TY - JOUR
T1 - Effect of humic acid on CO2-wettability in sandstone formation
AU - Ali, Mujahid
AU - Awan, Faisal Ur Rahman
AU - Ali, Muhammad
AU - Al-Yaseri, Ahmed
AU - Arif, Muhammad
AU - Sánchez-Román, Mónica
AU - Keshavarz, Alireza
AU - Iglauer, Stefan
N1 - Funding Information:
The authors would like to acknowledge the ECU-HEC Joint Scholarship – 2018 for their support.
Publisher Copyright:
© 2020 Elsevier Inc.
PY - 2021/4/15
Y1 - 2021/4/15
N2 - Hypothesis: Millions of tons of CO2 are stored in CO2 geological storage (CGS) formations (depleted oil reservoirs and deep saline aquifers) every year. These CGS formations naturally contain small concentrations of water-soluble organic components in particular humic acid (HA), which may drastically affect the rock wettability - a significant factor determining storage capacities and containment security. Hence, it is essential to characterise the effect of humic acid concentration on CO2-wettability and its associated impact on storage capacity. Experimental: To achieve this, we measured advancing and receding contact angles at reservoir conditions using the pendant drop tilted plate method for various humic acid concentrations (1, 10, and 100 mg/L) as a function of pressure (0.1–25 MPa), temperature (303–333 K), and brine salinity (0–0.3 M NaCl). Further, the influence of humic acid adsorption on the mineral's surface was examined by several independent techniques. Results: Our results demonstrate that humic acid significantly changes rock wettability from water-wet (0–50°) towards CO2-wet (90–110°). An increase in pressure, temperature, and salinity had a similar effect. Humic acid adsorption also increased the surface roughness of the substrates. We conclude that even trace amounts of humic acid (i.e. 1 mg/L), which exist in storage aquifers, significantly increase CO2-wettability and thus reduce structural and residual trapping capacities. Therefore, it is pertinent to account for these humic acid concentrations to de-risk CGS projects.
AB - Hypothesis: Millions of tons of CO2 are stored in CO2 geological storage (CGS) formations (depleted oil reservoirs and deep saline aquifers) every year. These CGS formations naturally contain small concentrations of water-soluble organic components in particular humic acid (HA), which may drastically affect the rock wettability - a significant factor determining storage capacities and containment security. Hence, it is essential to characterise the effect of humic acid concentration on CO2-wettability and its associated impact on storage capacity. Experimental: To achieve this, we measured advancing and receding contact angles at reservoir conditions using the pendant drop tilted plate method for various humic acid concentrations (1, 10, and 100 mg/L) as a function of pressure (0.1–25 MPa), temperature (303–333 K), and brine salinity (0–0.3 M NaCl). Further, the influence of humic acid adsorption on the mineral's surface was examined by several independent techniques. Results: Our results demonstrate that humic acid significantly changes rock wettability from water-wet (0–50°) towards CO2-wet (90–110°). An increase in pressure, temperature, and salinity had a similar effect. Humic acid adsorption also increased the surface roughness of the substrates. We conclude that even trace amounts of humic acid (i.e. 1 mg/L), which exist in storage aquifers, significantly increase CO2-wettability and thus reduce structural and residual trapping capacities. Therefore, it is pertinent to account for these humic acid concentrations to de-risk CGS projects.
KW - CO Storage
KW - EOR
KW - Humic Acid
KW - Organic Acids
KW - Trapping Capacities
KW - Wettability
UR - http://www.scopus.com/inward/record.url?scp=85098991290&partnerID=8YFLogxK
U2 - 10.1016/j.jcis.2020.12.058
DO - 10.1016/j.jcis.2020.12.058
M3 - Article
C2 - 33412352
AN - SCOPUS:85098991290
SN - 0021-9797
VL - 588
SP - 315
EP - 325
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
ER -