The Experts below are selected from a list of 462 Experts worldwide ranked by ideXlab platform

N. Richardson - One of the best experts on this subject based on the ideXlab platform.

  • FLUID-STRUCTURE INTERACTION STUDY ON DYNAMIC RESPONSE OF A CAPPED DRILLING RISER FILLED WITH MUD
    2020
    Co-Authors: K W Paczkowski, R. Rogers, P Zhang, N. Richardson
    Abstract:

    ABSTRACT In the offshore drilling, during Emergency Disconnect scenario the drilling operation must not be maintained and forced LMRP Disconnect procedure takes plac

  • Fluid Structure Interaction Study on Dynamic Response of a Capped Drilling Riser Filled With Mud
    Volume 2: CFD and VIV, 2014
    Co-Authors: Karen Paczkowski, P Zhang, R. Rogers, N. Richardson
    Abstract:

    In the offshore drilling, during Emergency Disconnect scenario the drilling operation must not be maintained and forced LMRP Disconnect procedure takes place [1,2]. Such procedure allows drilling mud to interact with seawater. The paper presents hydrodynamic behavior of a drilling riser when mud is retained and not interacted with seawater. A two-way coupled fluid-structure interaction (FSI) model between a simplified drilling riser structure and mud fluid was studied through techniques of computational fluid dynamics (CFD). The volume of fluid (VOF) hydrodynamics model was used with commercially available software STAR-CCM+ [3]. A 3D finite element (FE) model of a drilling riser was created in FE software ABAQUS [4] to determine the stress and deflection of structural parts of the model due to hydrodynamic loads. In the model, the compressibility [5] and non-linear behavior of the mud was included. The dynamic frequencies of the two domains and possible resonance of the coupled system were investigated. The aim of the study was to verify the dynamic behavior of a riser system with a drilling mud enclosed within the system. The authors of this paper know no similar study of such a problem.Copyright © 2014 by ASME

Fredrik Haugland Danielsen - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic loads on telescopic safety joint for workover riser
    University of Stavanger Norway, 2014
    Co-Authors: Fredrik Haugland Danielsen
    Abstract:

    Master's thesis in Offshore technologyThe push in the industry towards increasing the weather window for marine operations offshore leads to a focus on new technology. When performing workover operations in a subsea well, the workover riser is a physical connection between the well and the floating workover vessel. A floating vessel will experience wave induced motion and is therefore equipped with a heave compensator to allow for this relative motion without increasing the load to the riser. If the heave compensator fails or if the heave of the vessel exceeds the stroke length of the heave compensator, the workover riser can be subjected to an excessive axial force that could rupture the riser and damage subsea well barriers. A safety joint that is to be installed in the riser can improve the window for safe operation while reducing consequences if an accident were to occur. It is called the Telescopic Safety Joint (TSJ) and has been developed by FMC Technologies. The joint is designed to telescope when subjected to a predetermined axial force. The telescoping function of the joint will ensure that there is sufficient time for personnel onboard the vessel to activate the Emergency Disconnect function so that the riser can safely be Disconnected from the well. The safety joint is a weak link. During installation of the workover system, the riser experiences loading conditions exceeding that of normal operation. There is a concern that the safety joint may take plastic damage during this installation. Hence the TSJ is equipped with an over-ride function that temporarily can increase the strength of the joint. The over-ride function works by pumping hydraulic pressure into external cylinders. The increase in the strength of the joint from the over-ride function depends upon the hydraulic pressure. This thesis studies the effect the over-ride function has on the weather window for installation of a workover system, comparing a fully pressurized over-ride function to a semi-pressurized over-ride function. Simulations in Orcaflex for various environmental conditions found the loads that the TSJ must be able to withstand for installation to be possible. A model of the joint was created in AUTODESK Inventor. Using ANSYS workbench, the model was tested to find out which loads that are acceptable and which loads leads to plastic damage of the joint both for the fully pressurized and semi-pressurized over-ride function. Combining the results for the fully- and semi-pressurized over-ride function test, with the results from the dynamic simulations performed in Orcaflex revealed an increase in installation window when using the fully pressurized over-ride function. The joint using the full capacity of the over-ride function was able to withstand 620kNm before plastic damage took place. The joint using a semi-pressurized over-ride function began taking plastic damage at 400kNm. The over-ride function increases the bending moment capacity of the joint by 55%. Using the scatter diagram for the Draugen field to see how many observations has been made of the different sea states, the increased availability for installation when using the full capacity of the over-ride function, as opposed to the semi-pressurized joint was calculated. When installing the TSJ as the 2nd riser joint, the availability increased by 21,7%. Installing the TSJ as the 3rd joint increases the availability by 16,7%. Installation of the TSJ on the 4th and 5th joint gives an increase of respectively 2,8% and 0,3% when the full over-ride capacity is used. The over-ride functions proved to be so effective that the joint became stronger than the actual workover riser. Hand calculations showed that the riser would yield before the safety joint and thus the safety joint would not be a limiting factor for the workover installation activity if the over-ride function is active

