Abstract

As per January 2014, Petronas estimated Malaysia has some 106 marginal oil fields with approximately 580 million barrels of oil. Development of these fields require platforms almost similar to commercial fields, while total production is typically lower due to smaller reservoirs. Therefore, the total revenues are smaller and thus development is often questionable. More efficient technical solutions can contribute to cost reductions and hence turning marginal fields into commercial fields. This paper outlines a cost-efficient technical solution that contributes to profitability of marginal field platforms.

Re-use of platforms will lower the total investment required. The main technical challenge is to find a foundation method that is suitable for decommissioning and allows for reinstallation. A suction pile foundation is characterized by relatively fast installation and easy decommissioning. Installation is done by a discharge of water from the inside of the suction pile, leading to pressure difference between the inside and outside of the suction pile. This causes a net downward installation force, resulting in a penetration of the soil. The reversed principle is used for decommissioning or relocation of a suction pile founded platform.

Cost reductions in construction, installation and decommissioning phases are combined in the Self-Installing Platform (SIP) concept. The concept comprises of onshore construction of a one-piece platform, followed by transportation to field location without the need of HLV's. Hence, transportation is done either floating, towed or lifted by a sheer leg vessel. At site, the platform is lowered on the seabed and subsequently the suction piles are installed to target penetration. Once the wells are depleted, the SIP allows for relocation and subsequent installation at other marginal fields.

Suction piles are successfully used since 90's for many offshore applications with soils ranging from soft to stiff clays, loose and dense sands and in layered soils. Currently, four (4) SIP-1 concepts and three (3) SIP-2 concepts are successfully installed. This proves the potential economical benefit of future developments of the SIP concept in marginal fields.

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