Comparison of two different approaches to build a 1D geomechanical model - A case study

The geomechanics community in the industry has generally adopted two different approaches to build geomechanical models: (1) determining subsurface horizontal stresses from acoustic dipole logs acquired at sonic frequencies and requires detectable amount of shear wave anisotropy; this approach produces rapidly varying stress profiles reflecting changes between and also within different lithological units. (2) Observation of stress-induced borehole failures (borehole breakouts or tensile fractures) and constrains horizontal stresses at discrete depth points; stress profiles are then extrapolated over the depth intervals of interest generally resulting in smooth horizontal stress profiles without appreciable variations across lithological boundaries. Each approach has its benefits and limitations and depending on the application and also the (service) provider utilized for geomechanics one model is preferred over the other. To better understand and compare results for the two approaches outlined above, OMV Austria Exploration and Production GmbH (OMV) commissioned two service providers with the scope to build a geomechanical model for one of its fields located in the Vienna Basin with the request to utilize "state of the art" modeling technology. This model was then to be calibrated and verified with drilling experiences and wellbore failures/enlargements (detected from provided caliper and image logs).