Multifractal Doyle-Eriksen-Seth-Hill deformation measurements applied to acoustic velocities on halite samples under compression

The process of monitoring pre-salt hydrocarbon reservoirs by using 4D Seismics and correlating the data with Geomechanical properties may be a challenge due to the large volumes of subsurface evaporites and their unique properties, like high creep deformation rate, high solubility and anisotropic interfaces. These factors impose difficulties in seismic interpretation, so acoustic and mechanical data from controlled lab-scale experiments end up being a source of valuable information for caprock and reservoir characterization. However, in the literature, it is pointed out that the R factor, which correlates the time-lapse time shift of elastic waves propagating through a medium during a time interval and its deformation in the same propagation direction, is a linear measure of deformation. Furthermore, the R factor obtained from laboratory experiments is usually different from the ones estimated in large seismic models. The authors propose a non-linear multifractal mathematical model from the Doyle-Ericksen-Seth-Hill family of strain measurements for coupled acoustic-mechanical data from compression tests on halite samples and compare with the lab- scale linear R factor model and assess the types and levels of stresses at which both models may be comparable and representative.