Page 209 - Enhanced Oil Recovery in Shale and Tight Reservoirs

192 Enhanced Oil Recovery in Shale and Tight Reservoirs

Figure 8.17 (A) Stress (s 1 es 3 ) required to generate shear-induced fractures in Mancos
after being hydrated, (B) CT images before and after being fractured.
Akrad et al. (2011) measured the shale rock strength before and after they
exposed to 2% KCl slick water and fresh water. Fig. 8.18 shows that 2% KCl
slick water weakened the shale rocks by reducing Young’s modulus. The
rock was defined a soft rock if the Young’s modulus was <30 GPa, and

Figure 8.18 Young’s moduli for different shale rocks before exposure to slick water at

the room temperature (X-axis) and after (Y-axis) exposure to slick water at 300 F for
48 h. Data from Akrad, O.M., Miskimins, J.L., Prasad, M., 2011. The effects of fracturing
fluids on shale rock mechanical properties and Proppant Embedment. Paper SPE 146658
Presented at the SPE Annual Technical Conference and Exhibition, Denver, Colorado, USA,
30 October-2 November. doi:10.2118/146658-MS.