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Wettability Determination of HVBB Coal – Water System with Injection of Model Flue Gas and CO2
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 73rd EAGE Conference and Exhibition incorporating SPE EUROPEC 2011, May 2011, cp-238-00020
- ISBN: 978-90-73834-12-5
Abstract
Geological sequestration of carbon dioxide (CO2) in coal is one possible method to sequester CO2. CO2 or flue-gas injection into coal layers provides the dual benefits of enhancing coal-bed methane production (ECBM) and sequestering CO2. The success of this combined process depends strongly on the wetting behavior of the coal as a function of coal rank and roughness, system pressure and temperature, and also the composition of the gas. The wetting behavior can be evaluated from the contact angle of a gas bubble on the coal surface. In this study, we determine contact angles of a model flue gas (80/20 N2/ CO2 mixture) and pure CO2on a wet Warndt Luisenthal coal (WL), representing a high volatile bituminous coal (hvbB coal). Experiments were performed in the pressure range between 0 and 150 bar using a modified pendant drop cell at a constant temperature of 318 K. In general, contact angles of flue gas on WL coal are smaller than of CO2 on WL coal. The contact angle of flue gas against water on WL coal changes from water-wet to intermediate-wet with increasing pressure. With CO2 injection the wettability of WL coal becomes gas-wet for pressures above 90 bar.