Senior scientist Risk Management Øystein Arild at OTD 2013.
OTD 2013: Uncertainty modeling in drilling operations
19.11.2013Senior scientist Øystein Arild: Prior to a drilling operation, there is a range of uncertainties; subsurface uncertainties, equipment uncertainties and possible human errors.
Prior to a drilling operation, there is a range of uncertainties; subsurface uncertainties, equipment uncertainties and possible human errors. Since uncertainty obscures the excact values that we would like to have, it makes decision-making more challenging and thus are regarded as something negative.
Current well planning takes uncertainties into account to a varying degree. When it comes to the technical well design, some uncertainties, like the pore- and fracturing pressure, are often expressed as probability distributions, however, these uncertainties are rarely used in a consistent way for selecting for example the mud weight. On the other hand, when it comes to estimating well costs, uncertainties are being quantified on a relatively detailed level and aggregated consistently to make a probabilistic cost estimate that is being used as the bases for AFE (Authorization for Expenditure).
The group “New energy, risk management and well construction” of IRIS Energy is working with projects where uncertainty and classical drilling engineering is being integrated. One recent example is the software tool BlowFlow, which allows the calculation of blowout rate and duration to be performed both deterministically and probabilistically. This has been achieved by combining the competence that IRIS has on flow models and uncertainty modeling. The tool has been sponsored by Statoil and Eni Norge and is currently used internally in Statoil for blowout rate evaluations. The results from a BlowFlow analysis can also be used as the starting point for an environmental risk analysis. We are currently working on establishing a project where BlowFlow is combined with ocean drift models and biological dose-response models in order to provide environmental risk analyses that captures uncertainties from start to end.