Steel Catenary Riser Design Based on Prescribed Motions From Coupled Analysis Methodology

2008 ◽  
Author(s):  
Marcos Vinicius Rodrigues ◽  
Vigleik L. Hansen ◽  
Rodrigo Almeida Bahiense ◽  
Celso Velasco Raposo
Keyword(s):  
Coupled Analysis ◽  
Steel Catenary Riser ◽  
Analysis Methodology ◽  
Riser Design

Strength Performance of Steel Catenary Riser Using Short Term and Long Term Analysis Methodologies

2016 ◽  
Author(s):  
Feng Wang ◽  
Roger Burke ◽  
Anil Sablok ◽  
Kristoffer H. Aronsen ◽  
Oddgeir Dalane
Keyword(s):  
Bending Moment ◽  
Current Profile ◽  
Short Term ◽  
Sea State ◽  
Strength Performance ◽  
Steel Catenary Riser ◽  
Analysis Methodology ◽  
Riser Design ◽  
Term Analysis

Strength performance of a steel catenary riser tied back to a Spar is presented based on long term and short term analysis methodologies. The focus of the study is on response in the riser touch down zone, which is found to be the critical region based on short term analysis results. Short term riser response in design storms is computed based on multiple realizations of computed vessel motions with various return periods. Long term riser response is based on vessel motions for a set of 45,000 sea states, each lasting three hours. The metocean criteria for each sea state is computed based on fifty six years of hindcast wind and wave data. A randomly selected current profile is used in the long term riser analysis for each sea state. Weibull fitting is used to compute the extreme riser response from the response of the 45,000 sea states. Long term analysis results in the touch down zone, including maximum bending moment, minimum effective tension, and maximum utilization using DNV-OS-F201, are compared against those from the short term analysis. The comparison indicates that the short term analysis methodology normally followed in riser design is conservative compared to the more accurate, but computationally more expensive, long term analysis methods. The study also investigates the important role that current plays in the strength performance of the riser in the touch down zone.

Steel Catenary Riser Design Based on Coupled Analysis Methodology

2008 ◽  
Author(s):  
Marcos V. Rodrigues ◽  
Rodrigo A. Bahiense ◽  
Oddrun Steinkjer ◽  
Celso V. Raposo
Keyword(s):  
Computational Effort ◽  
Computational Time ◽  
Coupled Analysis ◽  
Coupling Effects ◽  
Usual Practice ◽  
Environmental Loads ◽  
Steel Catenary Riser ◽  
Deep Waters ◽  
Riser Design ◽  
Platform Motions

In a riser design, the traditionally assessment adopted by industry for attainment of platform motions applied to the top of riser consists in the use of de-coupled methodologies. These formulations consider the static environmental loads over the platform (current and wind) through a static offset and the dynamic environmental loads due to wave through imposition of top riser displacement calculated from cross spectral response of sea spectrum and vessel’s RAOs (Response Amplitude Operators). Nowadays due to shift of oil and gas exploitation to deeper waters more accurate methodologies, based on coupled analysis, have been introduced. The coupled analysis considers the interaction between the hydrodynamic behavior of the hull and the structural behavior of mooring lines and risers submitted to environmental loads. For deep waters the coupling effects of lines over platform motions are especially significant and a reduction of the amplification of platform motions if compared to the platform motions obtained from de-coupled analysis is observed. This paper presents a typical Steel Catenary Riser design, connected to a semi-submersible platform, where the motions applied to the top of riser are obtained from the “traditional” way (de-coupled) and from the coupled analysis. Numerical application is presented in order to assess the comparison of the two presented methods in terms of SCR analysis results and to confirm the reduction of platform motions due to coupling effects. The coupled model here studied is composed of approximately 80 lines connected to the platform which requires an excessive computational effort. In order to reduce the computational time some additional studies are performed considering the variation of line mesh discretization and time step size. The objective of this study is the adoption of an optimized model where the required accuracy is achieved and the computational time consuming is the minimum possible. The computational time consuming and platform motions are also presented. The conclusion of this work is that coupled analysis should be adopted by industry as usual practice of SCR design in deep waters, where more realistic and optimum results are presented, without an excessive computational effort.

Drilling Riser Design and Analysis for Deepwater Applications

2013 ◽  
Author(s):  
Yongming Cheng ◽  
Tao Qi
Keyword(s):  
High Pressure ◽  
Production Systems ◽  
Dynamic Performance ◽  
Design Procedure ◽  
Dynamic Strength ◽  
Low Pressure ◽  
Strength Analysis ◽  
Global Dynamic ◽  
Analysis Methodology ◽  
Riser Design

A riser is a fluid conduit from subsea equipment to surface floating production systems such as spars, TLPs, and semi-submersibles. It is a key component in a drilling and producing system. Drilling risers include the applications in marine drilling (low pressure) and tie-back drilling (high pressure). This paper discusses drilling riser design and analysis for a deepwater application. This paper first discusses the configuration of marine drilling and tie-back drilling risers. It then presents the drilling riser design procedure and analysis methodology. The riser design and analysis cover the riser tensioner setting, marine operation window, strength and fatigue, etc. A marine drilling riser example is used in the paper to demonstrate the design and analysis for a deepwater application. This paper shows the dynamic strength analysis results for the riser. It then identifies governing locations for the riser design. A tie-back drilling riser example is also provided to illustrate its global dynamic performance. This paper finally discusses the design and analysis challenges of a drilling riser for a deepwater application.

