Modelling Unexpected Breakdown

So, as we said in the first blog post of the series, we also not only have a mechanism for modelling expected breakdowns, but can use this mechanism with a systematic philosophy of failure management for modelling unexpected breakdown on short operations.

Before we get into it, let’s consider the question we want to ask. On the face of it, we might want to know the P50 of the duration of the operation, with all risk taken into account. However, on a short operation with failures this doesn’t give us such a useful answer. It certainly doesn’t help us with an FMEA-like approach where we want to know the impact of the failure of particular components on the overall operation.

We don’t want to ask so much of a “how-likely” question – that’s answered by component and equipment supplier. Instead, we really want to ask a “what-if” question, so that we can understand the impact of, and mitigate the risk.

So, let’s model an operation where we get a crane breakdown on a DP Jack-Up. In this scenario, we are doing just a single lift, but if it happens then we need to get parts transported from the nearest port.


Now, to manage the scenarios, we use the same option to make the “Crane Failure” group only occur occasionally as before, but now we set the maximum number of occurrences to zero:


When we run this analysis, the group will not be included at all – the Gantt chart will be like this:


Setting the maximum number of occurrences to something non-zero yields this:


Running the two scenarios helps us to understand the impact of crane failure on the operation as a whole. Because the barge can stay jacked through the whole repair, then there is no hanging around for a suitable jacking weather window. However, it is necessary to find a suitable window for the supply vessel to come out and transfer the kit.

You can imagine using this facility to model a variety of different repair strategies, and modelling different response strategies for different kinds of failures. In short, Mermaid provides an analytical approach to managing the impacts of technical risk, with the knowledge that all your analysis will be thoroughly integrated with your weather risk model.

In summary, not only does Mermaid give you serious insight into the combination of technical and weather risks, but because Mermaid allows you to leave in the repair scenario whilst optimising your main operation, switching the scenario on and off as you wish, it’s straightforward to consider technical failure from the very start of the planning process.