  • Dynamic loads on telescopic safety joint for workover riser
    University of Stavanger Norway, 2014
    Co-Authors: Fredrik Haugland Danielsen
    Abstract:

    The push in the industry towards increasing the weather window for marine operations offshore leads to a focus on new technology. When performing workover operations in a subsea well, the workover riser is a physical connection between the well and the floating workover vessel. A floating vessel will experience wave induced motion and is therefore equipped with a heave compensator to allow for this relative motion without increasing the load to the riser. If the heave compensator fails or if the heave of the vessel exceeds the stroke length of the heave compensator, the workover riser can be subjected to an excessive axial force that could rupture the riser and damage subsea well barriers. A safety joint that is to be installed in the riser can improve the window for safe operation while reducing consequences if an accident were to occur. It is called the Telescopic Safety Joint (TSJ) and has been developed by FMC Technologies. The joint is designed to telescope when subjected to a predetermined axial force. The telescoping function of the joint will ensure that there is sufficient time for personnel onboard the vessel to activate the Emergency Disconnect function so that the riser can safely be Disconnected from the well. The safety joint is a weak link. During installation of the workover system, the riser experiences loading conditions exceeding that of normal operation. There is a concern that the safety joint may take plastic damage during this installation. Hence the TSJ is equipped with an over-ride function that temporarily can increase the strength of the joint. The over-ride function works by pumping hydraulic pressure into external cylinders. The increase in the strength of the joint from the over-ride function depends upon the hydraulic pressure. This thesis studies the effect the over-ride function has on the weather window for installation of a workover system, comparing a fully pressurized over-ride function to a semi-pressurized over-ride function. Simulations in Orcaflex for various environmental conditions found the loads that the TSJ must be able to withstand for installation to be possible. A model of the joint was created in AUTODESK Inventor. Using ANSYS workbench, the model was tested to find out which loads that are acceptable and which loads leads to plastic damage of the joint both for the fully pressurized and semi-pressurized over-ride function. Combining the results for the fully- and semi-pressurized over-ride function test, with the results from the dynamic simulations performed in Orcaflex revealed an increase in installation window when using the fully pressurized over-ride function. The joint using the full capacity of the over-ride function was able to withstand 620kNm before plastic damage took place. The joint using a semi-pressurized over-ride function began taking plastic damage at 400kNm. The over-ride function increases the bending moment capacity of the joint by 55%. Using the scatter diagram for the Draugen field to see how many observations has been made of the different sea states, the increased availability for installation when using the full capacity of the over-ride function, as opposed to the semi-pressurized joint was calculated. When installing the TSJ as the 2nd riser joint, the availability increased by 21,7%. Installing the TSJ as the 3rd joint increases the availability by 16,7%. Installation of the TSJ on the 4th and 5th joint gives an increase of respectively 2,8% and 0,3% when the full over-ride capacity is used. The over-ride functions proved to be so effective that the joint became stronger than the actual workover riser. Hand calculations showed that the riser would yield before the safety joint and thus the safety joint would not be a limiting factor for the workover installation activity if the over-ride function is active

Yuanjiang Chang - One of the best experts on this subject based on the ideXlab platform.

