Field Experience With the Construction of Large Diameter Steel Catenary Risers in\ Deep Water

2005 ◽  
Author(s):  
J. van der Graaf ◽  
D. Wolbers ◽  
P. Boerkamp
Keyword(s):  
Deep Water ◽  
Field Experience ◽  
Large Diameter ◽  
Steel Catenary Risers

Optimisation of Steel Catenary Risers

2013 ◽  
Author(s):  
Per Erlend Voie ◽  
Nils Sødahl
Keyword(s):  
Objective Function ◽  
Deep Water ◽  
Large Diameter ◽  
Technical Solution ◽  
Field Development ◽  
Steel Catenary Risers ◽  
Fit For Purpose ◽  
Vital Component ◽  
New Applications ◽  
Mathematical Optimisation

The riser system is a vital component of deep water floating production installations. Field specific optimised solutions are generally required to obtain a technical solution fit for purpose and to secure an economic field development. In some cases, the riser system is a potential technology stopper preventing use of existing field proven floater/station keeping solutions for new applications. One such example is operation of large diameter steel catenary risers (SCR) from floating production units in harsh environmental conditions. This study is focused on methodology for optimisation of riser systems by use of a mathematical optimisation scheme. An optimisation problem may formally be described as minimisation of a function in several variables (objective function) subjected to additional constraints. For the first time the general optimisation framework Optima is outlined allowing for use of standard riser analysis software for evaluation of objective function and constraints. Principles for selection of objective function and constraints are discussed for practical design applications with reference to design codes. Finally, an optimisation study of a steel riser for deep water and harsh environment is presented.

Probabilistic Fatigue Reliability of Large Diameter Steel Catenary Risers (SCR) for Ultra-Deepwater Operations

2007 ◽  
Author(s):  
U. O. Akpan ◽  
T. S. Koko ◽  
P. A. Rushton ◽  
A. Tavassoli ◽  
M. Else
Keyword(s):  
Fatigue Strength ◽  
Case Studies ◽  
Material Properties ◽  
Large Diameter ◽  
Random Variables ◽  
Fatigue Reliability ◽  
Strength Parameters ◽  
Stress Levels ◽  
Steel Catenary Risers

For deepwater development in the Gulf of Mexico, steel catenary risers (SCRs) supported from both SPAR and semi-submersible platforms have proven to be successful solutions for in-field flowlines, tie-backs, and export systems. It is envisaged that this will continue to be a promising solution in ultra deep-water applications, up to and beyond 10,000 ft. The study, commissioned by the Mineral Management Service (MMS), investigated the reliability of large-diameter SCRs in ultra-deepwater operations. The primary damage mode considered is fatigue failure. A probabilistic methodology for fatigue reliability is developed, which utilizes deterministic cumulative fatigue damage indicators, namely the stress levels and cycles associated with the various sea states and the fatigue strength of the members. Uncertainties in structural load and material properties are accounted for by assigning probability distributions and standard deviations to the deterministic stress levels. Furthermore, fatigue strength parameters, Miner’s indices, and capacities are modeled as random variables. First order reliability method (FORM) is employed for estimating fatigue reliability. The methodology is applied to three deterministic case studies presented by Intec Engineering (2006a, 2006b). The case studies involved either a SPAR or a semi-submersible platform. For the sake of brevity, a case study involving only a SPAR platform is presented in this paper. The effect of uncertainties in parameters on fatigue reliabilities is investigated. It is observed that the fatigue reliability estimates followed similar trends as the deterministic cumulative damage results, and hence can be used to complement deterministic estimates. Additional benefit and insight gained from the probabilistic study, which can be used for design decisions, include information regarding probabilistic importance and probabilistic sensitivity analysis. For case study presented here, it is seen that in general, uncertainty in the fatigue strength exponent (m) has the highest impact on fatigue reliability of SCRs. The second most important random variable is the stress range (S), which captures uncertainties in parameters such as loads and material properties. Parametric sensitivity studies on the fatigue strength parameters indicate that SCR reliability is sensitive to both the standard deviation and probability distribution of the parameters, thus highlighting the need for accurate probabilistic calibration of the random variables.

Numerical Simulation of UOE Pipe Process and its Effect on Pipe Mechanical Behavior in Deep-Water Applications

2015 ◽  
Author(s):  
Giannoula Chatzopoulou ◽  
Spyros A. Karamanos ◽  
George E. Varelis
Keyword(s):  
Deep Water ◽  
Manufacturing Process ◽  
Large Diameter ◽  
Structural Response ◽  
Structural Instability ◽  
External Pressure ◽  
Line Pipe ◽  
Simulation Tools ◽  
Large Diameter Pipes ◽  
Pipe Manufacturing

Large-diameter thick-walled steel pipes during their installation in deep-water are subjected to a combination of loading in terms of external pressure, bending and axial tension, which may trigger structural instability due to excessive pipe ovalization with catastrophic effects. In the present study, the UOE pipe manufacturing process, commonly adopted for producing large-diameter pipes of significant thickness, is considered. The study examines the effect of UOE line pipe manufacturing process on the structural response and resistance of offshore pipes during the installation process using nonlinear finite element simulation tools.