Robustness of an SCR in Gulf of Mexico Hurricane Conditions

2010 ◽  
Author(s):  
Partha Sharma ◽  
Kim Mo̸rk ◽  
Vigleik Hansen ◽  
Celso Raposo ◽  
Srinivas Vishnubhotla
Keyword(s):  
Gulf Of Mexico ◽  
Time Domain ◽  
Offshore Structures ◽  
Coupled Analysis ◽  
Floating Structure ◽  
Steel Catenary Riser ◽  
Strength Capacity ◽  
Critical Components ◽  
Robustness Check ◽  
Robustness Assessment

Recent hurricanes in Gulf of Mexico, most notably Ivan (2004), Katrina & Rita (2005), Ike (2008), were more severe than the local 100 year extremes in the Gulf of Mexico (GoM). As a result API has issued an interim metocean bulletin, API Bulletin 2INT-MET [1]. Concurrently, API also issued API Bulletin 2INT-EX [2] for assessment of existing offshore structures for hurricane conditions. API Bulletin 2INT-EX recommends a robustness check to evaluate floating structure critical components including production and export risers. The robustness check for risers as a minimum should consider the capacity and ductility of the key riser components. This paper investigates the robustness of a steel catenary riser (SCR) suspended from a deepwater tension leg platform (TLP) unit in Central GoM. The robustness assessment is performed for the 1000 year Central GoM hurricane conditions provided in API 2INT-MET. Time domain coupled analysis using the program DeepC is performed to determine the TLP motions and the associated loading on the SCR. SCR strength capacity checks are performed as per the methods outlined in new ISO 13628-12 [3].

Deepwater SCR Benchmarking Methodology

2011 ◽  
Author(s):  
Songcheng Li ◽  
Lee Tran ◽  
Prahlad Enuganti ◽  
Mike Campbell ◽  
Yiannis Constantinides
Keyword(s):  
Gulf Of Mexico ◽  
Design Process ◽  
Environmental Conditions ◽  
Field Measurements ◽  
Design Parameters ◽  
Spar Platform ◽  
Steel Catenary Riser ◽  
Comprehensive Database ◽  
Riser Design

One of the primary goals of riser monitoring is to build a database of measured riser behavior during different environmental conditions and compare against design predictions during each period. A comprehensive database of field measured riser response provides not only a dataset to benchmark riser performance but enables the calibration of design parameters for future risers. The calibrated set of design parameters would feedback to establish a more representative riser design process and provide greater confidence during future riser designs. The following paper establishes a methodology to benchmark riser behavior against software predictions with applications specific to a steel catenary riser (SCR) suspended from a spar platform. Aspects and challenges dealing with processing of inclined sensors to derive global motions and operational effects are discussed and addressed. A demonstration of the methodology is presented using field measurements from a Gulf of Mexico deepwater SCR under storm conditions. The riser behavior of interest for this study is specifically the touchdown motions and stress but additional comparisons are made along the entire riser length.

Lazy Wave Steel Catenary Riser Design Optimisation in Digital Field Twin

2020 ◽  
Author(s):  
Subrata Bhowmik ◽  
Harit Naik ◽  
Gautier Noiray
Keyword(s):  
Design Optimisation ◽  
Steel Catenary Riser ◽  
Riser Design

Steel Catenary Riser Response Identification Based on Field Measurements

2011 ◽  
Author(s):  
Yiannis Constantinides ◽  
Lee Tran ◽  
Prahlad Enuganti ◽  
Mike Campbell
Keyword(s):  
Large Scale ◽  
Field Measurements ◽  
Small Scale ◽  
Steel Catenary Riser ◽  
The Past ◽  
Need To Evaluate ◽  
Large Scale Field ◽  
Steel Catenary Risers ◽  
Riser Design ◽  
Touchdown Point

The existing riser design and analysis methodologies rely on empirically derived parameters to conservatively represent the complex dynamic behavior. With exploration moving to deeper water and the increasing need of existing asset support, there is a strong need to evaluate and refine these methodologies. This is especially true for Steel Catenary Risers (SCR) as they are the most widely used riser type and due to their complex soil-pipe interaction at the touchdown point. Given the small amount of small scale experiments that have been performed in the past, there is a strong industry need for large scale field measurements. This paper presents valuable field data collected from a deepwater SCR under storm conditions. The presented data includes riser accelerations and strains compared against vessel motions. The measured SCR response is also analyzed and qualitatively compared against the current understanding of SCR response that constitutes the industry analysis methodologies.

Lazy Wave Riser Design in High Current and Mild Sour Environment

2019 ◽  
Author(s):  
Rupak Ghosh ◽  
Carlo Pellegrini ◽  
Tyler J. Visco
Keyword(s):  
High Current ◽  
Design Requirement ◽  
Innovative Design ◽  
Steel Catenary Riser ◽  
Fatigue Design ◽  
Design Life ◽  
Significant Damage ◽  
New Frontier ◽  
Riser Design ◽  
Very High

Abstract This paper presents an innovative design of Lazy Wave Steel Catenary Riser (LWSCR) associated with a major deepwater development in a new frontier and in very high current. The conventional LWSCR design with distributed buoyancy is not found acceptable considering fatigue design acceptance criteria in mild sour environment. The major design requirement is to meet acceptable design life of 20-yrs considering significant damage accumulated due to Vortex-induced-vibration (VIV) and motion fatigue. Further, other development basis including flow assurance requirements and reservoir souring are critical requirements for the design of the riser system. The paper presents a very useful insight in how several qualified technologies can be leveraged to result in a workable riser design in a very aggressive execution schedule. The results from the analyses of a production LWSCR are presented in the paper.

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