Optimization of weight of an offshore sub-structure

Many shallow marginal gas fields remain unexploited in the North Sea, mainly due to higher infrastructure capital expenditure for its exploitation. A study carried by Iv Oil & Gas to formulate a potential solution concludes that a conventional tripod structure with a suction bucket foundation and minimum topside facilities is a viable solution.This tripod structure designed was governed by the D/t < 100 criteria, where D is the diameter and t is the thickness. This resulted in a conservative thick walled structure which is heavy and expensive. The first objective of this study was to redesign the reference structure for an optimized weight by not limiting the design to D/t criteria. The second objective was to adopt longitudinally stiffened tubular member design for the main tubular parts of tripod structure. From the study it is concluded that a significant weight reduction is achieved by not limiting the tubular design for D/t ratio. Also, it is concluded that internal stiffening of the main tubular part of the tripod structure is not beneficial for reducing weight of the structure.

Subject

offshore sub-structure

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Embargo date

2015-12-09

Part of collection

Student theses

Document type

master thesis

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MSc_Thesis.pdf

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