Digital Workflow for analysis of flow on the pore scale.

Fluid transport in subsurface reservoirs is a key element to some of our main technical and environmental challenges we face today. Flow in reservoirs is flow in porous media and needs to be treated on many different scales – from the tiniest pores to kilometer wide reservoir zones. 

The smallest scale we treat is the pore scale where individual pores can be resolved. These are void spaces in between grains, sediments or other solid material, and can attain many different shapes, sizes and textures. In these pores the fluid phases reside and interact with the each other and the grain surfaces creating fluid –fluid and fluid-grain interface. The physical behavior on this scale determines the constitutive flow relations on larger scales, properties that are commonly measured by flooding of core material from reservoir rocks. 

Advances in x-ray CT imaging has opened new opportunities to get insight into flow on the pore scale and better knowledge of pore scale transport phenomena. Such imaging techniques open up for digital workflows and pore scale flow modelling, combining high resolution CT images, image analysis and simulation tools. This can augment flooding experiments and reveal more knowledge of fundamental processes.

From small samples of rocks, it is possible to use micro-CT to image the pore structures in three dimensions, make digital porosity models including open pores and micro-porosity, and ultimately run flow simulations as shown in Figure 1. Pore scale simulations can be performed directly on the 3D images or on extracted topological pore network models. In this case, direct simulations have been performed using the open source LBPM software package. 

Wettability (fluid-solid interaction) distribution and effects are some of the most relevant aspects to study with such a digital pore scale workflow. The wettability influences how fluids are distributed and by characterizing that through geometric state functions, a new framework is emerging for upscaling flow functions and treat hysteresis.