It is not unusual that the difficulties encountered during a drilling operation can be tracked to choices made during planning. However, generating a robust drilling-operation plan is not easy because substantial uncertainties are often associated with the actual geological context. To address this problem, this paper presents a method that quantitatively evaluates the risk levels of a drilling-operation plan as a function of the underlying uncertainty associated with its description.
Introduction
A drilling operation is always subject to operational risks (e.g., formation-fluid influx, lost circulation, borehole instability, packoff, stuck pipe, or drillstring failure). The chance of occurrence of some of those threats may be small in a particular well design. But, in other configurations, it may be known already at the planning stage that potential drilling problems are likely, because of tight operational margins for instance.
