Recently, I reviewed about 90 geomechanical lab reports (different labs, different formations, different companies) containing extensive measurements of all different sorts of mechanical rock properties and I could not find even a trace of Biot’s coefficient measurement. Due to its role in definition of effective stresses, we know that it is unlikely to solve any problem in geomechanics without direct use of poroelasticity theory. Nevertheless, in comparison to other geomechanical parameters (i.e., pore pressure, stresses, elastic and failure properties), Biot’s coefficient seems to be the most undervalued parameter in our studies as we leave it for our back-calculations or lucky guestimations. This does not seem scientifically just as the role of this parameter is not less than many of the other parameters. So, why don’t we put more effort in measurement of this parameter? Is this because we have a great knowledge of this parameter and we know how to do accurate estimation??? Or only because it is complicated and expensive to measure? Or maybe because it is not in the routine procedure of commercial labs? Is any or all of these reasons good enough to neglect this important parameter and its influence on the results? What do you think?
Unfortunately, this is not our only issue with Biot’s coefficient. Probably a more fundamental one is the eligibility of poroelastic models for modeling many of the rocks especially the unconventional plays.