It is essential to know about any adverse interactions between a shale and fracturing fluid additives. Some frac fluids can alter shale rock petrophysical properties and this can lead to shale softening and fines generation. The softer the shale, the more proppant embedment will occur, and the more severe reduction in fracture conductivity as the effective stress increases. In this study, we present a Nuclear Magnetic Resonance (NMR) technique to evaluate various frac fluids. We show that the extent of proppant embedment measured with proppant embedment tests correlates very well with the extent of imbibition of water into the shale (as measured by NMR).