| Wettability refers to a phenomenon of solid interface changes from solid-gas interfaces to solid-liquid interfaces. It is usually measured by solid-liquid contact angle. This papr analyzes the wetting characteristics of Binchang, Shang Gaozhai and Sihe, which standforlow-medium-high three types of rank coals.Study on effect of wettability on moisture content of coal. According to three areas of coal samples with different moistur eadsorption/desorption experiments. Description coal wettability effect on the adsorption/desorption of coalbed methane.The contact angle of coal-water interface increases with increasing metamorphic grade of coal, decreases with the increase of coal ash.We can use surfactant change liquid surface tension, and change the interface of coal and liquid contact angle. By comparing multiple surfactants we can found that alkanolarnide 6501 have best results in reducing coal-water contact angle.When the wettability changes for the better the moisture content of coal will appropriate increase. Water molecules on surface of coal could be competitive with CH4 in adsorption. Reducing coalbed methane adsorption amount and absorption capacity will be bad for coalbed methane adsorption. When the wettability changes for the better wetting heat will increase. Wetting heat will be appropriate to supply the energy of coal bed methane desorption, and promote coalbed methane desorption.When coalbed methane wells drainage to relieve pressure, coalbed water mainly through microfractures and partial pore flow to the wellbore, capillary forces are the main drag. Same pore radius of wettability in coal pores haverelatively small capillary forces. It is benefit for coalbed water discharged and the expansion of pressure drop funnel. We can use surfactants reduce the surface tension in water and coal-water contact angle,to improve drainage efficiency and expanding pressure drop funnel. And improve the capacity of coalbed methane wells. |
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