Session: 10-03-01 Anchoring and Mooring Systems

Paper Number: 130911

130911 - An Optimized Consideration for Catenary Mooring System Designs 

Catenary mooring systems have been widely used in offshore industry when oil and gas exploration and production was conducted in shallow to deep water. To ensure a catenary mooring system arrives at the seabed horizontally, a very long seabed anchor chain is usually used. In actual applications, a substantial length of anchor chain could be saved if a small load angle at Touch-Down Point (TDP) can be considered in the design. This paper first reviews the chain-soil interaction analysis model from previous studies. Based on this, an excel spreadsheet tool to simulate the behavior of chain-soil interaction has been developed. Then, the chain’s configuration in soft clay is investigated using the developed tool. The influence of a small load angle at TDP on the embedded chain length in soil and the influence of a load angle at TDP on the padeye load or load components are checked. Finally, a recommendation is made to improve (or optimize) the traditional design concept of a catenary mooring system (i.e., no uplift load at TDP for any stage) by considering a small load angle at TDP (i.e., 1^o - 5^o) for the intact and damage conditions under the maximum design environment (i.e., extreme design loading cases).

Presenting Author: Jianchun CAO Bechtel

Presenting Author Biography: Dr. Jianchun Cao, Senior Geotechnical Engineering Specialist at Bechtel, with 30 years
experience in both onshore and offshore industries, including design, analysis and construction assistance of shallow foundations as well as deep foundations; slope stability analysis using various methods including three-dimensional finite element analysis (FEA) methods; soft soil improvement design and construction monitoring; numerical modeling of soil-structure interaction problems using FEA; pile driving analyses using GRLWEAP for excessively long and large diameter piles under various soil conditions; geophysical survey and geotechnical
exploration; preparation of specifications for geophysical & geotechnical survey and foundation design for mega projects on behalf of the owners; deep excavation support design and retaining wall design; and performing design review as the owner’s representative.

Authors:

Jianchun CAO Bechtel
Anil Bhandari Bechtel
Mahi Galagoda Bechtel