Experimental Study On Water Injection With Adding Surfactant To Displace Coal Seam Gas

On the basis of analyzing displacement gas with water injection technology research at home and abroad,and based on the experimental device independently developed about displacement gas of coal seam with water injection, the experiment of displacement gas with pure water and surface active agent injection is done. Regularity and mechanism of displacement gas with water injection in condition of different degree of coal sample, different water injection pressure and gas adsorption equilibrium pressure is researched.Combination with pore distribution determined by Mercury injection experiment、Contact Angle and surface tension determined by Contact Angle meter,to explore relationship between pore structure and capillary force parameters. Using laboratory experiments, theoretical analysis and field test, and combining with adding surfactant and capillary force on the pure water in the water flooding displacement gas injection effect, systematically reveals the influence mechanism.The experimental results show that: Adding surfactants aqueous solution can effectively reduce the surface tension, increase the penetration of aqueous solution its effect on displacing gas is more obvious than pure water. With the increase of injection pressure, aqueous solution infiltration to the critical measure of coal sample decreases, can effective displace gas in smaller aperture, Through the study of the pore distribution of coal samples before and after water injection, found that water injection effectively expand the pore structure of coal, coal samples of total entrance increased by 10.9% ~ 14.5%. Aqueous solution of gas displacement mechanism is embodied in three aspects: driven in large aperture, imbibition displacement in small aperture and competitive adsorption in microporous.