关键词: 老龄导管架平台, 检修规划, 经济寿命预测, 边际利润, 老龄退化

Abstract:

Ageing offshore jacket platforms that have been in service for a long term were taken as research examples,and both the increase of crack initiation rates resulted from ageing deterioration and the effect of non-perfect repairs on maintenance intervals were dealt with. Calculation results showed that inspection and repair times increased with time during the late-phase service of platforms and correspondingly maintenance intervals decreased. A maintenance planning model based on profit analysis was established for ageing offshore platforms subject to fatigue crack damage, in terms of the risk analysis theory, and the planning was made as a decision-making object that platform profits during the designed service period were maximized under the condition that the annual failure probability was guaranteed less than the given failure threshold. Calculation results were given to illustrate the profit assessment by this model for selecting the optimal inspection and maintenance strategy, and the effect of failure threshold determinations on a decision-making scheme was discussed as well. Furthermore, in terms of the marginal-profit analysis of economics, an optimized economic life model was established based on the principle of maximal profits within the life cycle of platforms. By calculating the service time when the marginal revenue of platform structures equals to the marginal outlay, an optimized economic life for ageing offshore platforms inspected under an optimized maintenance plan could be obtained. This approach is of definite guidance in assessing the maintenance strategy and service life of ageing jacket platforms in actual offshore petroleum engineering.

Key words: ageing jacket platform, maintenance planning, economic life prediction, marginal profit, ageing deterioration