深煤层井组 CO2 注入提高采收率关键参数模拟和试验.

CO2-ECBM technology in deep coal seam is that CO2 can replace more CH4 and be buried in a long-term because of its strong adsorption effect. Experimental analysis in northern Shizhuang shows that the CO2 adsorption capacity is two times of CH4. With desorption pressure decrease, CH4 has higher desorption speed than CO2 so that it can be displaced effectively. CO2 injection causes the change of the physical property of coal reservoir, mainly refers to permeability variation caused by matrix shrinkage and swelling during CO2 adsorption and desorption, and the permeability decreases at first and increases rapidly with the decrease of pressure. By applying the permeability change rule, the geological model and numerical model were established. The influences of CO2 injection quantity, frequency and injection mode on the yield, recovery ratio and CO2 burial of the well group or single well were analyzed. The simulation results show that the gas recovery increases after two years CO2 injection with the injection rules such as the injection rate of 10-15 tons per day, continuous injection for 90 days, closing well for 90 days. Field test indicates that the CO2 adsorption capacity of No.3 coal seam is 8 tons/day.The group well burial potential is about 12 616 t. [ABSTRACT FROM AUTHOR]