The Experts below are selected from a list of 72 Experts worldwide ranked by ideXlab platform
Suhail Ahmad - One of the best experts on this subject based on the ideXlab platform.
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probabilistic analysis and risk assessment of deep water composite Production Riser against fatigue limit state
ASME 2015 34th International Conference on Ocean Offshore and Arctic Engineering, 2015Co-Authors: Manander Singh, Suhail AhmadAbstract:Deep water composite Risers are subjected to randomly fluctuating loads, induced by wind and waves in the presence of fluctuating axial tension which may be critical in deep sea conditions. Therefore, Risers experience the extreme bending and randomly fluctuating stresses throughout their service life. Cumulative fatigue damage is a critical assessment of Riser life in the presence of large dynamic stresses. Probabilistic analysis and risk assessment of composite Risers for cumulative fatigue is a vital design requirement for its satisfactory service and survival for stipulated period. Without addressing the reliability assessment, composite Risers may not be recommended for deep water oil and gas exploration and Production. Hence, the reliability assessment is a critical issue that is to be addressed for the safety of the deep water composite Riser. It is studied for the entire system for all possible sea states occurring in the exploration region. Unlike conventional Risers, the wall structure of a composite Riser is more complicated. Therefore, multiple failure mechanisms are used jointly to assess the safety of the composite Riser. Fatigue reliability is a challenging task due to complex nature of dynamic response and associated uncertainties caused by the material and external loads. The present study is focused on reliability assessment using stochastic finite element analysis. Response time histories for random sea plus current have been obtained. Requisite numbers of sea states are considered for the simulation of a wide range of off-shore environment and estimation of accumulated damage. By using the S-N data, damage fractions are calculated then summed linearly using Miner-Palmgren rule. The total damage has been obtained by summing the accumulated damages over all the sea states under consideration. Non-linear limit state function is derived based upon the above given approach to calculate the fatigue life. Important uncertainties associated with random variables are considered while deriving the limit state function. Numerical methods, such as Monte Carlo simulation and Advanced First Order Reliability Method, are used for the calculation of the reliability. The sensitivities of various random variables on overall probability of failure have been studied and design points have been located on failure surface. Probabilities of failure for important parameters are investigated.Copyright © 2015 by ASME
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Bursting Capacity and Debonding of Ultra Deep Composite Production Riser: A Safety Assessment
Volume 6A: Pipeline and Riser Technology, 2014Co-Authors: Manander Singh, Suhail AhmadAbstract:Due to depleting sources of oil and gas reserves in shallow water depths, exploration and Production activities have moved into ultra-deep offshore oil fields. Risers are an essential part of any offshore drilling facility. A Riser tensioner located on the drilling platform has to provide an adequate vertical tension to maintain the stability of the Riser. It is essential for a successful operation. Composite Risers in deep sea conditions require much lower top vertical forces due to their high strength to weight ratio. Carbon/epoxy composite has been considered in the present study to carry out the burst analysis and to assess the safety of the composite Riser under internal and external pressures and other environmental loads due to random sea currents. In order to ensure the permissible pressure and no fluid leakage, composite Risers are provided with an internal steel liner. Initiation and propagation of debonding between the liner and composite has been studied and probability of failure is obtained. In burst analysis, maximum internal pressure is applied to a Riser section and the stresses in all (hoop and longitudinal layers) the composite layers are checked against the failure. High pressures are incremented in small steps until fiber rupture occurs due to bursting. Maximum normal stress theory is employed for checking the failure. The same theory provides the limit-state to assess the safe pressure considering uncertainties associated with random input parameters involved. A finite element analysis has been carried out in ABAQUS/AQUA for random sea motion and fluctuating axial tension considering salient non-linearities. A small Riser section modelled as a hybrid beam element (for global analysis) has been considered to study the bursting and debonding behavior. It is further discretized into thin shell elements (S4R). Steel liner and composite pipes are modeled separately and assembled together to ensure the overlapping various layers and sharing nodes. The composite body sustains the major stresses in the inner layers that diminish on moving outwards radially. An implicit time domain analysis has been carried out to obtain the response. The debonding through circumference and length are studied. The stresses obtained are compared with their ultimate strength.Copyright © 2014 by ASME
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local stress analysis of composite Production Riser under random sea
ASME 2014 33rd International Conference on Ocean Offshore and Arctic Engineering, 2014Co-Authors: Manander Singh, Suhail AhmadAbstract:The advantage of composite Riser is more pronounced due to its light weight and reduced axial tension and bending moment. Its characteristics provide more flexibility in the design of Riser system such as stress joint, tensioner or even the platform hull. The composite Riser under study consists of alternative hoop and axial layers. There is a marginal coupling between these two orientations hence, the Riser is spatially orthotropic. The pressure capabilities of Riser are governed by the performance of hoop layers under combined fluctuating axial tension and bending moment. The internal steel liner provided to ensure no leakage often limits the composite Riser capabilities. The steel liner provided for Production inevitably carries major share of loads. An attempt has been made to carry out a detailed local analysis of a segmental length under critical loads. Damage analysis for various combinations of axial tension and bending moment are performed. The results of global analysis are used to act as boundary/initial condition for the local and detailed dynamic analysis of the segmental length modeled as finite element assemblage of shell elements. The critical stress time histories obtained by global analysis are applied at the local level. The composite layers sustained the random stresses that lead to the failure of the composite. Some realistic failure criteria are chosen to check the damage at local level.Copyright © 2014 by ASME
Manander Singh - One of the best experts on this subject based on the ideXlab platform.
