Straked Riser Design With VIVA

VIVA is a vortex induced vibration (VIV) analysis software that to date has not been widely used as a design tool in the offshore oil and gas industry. VIVA employs a hydrodynamic database that has been benchmarked and calibrated against test data [1]. It offers relatively few input variables reducing the risk of user induced variability of results [2]. In addition to cross flow current induced standing wave vibration, VIVA has the capability of predicting traveling waves on a subsea riser, or a combination of standing and traveling waves. Riser boundary conditions including fixed, pinned, flex joint or SCR seabed interaction can be modeled using springs and dashpots. VIVA calculates riser natural frequencies and mode shapes and also has the flexibility to import external modal solutions. In this paper, the applicability of VIVA for the design of straked steel catenary risers (SCR) and top tensioned risers (TTR) is explored. The use of linear and rotational springs provided by VIVA to model SCR soil interaction and flex joint articulation is evaluated. Comparisons of the VIV fatigue damage output with internal and external modal solution is presented in this paper. This paper includes validation of the VIVA generated modal solution by comparing the modal frequencies and curvatures against a finite element (FE) model of the risers. Fatigue life is calculated using long term Gulf of Mexico (GoM) currents and is compared against the industry standard software SHEAR7. Three different lift curve selections in SHEAR7 are used for this comparison. The differences in riser response prediction by the two software tools are discussed in detail. The sensitivity of the VIVA predicted riser response to the absence of VIV suppression devices is presented in this paper. The riser VIV response with and without external FE generated modal input is compared and the relative merits of the two modeling approaches are discussed. Finally, the recommended approach for VIVA usage for SCR and TTR design is given.

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Innovative Optical-Sensing Technology for the Online Fouling Characterization of Silicon Carbide Membranes during the Treatment of Oily Water

Sensors ◽

10.3390/s20041161 ◽

2020 ◽

Vol 20 (4) ◽

pp. 1161

Author(s):

Mehrdad Ebrahimi ◽

Axel A. Schmidt ◽

Cagatay Kaplan ◽

Oliver Schmitz ◽

Peter Czermak

Keyword(s):

Silicon Carbide ◽

Oil Recovery ◽

Oil And Gas ◽

Produced Water ◽

Cross Flow ◽

Oil And Gas Industry ◽

Ceramic Membranes ◽

Transmembrane Pressure ◽

Sensing Technology ◽

Water Sensor

The oil and gas industry generates a large volume of contaminated water (produced water) which must be processed to recover oil before discharge. Here, we evaluated the performance and fouling behavior of commercial ceramic silicon carbide membranes in the treatment of oily wastewaters. In this context, microfiltration and ultrafiltration ceramic membranes were used for the separation of oil during the treatment of tank dewatering produced water and oily model solutions, respectively. We also tested a new online oil-in-water sensor (OMD-32) based on the principle of light scattering for the continuous measurement of oil concentrations in order to optimize the main filtration process parameters that determine membrane performance: the transmembrane pressure and cross-flow velocity. Using the OMD-32 sensor, the oil content of the feed, concentrate and permeate streams was measured continuously and fell within the range 0.0–200 parts per million (ppm) with a resolution of 1.0 ppm. The ceramic membranes achieved an oil-recovery efficiency of up to 98% with less than 1.0 ppm residual oil in the permeate stream, meeting environmental regulations for discharge in most areas.

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Small-Scale FE Modelling for the Analysis of Flexible Risers

Volume 5A: Pipeline and Riser Technology ◽

10.1115/omae2015-41825 ◽

2015 ◽

Cited By ~ 2

Author(s):

M. T. Rahmati ◽

G. Alfano ◽

H. Bahai

Keyword(s):

