Study of coal gas wettability for CO2 storage and CH4 recovery. Issue 3 (14th March 2014)

• Record Type: Journal Article
• Authors: Saghafi, A.; Javanmard, H.; Pinetown, K.
• Is Part Of: Geofluids. Volume 14:Issue 3(2014:Aug.)
• Page Start: 310
• Page End: 325
• Publication Date: 2014-03-14
• Subjects: Hydrogeology -- Periodicals; Sedimentary basins -- Periodicals; Fluids -- Migration -- Periodicals; Groundwater flow -- Periodicals; Geothermal resources -- Periodicals; Fluid dynamics -- Periodicals; Earth -- Crust -- Periodicals; 551.49
• DOI: 10.1111/gfl.12078
• Languages: English
• ISSNs: 1468-8115

Abstract

<abstract abstract-type="main" id="gfl12078-abs-0001"> <title>Abstract</title> <p>To quantify and rank gas wettability of coal as a key parameter affecting the extent of CO<sub>2</sub> sequestration in coal and CH<sub>4</sub> recovery from coal, we developed a contact angle measuring system based on a captive gas bubble technique. We used this system to study the gas wetting properties of an Australian coal from the Sydney Basin. Gas bubbles were generated and captivated beneath a coal sample within a distilled water‐filled (pH 5.7) pressurised cell. Because of the use of distilled water, and the continuous dissolution and shrinkage of the gas bubble in water during measurement, the contact angles measured correspond to a 'transient receding' contact angle. To take into account the mixed‐gas nature (CO<sub>2</sub>, CH<sub>4</sub>, and to a lesser extent N<sub>2</sub>) of coal seam gas in the basin, we evaluated the relative wettability of coal by CH<sub>4</sub>, CO<sub>2</sub> and N<sub>2</sub> gases in the presence of water. Measurements were taken at various pressures of up to 15 MPa for CH<sub>4</sub> and N<sub>2</sub>, and up to 6 MPa for CO<sub>2</sub> at a constant temperature of 22°C. Overall, our results show that CO<sub>2</sub> wets coal more extensively than CH<sub>4</sub>, which in turn wets coal slightly more than N<sub>2</sub>. Moreover, the contact angle reduces as the pressure increases, and becomes < 90° at various pressures depending on the gas type. In other words, all three gases wet coal better than water under sufficiently high pressure.</p> </abstract>