Acknowledgements
We acknowledge Shell for  financial support and for providing the digital rock images. This study has mostly been performed using the Sherlock cluster at Stanford University. We are grateful to Stanford University and the Stanford Research Computing Center for providing computational resources and support in this research. We acknowledge the sponsors of the Stanford Center for Earth Resources Forecasting (SCERF) and support from Prof. Steve Graham, the Dean of the Stanford School of Earth, Energy and Environmental Sciences. The authors also would like to thank Math2Market for providing the GeoDict software.