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probabilistic analysis and risk assessment of deep water composite Production Riser against fatigue limit state
ASME 2015 34th International Conference on Ocean Offshore and Arctic Engineering, 2015Co-Authors: Manander Singh, Suhail AhmadAbstract:Deep water composite Risers are subjected to randomly fluctuating loads, induced by wind and waves in the presence of fluctuating axial tension which may be critical in deep sea conditions. Therefore, Risers experience the extreme bending and randomly fluctuating stresses throughout their service life. Cumulative fatigue damage is a critical assessment of Riser life in the presence of large dynamic stresses. Probabilistic analysis and risk assessment of composite Risers for cumulative fatigue is a vital design requirement for its satisfactory service and survival for stipulated period. Without addressing the reliability assessment, composite Risers may not be recommended for deep water oil and gas exploration and Production. Hence, the reliability assessment is a critical issue that is to be addressed for the safety of the deep water composite Riser. It is studied for the entire system for all possible sea states occurring in the exploration region. Unlike conventional Risers, the wall structure of a composite Riser is more complicated. Therefore, multiple failure mechanisms are used jointly to assess the safety of the composite Riser. Fatigue reliability is a challenging task due to complex nature of dynamic response and associated uncertainties caused by the material and external loads. The present study is focused on reliability assessment using stochastic finite element analysis. Response time histories for random sea plus current have been obtained. Requisite numbers of sea states are considered for the simulation of a wide range of off-shore environment and estimation of accumulated damage. By using the S-N data, damage fractions are calculated then summed linearly using Miner-Palmgren rule. The total damage has been obtained by summing the accumulated damages over all the sea states under consideration. Non-linear limit state function is derived based upon the above given approach to calculate the fatigue life. Important uncertainties associated with random variables are considered while deriving the limit state function. Numerical methods, such as Monte Carlo simulation and Advanced First Order Reliability Method, are used for the calculation of the reliability. The sensitivities of various random variables on overall probability of failure have been studied and design points have been located on failure surface. Probabilities of failure for important parameters are investigated.Copyright © 2015 by ASME
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Bursting Capacity and Debonding of Ultra Deep Composite Production Riser: A Safety Assessment
Volume 6A: Pipeline and Riser Technology, 2014Co-Authors: Manander Singh, Suhail AhmadAbstract:Due to depleting sources of oil and gas reserves in shallow water depths, exploration and Production activities have moved into ultra-deep offshore oil fields. Risers are an essential part of any offshore drilling facility. A Riser tensioner located on the drilling platform has to provide an adequate vertical tension to maintain the stability of the Riser. It is essential for a successful operation. Composite Risers in deep sea conditions require much lower top vertical forces due to their high strength to weight ratio. Carbon/epoxy composite has been considered in the present study to carry out the burst analysis and to assess the safety of the composite Riser under internal and external pressures and other environmental loads due to random sea currents. In order to ensure the permissible pressure and no fluid leakage, composite Risers are provided with an internal steel liner. Initiation and propagation of debonding between the liner and composite has been studied and probability of failure is obtained. In burst analysis, maximum internal pressure is applied to a Riser section and the stresses in all (hoop and longitudinal layers) the composite layers are checked against the failure. High pressures are incremented in small steps until fiber rupture occurs due to bursting. Maximum normal stress theory is employed for checking the failure. The same theory provides the limit-state to assess the safe pressure considering uncertainties associated with random input parameters involved. A finite element analysis has been carried out in ABAQUS/AQUA for random sea motion and fluctuating axial tension considering salient non-linearities. A small Riser section modelled as a hybrid beam element (for global analysis) has been considered to study the bursting and debonding behavior. It is further discretized into thin shell elements (S4R). Steel liner and composite pipes are modeled separately and assembled together to ensure the overlapping various layers and sharing nodes. The composite body sustains the major stresses in the inner layers that diminish on moving outwards radially. An implicit time domain analysis has been carried out to obtain the response. The debonding through circumference and length are studied. The stresses obtained are compared with their ultimate strength.Copyright © 2014 by ASME
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local stress analysis of composite Production Riser under random sea