  • Failure Probability Analysis for Emergency Disconnect of Deepwater Drilling Riser Using Bayesian Network
    Bayesian Networks for Reliability Engineering, 2020
    Co-Authors: Baoping Cai, Yuanjiang Chang, Zengkai Liu, Yonghong Liu, Lei Jiang
    Abstract:

    Drilling risers are the crucial connection of subsea wellhead and floating drilling vessel. Emergency Disconnect (ED) is the most important protective measure to secure the risers and wellhead under extreme conditions. This paper proposes a methodology for failure probability analysis of ED operations using Bayesian network (BN). The risk factors associated with ED operations and the potential consequences of ED failure were investigated. A systematic ED failure and consequence model was established through fault tree and event sequence diagram (FT-ESD) analyses and, then the FT-ESD model was mapped into BN. Critical root causes of ED failure were inferred by probability updating, and the most probable accident evolution paths as well as the most probable consequence evolution paths of ED failure were figured out. Moreover, the probability adaptation was performed at regular intervals to estimate the probabilities of ED failure, and the occurrence probabilities of consequences caused by ED failure. The practical application of the developed model was demonstrated through a case study. The results showed that the probability variations of ED failure and corresponding consequences depended on the states of critical basic events (BEs). Eventually, some active measures in drilling riser system design, drilling operation, ED test, and operation were proposed for mitigating the probability of ED failure.

  • a dbn go approach for success probability prediction of drilling riser Emergency Disconnect in deepwater
    Ocean Engineering, 2019
    Co-Authors: Zhenyu Nie, Yuanjiang Chang, Xiuquan Liu, Guoming Chen
    Abstract:

    Abstract Drilling risers are crucial connections of subsea wellhead and floating drilling vessel. Riser Emergency Disconnect (RED) is the most effective protective measure to secure risers and wellhead in case of Emergency. There are many different stages for RED depending on riser-connected operation. A novel approach based on Dynamic Bayesian Network and GO (DBN-GO) model is proposed to dynamically analyze the variation of RED risk over time in different stages. The GO model was built by translating the operation flow chart of RED and then mapped into BN. A DBN model was established considering the dynamic reliability of equipment. The cognitive reliability and error analysis method (CREAM) and improved analytic hierarchy process (IAHP) were used to determine and modify the probabilities of human factors in the DBN-GO model. The practical application of the developed model was demonstrated through a case study. The results showed that DBN-GO approach could be used to predict the dynamic success probability of RED under different stages during a drilling duration. Additionally, the key steps corresponding to each stage were identified, and some preventive measures to mitigate the failure risk of RED were proposed.

  • envelopes for connected operation of the deepwater drilling riser
    Petroleum Exploration and Development, 2012
    Co-Authors: J U Shaodong, Yuanjiang Chang, X U Liangbin, Guoming Chen, Rongyao Wang
    Abstract:

    Abstract The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling riser and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and slip joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible joint and reduce the drilling envelope rapidly. The non-drilling envelope and Emergency Disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded.

  • Envelopes for connected operation of the deepwater drilling riser
    KeAi Communications Co. Ltd., 2012
    Co-Authors: Yuanjiang Chang, Guoming Chen, Xiuquan Liu, Rongyao Wang
    Abstract:

    The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling riser and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and slip joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible joint and reduce the drilling envelope rapidly. The non-drilling envelope and Emergency Disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded. Key words: deepwater drilling, riser, drilling envelope, non-drilling envelope, EDS actuation envelop

Shuai Meng - One of the best experts on this subject based on the ideXlab platform.

