Fines Influence on Flow Through Porous Media Using Synchrotron Microtomography and Microfluidics

Abstract

The Middle East is the world's most water stressed region, where groundwater is a main source for drinking and irrigation. However diminishing rain rates stresses aquifers beyond safe limits, rendering water wells irrecoverable. To combat aquifer overuse, artificial recharge wells were developed, to inject surplus water into aquifers to ensure water security during the arid summer period. A significant challenge to aquifer recharge is fines migration, which involves pore-scale movement of small clay particles within the aquifer, which can clog pores, reducing permeability. Understanding and managing fines migration is crucial in maintaining wells. Another key challenge is the inability to observe fluids contact angles, during flow within pores. Studying fines effect on contact angles, which govern pressure at the pore-scale, can aid modeling multiphase flow in subsurface reservoirs. In light of opening the first Synchrotron microtomography beamline in the Middle East and Africa, "SESAME". Which offers the only pore-scale experimental technique to allow non-destructive microscopic observation of fines migration, during fluid flow through sediments. The high brilliance x-rays allow for fast scanning, enabling in-situ measurements of fines movements within pores. Silica, Mica, Kaolinite and Montmorillonite clays were studied. Dry samples were flooded with brine, while fines migration is being scanned at 1 μm/voxel. Also, microfluidic models of sedimentary porous media were engineered, fabricated and used to study the effect of colloidal fines on dynamic contact angles. Findings revealed how clay fines particles attach and detach within sediments' pores. Fines are influenced by elasticity of clay, and fines' ability of to swell with water. Depending on clay type, permeability of flooded sediments dropped or increased, along with clay content. Such direct observations and the corresponding quantification using digital rock physics can be used to benchmark the impact of aquifer recharge on the permeability of the formation. Also, microfluidic observations linked colloidal fines wettability with variations in fluids dynamic contact angles. Providing a workflow to benchmark fines influence on aquifer recharge, by accurately predicting pore pressure using measurements of advancing and receding dynamic contact angles. The developed workflows and findings facilitate calibrating aquifer models, to enhance water storage and recovery across the globe.