Objective
An investigation of the various natural gas liquefaction processes has been made in this study, enabling a simply operated and safe process to be selected.
Initial investigation of designs for plant capacity at each end of the scale considered showed that an mpsv having satisfactory seagoing performance would nominally be oversized for 3.4 mmscmd plant. The mpsv was found more suitable for larger process volumes and so was chosen for the technical part of the study at a throughput of 10.2 mmscmd.
The mlss was found to be very sensitive to topside payload, and so to minimise the gap between state of art designs and that for this study, the production throughput of 3.4. Mmscmd was chosen for this configuration.
A representative site in the northern north sea has been chosen in order to define environmental conditions for either liquefaction terminal. Following definition of the design requirements for each terminal these have been used to develop both schemes in sufficient detail for accurate model scale testing and realistic economic analyses to be carried out. Careful consideration of the requirements of statutory bodies for vessel certification has been taken throughout this study, since their requirements have a significant effect upon terminal general arrangements, and every system fitted.
In addition to testing physical models of both the mlss and mpsv terminals an analogue computer model has been developed to initially paralled the model tests and subsequently extend consideration of environmental conditions to typical storm rotations of wind and sea.
In the economic assessment of both, operating and capital costs have been estimated. Once overall cost for each scheme has been established and system availability calculated and economic analysis may be made, determining potential profitability and the sensitivity of profitability to changes in various parameters such as : field life, inflation, amortisation period, etc.
Two types of floating process have been considered, a multi-leg semi-submersible unit (mlss) and a barge-like moored process and storage vessel (mpsv). The mpsv can be constructed in a conventional shipyard and a steel structure is favoured. The mlss, however, may be constructed of steel or concrete, each having particular advantages. At the initial stage therefore, an investigation of both methods was made for the unit so that the design offering greatest promise could be chosen for detail design.
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DEM - Demonstration contractsCoordinator
Porchester
United Kingdom