Direct Measurement of Static and Dynamic Contact Angles Using a Random Micromodel Considering Geological CO2 Sequestration

Abstract

Abstract:The pore-level two-phase fluids flow mechanism needs to be understood for geological CO 2 sequestration as a solution to mitigate anthropogenic emission of carbon dioxide. Capillary pressure at the interface of water-CO 2 influences CO 2 injectability, capacity, and safety of the storage system. Wettability usually measured by contact angle is always a major uncertainty source among important parameters affecting capillary pressure. The contact angle is mostly determined on a flat surface as a representative of the rock surface. However, a simple and precise method for determining in situ contact angle at pore-scale is needed to simulate fluids flow in porous media. Recent progresses in X-ray tomography technique has provided a robust way to measure in situ contact angle of rocks. However, slow imaging and complicated image processing make it impossible to measure dynamic contact angle. In the present paper, a series of static and dynamic contact angles as well as contact angles on flat surface were measured inside a micromodel with random pattern of channels under high pressure condition. Our results showed a wide range of pore-scale contact angles, implying complexity of the pore-scale contact angle even in a highly smooth and chemically homogenous glass micromodel. Receding contact angle (RCA) showed more reproducibility compared to advancing contact angle (ACA) and static contact angle (SCA) for repeating tests and during both drainage and imbibition. With decreasing pore size, RCA was increased. The hysteresis of the dynamic contact angle (ACA-RCA) was higher at pressure of one megapascal in comparison with that at eight megapascals. The CO 2 bubble had higher mobility at higher depths due to lower hysteresis which is unfavorable. CO 2 bubbles resting on the flat surface of the micromodel channel showed a wide range of contact angles. They were much higher than reported contact angle values observed with sessile drop or captive bubble tests on a flat plate of glass in previous reports. This implies that more precaution is required when estimating capillary pressure and leakage risk.

Supercritical CO2 Effects on Calcite Wettability: A Molecular Perspective

“…A schematic of the contact angle θ considered in this work for the CO 2 –water–mineral system is shown in Figure . A number of studies measured contact angles as a function of pressure, temperature, surface chemistry, and brine composition, by either experiments or molecular dynamics (MD) simulations. − For example, Dickson et al developed a high-pressure apparatus to measure CO 2 /water/solid contact angles on glass substrates with different hydrophilicities as quantified by the silanol (SiOH) surface density. As the CO 2 pressure increased from atmospheric pressure to 61.2 bar at 23 °C, the results showed that θ increased from 71 to 99° on the substrate with 37% SiOH and from 98 to 141° on the substrate with 12% SiOH.…”

Atomistic Study of Dynamic Contact Angles in CO2–Water–Silica System

“…In addition to CO 2 –water–silica systems, contact angles for CO 2 –brine–kaolinite systems with both hydrophobic and hydrophilic surfaces have also been calculated using MD by Tenney and Cygan . As for dynamic contact angles, a few experiments studying supercritical CO 2 –water displacement have been reported in the literature. , To our knowledge, there has been no investigation of the effect of flow rates on dynamic contact angles for the CO 2 –water–silica system at the nanoscale. The behavior of the contact angle at different contact line velocities can directly affect the calculation of the capillary pressure based on the Young–Laplace equation.…”

Pore-Scale Dynamics of Liquid CO2–Water Displacement in 2D Axisymmetric Porous Micromodels Under Strong Drainage and Weak Imbibition Conditions: High-Speed μPIV Measurements

“…The static contact angle of water on the modified surfaces was measured to be ∼ 120 • . It is worth noting that during dynamic flow processes, what is most relevant is the dynamic contact angle (Sedev et al, 1993;Jafari and Jung, 2017). Figure 2 presents in-situ measurements of the contact angles under dynamic flow conditions in a baseline hydrophilic micromodel (Figure 2A), and a modified hydrophobic micromodel (Figure 2B), confirming that the receding contact angles are ∼ 9 • and ∼ 98 • for the former and latter cases, respectively.…”