Case Study: North Sea Operating Company improves wellbore stability and reduces drilling risk with SLB’s Sonic Scanner anisotropic stress modeling

Anisotropic Stress Modeling Reliably Determines Mud Weight to Improve Stability and Reduce Risk

SLB worked with North Sea Operating Company to improve mud-weight selection and wellbore stability in the Eldfisk field. The operator’s fracture-gradient approach was causing mud losses in the shale overburden and often overestimated the mud-weight window because it did not properly account for anisotropic rock behavior.

SLB used the Sonic Scanner acoustic scanning platform and an anisotropic stress model to calculate minimum horizontal stress from 3D acoustic data and offset wells. This produced a more accurate mud-weight window, improved wellbore stability, and reduced risk, nonproductive time, and costs; the fracture-gradient method had overstated minimum horizontal stress by about 500 to 600 psi in the deeper shale section.