and reliable and the engineering prototype machine meets the design criterion and can match the requirements of deep and ultra-deep water riser fatigue monitoring. The rich experience and field data gained in the sea trial which provide much technical support for optimization in the engineering prototype machine in the future.展开更多
基金financially supported by the Sichuan Science and Technology Program(Grant No.2023NSFSC1980)。
文摘An observer-based adaptive backstepping boundary control is proposed for vibration control of flexible offshore riser systems with unknown nonlinear input dead zone and uncertain environmental disturbances.The control algorithm can update the control law online through real-time data to make the controller adapt to the environment and improve the control precision.Specifically,based on the adaptive backstepping framework,virtual control laws and Lyapunov functions are designed for each subsystem.Three direction interference observers are designed to track the timevarying boundary disturbance.On this basis,the inverse of the dead zone and linear state transformation are used to compensate for the original system and eliminate the adverse effects of the dead zone.In addition,the stability of the closed-loop system is proven by Lyapunov stability theory.All the system states are bounded,and the vibration offset of the riser converges to a small area of the initial position.Finally,four examples of flexible marine risers are simulated in MATLAB to verify the effectiveness of the proposed controller.
文摘The mooring and riser system is the most critical part of an ofshore oil terminal.Traditionally,these two parts are designed separately without considering the nonlinear interaction between them.Thus,the present paper aims to develop an inte-grated design process for riser systems with a lazy-S confguration and mooring systems in the ofshore catenary anchor leg mooring(CALM)oil terminal.One of the important criteria considered in this integrated design is the ofset diagram and safe operation zone(SAFOP)related to the mooring system and the riser,respectively.These two diagrams are obtained separately by diferent analyses;therefore,codes or standards are available separately for two components.In this methodol-ogy,the diagrams of both risers and mooring lines are incorporated into a single spiral,thus identifying the safe and failure zones of risers and the mooring lines of the oil terminal.This,in turn,leads to substantial benefts in terms of overall system response,cost reduction,and safety to the ofshore oil terminal.To implement this process,three diferent riser lengths with the lazy-S confguration are considered at three diferent sea depths at the terminal installation site.For each condition,the integrated design of the mooring system and riser is executed according to the derived procedure.Then,coupled dynamic models,wherein both buoys and hoses are included,are developed using OrcaFlex.Results show that the criteria of the relevant regulations are not satisfed by reducing the length of the riser relative to the designed size.Further,as water depth increases,this type of riser confguration shows good coupled performance while interacting with the mooring system.In the cross ofset mode,the maximum margin is created between the ofset diagram and the SAFOP diagram,while the most critical dynamic response of the tanker and terminal system occurs in the near and far modes.Therefore,with this method,the best position for the riser direction with the tanker direction is 90°in the best case.
基金This work was financially supported by National Natural Science Foundation of China(Grant No.51809279)Major National Science and Technology Program(Grant No.2016ZX05028-001-05)+3 种基金National Key R&D Program of China(Grant No.2017YFC0804500)Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT14R58)the Fundamental Research Funds for the Central Universities(Grant No.20CX02302A)the Opening Fund of National Engineering Laboratory of Offshore Geophysical and Exploration Equipment(Grant No.20CX02302A)。
文摘A multibody system including a drilling riser system,tensioners and a floating platform is key equipment for offshore oil and gas drilling.Most of the previous studies only focus on the drilling riser system rather than the multibody system.Mechanical characteristics of the deepwater drilling riser system cannot be analyzed accurately in a simplified model.Therefore,a three-dimensional multibody analysis program is developed.The static and dynamic characteristics of the deepwater drilling riser system under different platform motions are analyzed based on the developed program.The results show that the static displacement of the riser system with tensioners is smaller than that without tensioners,which means the tensioners can suppress the deformation of the riser system.Under surge and sway motions of the platform,the dynamic displacement of the riser system with tensioners is also smaller than that without tensioners due to the tensioner suppression effect.Besides,the heave motion induces a uniform axial vibration of the riser system,while roll and pitch motions excite the riser system to vibrate laterally.Compared with the stress amplitude due to surge and sway motions,the stress amplitude of the riser system due to heave,roll and pitch motions is relatively small but cannot be neglected.