Boundary Conditions ◽

Large Scale ◽

Oil And Gas ◽

Oil And Gas Industry ◽

Small Scale ◽

Fe Model ◽

Fe Modelling ◽

Sequential Approach ◽

Multi Scale ◽

Flexible Risers

Flexible risers which are used for transporting oil and gas between the seabed and surface in ultra-deep waters have a very complex internal structure. Therefore, accurate modeling of their behaviour is a great challenge for the oil and gas industry. Constitutive laws based on beam models which allow the large-scale dynamics of pipes to be related to the behaviour of its internal components can be used for multi-scale analysis of flexible risers. An integral part of these models is the small-scale FE model chosen and the detailed implementation of the boundary conditions. The small scale FE analyses are typically carried out on models of up to a few meters length. The computational requirements of these methods limit their applications for only multi-scale structural analysis based on a sequential approach. For nested multi-scale approaches (i.e. the so called FE2 method) and for multi-scale multi-physic analyses, e.g. fluid structure interaction modeling of flexible risers, more efficient methods are required. The emphasis of the present work is on a highly efficient small-scale modelling method for flexible risers. By applying periodic boundary conditions, only a small fraction of a flexible pipe is used for detailed analysis. The computational model is firstly described. Then, the capability of the method in capturing the detailed nonlinear effects and the great advantage in terms of significant CPU time saving entailed by this method are demonstrated. For proof of concept the approach is applied on a simplified 3-layer pipe made of inner and outer polymer layers and an intermediate armour layer made of 40 steel tendons.

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Manufacture and Qualification of Small Diameter / Thickwall Reelable DSAWL Linepipe

Volume 3: Operations, Monitoring and Maintenance; Materials and Joining ◽

10.1115/ipc2016-64406 ◽

2016 ◽

Author(s):

Stephen Hall ◽

Martin Connelly ◽

Graham Alderton ◽

Andrew Hill ◽

Shuwen Wen

Keyword(s):

Oil And Gas ◽

Small Diameter ◽

Oil And Gas Industry ◽

Fe Model ◽

External Diameter ◽

Gas Industry ◽

The North ◽

Innovative Thinking ◽

The North Sea ◽

The Cost

Tough market conditions have seen the price of oil drop which with the subsequent uncertainty surrounding the industry have seen the oil and gas industry concentrate on reducing the cost of designing, installing and operating pipelines. A critical process for the industry is the procurement, manufacture and installation of appropriate linepipe. The method of installation is often dictated by the pipe size and the water depth that the pipe is to be laid in, however there are times when the choice of lay method is due to vessel availability and relative costs for each technique. In early 2014, Tata Steel successfully manufactured and delivered 16"OD × 0.875”WT X65 submerged arc welded longitudinal (SAWL) linepipe for installation via the reel lay method. Notable features about this fact were the size, which represents the thickest 16” external diameter UOE pipe yet delivered by Tata Steel, and that this was to be the first UOE pipe to be installed by the reel lay method in the North Sea. The ability to manufacture small diameter thickwall linepipe was only possible due to recent operational developments including an established tooling programme and a fully validated Finite Element (FE) model of the UOE process, along with years of experience of integrating these tools into the manufacturing process. This paper discusses the manufacturing challenges for small diameter thickwall linepipe, and how with the aid of modelling tools, innovative thinking and previous experience in supplying small diameter thickwall linepipe into two reel-installed projects, the pipe was manufactured and delivered with the properties shown to be compliant with DNV OS-F101 Supplementary Requirement P.

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Pitting and CO2 corrosion behavior of oil and gas pipeline welds

Materials Testing ◽

10.1515/mt-2021-0034 ◽

2021 ◽

Vol 63 (11) ◽

pp. 1018-1024

Author(s):

Huan Xie ◽

Xiang Chen ◽

Yongxin Lu ◽

Qian Zhang ◽

Haitao Wang

Keyword(s):

Corrosion Behavior ◽

Oil And Gas ◽

Welded Joint ◽

Oil And Gas Industry ◽

Gas Pipeline ◽

Co2 Corrosion ◽

Fe Model ◽

Gas Industry ◽

Remaining Service Life ◽

Pit Depth

Abstract A finite element (FE) model is presented in this work that is used to analyze the effect of pitting corrosion on the CO2 corrosion behavior of oil and gas pipeline welds. The FE model contains two parts, i. e., stress calculation of the welded joint using Abaqus software, and of the chemical reaction at the welded joint using COMSOL Multiphysics® software. The effect of transportation pressure, pit depth and welding material on the CO2 corrosion behavior of weld metal was investigated using the FE model. It turned out that the FE model is helpful to instruct the management and to assess the remaining service life prediction of pipelines in the oil and gas industry.

