Session: 01-01-01 Offshore Platforms-1

Submission Number: 180167

Parametric Study of Launch Scenarios for Self-Upending Offshore Jacket 

Jacket launch is a widely adopted technique used for offloading an offshore jacket structure from its transportation barge or vessel before it is installed on the seabed at its designated location. This method is particularly recommended when the jacket is exceptionally heavy, making the use of a high-capacity derrick barge economically unfeasible. Launching offers a more cost effective and time efficient alternative, as the operation is generally quicker, thereby minimizing offshore installation time and associated risks. The efficiency of this method is further enhanced when the jacket is designed to self-upend, eliminating the need for additional lifting equipment for upending purpose. Once upright, controlled ballasting of the structural compartments can be performed sequentially, facilitating the descent of the jacket onto the seabed.

This paper presents a comprehensive comparative study of launch and self-upending scenarios for a jacket structure weighing 13,000 metric tons, designed for installation in a water depth of 60 meters. The study explores two distinct launch configurations: one where the jacket’s top section enters the water first, and another where the bottom section, specifically the mudmat, makes initial contact with the water surface. Each configuration is analyzed for its impact on launch dynamics. Furthermore, the paper evaluates the influence of launch barge configurations, comparing single versus double rocker arm systems for both scenarios. These rocker arm systems play a critical role in controlling the jacket’s rotation and descent during launch. The findings aim to guide offshore installation engineers in selecting the most efficient and safe method for jacket installation under varying operational constraints.

Each launch configuration offers unique advantages and limitations, particularly in relation to critical parameters such as jacket slam velocity, clearance between the jacket bottom and the seabed during its descent, rocker arm reactions, launch trajectory, buoyancy tank arrangements, and the likelihood of post-launch contact between the jacket and the barge. These factors significantly influence the safety, efficiency, and overall success of the offshore installation process. Therefore, conducting a thorough comparative analysis of these parameters during the FEED (Front End Engineering Design) stage is highly beneficial. It empowers engineers to make informed decisions that optimize jacket structural design, improve operational reliability, and reduce associated risks. Moreover, such early-stage evaluations contribute to reducing installation costs by identifying the most suitable launch configuration and barge setup, ultimately improving project execution.

Presenting Author: Mashood Munaz Kalathingal McDermott

Presenting Author Biography: Mr. Mashood Munaz Kalathingal is an accomplished Naval Architect, bringing over 18 years of diverse experience in the shipbuilding and offshore engineering industries. He began his career at Grandweld Shipyards in Dubai, where he gained hands-on expertise in ship design and construction. He later expanded his professional scope by working with an offshore EPCI company, further enhancing his proficiency in the transportation and installation of offshore and subsea structures. Currently, Mr. Kalathingal serves as a Senior Naval Architect at McDermott, based in Dubai, UAE.
He holds a Bachelor’s degree in Naval Architecture and Shipbuilding (2006) from Cochin University of Science and Technology, India, and a Master’s degree in Offshore Floating Systems (2015) from University of Strathclyde, Glasgow, United Kingdom. He is a Chartered Engineer accredited by the Engineering Council UK and a Member of The Royal Institution of Naval Architects (RINA).

Authors:

Mashood Munaz Kalathingal McDermott
Saibal Paul McDermott
Vijoy Koottungal McDermott
Toms Jacob McDermott