analysis and mooring details. The importance of detailed planning is further emphasised as the IC installation barge normally has to be locked in or booked as early as two years prior to scheduled installation.
The heavy FEL activities required for the IC method may accelerate the achievement of first production date of up to six months compared with the ML method. This results in early monetisation hence maximising production during the Petroleum Sharing Contract( PSC) term. Figure 5 depicts an actual overall duration project comparison of two projects of similar size and complexity, constructed under both the IC and MC method respectively.
Description
Modular Concept( Months)
Integrated Float-over( Months)
Detail Engineering Support Engineering Procurement Support Procurement Fabrication + 4
TOTAL( A)( Engineering, Procurement & Fabrication
Load out + 0.1 Transportation Topside Installation + 0.6 Jacket Installation Hook Up + 1.7 Commissioning + 1.3
TOTAL( B)( Loadout, Transportation,
+ 3.7
Installation & HUC)
TOTAL( A + B) PROJECT DURATION + 3.7 COMPARISON
* less lead time for structural procurement enabling early start of fabrication for IC
Figure 5: Schedule comparison
The figures presented above validate the trend where the overall duration of a project can be shortened using the IC method. The fabrication stage of an IC deck is longer due to lower work accessibility. However with proper schedule control and starting the work earlier, the whole duration for procurement and fabrication is similar for both an IC and MC deck. In other words, the longer fabrication duration required for IC is manageable. In addition, this constraint is also well compensated for by the advantage of early achievement of first production caused by the shorter duration for the installation and HUC of an IC topsides.
Project Cost
Given the unique nature of each project, costs differ from one project to another. However, in general, the IC method normally results in a cheaper total overall project cost.
The construction costs for an IC topside is normally higher than that of the MC topside due to the requirements for the construction of the LSF, LMU, bulkhead strengthening( if any), dredging( if any) and mooring spread. However, the IC deck has a significant cost advantage when compared with the cost of installation and HUC. With the majority of the commissioning work for an IC topside done onshore, the project duration for offshore installation and HUC could be significantly reduced. This translates into cost savings from shorter duration for barge daily charter, equipment hire and offshore manpower.
The procurement and fabrication of a jacket for an IC topsides incurs a higher cost since more bracings and reinforcement are required. The tonnage of piling required for an IC jacket also exceeds that of an MC. However, the MC topsides are more expensive as more steel is required for interfacing and lifting integrity. Furthermore, the installation cost for the IC topside surpasses that of the MC due to barge preparation. This downside is however, compensated by the significant savings during HUC work whereby the cost for the IC deck is far cheaper. As a result, a total cost saving of approximately 15 % can be achieved for an IC deck as compared with an MC deck, given the same topside weight and complexity. Figure 6 illustrates the cost comparison of two similar projects executed on the MC and IC method respectively.
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