Abstract
Wellbore instabilities significantly increase costs associated with drilling operations worldwide. Information on rock properties, stresses, and pore pressure along the planned well trajectory is necessary for obtaining a safe mud weight window and avoiding issues such as stuck pipe, mud loss, and well control problems. Drilling teams often face uncertainties when predicting pore pressure and wellbore stability, which can lead to extensive non-productive time. We have tested a digital workflow that starts with pre-drill 3D basin-scale pore pressure modelling using a Monte-Carlo approach. It continues with an automated update of pressure prognosis while drilling, utilizing sonic or resistivity data to narrow the uncertainty in pore pressure ahead of the bit. The work demonstrates a unique automated approach enabling real-time prediction of pore pressure and wellbore stability, ahead of bit during drilling and well operations. This will enable efficiently informed and smoother decisions by continually updating the drilling plan. We tested the workflow for two drilling campaigns, one using sonic log and one using resistivity log for pressure updates in drilling operations in the Norwegian Sea. The best results were achieved using sonic well log data as update for pore pressure: Also, resistivity log for pore pressure update has potential, but then the raw data must be filtered to correct for lithology variations, mineralogy effects and anisotropy due to well inclinations. A workflow for resistivity filters is presented.