  • Coupling Effects of A Deep-Water Drilling Riser and the Platform and the Discharging Fluid Column in An Emergency Disconnect Scenario
    China Ocean Engineering, 2020
    Co-Authors: Shuai Meng, Yong Chen, Chi-dong Che
    Abstract:

    As drilling operations move into remote locations and extreme water depths, recoil analysis requires more careful considerations and the incidence of Emergency Disconnect is increased inevitably. To accurately capture the recoil dynamics of a deep-water riser in an Emergency Disconnect scenario, researchers typically focus on modelling the influential subsystems (e.g., the tensioner, the mud discharge and seawater refilling process) which can be solved in the preprocessing, and then the determined parameters are transmitted into an existing global riser analysis software. Distinctively, the current study devotes efforts into the coupling effects resulting from that the suspended riser reacts the platform heave motion via the tensioner system in the course of recoil and the discharging fluid column follows the oscillation of the riser in the mud discharge process. Four simulation models are established based on lumped mass method employing different formulas for the top boundary condition of the riser and the discharging flow acceleration. It demonstrates that the coupling effects discussed above can significantly affect the recoil behavior during the transition phase from initial Disconnect to the final hang-off state. It is recommended to develop a fully-coupled integrated model for recoil analysis and anti-recoil control system design before extreme deep-water applications.

  • Discharging flow effect on the recoil response of a deep-water drilling riser after an Emergency Disconnect
    Ocean Engineering, 2018
    Co-Authors: Shuai Meng, Weijing Zhang
    Abstract:

    Abstract To account for the discharging flow effect in recoil analysis of a drilling riser during an Emergency Disconnection scenario, researchers have developed two notable fluid column models (i.e. “SFM, Slug force model” and “WFCM, Whole fluid column model”) which can be solved in the pre-processing of an existing global riser analysis code. It is found that the “SFM” is developed based on the dynamical equilibrium of the internal drilling mud column, whereas the “WFCM” is established by analyzing the whole drilling mud and refilled seawater column. This study devotes efforts on the discharging flow effect on the recoil behaviour of a deep-water drilling riser employing “SFM” and “WFCM”. Large deviations are observed when comparing the results adopting these two fluid models, which can be contributed to the different resultant restoring forces exerted on the inner fluid columns. Nevertheless, same conclusions are drawn on the discharging flow effect, and the drag loading, mass loss and frontal force effects have been identified. An important finding is that when considering the inner fluid follows the oscillation of the riser, the recoil response of the riser can be affected remarkably, highlighting the great significance of this coupling effect.

Guoming Chen - One of the best experts on this subject based on the ideXlab platform.

  • a dbn go approach for success probability prediction of drilling riser Emergency Disconnect in deepwater
    Ocean Engineering, 2019
    Co-Authors: Zhenyu Nie, Yuanjiang Chang, Xiuquan Liu, Guoming Chen
    Abstract:

    Abstract Drilling risers are crucial connections of subsea wellhead and floating drilling vessel. Riser Emergency Disconnect (RED) is the most effective protective measure to secure risers and wellhead in case of Emergency. There are many different stages for RED depending on riser-connected operation. A novel approach based on Dynamic Bayesian Network and GO (DBN-GO) model is proposed to dynamically analyze the variation of RED risk over time in different stages. The GO model was built by translating the operation flow chart of RED and then mapped into BN. A DBN model was established considering the dynamic reliability of equipment. The cognitive reliability and error analysis method (CREAM) and improved analytic hierarchy process (IAHP) were used to determine and modify the probabilities of human factors in the DBN-GO model. The practical application of the developed model was demonstrated through a case study. The results showed that DBN-GO approach could be used to predict the dynamic success probability of RED under different stages during a drilling duration. Additionally, the key steps corresponding to each stage were identified, and some preventive measures to mitigate the failure risk of RED were proposed.

  • envelopes for connected operation of the deepwater drilling riser
    Petroleum Exploration and Development, 2012
    Co-Authors: J U Shaodong, Yuanjiang Chang, X U Liangbin, Guoming Chen, Rongyao Wang
    Abstract:

    Abstract The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling riser and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and slip joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible joint and reduce the drilling envelope rapidly. The non-drilling envelope and Emergency Disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded.

  • Envelopes for connected operation of the deepwater drilling riser
    KeAi Communications Co. Ltd., 2012
    Co-Authors: Yuanjiang Chang, Guoming Chen, Xiuquan Liu, Rongyao Wang
    Abstract:

    The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling riser and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and slip joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible joint and reduce the drilling envelope rapidly. The non-drilling envelope and Emergency Disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded. Key words: deepwater drilling, riser, drilling envelope, non-drilling envelope, EDS actuation envelop