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.

Comparison of SCR Field Response With Analytical Predictions

2011 ◽  
Author(s):  
Yiannis Constantinides ◽  
Jen-hwa Chen ◽  
Lee Tran ◽  
Prahlad Enuganti ◽  
Mike Campbell
Keyword(s):  
Structural Response ◽  
Field Measurements ◽  
Design Parameters ◽  
Element Analysis ◽  
Steel Catenary Riser ◽  
Analysis And Design ◽  
Industry Standard ◽  
Fea Modeling ◽  
Actual Field ◽  
Deepwater Risers

Design of deepwater risers involves the use of multiple conservative design parameters to account for the uncertainty in the understanding of the behavior of complex structures. As the oil industry moves into deeper and harsher waters, the design tolerances are getting stretched. Chevron has been monitoring the structural response of a deepwater Gulf of Mexico steel catenary riser (SCR) to improve the understanding of riser behavior and to evaluate the existing analysis and design methodologies against actual field measurements. The following paper presents a selected set of results from benchmark of SCR response in storm conditions against analytical predictions, based on industry standard methodologies. The predictions are based on a finite element analysis (FEA) modeling of the riser structure with empirically formulated models for hydrodynamics and soil-structure interaction. Predicted riser response in terms of accelerations and stresses along the length are compared against field measurements showing good overall agreement.

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.

Thunder Hawk Riser System Design: An Integrated Experience

2010 ◽  
Author(s):  
Peimin Cao ◽  
Sherry Xiang ◽  
Luc Chabot ◽  
Paul Fourchy ◽  
Rafik Boubenider
Keyword(s):  
System Design ◽  
Integrated Design ◽  
Sensitivity Analyses ◽  
Design Parameters ◽  
Analysis Model ◽  
Steel Catenary Riser ◽  
Fatigue Design ◽  
Fatigue And Fracture ◽  
Riser Design ◽  
Scr System

The Thunder Hawk field was developed through a Steel Catenary Riser (SCR) system connected to a DeepDraft Semi® Floating Production Unit (FPU) installed in approximately 6,060-ft. water depth in the central Gulf of Mexico (GoM). This paper presents an integrated riser design experience, focusing on the significant design challenges and solutions. The Thunder Hawk FPU was one of the first deepwater projects to address the enhanced GoM environment criteria. These criteria required the integrated design team to configure a feasible and robust hull, mooring and riser system. Model tests were performed to validate the design and calibrate the analysis model. Other challenges included the SCR fatigue and fracture design, titanium stress joint and receptacle design for the high pressure production risers, flex joint over-rotation design, and porch fatigue design. A significant amount of sensitivity analyses were performed to cover the uncertainty of the various hull, mooring, and riser design parameters that affected the SCR performance. The SBM Atlantia (SBMA) riser team worked closely with the Murphy Integrated Project Team (IPT) to achieve a robust and comprehensive riser design 16 months before the first SCR was installed. The highly integrated engineering approach enabled prompt and full considerations of the system interactions, and provided instant design evaluation throughout the project. The sensitivity analyses established the system design envelopes, and resulted in significant flexibility in offshore installation and operation.

Green roof hydrologic performance and modeling: a review

2013 ◽  
Vol 69 (4) ◽  
pp. 727-738 ◽  
Author(s):  
Yanling Li ◽  
Roger W. Babcock
Keyword(s):  
Peak Flow ◽  
Green Roof ◽  
Field Measurements ◽  
Green Roofs ◽  
Economic Benefits ◽  
Design Parameters ◽  
Technical Literature ◽  
Factors Affecting ◽  
Model Soil ◽  
Runoff Volume

Green roofs reduce runoff from impervious surfaces in urban development. This paper reviews the technical literature on green roof hydrology. Laboratory experiments and field measurements have shown that green roofs can reduce stormwater runoff volume by 30 to 86%, reduce peak flow rate by 22 to 93% and delay the peak flow by 0 to 30 min and thereby decrease pollution, flooding and erosion during precipitation events. However, the effectiveness can vary substantially due to design characteristics making performance predictions difficult. Evaluation of the most recently published study findings indicates that the major factors affecting green roof hydrology are precipitation volume, precipitation dynamics, antecedent conditions, growth medium, plant species, and roof slope. This paper also evaluates the computer models commonly used to simulate hydrologic processes for green roofs, including stormwater management model, soil water atmosphere and plant, SWMS-2D, HYDRUS, and other models that are shown to be effective for predicting precipitation response and economic benefits. The review findings indicate that green roofs are effective for reduction of runoff volume and peak flow, and delay of peak flow, however, no tool or model is available to predict expected performance for any given anticipated system based on design parameters that directly affect green roof hydrology.