基金supported by the National High Technology Research and Development Program of China (863 Program,Grant No. 2008AA09A105-04)
文摘Stress Joint （SJ） plays a key role in the Top Tensioned Riser （TTR） system for deep water engineering. A preliminary design method of tapered SJ is proposed in the paper, which could help designers obtain accurate design data. After a further sensitive analysis is carried out, the related parameters choice and control methods are recommended in the engineering practice. By taking the extreme environment conditions into consideration, the effects of bending stress reduction and curve control are analyzed, and the 3-D FE models are established by ABQOUS for numerical evaluation to verify the correctness of design results. At last, dynamic analysis and fatigue analysis, based on actual project, are carried out with designed stress joint. The analysis results prove the feasibility and guidance of this method in the practical engineering applications.
文摘In this study,the dynamics of the tendon/top tension riser(TTR)system of a tension-leg platform(TLP)are investigated through an experiment and by using absolute nodal coordinate formulation(ANCF).First,the model test of the TLP system is conducted in the water tank of Harbin Engineering University to examine the motion response of the TLP and the dynamic response characteristics of the tendon and TTR.The test scale ratio is set to 1:66.3.Then,on the basis of the ANCF,the stiffness,external load,and mass matrices of the element are deduced to establish the motion equation of the tendon/riser.Finally,the static and dynamic characteristics of the tendon/TTR system of TLP are analyzed systematically by using the ANCF method.The results are compared with commercial software and test results.The motion response of tendon/TTR is affected by the TLP movement and environmental load simultaneously.The analysis proves the effectiveness and accuracy of the ANCF method despite the low number of riser units,suggesting the superiority of the ANCF method for calculating the dynamics of tendon/riser in the field of ocean engineering.
基金the financial support received from the China National Key Research and Development Project(Grant No.2022YFC2806202)the Fundamental Research Funds for the Central Universities(Grant No.xtr042024002).
文摘When using topside choking to eliminate severe slugging in offshore pipeline-riser systems,the resulting stability and effectiveness depend critically on the choice of variables in the associated control model.In this study,both potential process variables and manipulated variables are investigated via manual choking experiments.Monotonicity and linearity are adopted as principles for selecting the optimal variables,and the availability of signals in an offshore field is also considered.Both amplitude-domain and time-domain variables are studied,of which five are recommended as the process variable,while the resistance factor of the choking valve is the optimal manipulated variable;other variables may act as auxiliary variables in the control model.How to determine the set value of the process variable is also discussed.Validation experiments with automatic control show that the optimized variables enable faster stabilization.This study offers a reference for the design of slugging control for offshore fields.
基金Supported by Finance Science and Technology Project of Hainan Province under Grant No.ZDKJ2021027the National Natural Science Foundation of China under Grant No.52231012.
文摘The deep seabed is known for its abundant reserves of various mineral resources.Notably,the Clarion Clipperton(C-C)mining area in the northeast Pacific Ocean,where China holds exploration rights,is particularly rich in deep-sea polymetallic nodules.These nodules,which are nodular and unevenly distributed in seafloor sediments,have significant industrial exploitation value.Over the decades,the deep-sea mining industry has increasingly adopted systems that combine rigid and flexible risers supported by large surface mining vessels.However,current systems face economic and structural stability challenges,hindering the development of deep-sea mining technology.This paper proposes a new structural design for a deep-sea mining system based on flexible risers,validated through numerical simulations and experimental research.The system composition,function and operational characteristics are comprehensively introduced.Detailed calculations determine the production capacity of the deep-sea mining system and the dimensions of the seabed mining subsystem.Finite element numerical simulations analyze the morphological changes of flexible risers and the stress conditions at key connection points under different ocean current incident angles.Experimental research verifies the feasibility of collaborative movement between two tethered underwater devices.The proposed deep-sea mining system,utilizing flexible risers,significantly advances the establishment of a commercial deep-sea mining system.The production calculations and parameter determinations provide essential references for the system’s future detailed design.Furthermore,the finite element simulation model established in this paper provides a research basis,and the method established in this paper offers a foundation for subsequent research under more complex ocean conditions.The control strategy for the collaborative movement between two tethered underwater devices provides an effective solution for deep-sea mining control systems.
