Capillary Pressure–Saturation Relations for Supercritical CO ₂ and Brine in Limestone/Dolomite Sands: Implications for Geologic Carbon Sequestration in Carbonate Reservoirs

Journal Article · Mon Jun 01 00:00:00 EDT 2015 · Environmental Science and Technology

DOI:https://doi.org/10.1021/acs.est.5b00826· OSTI ID:1183244

Wang, Shibo ^[1]; Tokunaga, Tetsu K. ^[1]

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1. Earth Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States

In geologic carbon sequestration, capillary pressure (P_c)–saturation (S_w) relations are needed to predict reservoir processes. Capillarity and its hysteresis have been extensively studied in oil–water and gas–water systems, but few measurements have been reported for supercritical (sc) CO₂–water. Here, P_c–S_w relations of scCO₂ displacing brine (drainage), and brine rewetting (imbibition) were studied to understand CO₂ transport and trapping behavior under reservoir conditions. Hysteretic drainage and imbibition P_c–S_w curves were measured in limestone sands at 45 °C under elevated pressures (8.5 and 12.0 MPa) for scCO₂–brine, and in limestone and dolomite sands at 23 °C (0.1 MPa) for air–brine using a new computer programmed porous plate apparatus. scCO₂–brine drainage and imbibition curves shifted to lower P_c relative to predictions based on interfacial tension, and therefore deviated from capillary scaling predictions for hydrophilic interactions. Fitting universal scaled drainage and imbibition curves show that wettability alteration resulted from scCO₂ exposure over the course of months-long experiments. Residual trapping of the nonwetting phases was determined at P_c = 0 during imbibition. Amounts of trapped scCO₂ were significantly larger than for those for air, and increased with pressure (depth), initial scCO₂ saturation, and time. These results have important implications for scCO₂ distribution, trapping, and leakage potential.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Center for Nanoscale Control of Geologic CO2 (NCGC)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1183244
• Alternate ID(s): OSTI ID: 1386022
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Vol. 49 Journal Issue: 12; ISSN 0013-936X
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
Bio-inspired
Mechanical behavior
Carbon sequestration
Saturation
Atmospheric chemistry
Wetting
Hysteresis
Fluids