VIV Predictions for an SCR in Sheared Ocean Currents

2002 ◽  
Author(s):  
Christopher J. Wajnikonis
Keyword(s):  
Experimental Data ◽  
Design Parameters ◽  
Finite Element Analyses ◽  
Steel Catenary Riser ◽  
Specialized Software ◽  
Design Engineers ◽  
Sensitivity Studies ◽  
Deepwater Riser ◽  
Extended Program ◽  
Areas Of Interest

Vortex Induced Vibration (VIV) prediction is one of the key areas of interest in Deepwater Riser Engineering. Several Joint Industry Projects (JIPs) are currently in progress in this field, which results in an increase of experimental data available to design engineers, in revisions of specialized software and in development of new engineering tools. This paper presents VIV predictions for a hypothetical Steel Catenary Riser (SCR) using the latest versions of the SHEAR7 and the VIVA/VIVARRAY Programs. Both built-in and extended program capabilities are utilized and detailed plots of computation results are presented. Sensitivity studies on the influence of variations of selected design parameters are also included in the paper. Finite Element Analyses (FEAs) results and simple engineering tools were utilized in parallel to built-in program features. The calculations demonstrated, that for the riser investigated and presumably also for a wide variety of similar SCRs, that the built in program features are sufficient to predict VIVs conservatively. Notes on VIV predictions in a real ocean and on selected areas that require investigation are also included.

Optimal Offloading Configuration of Spread-Moored FPSOs

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Steven M. Wilkerson ◽  
Satish Nagarajaiah
Keyword(s):  
Environmental Conditions ◽  
Main Tool ◽  
Design Parameters ◽  
Optimization Approach ◽  
Analysis Model ◽  
Simple Analysis ◽  
Formal Approach ◽  
Fine Tune ◽  
Formal Optimization ◽  
Selection Of

As the oil offloading operations of floating production storage and offloading (FPSO) units become more routine, the desire grows to increase the availability for offloading and thus decrease production downtime. Experience with these operations is the main tool available to increase the efficiency of this aspect of deepwater production. However, it is clear that a formal optimization approach can help to fine tune design parameters so that not only is availability increased but the significance of each design parameter can be better understood. The key issue is to define the environmental conditions under which the vessels involved in offloading are able to maintain position. By this, we reduce the notion of availability to a set of operating criteria, which can or cannot be met for a particular set of environmental conditions. The actual operating criteria such as relative vessel heading depend on selection of design parameters, such as the direction and magnitude of external force applied by thrusters or tugs. In the earliest offloading operations, engineering judgment was used to determine the feasibility of offloading at a particular time. For example, if wind and current were not expected to exceed a 1year return period, offloading may be considered safe. This approach can be both conservative and unconservative, depending on the nuances of the particular environmental conditions. This study will propose a formal approach to choosing the design parameters that optimize the availability of a FPSO for offloading. A simple analysis model will be employed so that optimization can be performed quickly using a robust second order method. The proposed analysis model will be compared to model test data to demonstrate its agreement with the more complex system.

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.

Sensitivity Study of Critical Parameters Influencing the Uncertainty of Fatigue Damage in Steel Catenary Risers

2010 ◽  
Author(s):  
Feng Zi Li ◽  
Ying Min Low
Keyword(s):  
Fatigue Damage ◽  
Cost Effective ◽  
Sensitivity Study ◽  
Structural Safety ◽  
Critical Parameters ◽  
Design Parameters ◽  
Steel Catenary Riser ◽  
Bending Stresses ◽  
Steel Catenary Risers ◽  
Touchdown Point

The most challenging aspect of a deepwater development is the riser system, and a cost-effective choice is the Steel Catenary Riser (SCR). Fatigue is often a governing design consideration, and it is usually most critical at the touchdown point (TDP) where static and dynamic bending stresses are highest. Unfortunately, it is also at this region that uncertainty is the maximum. The increased uncertainty casts doubt on the applicability of generic safety factors recommended by design codes, and the most consistent way of ensuring the structural safety of the SCR is to employ a reliability-based approach, which has so far not received attention in SCR design. As the number of basic random variables affects the complexity of a reliability analysis, these variables should be selected with caution. To this end, the aim of this paper is to draw up a comprehensive list of design parameters that may contribute meaningfully to the uncertainty of the fatigue damage. From this list, several parameters are selected for sensitivity studies using the commercial package Orcaflex. It is found that variations in seabed parameters such as soil stiffness, soil suction and seabed trench can have a pronounced influence on the uncertainty of the fatigue damage at the touchdown point.

scholarly journals Design of a tablet holder with the help of Axiomatic Design International Conference of Axiomatic Design 2017

2018 ◽  
Vol 223 ◽  
pp. 01009
Author(s):  
Auðunn Herjólfsson ◽  
Haraldur Helgason ◽  
Sindri S. Ingvason ◽  
þráinn þórarinsson ◽  
Joseph Timothy Foley
Keyword(s):  
Design Process ◽  
Axiomatic Design ◽  
Design Parameters ◽  
Smart Devices ◽  
Functional Requirements ◽  
Modern Life ◽  
Customer Needs ◽  
International Conference ◽  
Viewing Experience

With the explosion of smart devices, tablets can currently be found everywhere. From schools to kiosks to watching movies in bed, these devices are prevalent everywhere in modern life. The problem with watching movies in bed using tablets is the necessity of hand usage. The market currently holds a few products that attempt to solve this, but none truly frees the user, allowing them hands-free usage with an easy exit of the bed. In this paper, we will describe a design which, utilizing axiomatic design, will out-perform anything currently existing in the same field, by giving a stable viewing experience while fitting to nearly any bed or sofa. Axiomatic Design ensured a comprehensive design process by ensuring customer needs were transformed into carefully thought out functional requirements and design parameters while maintaining modularity.

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
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