PSI views Geomechanics as comprising two fundamentally different parts, Rock Physics and Earth Stresses. Traditionally these have been seen as one as shown in the diagram below taken from Schlumberger’s 1999 Mechanical Earth Model, both sets of information being totally derived from measured data such as well-logs, minifracs, laboratory rock strength tests, etc.


To the left of the Schlumberger diagram the key Earth stresses requirements for most geomechanical studies relate to the maximum horizontal stress SHmax or SH, namely, direction SHD and magnitude SHM. In the top half , these parameters are measured at considerable cost and at selected points (in red lettering), post drill. The lower half of the text shows the same parameters derived pre-drill (in green lettering), when they are needed, in 3Dimensions, not 2D. The data come from the same interpreted seismic used to construct standard horizon structure maps, and therefore at a fraction of the cost of post-drill methods.


The industry is now at a point that PSI can determine stress from 2D or 3D interpreted reflection seismic using its patented method within patented software, 4DGeoStress. These stresses can then be used by numerous companies specialising in the rock physics side of geomechanics in calculations for wellbore breakouts and best mud weights for mitigation, etc. This should also help eliminate the current practice of simply averaging measured SH Directions (SHD’s) which in fact are vectors.