基金supported by the National Natural Science Foundation of China(Grant No:52271300,52071337)National Key Research and Development Program of China(2022YFC2806501)+1 种基金High-tech Ship Research Projects Sponsored by MIIT(CBG2N21-4-25)Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT14R58).
文摘A new hang-off system has been proposed to improve the security of risers in hang-off modes during typhoons.However,efficient anti-typhoon evacuation strategies have not been investigated.Optimiza-tion model and method for the anti-typhoon evacuation strategies should be researched.Therefore,multi-objective functions are proposed based on operation time,evacuation speed stability,and steering stability.An evacuation path model and a dynamic model of risers with the new hang-off system are developed for design variables and constraints.A multi-objective optimization model with high-dimensional variables and complex constraints is established.Finally,a three-stage optimization method based on genetic algorithm,least square method,and the penalty function method is proposed to solve the multi-objective optimization model.Optimization results show that the operation time can be reduced through operation parameter optimization,especially evacuation heading optimization.The optimal anti-typhoon strategy is evacuation with all risers suspended along a variable path when the direction angle is large,while evacuation with all risers suspended along a straight path at another di-rection angle.Besides,the influencing factors on anti-typhoon evacuation strategies indicate that the proposed optimization model and method have strong applicability to working conditions and remarkable optimization effects.
基金Project supported by the National Natural Science Foundation of China(Nos.62373220 and 62173209)the Shandong Provincial Natural Science Foundation of China(No.ZR2023MF011)。
文摘This paper investigates the recoil control of the deepwater drilling riser system with nonlinear tension force and energy-bounded friction force under the circumstances of limited network resources and unreliable communication.Different from the existing linearization modeling method,a triangle-based polytope modeling method is applied to the nonlinear riser system.Based on the polytope model,to improve resource utilization and accommodate random data loss and communication delay,an asynchronous gain-scheduled control strategy under a hybrid event-triggered scheme is proposed.An asynchronous linear parameter-varying system that blends input delay and impulsive update equation is presented to model the nonlinear networked recoil control system,where the asynchronous deviation bounds of scheduling parameters are calculated.Resorting to the Lyapunov-Krasovskii functional method,some solvable conditions of disturbance attenuation analysis and recoil control design are derived such that the resulting networked system is exponentially mean-square stable with prescribed H∞performance.The obtained numerical results verified that the proposed nonlinear networked control method can achieve a better recoil response of the riser system with less transmission data compared with the linear control method.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52271300,52071337,and 51809279)the National Key Research and Development Program of China(Grant No.2022YFC2806501)the High-tech Ship Research Projects Sponsored by MIIT(Grant No.CBG2N21-4-2-5).
文摘The safety of risers in hang-off states is a vital challenge in offshore oil and gas engineering.A new hang-off system installed on top of risers is proposed for improving the security of risers.This approach leads to a challenging problem:coupling the dynamics of risers with a new hang-off system combined with multiple structures and complex constraints.To accurately analyze the dynamic responses of the coupled system,a coupled dynamic model is established based on the Euler-Bernoulli beam-column theory and penalty function method.A comprehensive analysis method is proposed for coupled dynamic analysis by combining the finite element method and the Newmarkβmethod.An analysis program is also developed in MATLAB for dynamic simulation.The simulation results show that the dynamic performances of the risers at the top part are significantly improved by the new hang-off system,especially the novel design,which includes the centralizer and articulation joint.The bending moment and lateral deformation of the risers at the top part decrease,while the hang-off joint experiences a great bending moment at the bottom of the lateral restraint area which requires particular attention in design and application.The platform navigation speed range under the safety limits of risers expands with the new hang-off system in use.
