CO₂–Brine Contact Angle Measurements on Navajo, Nugget, Bentheimer, Bandera Brown, Berea, and Mt. Simon Sandstones

Abstract

In this study, contact angles were measured for CO2 bubbles on six different sandstones (Navajo, Nugget, Bentheimer, Bandera Brown, Berea, and Mt. Simon) that could potentially represent properties of CO2 storage depositional environments. The impacts of pressure and temperature were studied by focusing on the CO2 phase behavior in three different scenarios: gaseous, liquid, and supercritical conditions. Despite controlling the sample preparation and cleanliness, CO2–brine equilibration conditions, and pressure and temperature, there were inconsistencies in contact angle trends that could largely be attributed to natural sample heterogeneity resulting from localized variations in topography, surface roughness, and mineral composition across the surface. Despite these variations, the analysis of 298 measurements from this study showed that 81% of the contact angles were <40°, representing strongly water-wet to (moderately) water-wet behaviors. Also, 17.3% of the measurements were between 40° and 60° (weakly water-wet) and primarily belonged to small CO2 bubbles (<500 μm) that were heavily impacted by localized surface heterogeneity in natural sandstone samples. In addition, only 1.7% of the measurements had angles greater than 60° and could be classified as no longer water-wet, but these measurements occurred on extremely small bubbles (100–200 μm) that were very dependent on localized surface heterogeneity. While some of the detailed physics of the CO2/brine/sandstone interface is still poorly understood, from an application standpoint, the sandstones of this study were best characterized as strongly water-wet to (moderately) water-wet.

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“…One of the shale chips was aged in Eagle Ford oil for 2 weeks and one was not aged. The two chips were placed on the sample holder in a customized windowed Hastelloy high-pressure, high-temperature cell, which has been described in a previous publication (Figure C) . Eagle Ford oil (3 mL) was added to the bottom of the cell, below the sample holder The cell was pressurized with CO 2 (41 g) to 6.9 MPa, and then, the cell was heated to 80 °C.…”

The Hole Sealing Technology of Solid–Liquid Materials with Three Pluggings and Two Injections for Gas Extraction Hole in the Coal Mine

“…In turn, the contact angle between sealing grout with (without) modifier and different coal rock was tested. 41 3.2.3. Hole Sealing Quality Test.…”

“…When the droplet stays on the surface of the sample for 5–10 s, the sealing slurry hanging on the sample can be captured by an optical system, and then the contact angle between the droplet and the sample can be calculated through image analysis software. In turn, the contact angle between sealing grout with (without) modifier and different coal rock was tested …”