The Sakhalin II Phase 2 project represents one of the most technically challenging offshore platform installations ever undertaken in the harsh environmental conditions of the Sea of Okhotsk. TECON provided comprehensive engineering services for the transportation and installation of two massive offshore production platform topsides for Samsung Saipem, working on behalf of Sakhalin Energy Investment Company Ltd.

This landmark project required the deployment of specialized float-over mating technology to safely position the LUNSKOYE (LUN-A) and PILTUN-ASTOKHSKOYE (PA-B) platform topsides onto their respective jacket structures. The challenging weather window, extreme sea conditions, and the sheer scale of the structures demanded innovative engineering solutions and meticulous planning to ensure successful installation while maintaining the highest safety standards.

Project Scope

TECON’s scope of work encompassed the complete engineering analysis and detailed design for the transportation and float-over installation operations. The project involved managing structures with maximum displacements exceeding 50,000 tonnes, transported on purpose-built T-shaped cargo barges specifically designed for these challenging operations.

Transportation Engineering

• Comprehensive transportation analyses including route planning, weather window assessment, and motion response studies for the voyage from fabrication yard to offshore installation site
• Detailed hydrodynamic analysis of barge and topside behavior during transit through the Sea of Okhotsk
• Development of operational procedures and contingency plans for various weather scenarios

Sea-Fastening Design

• Complete structural design of sea-fastening systems to secure the massive topsides during ocean transportation
• Finite element analysis of load distribution and structural integrity under extreme weather conditions
• Design of temporary support structures capable of withstanding accelerations from wave-induced motions
• Interface design between topside support points and barge deck structure

Float-Over Mating Operations

• Advanced numerical modeling of float-over mating procedures, including ballasting sequences and environmental loading scenarios
• Detailed analysis of clearances, tolerances, and positioning accuracy requirements during the critical mating phase
• Assessment of combined effects of waves, current, and wind during installation operations
• Development of real-time monitoring and control strategies for safe execution

Float-Over System Detailed Design

• Complete engineering design of the float-over mating system including docking cones, guide frames, and load transfer mechanisms
• Design of hydraulic and mechanical systems for controlled load transfer from barge to jacket structure
• Structural design of interface components to accommodate tolerances and ensure proper load distribution
• Integration of monitoring instrumentation and control systems for the mating operation

Engineering Approach

TECON employed state-of-the-art engineering software and methodologies to model the complex interactions between the cargo barges, topsides, and environmental forces. Our multidisciplinary team integrated structural, hydrodynamic, and marine engineering expertise to deliver a comprehensive solution that met the stringent requirements of this world-class project. The float-over method was selected for its ability to minimize offshore installation time in the limited weather window available in the challenging Sakhalin environment, while the T-shaped barge configuration provided optimal stability and positioning capability during the critical mating operations.