We develop an approach for efficient 3D simulation of the quasistatic fully coupled poroelastic response of a reservoir during depletion and subsequent reinjection. The approach uses a scaling of the solid and fluid densities in Biot’s poroelastic equations. This scaling impacts the critical frequency [Formula: see text] of Biot’s slow wave that defines diffusive flow ([Formula: see text]) and wave propagation ([Formula: see text]). We find the criterion for the density scaling range over which the poroelastic response is accurately modeled and benchmark the approach against Terzaghi’s 1D and Rudnicki’s 3D analytic solutions. The density scaling approach is presently limited to single-phase fluid flow. To illustrate the utility of this approach, we simulate microseismic depletion delineation (MDD) in a fractured unconventional reservoir. The reservoir, which is subjected to an anisotropic stress field, is first produced for 1000 days, and then a reinjection (below the in situ pressure) is performed for 100 days. We find that stress reorientation during production produces favorable conditions for the generation of Mohr-Coulomb slip-related microseismicity. The locations of these microseismic events are found to be consistent with depleted portions of the fracture system, in accordance with the MDD concept.