Strength and Fatigue Performance of Steel Lazy Wave Risers With Change in Configuration Parameters

2019 ◽  
Author(s):  
Mayank Lal ◽  
Feng Wang ◽  
Xiaohua Lu ◽  
Abhilash Sebastian
Keyword(s):  
Deep Water ◽  
Parametric Study ◽  
Fatigue Performance ◽  
Design Criteria ◽  
Cost Assessment ◽  
Fatigue Design ◽  
Design Variables ◽  
Steel Catenary Risers ◽  
Normative Cost ◽  
The Impact

Abstract Steel Lazy wave risers are being increasingly used for deep water applications due to better strength and fatigue performance in the touchdown zone compared to steel catenary risers. Several parameters govern the design of steel lazy wave risers including the length of the catenary from hang-off to start of buoyancy section and the length of the buoyancy section. In this paper, a parametric study is performed to investigate the trends in strength and fatigue performance of steel lazy wave risers with change in configuration parameters. A normative cost assessment is also performed to show the impact of these design variables on overall cost of the system. Dynamic analysis is performed to check the change in strength and fatigue performance of steel lazy wave risers as the configuration parameters are changed. The results from the parametric study will assist in designing steel lazy wave risers which satisfy the strength and fatigue design criteria.

Field Experience to Assess Efficiency of Scale Dissolver Treatment in a SubSea Deep Water Well

2006 ◽  
Author(s):  
Jose Sergio Daher ◽  
J. A. T. Gomes ◽  
Francisca Ferreira Rosario ◽  
Maria Carmen Moreira Bezerra ◽  
Vera Cristina Amorim ◽  
...  
Keyword(s):  
Deep Water ◽  
Field Experience ◽  
Water Well

scholarly journals Horizontal Forces Due to Waves Acting on Large Vertical Cylinders in Deep Water

1972 ◽  
Vol 94 (4) ◽  
pp. 862-866
Author(s):  
E. R. Johnson
Keyword(s):  
Deep Water ◽  
Large Diameter ◽  
Wave Force ◽  
Circular Cylinders ◽  
Wave Forces ◽  
Typical Application ◽  
Model Studies ◽  
Horizontal Wave ◽  
Horizontal Wave Force ◽  
Vertical Cylinders

The special case of horizontal wave forces on large vertical cylinders in deep water is considered. The typical application for such a case is the calculation of horizontal forces on column stabilized floating ocean platforms. Existing literature discussing horizontal wave forces on cylinders does not generally agree on how to predict these forces. Since for large diameter cylinders in deep water the maximum force is completely inertial, the problem of deriving a solution is considerably simplified. In this study, an expression for the maximum horizontal wave force on large diameter circular cylinders mounted vertically in deep water has been analytically derived. Experimental model studies were also conducted and the resulting measured forces were within 20 percent of predicted forces. An example of how to predict horizontal wave forces using the methods of this report is given.

scholarly journals First access to the ocean beneath Ekströmisen, Antarctica, by means of hot-water drilling

1994 ◽  
Vol 20 ◽  
pp. 110-114 ◽  
Author(s):  
U. Nixdorf ◽  
H. Oerter ◽  
H. Miller
Keyword(s):  
Water Column ◽  
Deep Water ◽  
Water Samples ◽  
Large Diameter ◽  
Hot Water ◽  
Easy Access ◽  
Ice Shelf ◽  
Valuable Data ◽  
The Past ◽  
Ultrasonic Echo

A hot-water drill developed during the past 2 years at Alfred-Wegener- Institut was used to penetrate Ekströmisen several times near the German wintering-over base, Neumayer (70°39´S, 08° 15´W). The drilling operation was very successful and the initial large diameter (≥ 35 cm) allowed easy access to the ocean. One hole was used to install an ultrasonic echo-sounder which recorded the ablation at the ice-shelf bottom continuously. Another hole was destined for emplacement of a thermistor string throughout the 237 m thick ice shelf for ice-temperature measurements. Several CTD profiles in the 175 m deep water column and the analysis of water samples provided valuable data for the understanding of ice-shelf-ocean interactions.

Large Diameter Steel Pipe Design under Deep Water: Lake Travis Experience

2011 ◽  
Author(s):  
Xiaohong He ◽  
Shelby Eckols ◽  
William Stauber
Keyword(s):  
Deep Water ◽  
Large Diameter ◽  
Steel Pipe ◽  
Water Lake

A Parametric Study on Effects of Environmental Loadings on Fatigue Life of Steel Catenary Risers (Using a Nonlinear Cyclic Riser-Soil Interaction Model)

2010 ◽  
Author(s):  
Mehrdad Kimiaei ◽  
Mark Randolph ◽  
Ivan Ting
Keyword(s):  
Fatigue Damage ◽  
Deep Water ◽  
Interaction Model ◽  
Fatigue Assessment ◽  
Wide Range ◽  
Non Linear ◽  
Wave Heights ◽  
Steel Catenary Risers ◽  
Vessel Motion ◽  
Floating Platforms

Steel catenary risers (SCRs) are often the preferred option for subsea tie-back to floating platforms in deep water due to their conceptual simplicity, ease of construction and installation and simple interface with the flowlines. Fatigue design of SCRs, particularly in the touch down area (TDA), has always been one of the major engineering challenges. Traditionally, fatigue assessment of SCRs has usually been highly conservative, because of lack of precise understanding of the non-linear soil-riser-interaction in the TDA. Most fatigue studies are based on assumed linear stiffness for the seabed, partly because of the lack of robust non-linear riser-seabed interaction models and partly because the linear response simplifies the fatigue study. The recent availability of non-linear seabed response models provides an opportunity to improve fatigue assessment, but it is first necessary to evaluate how best to conduct fatigue studies for such nonlinear systems which can be sensitive to wide range of input parameters. This paper outlines a new advanced numerical model, considering nonlinear cyclic riser-soil interaction behavior, used to determine the contribution of different loading parameters on fatigue damage of SCRs in the TDA in deep water soft sediments. The main loading parameters considered are: different motions of floating vessels, wave heights, wave periods and wave packs ordering. Numerical modeling has shown that over 95% of the fatigue damage corresponds to floating vessel motion parallel to the riser axis at the connection point to the vessel. It is also shown that riser response at TDA is highly influenced with amplitude and period of the environmental loadings.

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