Session: 08-06-01 non-presentations
Paper Number: 128519
128519 - Field Monitoring Data Inversion Solution for Mooring Lines and Risers Integrity Assessment in a Semi-Submersible Production Platform
Semi-submersible production platforms with mooring lines and risers need to resist complex environmental conditions in long-term deepwater production projects. Changes in wind, current, and wave loads provoke variable motion and stress in the mooring lines and risers. Such information regarding the actual environment, platform, mooring lines, and risers is periodically collected from field monitoring sensors. Taking advantage of field monitoring data, this work presents an inversion solution for mooring lines and risers integrity assessment. First, considering the coupling mechanical behavior of the platform-mooring lines-risers multibody system, a single measured record consists of environment, platform motion, mooring tension, and riser strain. Multiple records are sorted in chronological order to form the invasion dataset. In the remaining stage, the Long short-term memory neural network is applied to reconstruct the structural response of mooring lines and risers under environment loads. Finally, the present fatigue damage is calculated from S-N curves and the rain flow counting method.The approach is tested on the first ultra-deepwater gas development project in the South China Sea, which employs a semi-submersible production platform with sixteen hybrid polyester mooring lines and six steel catenary risers. Through the retrospective analysis of the environmental conditions and variable motions among the platform, mooring lines, and risers during the past two years, the fatigue damage distributions of the mooring lines and risers are expressed in distance from the suspension point. The results show that the severe fatigue damage area is at the touchdown point with a remaining life of 713 years. By the frequent wind, current, and wave from the northeast, the fatigue damage to the #M3 mooring line is the most obvious, with a remaining fatigue life of 692 years. For now, both the mooring lines and the risers meet the 30-year design life integrity requirement.This inversion solution may be seen as one part in the development of a digital twin for offshore structures. With the reflection of the dynamic response under a certain environmental load, it allows field operators to identify the damage locations and status of offshore structures, so as to reduce the repair cost and the accident risk in the further stages of development.
Presenting Author: Kejin Chen China University of Petroleum, Beijing
Presenting Author Biography: Chen Kejin is a Ph. D student in Mechanical Engineering at China University of Petroleum (Beijing). His research interest covers the integrity evaluation of floating platform-riser-mooring multi-body systems.
Authors:
Kejin Chen China University of Petroleum, BeijingJin Yang China University of Petroleum, Beijing
Qishuai Yin China University of Petroleum, Beijing
Field Monitoring Data Inversion Solution for Mooring Lines and Risers Integrity Assessment in a Semi-Submersible Production Platform
Submission Type
Technical Paper Publication