Experimental study on response law of permeability of coal to acidification

Acidification method is an important mean in oil and gas wells for increasing production. Small scale acidifi- cation measure can greatly enhance the hydrocarbon production capacity. This has important enlightenment on the ca- pacity of coal-bed methane wells productivity improvement. Through the indoor experiment to determine the acid disso- lution rate of pulverized coal and coal core permeability variation,the analysis of the acid effect on coal reservoir per- meability change rule was conducted. The results showed that the original fracture development in coal reservoir and mineral composition have a significant effect on permeability. Acidification method can effectively improve the permea- bility of coal seam with about 18. 42 times improvement. The mass fraction of acid at 12% -15% is the best concentra- tion. The long time of acidification will cause the decrease of permeability,and thus the control response time is about 12 hours.