CARISIMA: A Catenary Riser/Soil Interaction Model for Global Riser Analysis

Author(s):  
Egil Giertsen ◽  
Richard Verley ◽  
Knut Schro̸der

Steel or titanium catenary type risers may provide cost effective alternatives to flexible risers, particularly for deeper water (>300 meters). Existing analysis tools for riser response have proven reliable for most types of risers. However, in the area where catenary risers are resting on the seafloor, existing models for riser/soil contact are too simplified to capture the complexity of the interaction. Some of the key findings of earlier work are that the fatigue life predictions at the touchdown area are sensitive to the FEM modelling, fatigue accumulation procedures and, in particular, the soil model. Hence, an important step forward in improving riser analysis tools is to improve the riser/soil interaction model. This issue was the key objective of the CARISIMA JIP. This paper gives an overview of the main activities in the CARISIMA project.

Author(s):  
Fei Song ◽  
Ke Li

Abstract In this paper, a hybrid computational framework that combines the state-of-the art machine learning algorithm (i.e., deep neural network) and nonlinear finite element analysis for efficient and accurate fatigue life prediction of rotary shouldered threaded connections is presented. Specifically, a large set of simulation data from nonlinear FEA, along with a small set of experimental data from full-scale fatigue tests, constitutes the dataset required for training and testing of a fast-loop predictive model that could cover most commonly used rotary shouldered connections. Feature engineering was first performed to explore the compressed feature space to be used to represent the data. An ensemble deep learning algorithm was then developed to learn the underlying pattern, and hyperparameter tuning techniques were employed to select the learning model that provides the best mapping, between the features and the fatigue strength of the connections. The resulting fatigue life predictions were found to agree favorably well with the experimental results from full-scale bending fatigue tests and field operational data. This newly developed hybrid modeling framework paves a new way to realtime predicting the remaining useful life of rotary shouldered threaded connections for prognostic health management of the drilling equipment.


Author(s):  
Mario A. Polanco-Loria ◽  
Håvar Ilstad

This work presents a numerical-experimental methodology to study the fatigue behavior of dented pipes under internal pressure. A full-scale experimental program on dented pipes containing gouges were achieved. Two types of defects were studied: metal loss (plain dent) and sharp notch. Both defects acting independently reduce the fatigue life performance but their combination is highly detrimental and must be avoided. We did not find a severity threshold (e.g. dent depth or crack depth) where these defects could coexist. In addition, based on numerical analyses we proposed a new expression for stress concentration factor (SCF) in line with transversal indentation. This information was successfully integrated into a simple fatigue model where the fatigue life predictions were practically inside the window of experimental results.


Author(s):  
Silvia Corbani ◽  
Luiz Fernando Martha ◽  
Jaime Tupiassú Pinho de Castro ◽  
Bruce Carter

Sign in / Sign up

Export Citation Format

Share Document