  The paper presents a workflow for fast pore-scale simulation of single-phase
flow in tight reservoirs typically characterized by low, multiscale porosity.
Multiscale porosity implies that the computational domain contains porous
voxels (unresolved porosity) in addition to pure fluid voxels. In this case,
the Stokes-Brinkman equations govern the flow, with the Darcy term needed to
account for the flow in the porous voxels. As the central part of our workflow,
robust and efficient solvers for Stokes and Stokes-Brinkman equations are
presented. The solvers are customized for low-porosity binary and multiclass
images, respectively. Another essential component of the workflow is a
preprocessing module for classifying images with respect to the connectivity of
the multiscale pore space. Particularly, an approximation of the
Stokes-Brinkman problem, namely, the Darcy problem, is investigated for the
images that do not have pure fluid percolation paths. Thorough computational
experiments demonstrate efficiency and robustness of the workflow for
simulations on images from tight reservoirs. Raw files describing the used CT
images are provided as supplementary materials to enable other researchers to
use them.
