Publications

A marginal field is an oil/gas field that is considered uneconomical to invest in and is difficult to be developed in a conventional matter due to small reserves, remote area and / or geological difficulty. With this type of field, many appropriate designs have been produced to turn uneconomical aspects into economical justifications. This study evaluates the operability of the Anthasena Donut Shaped Semi-submersible design in ITS to support wildcat drilling and production activity. This platform is a mobile modular platform that can perform equipment replacement, so that can it can be adapted to certain fields. When a field is depleted, the platform can be transported to another field, allowing the platform to serve several fields and reducing the need of a dedicated production platform for each marginal field. This significantly decreases operation time and field OPEX by up to 20% that leads to increasing economic feasibility in the offshore oil and gas industry. With LWT displacement of 64,500-ton, computations of motion intensities of this semi-submersible in regular waves have been performed by running a finite element method based on 3-dimension diffraction theory. The results of these computations were then combined with a wave spectrum to obtain the motion characteristics in random waves where those semi-submersibles are operated. This evaluation indicates that the Anthasena seems to have better structure behavior. Motion characteristics in random waves were then correlated to the operational criteria, comprising of the maximum motion intensities for drilling operations and the vertical motion acceleration, which would affect the operator working performance. Final results reveal that the semi-submersible is able to attain a 100% level of operability when operated in the East Deep-water Indonesia Sea in a yearly sea state condition of extreme waves as high as Hs=5.745 m, making this platform suitable for future marginal field exploitation.