## Stress / Permeability Calculators

Estimation of the stress state: stress polygon

The stress polygon allows the estimation of the stress state for a given set of observations from image logs, pore pressure, vertical stress, minimum horizontal stress Shmin, and mechanical properties. Once we get an idea of the possible ranges of stress anisotropy, we can use this information to calibrate a given fracture geometry with effective permeability measurements at the well. Click here to go to the stress polygon calculator and estimate the stress state using your own geomechanical data

###### Estimation of fault or fractures slip potential

Propensity of existing, closed natural fractures to get reactivated after increased pore pressure due to fluid injection depends mostly on the relative orientation of the fracture plane with respect to the orientation of maximum stress and the coefficient of friction. Under the assumption of vertical fractures, this spreadsheet helps determine which natural fractures from a given set are critically stressed under a certain stress state. If they are not, the calculator determines the additional pore pressure needed to reactivate them. Reactivated fractures will determine the preferential orientations of flow.

###### Estimation of effective fracture permeability for a given stress state and natural fracture geometry

The effective fracture permeability anisotropy in a cell is controlled not only by the particular fracture geometry and intensity but also by the individual fracture apertures and stress state that affects them by making critically stressed fractures more conductive than non-critically stressed ones. Click here to use our effective fracture permeability anisotropy calculator that takes into account all these aspects with your own data to get a sense of how we would calibrate a complete 3D volume derived from seismic data. You can also use this calculator to calibrate with your own measured perms at the well.