基金support of the School of Engineering,Lancaster University,UK,for the Engineering Department Studentship as well as the Engineering and Physical Sciences Research Council(EPSRC)’s Doctoral Training Centre(DTC)。
文摘With the increasing exploration of oil and gas into deep waters,the necessity for material development increases for lighter conduits such as composite marine risers,in the oil and gas industry.To understand the research knowledge on this novel area,there is a need to have a bibliometric analysis on composite marine risers.A research methodology was developed whereby the data retrieval was from SCOPUS database from 1977–2023.Then,VOSviewer was used to visualize the knowledge maps.This study focuses on the progress made by conducting knowledge mapping and scientometric review on composite marine risers.This scientometric analysis on the subject shows current advances,geographical activities by countries,authorship records,collaborations,funders,affiiliations,co‑occurrences,and future research areas.It was observed that the research trends recorded the highest publication volume in the U.S.A.,but less cluster affiiliated,as it was followed by countries like the U.K.,China,Nigeria,Australia and Singapore.Also,thisfiield has more conference papers than journal papers due to the challenge of adaptability,acceptance,qualifiication,and application of composite marine risers in the marine industry.Hence,there is a need for more collaborations on composite marine risers and more funding to enhance the research trend.
基金sponsored by the National Key Research and Development Program of China(No.2022YFA1506200)the CNPC Innovation Found(No.2024DQ02-0203)the open foundation of State Key Laboratory of Chemical Engineering(No.SKL-ChE-23B02).
文摘By large-scale cold mold experiments,pressure pulsation signals within the jet influence zone of riser reactor are processed by using Hilbert-Huang analysis(HHT)in this study.Effects of different jet forms and operating conditions on the intrinsic mode function(IMF)energy and Hilbert-Huang spectrum are compared.Results show that the IMF energy and Hilbert-Huang spectrum of pressure pulsation signals show significant differences under the influence of upward and downward jets.Moreover,the change of jet velocity will also lead to significant changes in IMF energy and Hilbert-Huang spectrum.Among them,energy values and energy proportions corresponding to high-frequency pressure pulsations show a good correlation with the jet velocity.On this basis,energy value and energy proportion data in the high frequency range of the original pressure signal are clustered and analyzed by using the K-means clustering algorithm.Based on clustering results,the jet influence zone of riser can be defined into three regions.From partitioning results,it is found that the introduction of downward inclined jets could effectively improve the gas-solid mixing in the feed injection zone of riser.
基金the financial support from National Key R&D Program of China(Grant number:2024YFC2815100)Natural Science Foundation of China(Grant number:52322110)Beijing Nova Program(Grant number:20230484341).
文摘Deepwater drilling riser is the key equipment connecting the subsea wellhead and floating drilling platform.Due to complex marine environment,vortex-induced vibration(ViV)will be generated on riser,which will induce fatigue failure and even cause unpredictable drilling accidents.Therefore,it is important to study the ViV characteristics of deepwater drilling riser and reveal the main controlling factors for ensuring the safe and efficient operation of deepwater drilling engineering.In this paper,the ViV of deepwater drilling riser is numerically simulated in time domain based on the discrete vortex method(DvM).A hydrodynamic analysis model and governing equation of VIV is proposed with considering the effect of riser motion using DVM and slice method,where the governing equation is solved by Runge-Kutta method.Model validation is performed,which verified the correctness and accuracy of the mechanical model and the solution method.On this basis,the influence of the number of control points,current velocity,riser outer diameter,shear flow and top tension on the ViV characteristics of deepwater drilling risers are discussed in detail.The results show that with the increase of current velocity,the vibration amplitude of deepwater drilling riser decreases obviously,while the vibration frequency increases gradually.However,if the outer diameter of riser increases,the vibration amplitude increases,while the vibration frequency decreases gradually.The top tension also has great influence on the VIV of riser.When the top tension is 1.25 G,the VIV is suppressed to a certain extent.This study has guiding significance for optimal design and engineering control of deepwater drilling riser.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51879189 and 52071234).
