Optimal control of far north pipelines integrity and maintenance

摘要

Existing maintenance management systems are either only qualitative using a subjective pipeline index (Davis, 1988), or use relative-risk numbers for prioritizing pipeline segments for inspection/maintenance (Kiefner et al, 1990) or are based on previous statistics, without accounting for intrinsic individual properties of each pipeline in consideration (Kulkarni and Conroy, 1994, 1998). These systems do not take into account safety levels that have to be assured, or else consider them as constraints. In the latter case, their values are not given. The paper presents a new approach to optimal control of integrity and maintenance for main pipelines layed across the Eurasian Far North permafrost. The technology of controlling pipeline's integrity and risk of operation in this kind of environment is based on using the central maintenance problem, which is outlined as a control problem. Further an optimal cessation of pipeline operation procedure is developed, based on the notion of conditional probability of failure. The central maintenance problem is embedded into the optimal cessation of performance procedure, allowing the explicit determination of the dependence of pipeline reliability and lifetime as a function of the main parameters of loading, degradation, monitoring, diagnostics I inspection and renewal processes. The pipeline maintenance theory outlined in this paper gives the state-of-art of the considered problem in Russia and was used to optimize risk of operation of several oil pipelines located in the Far North of West Siberia.