Anisotropic Model

For the anisotropic models, the input definition to calculate the horizontal stresses require additional inputs. In the Anisotropic Model (1D MODEL > Horizontal Stress > Anisotropic Model) button group, you can define these model inputs and also select the logs that are generated as output.

Reservoir rocks are, generally, anisotropic by nature due to the presence of laminations, bedding planes or naturally-induced fractures and micro-fractures. The anisotropy in the reservoirs is not limited to the variations in vertical and horizontal directions but also vary azimuthally. Hence, a vertically transverse isotropic or fully orthogonal anisotropic models are used to generate the horizontal stresses as a function of stiffness tensor components, and to model the relationship between the orthotropic rock properties and stiffness tensors. Equations used for calculating the stiffness tensor coefficients and the horizontal stress terms are listed in the Horizontal stress methods in Appendix C. general overview of the horizontal stress profiling for orthotropic rocks [1] in shown in the workflow diagram below:

Reference

1. Fracquet J.A. and Rodriguez, E.F., Baker Hughes. Orthotropic Horizontal Stress Characterization from Logging and Core Derived Acoustic Anisotropies. 46^th US Rock Mechanics / Geomechanics Symposium, Chicago, USA, 24-27 June 2012.