Testing diagnosis strategy based on equivalent fault tree for offshore oil platforms

Offshore oil platform testing is still in its initial stages. Owing to the complexity and maintainability of offshore oil platform systems, testing diagnostic strategies at the system level have not yet been established. In this paper, such a complex system is simplified using an equivalent fault tree with only three levels. The concept of critical importance of a minimum cut set (MCS) is also defined to determine the MCSs with larger importance to establish the fault diagnosis strategy. The fault diagnosis sequence for MCSs is determined by their critical importance. The test sequence for the bottom events in the MCSs is decided by the critical importance values of units and the mean time to detection (MTTD). If a bottom event has been diagnosed to be normal, the minimum cut set it belongs to can be evaluated based on the critical importance of the unit and MTTD; otherwise, this MCS can be excluded for testing diagnosis and the next MCS is diagnosed. Three factors, namely, unit critical importance, MTTD, and test cost, should be considered when installing online test devices. At the end of this paper, the power system of ChengDao No. 1 Center offshore oil platform in Shengli oil field is used as the research object to establish the testing diagnosis strategy through the developed method. Results show that this method can not only establish a systematic diagnosis strategy but can also provide a basis for the systematic placement of test devices.