A digitized workflow from pre-drill pore pressure modelling with Monte-Carlo approach, till update of pressure prognosis while drilling from e.g. sonic and/or resistivity data is described. The innovative approach will reduce the uncertainty in the mud-weight window ahead of the bit. For the 3D pressure modelling, a basin modelling software method is used, where the pressure compartments in the study area are defined by faults interpreted from seismic. Key input parameters like minimum horizontal stress, vertical stress and frictional coefficients for failure criteria are varied. The output is pressure profiles along the planned well path, with uncertainties. The work presented in this paper was carried out on a North Sea dataset. The results show that the uncertainty in the pore pressures will highly influence the uncertainty span in both the fracture gradient and the collapse gradient. Representing the mud-window in terms of a most likely collapse and fracturing curve, with on each side of both, limits the minimum and maximum pore pressure derived limits, makes for a more realistic prediction, stating the uncertainty in the result. While drilling, log-data will be automatically used to update the pressure and mud-weight prognosis ahead of bit. The digital updated prognosis can help the drilling crew in the decision-making during drilling campaigns.
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