文摘This study proposed a novel experimental platform to conduct dynamic loading tests of a truncated model steel catenary riser(SCR)within the touchdown zone(TDZ).The facilities of the platform,including a soil tank,a loading system,and a soil stirring system,are introduced in detail.A steel pipe with the same diameter as the in situ SCR has been used in the laboratory tests to investigate the vertical motion of the pipe and the effect of the trench on the lateral motion.As the amplitude of the vertical motion increases,the depth of the trench deepens,the bending moment range increases,and the excess pore water pressure at the bottom of the pipeline first accumulates and then dissipates during loading.The development trend of the trench depth and the influence of the soil strength on the SCR bending moment are also studied.During the test,a seabed trench develops,and its shape is similar to that of the in situ trench.
基金supported by the National Natural Science Foundation of China(Grant Nos.52471275,U23A20663,51809048,51909236)the Natural Science Foundation of Fujian Province(Grant No.2022J01092)+1 种基金the Natural Science Foundation of Zhejiang Province(Grant No.LY23E090004)the Ningbo Natural Science Foundation(Grant No.2021J039).
文摘Steel lazy-wave riser(SLWR)is one of the key technical components of offshore oil-gas production systems and is widely utilized in deepwater areas.On the basis of the vector form intrinsic finite element(VFIFE)method,this study develops a reasonable numerical model for the SLWR to investigate the effects of the buoyancy section on its mechanical characteristics.In the SLWR model,the buoyancy section is simulated using an equivalent riser segment with the same outer diameter and unit weight.The riser is considered to be composed of a series of space vector particles connected by elements,and virtual reverse motions are applied to establish the fundamental equations of forces and displacements.The explicit central difference technique is used to solve the governing equations for particle motion within the riser through programming implementation.To provide a detailed explanation of the process by which the SLWR achieves a stable lazy-wave configuration,a numerical model of a 2800-m-long riser is established at a water depth of 1600 m,and the feasibility of this model for riser behavior analysis is validated.The remarkable influences of the position,length,number and spacing of the buoyancy section on the mechanical behavior of the SLWR are observed,which provides a theoretical foundation for the optimal design of the SLWR in deepwaters.
基金Project supported by the Natural Science Foundation of Jiangsu Province,China(No.BK20201340)the 333 High-level Talents Training Project of Jiangsu Province,Chinathe Blue Project for Colleges and Universities of Jiangsu Province,China。
文摘In this study,we develop an adaptive neural network based boundary control method for a flexible marine riser system with unknown nonlinear disturbances and output constraints to suppress vibrations.We begin with describing the dynamic behavior of the riser system using a distributed parameter system with partial differential equations.To compensate for the effect of nonlinear disturbances,we construct a neural network based boundary controller using a radial basis neural network to reduce vibrations.Under the proposed boundary controller,the state of the riser is guaranteed to be uniformly bounded based on the Lyapunov method.The proposed methodology provides a way to integrate neural networks into boundary control for other flexible robotic manipulator systems.Finally,numerical simulations are given to demonstrate the effectiveness of the proposed control method.