ASME 2014 33rd International Conference on Ocean Offshore and Arctic Engineering, 2014Co-Authors: Manander Singh, Suhail AhmadAbstract:The advantage of composite Riser is more pronounced due to its light weight and reduced axial tension and bending moment. Its characteristics provide more flexibility in the design of Riser system such as stress joint, tensioner or even the platform hull. The composite Riser under study consists of alternative hoop and axial layers. There is a marginal coupling between these two orientations hence, the Riser is spatially orthotropic. The pressure capabilities of Riser are governed by the performance of hoop layers under combined fluctuating axial tension and bending moment. The internal steel liner provided to ensure no leakage often limits the composite Riser capabilities. The steel liner provided for Production inevitably carries major share of loads. An attempt has been made to carry out a detailed local analysis of a segmental length under critical loads. Damage analysis for various combinations of axial tension and bending moment are performed. The results of global analysis are used to act as boundary/initial condition for the local and detailed dynamic analysis of the segmental length modeled as finite element assemblage of shell elements. The critical stress time histories obtained by global analysis are applied at the local level. The composite layers sustained the random stresses that lead to the failure of the composite. Some realistic failure criteria are chosen to check the damage at local level.Copyright © 2014 by ASME
Paulo Dias - One of the best experts on this subject based on the ideXlab platform.
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ALUMINUM CATENARY Production Riser: DESIGN, TESTING RESULTS, WAYS TO IMPROVEMENT
2016Co-Authors: Vadim Tikhonov, Rudolf Alikin, Valery Chizhikov, Valery Shaposhnikov, Paulo Dias, Cenpes PetrobrasAbstract:One of the widely used systems for offshore oil Production in water depths up to 500-2500 meters is a steel catenary Riser (SCR). Requirements for long-term corrosion resistance of SCR are very stringent, that obliges to manufacture it from expensive steels. Still, the increased water depth leads to increased Riser tension, grown pressure, aggravated buckling and oscillation problems. Among alternative materials to manufacture catenary Risers, i.e., steel, titanium and aluminum alloys, the aluminum is the best from the “Strength/Weight/Cost ” aspects with its high corrosion strength. Design of an aluminum catenary Production Riser (ACPR) was developed in Russia; and comprehensive tests were performed on mechanical characteristics and corrosion resistance properties of ACPR tubes and their connections. Two possible connections of Riser sections were considered, i.e., welded and threaded. Strength analysis of threaded connection was performed by FEM. Mechanical testing included: testing of small samples of pipe material and welded connection cut out of Riser section, testing of full-scale specimens of connection prototypes, and measurement of residual stresses. Structural and corrosion tests of samples consist of investigation of standard metallographic characteristics of pipe material and welded connection, and assessment of effects of different types of corrosion in seawater and oil fluid. The results of performed work have led to the conclusion that welded connection is most prospective for ACPR manufacturing. At the same time, the testing revealed certain improvements need to be done in the course of further work on this project. 1
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Aluminum Catenary Production Riser: Design, Testing Results, Ways to Improvement
Volume 3: Pipeline and Riser Technology, 2012Co-Authors: Vadim S. Tikhonov, Mikhail Y. Gelfgat, Rudolf Alikin, Valery Chizhikov, Valery Shaposhnikov, Paulo DiasAbstract:One of the widely used systems for offshore oil Production in water depths up to 500–2500 meters is a steel catenary Riser (SCR). Requirements for long-term corrosion resistance of SCR are very stringent, that obliges to manufacture it from expensive steels. Still, the increased water depth leads to increased Riser tension, grown pressure, aggravated buckling and oscillation problems. Among alternative materials to manufacture catenary Risers, i.e., steel, titanium and aluminum alloys, the aluminum is the best from the “Strength/Weight/Cost” aspects with its high corrosion strength.Design of an aluminum catenary Production Riser (ACPR) was developed in Russia; and comprehensive tests were performed on mechanical characteristics and corrosion resistance properties of ACPR tubes and their connections. Two possible connections of Riser sections were considered, i.e., welded and threaded. Strength analysis of threaded connection was performed by FEM.Mechanical testing included: testing of small samples of pipe material and welded connection cut out of Riser section, testing of full-scale specimens of connection prototypes, and measurement of residual stresses. Structural and corrosion tests of samples consist of investigation of standard metallographic characteristics of pipe material and welded connection, and assessment of effects of different types of corrosion in seawater and oil fluid. The results of performed work have led to the conclusion that welded connection is most prospective for ACPR manufacturing. At the same time, the testing revealed certain improvements need to be done in the course of further work on this project.Copyright © 2012 by ASME
Roy Shilling - One of the best experts on this subject based on the ideXlab platform.