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Development of an Analytical Tool for the Design of Deepwater Riser/Flowline Thermal Insulation Systems

Volume 2: Safety and Reliability; Pipeline Technology ◽

10.1115/omae2003-37101 ◽

2003 ◽

Author(s):

Dara Williams ◽

Annette Harte ◽

Frank Grealish

Keyword(s):

Thermal Insulation ◽

Oil And Gas ◽

Oil And Gas Industry ◽

Design Tool ◽

Flow Assurance ◽

Gas Industry ◽

Analysis And Design ◽

Insulation Systems ◽

Key Issues ◽

Offshore Oil And Gas

The offshore oil and gas industry is predicting the discovery of more and more deepwater reservoirs. Increased water depths create a requirement for reliable pipelines to economically recover these deepwater fields and also to minimise flow assurance problems. Increased flow assurance problems in deeper waters increase the need for thermally insulated pipelines. This paper presents an overview of the key issues in the analysis and design of thermal insulation systems, identifies and discusses how these are addressed by the design tools developed within the DeFRIS [1] project and presents results used to validate the algorithms incorporated into the design tool.

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Development of an Analytical Tool for the Design of Deep Water Riser/Flow Line Thermal Insulation Systems

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.1894403 ◽

2004 ◽

Vol 127 (2) ◽

pp. 96-103 ◽

Cited By ~ 1

Author(s):

Dara Williams ◽

Annette Harte ◽

Frank Grealish

Keyword(s):

Thermal Insulation ◽

Deep Water ◽

Oil And Gas ◽

Flow Line ◽

Oil And Gas Industry ◽

Design Tool ◽

Flow Assurance ◽

Gas Industry ◽

Analysis And Design ◽

Insulation Systems

The offshore oil and gas industry is predicting the discovery of more and more deep water reservoirs. Increased water depths create a requirement for reliable pipelines to economically recover these deep water fields and also to minimize flow assurance problems. Increased flow assurance problems in deeper waters increase the need for thermally insulated pipelines. In this paper we present an overview of the key issues in the analysis and design of thermal insulation systems, identify and discuss how these are addressed by the design tools developed within the DeFRIS project and present results used to validate the algorithms incorporated into the design tool.

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Tandem Riser VIV Suppression Fairing Model Test

Volume 2: CFD and VIV ◽

10.1115/omae2014-23412 ◽

2014 ◽

Cited By ~ 1

Author(s):

David Jinq Tyng Ng ◽

Yih Jeng Teng ◽

Allan Magee ◽

Shankar Bhat Aramanadka ◽

NorBahrain Ahmad Zukni ◽

...

Keyword(s):

Model Test ◽

Vortex Shedding ◽

Oil And Gas ◽

Oil And Gas Industry ◽

Test Model ◽

Offshore Platforms ◽

Gas Industry ◽

Test Models ◽

Offshore Industry ◽

Viv Suppression

In deepwater development areas of Southeast Asia, the current is strong and relatively more persistent compared to other deepwater regions. Top tensioned risers (TTR) are critical submerged components of offshore platforms, constantly exposed to currents. These currents cause unsteady flow patterns around the risers i.e. vortex shedding. When the vortex shedding frequency is near the riser’s natural frequency, undesirable resonant vibration of the riser also known as Vortex Induced Vibration (VIV) occurs. Several types of VIV suppression devices are used in the offshore industry. Among them, the U-shaped fairing claims to have the capabilities of reducing VIV effectively as well as lowering drag loads. This study investigates the effectiveness of a U-shaped fairing in suppressing riser VIV. The model test was successfully performed in a towing tank facility located at Universiti Teknologi Malaysia (UTM), Johor Bahru, Malaysia. This study is a significant collaboration between a local academic institution and the offshore oil and gas industry, aligned with the industry’s initiative of increasing local capabilities for research and development. In this study, the VIV of two risers in tandem is simulated using scaled test models. The current flow is simulated by towing the vertically submerged test models with a moving carriage. The riser with fairing models are attached to a pair of custom-designed test rigs which are able to measure the forces and also allow movement of the test model during towing tests. The two test rigs are attached to a steel structure under the carriage which accommodates different tandem riser configurations and spacings. Two different sizes of risers and fairings are tested to check for Reynolds number effects. For each tandem riser configuration, three different riser conditions are tested, i.e. (a) bare risers without fairings; (b) risers with weathervaning fairings, and (c) upstream riser with fairing stuck at different orientations and downstream riser with weathervaning fairing. The test results show significant reduction in drag and VIV for the risers with weathervaning fairings in different tandem configurations. Interesting motion characteristics are shown in some of the stuck fairing cases highlighting the adverse effects should the fairings fail to perform normally in the field. Effective mitigation of VIV in risers using fairing suppression devices could lead to improved riser fatigue life and overall a more economical platform design. These benefits are highly applicable to local deepwater developments for the oil and gas industry.

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