基金Project supported by the National Natural Science Foundation of China(Grant No.51779243)the Strategic Priority Research Program of the Chinese Academy of Science(Grant No.XDB22030101)
文摘The effect of the surfactant additive on the upward intermittent flows in a pipeline-riser system is studied experimentally, in a 3 m long horizontal pipe connected to a Perspex pipe of 2.0 m long and 25 mm in diameter, inclined to the horizontal plane by 7？, followed by the vertical PVC riser of 3.5 m high and 25 mm in diameter, operating at the atmospheric end pressure. Based on the analysis of the pressure signal and the visual observation of the riser, it is shown that the additive of surfactant to the carrying liquid makes bubbles smaller in size but much larger in number in the upward intermittent flows. In addition, the additive of surfactant to a two-phase flow does not have a significant impact on the in-situ gas fraction, the pressure drop and the frequency of the liquid slug, but it reduces significantly the velocity of the liquid slug. When the superficial liquid velocity is set, an exponential relationship between the dimensionless velocity of the liquid slug and the Webber number can be obtained. These results might be used for estimating the characteristic parameters of the upward intermittent flow based upon the input operating conditions.
基金support from the National Natural Science Foundation of China (granted number 50979113)the National 863 Program of China (granted number 2006AA09A105)
文摘An S-lay crane barge,named CNOOC 201,has been built for pipe laying in deepwater oil/gas fields in the South China Sea.It is due to be commissioned by the end of the year 2010.A special lifting system is developed to meet the challenge that installing deepwater risers from an S-lay barge is difficult and has not been achieved.The purpose of this paper was to investigate the model test on such an innovative system,which has to be done before field application.By applying the similarity theory,the movement of the S-lay barge is simulated through a six degrees-of-freedom motion platform,and a truncated model riser is utilized for the model testing.The displacement and force boundary conditions at the truncated position of the riser are obtained from the catenary governing equation and become realized by a slideway cart and a loading system designed to control the configuration of the model riser,which presents a similar configuration to a real riser in deepwater.The test results are in very good agreement with theoretical calculations,showing that the active truncated test is applicable for controlling the configuration of the deepwater riser in model testing investigation.
基金supported by the National Natural Science Foundation of China(Grant No. 50979113)the High Technology Research and Development Program of China(863 Program,Grant No. 2006AA09A105)
文摘Along with the consumption increase of the petroleum products, more countries have transferred their attentions to the offshore fields, especially the deepwater oil and gas reserves. For deepwater exploitation, the risers must be installed to act as the conduits connecting surface platforms to subsea facilities. In this paper, the typical risers sorted by different classes are introduced, and the correspondent installation methods are presented. By investigating the recent projects performed in the deepwater hot spots, and combining the challenges of HYSY20 l for riser installation, a lifting device developed for assisting riser installation is proposed and detailed to satisfy the installation of deepwater risers in the LW3-1 Gas Field of 1500 m in the South China Sea. Tests on both the functions and performances of such a new system exhibit the satisfaction of meeting all challenging requirements of HYSY201 for application to riser installation in waters up to a depth of 3000 m in the South China Sea.
基金supported in part by the National Science and Technology Major Project of China (2011ZX 05026-001-06)the National Natural Science Foundation of China (51249005 60972153)
文摘Marine risers play a key role in the deep and ultra-deep water oil and gas production. The vortex-induced vibration （VIV） of marine risers constitutes an important problem in deep water oil exploration and production. VIV will result in high rates of structural failure of marine riser due to fatigue damage accumulation and diminishes the riser fatigue life. In-service monitoring or full scale testing is essential to improve our understanding of V1V response and enhance our ability to predict fatigue damage. One ma- rine riser fatigue acoustic telemetry scheme is proposed and an engineering prototype machine has been developed to monitor deep and ultra-deep water risers＇ fatigue and failure that can diminish the riser fatigue life and lead to economic losses and eco-catastrophe. Many breakthroughs and innovation have been achieved in the process of developing an engineering prototype machine. Sea trials were done on the 6th generation deep-water drilling platform HYSY-981 in the South China Sea. The inclination monitoring results show that the marine riser fatigue acoustic telemetry scheme is feasible and reliable and the engineering prototype machine meets the design criterion and can match the requirements of deep and ultra-deep water riser fatigue monitoring. The rich experience and field data gained in the sea trial which provide much technical support for optimization in the engineering prototype machine in the future.
