Page 206 - Enhanced Oil Recovery in Shale and Tight Reservoirs

Fluid-rock interactions 189

solution, while it reduced from 8 psi to almost 7 psi when flooded by DI
water, indicating the fractured core permeability was increased. In their
experiment, the core was not confined in the axial direction. They found
that rock particles had been detached from the fracture surface due to hydra-
tion (see Fig. 8.14). The surface hydration increased the internal forces
within clay minerals mostly through crystalline swelling and caused the
clay or surrounding particles to detach from the fracture surfaces to be
subsequently washed out by water flowing through the fracture. As the
effective aperture of the fracture became wider, the permeability was

Figure 8.14 (A) Swelling of the sample with deionized water injection, (B) the disinte-
gration of the rock particles on the fracture surface (Roshan et al., 2015).