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design and qualification of fatigue resistant heavy wall threaded and coupled premium connectors for drilling and Production Riser applications in deepwater hpht dry tree systems
29th International Conference on Ocean Offshore and Arctic Engineering: Volume 5 Parts A and B, 2010Co-Authors: Ce Line Sches, Roy ShillingAbstract:In the late 2006, as a part of its GoM HPHT technology program, BP initiated with V&M the design and qualification of a 15k dual barrier dry tree Production Riser system capable of being installed in water depths up to 10,000 ft. This was driven by the fact that X-80 Riser systems became so heavy that they were not considered workable, whereas switching to higher strength steel and T&C connector designs made the systems much lighter and became enabling technologies for dry trees. Developments concern an 11 3/4″ OD with 1.1″ wall thickness C-110 sour service resistant material as the inner Riser rated to 15k, a 16″ OD with 1″ wall thickness Q-125 material as the outer Riser rated to 10k, and a 21″ OD with 1″ wall thickness Q-125 material as the drilling Riser rated to 10k. The specification called for all three connections to be designed with an external environmental metal to metal seal, and superior fatigue performance. Based on existing know-how on fatigue resistant T&C connectors, the development work started with the 11 3/4″ inner Riser, with a need to accommodate existing design rules for such a heavy pipe. A comprehensive evaluation program was built, with a total of 39 samples including 5 design variations, and full scale tests combining Make & Break, sealability, fatigue, and thermal cycles. The qualification was completed with a connector achieving over 25 M&B and a stress factor less than 1.5 compared to DNV-B1 curve, that is a stress factor matching DNV-C. With success on the 11 3/4″ and some lessons learned along the way, focus was then shifted to the 16″ outer Riser. Key issues were identified here concerning the surface treatment quality of the metal to metal seals when combining large sliding distance and high contact pressure. The 21″ drilling Riser development is on-going. As we near full product qualification, we focus on final optimizations to ensure easy field running. This paper will prove the robustness of the design process elaborated to develop heavy wall Riser T&C premium connectors, leading to outstanding fatigue performance and fatigue compliant internal and external environmental metal to metal seals. Such results prove the applicability of T&C for dry tree HPHT systems, and further establish the potential of T&C to be used for SCR and Flowline applications.Copyright © 2010 by ASME
Cenpes Petrobras - One of the best experts on this subject based on the ideXlab platform.
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ALUMINUM CATENARY Production Riser: DESIGN, TESTING RESULTS, WAYS TO IMPROVEMENT
2016Co-Authors: Vadim Tikhonov, Rudolf Alikin, Valery Chizhikov, Valery Shaposhnikov, Paulo Dias, Cenpes PetrobrasAbstract:One of the widely used systems for offshore oil Production in water depths up to 500-2500 meters is a steel catenary Riser (SCR). Requirements for long-term corrosion resistance of SCR are very stringent, that obliges to manufacture it from expensive steels. Still, the increased water depth leads to increased Riser tension, grown pressure, aggravated buckling and oscillation problems. Among alternative materials to manufacture catenary Risers, i.e., steel, titanium and aluminum alloys, the aluminum is the best from the “Strength/Weight/Cost ” aspects with its high corrosion strength. Design of an aluminum catenary Production Riser (ACPR) was developed in Russia; and comprehensive tests were performed on mechanical characteristics and corrosion resistance properties of ACPR tubes and their connections. Two possible connections of Riser sections were considered, i.e., welded and threaded. Strength analysis of threaded connection was performed by FEM. Mechanical testing included: testing of small samples of pipe material and welded connection cut out of Riser section, testing of full-scale specimens of connection prototypes, and measurement of residual stresses. Structural and corrosion tests of samples consist of investigation of standard metallographic characteristics of pipe material and welded connection, and assessment of effects of different types of corrosion in seawater and oil fluid. The results of performed work have led to the conclusion that welded connection is most prospective for ACPR manufacturing. At the same time, the testing revealed certain improvements need to be done in the course of further work on this project. 1
