Electrostatic Origins of CO2-Increased Hydrophilicity in Carbonate Reservoirs
Scientific Reports , Volume 8; doi:10.1038/s41598-018-35878-3
Abstract: Injecting CO2 into oil reservoirs appears to be cost-effective and environmentally friendly due to decreasing the use of chemicals and cutting back on the greenhouse gas emission released. However, there is a pressing need for new algorithms to characterize oil/brine/rock system wettability, thus better predict and manage CO2 geological storage and enhanced oil recovery in oil reservoirs. We coupled surface complexation/CO2 and calcite dissolution model, and accurately predicted measured oil-on-calcite contact angles in NaCl and CaCl2 solutions with and without CO2. Contact angles decreased in carbonated water indicating increased hydrophilicity under carbonation. Lowered salinity increased hydrophilicity as did Ca2+. Hydrophilicity correlates with independently calculated oil-calcite electrostatic bridging. The link between the two may be used to better implement CO2 EOR in fields.
Keywords: Greenhouse gas emission / model / Electrostatic / CO2 / calcite / oil / Hydrophilicity in Carbonate / increased hydrophilicity under carbonation
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