Lift the Veil of Secrecy in Sub-Resolved Pores by Xe-Enhanced Computed Tomography

The efficient development of tight hydrocarbon resources based on the proper understanding of rock properties can be underlined as a game-changing scenario of the energy market during the coming years. Digital Rock Physics (DRP) is an advanced technique for the accurate assessment of formation properties with respect to the effects of pore structures. However, there are doubts about the usefulness of DRP for tight systems where a large portion of pores are sub-resolved, and subsequently, their effects on numerical computations cannot be taken into account. By taking advantage of Xenon-enhanced computed tomography and nano-scale imaging, the current research puts forward a hybrid workflow that reveals sub-resolved pores and assigns them a proper set of petrophysical properties that can be used for further numerical simulations. The introduced method was applied to a tight sandstone sample. Conventional micron-scale x-ray computed tomography images show no connectivity of the porous space. That is why computation of permeability is impossible. The developed workflow created a three-substance media including pores, solids and submicron porous segments. The triple reconstructed porous media allows introducing the Stokes-Brinkman equation to simulate flows. The results indicated that the computed permeability is reasonably close to the experimental value. The main advantage of the launched method is that the computations achieved satisfying results without increasing the spatial resolution of images or limiting the field of view